IMPORTANT The Abstracts contained in this Book of Abstracts are the Preliminary abstracts supplied by the authors and are only provided to assist you with choosing the presentations you wish to attend at the Symposium. Abstract Titles and/or text may have changed slightly and if so will be included with the final papers in the Symposium Proceedings. Please select the presentations you wish to attend prior to attending the symposium as the Book of Abstracts will not be provided as a handout and will only be available to view at the registration desk
IGNSS 2013 Book of Abstracts For Oral and Poster Presentations
www.ignss.org
Oral Presentations Abstracts – Tuesday 16 July, 2013 Session 1: Plenary Session 0900-1030 What does the Multi-GNSS Era Mean for Australia and the Region? Welcome Address - Capitalising on Australia's Unique Geopolitical Advantage in the Multi-GNSS Era Matthew B Higgins President of the IGNSS Society Manager Geodesy and Positioning, Department of Natural Resources and Mines, Queensland Australia Telephone: +61 7 389 63754 Facsimile: +61 7 3896 3697 Email: matt.higgins@qld.gov.au
ABSTRACT This presentation will commence with an overview of the IGNSS Symposium, with particular attention to the Plenary Sessions designed to address important issues for Australian GNSS users. It will then go on to outline recent work on the development of a GNSS Strategic Plan for Australia and its identification of some issues specific to Australia as we enter the Multi-GNSS era. The presentation will examine in detail a specific finding in the Strategic Plan related to how Australia can capitalise on its unique geopolitical advantages as a developed economy with a sophisticated GNSS user base. Those advantages stem from the fact that Australia will have access to the two regional navigation satellite systems being developed by Japan and India in addition to the 4 global systems from China, Europe, Russia and the United States of America. KEYWORDS: Australian GNSS Users, Geopolitical Advantages, GNSS Strategic Plan, GNSS,
RNSS.
Ensuring There is Leadership for the Australian GNSS Community Joe Andrews, Space Coordination Office, CANBERRA, AUSTRALIA
Abstract Not Provided
Adopting a Whole-of-Nation Approach to a Sustainable, Multi-GNSS Enabled National Positioning Infrastructure Dr John Dawson, Geoscience Australia, CANBERRA, AUSTRALIA
Abstract not provided
Session 2:
Plenary Session
1100-1230
Presentations from the GNSS System Providers giving updates on their systems and comments on their perspective on the issues raised in Session 1 Plenary
U.S. GPS Policy, Program and International Update Jeffrey Auerbach Office of Space and Advanced Technology, Department of State, United States Phone: 1 202 663 2388 Fax: 1 202 663 2402 Email: auerbachjm@state.gov
ABSTRACT This presentation provides an update on the status of United States (U.S.) Global Positioning System (GPS) policy and program, including its augmentation systems. The 2010 U.S. National Space Policy provides guidance to achieve the space-based position navigation and timing goal of maintaining leadership in the service, provision, and use of Global Navigation Satellite Systems. A key component includes the continued effort to achieve compatible and interoperable systems throughout the world. The primary means for accomplishing this is through bilateral and multilateral discussions and forums. The U.S. also continues to modernize the GPS and its augmentation systems, providing new capabilities in an effort to provide the highest level of service to users around the world. The U.S. performance commitment for civil service use of the GPS has been met continuously since December 1993. KEYWORDS: GPS, Compatibility, Interoperability
GLONASS Government Policy, Status and Modernization Plans Tatiana Mirgorodskaya Information and Analysis Center for PNT/Central Research Institute of Machine Building/Roscosmos/Russian Federation Tel.: +7 495 513 4882; Fax: +7 495 513 4139; e-mail: tatyana.mirgorodskaya@glonass-iac.ru
Sergey Revnivykh Information and Analysis Center for PNT/Central Research Institute of Machine Building/Roscosmos/Russian Federation Tel./Fax: +7 495 513 4139; e-mail: sergey.revnivykh@glonass-iac.ru
ABSTRACT The presentation will focus on programmatic issues, current status, performance and modernization of GLONASS system. It will cover the background principles of the government policy behind GLONASS Program implementation. GLONASS deployment phase is complete and the GLONASS Sustainment, Development and Utilization Program is under way bringing new opportunities to the users and new challenges to the Russian Government. The presentation will give some review of the modernization efforts currently under way with respect to space and ground segments, signals, augmentations and applications. The information on GLONASS performance evolution in terms of availability and accuracy will be provided followed by the outline of system modernization plans with the view of increasing that performance. The presentation will also include a brief summary of the System of Differential Corrections and Monitoring which is considered as a constituent part of GLONASS. With the increasing role of GLONASS as the operating GNSS in the multi-GNSS infrastructure
Russia's cooperation with other GNSS providers will become more important in terms of providing greater interoperability between existing and emerging systems. The presentation will address international activities of Russian Federation in the field of GNSS and space-based PNT. KEYWORDS: GLONASS, SDCM, CDMA signals, interoperability, international cooperation.
Positioning Performance of BeiDou Navigation Satellite System Qile Zhao GNSS Research Center, Wuhan University, China Phone:0086-27-68778240 Fax:0086-27-68778971 Email: zhaoql@whu.edu.cn
ABSTRACT Following the general guideline of starting with regional services and then expanding to global services, the BeiDou System is steadily accelerating the construction. By the end of 2012, the BeiDou System already consists of fourteen networking satellites, including five GEO satellites, five IGSO satellites, and four MEO satellites, and owns full operational capability for China and its surrounding areas. The positioning performance of current BDS (with 5GEO+5IGSO+4MEO satellites) from January to June of 2013 is introduced in this presentation. In China and its surrounding area, the positioning accuracy using BDS opening service is about 10 meters in both horizontal and vertical direction. Some high precise applications using Net RTK and PPP method are also shown in this contribution. From the results we know that users can get high precise service using BDS only, and both BDS and GPS users can be benefitted from combination of the two systems. KEYWORDS: BDS, GPS, Positioning performance, PPP, Net RTK.
Session 3:
Plenary Session
1330-1530
GNSS System Providers and the Key Issues for Australia and the Region (continued)
Current Status of Quasi-Zenith Satellite System Mr Eigo Nomura Counselor for Office of National Space Policy, Cabinet Office, Government of Japan
Abstract Not Provided
Information Centres of the International Committee on Global Navigation Satellite Systems Sharafat Gadimova Office for Outer Space Affairs/United Nations Office at Vienna/Austria +43 1 260605479/+43 1 260605830/sharafat.gadimova@unvienna.org
ABSTRACT Efforts to build capacity in space science and technology are considered a major focus of the Office for Outer Space Affairs and are of specific interest to the International Committee on Global Navigation Satellite Systems (ICG) with particular reference to global navigation satellite systems (GNSS). Such efforts should aim to provide support to the regional centres for space science and technology education affiliated to the United Nations (http://www.unoosa.org/oosa/en/SAP/centres/index.html), which would also act as information centres for ICG. The ICG Executive Secretariat and GNSS providers see two areas where they can assist the process of the development and progress towards the further development and progress towards the further development of ICG Information Centres: (1) the technical level, which will include various GNSS technologies, and (2) the cooperative level with possible collaboration with industry leaders and linkages with current and planned system and augmentation system providers. Linkages would be facilitated through collaboration with the ICG Providers’ Forum (seminars/trainings and supportive materials), as well as communication and outreach to the wider community through the ICG information portal, mailing lists, brochures and newsletter. KEYWORDS: ICG, GNSS, information centres.
Session 4:
Plenary Session The Reliance of Key Industries on GNSS
1600-1730
GNSS Use and Reliance in the Agricultural Industries Tim Neale PrecisionAgriculture.com.au Mobile: +61428157208, tim@precisionagriculture.com.au
ABSTRACT Agriculture has benefited greatly from the proliferation of GNSS technology. Australia has been leading the world in high precision GPS since the 1990’s, following the development of the autosteer guidance technology for tractors. Since then we have seen developments in GNSS access, advances in software and hardware, improved RTK performance, and CORS networks covering large areas. Tractors, sprayers, seeders, and harvesters can now be steered hands free for a relatively low cost. Autosteer systems have dropped from around $120,000 per unit in the late 1990’s, to around $25,000 per unit today. We have seen a rationalisation in the number of dominant manufactures in recent years from around eight to two. Not only does agriculture rely on high precision guidance for machinery auto-steering, but a wide range of applications use lower accuracy GNSS such as farm mapping, variable rate control, and yield mapping. These systems can autonomous GNSS successfully due to selective availability being turned off. Our adoption rates are almost certainly to be the highest of anywhere in the world, where 80% of crop farmers in a recent study claim they use autosteer, and 30% create yield maps using GNSS. There are around 42,000 crop farmers in Australia, which means that there could be in excess of 30,000 GNSS systems in use for autosteer, and 12,000 used in grain harvesters, if the study results were extrapolated. Robotics, drones (UAV’s), and machine control are also emerging in Agriculture; all of which rely on GNSS. KEYWORDS: Precision Agriculture, Farming, Autosteer, Guidance.
CORS RTK Corrections for Construction Projects – Status, Benefits and What’s Next? Martin Nix CEO Position Partners Pty. Ltd. Australia Phone: +61 2 9898 0066 Fax: +612 9898 0700 email: mnix@positionpartners.com.au
ABSTRACT It is almost 5 years since the release of the recommendation of the Allen Consulting Report on the Economic Benefits of High Resolution GNSS to establish a standardized nationwide CORS infrastructure. The construction industry, as one of 3 key industries studied in the report, is expected to gain between $6 and $10 billion in productivity benefits between 2008 and 2030 from a standardized national CORS network. The paper reviews the progress of CORS infrastructure and the use of CORS derived RTK corrections in the construction industry in the last 5 years. Practical examples of projects using the CORS delivered RTK versus other methods are compared for a cost benefit comment. The construction applications examined are GNSS machine control and tracking, GNSS surveying and new developments using GNSS technology such as UAV mapping, mobile scanning and collision avoidance, Technical and commercial barriers to further adoption of CORS derived RTK corrections remain. Yet, trends are uncovered that indicate future adoption rates are likely to increase. It is concluded that there are many technical, commercial and organizational issues to solve before the economic benefits of the Allen report are achieved for the construction industry. KEYWORDS: CORS. Machine Control, RTK corrections, AllDayRTK, construction.
Maritime Application of GNSS and the Need for Resilient PNT Capt. Mustafa Ali Australian Maritime Safety Authority P +61 (0)2 6279 5018, F +61 (0)2 6279 5966, mustafa.ali@amsa.gov.au
ABSTRACT International shipping carries more than ninety percent of global trade and relies almost entirely on Global Navigation Satellite System (GNSS) for Position, Navigation and Timing (PNT) information. GNSS has now become the primary means by which ships determine their positions. And PNT information from GNSS is vital input for shipboard devices such as Automatic Identification System (AIS), Electronic Chart Display and Information Systems (ECDIS), Global Maritime Distress and Safety System (GMDSS), Long Range Identification and Tracking (LRIT) and Dynamic Positioning (DP) systems. In turn, AIS information can be used by coastal states to fulfil a range of their obligations. In recent years, the development of new shipboard navigation technologies has been rapid. In order to better integrate new and existing navigational aids and enhance berth-to-berth navigation, the International Maritime Organization (IMO) is leading the development of an “e-navigation” concept. One of the central pillars of e-navigation is resilient PNT. Although the ubiquity of GNSS makes it a prime provider of PNT information for several e-navigation applications, the vulnerability of GNSS is a source of concern. Space and ground segment failures, atmospheric disturbances and unintentional and intentional interference can all impact on the performance of GNSS. IMO’s work on e-navigation has highlighted the importance of resilient PNT systems and has recognised that despite a growing number of satellite systems, they all suffer from a single mode of failure. Amongst the various alternatives mooted for PNT services, terrestrial solutions can be considered and further developed for maritime use. Such solutions should, as far as practicable, be applicable globally and not result in regional differentiation. A practical and achievable solution to mitigate the potential effects of GNSS vulnerabilities is important to ensure the safe navigation of ships in confined waters, environmentally sensitive areas and for the operations of the offshore oil and gas industry.
Oral Presentations Abstracts – Wednesday 17 July, 2013 Session 5:
Plenary Session Cooperative Intelligent Transport Systems and GNSS
0900-1040
Establishing a Framework for Cooperative Intelligent Transport Systems Dennis Walsh Department of Transport and Main Roads, Queensland, Australia P: +61 7 3066 8543, E: dennis.j.walsh@tmr.qld.gov.au
Stuart Ballingall Austroads, Australia P: +61 3 9229 6095, E: stuart.ballingall@roads.vic.gov.au
ABSTRACT Cooperative Intelligent Transport Systems (C-ITS) refers to a ubiquitous ecosystem in which vehicles will receive and share data wirelessly with other vehicles and roadside units. This will enable a range of emerging applications aimed at improving safety, efficiency and environmental outcomes from our land transport network. Also referred to as ‘connected vehicles’, C-ITS will use a combination of technologies including Dedicated Short Range Communications (DSRC), cellular networks, Global Navigation Satellite Systems (GNSS) and enhanced digital road maps. Significant technical developments are continuing internationally, including efforts to globally harmonise standards and processes. Progress has also been made with regulations and policies to support the deployment of C-ITS, particularly in Europe, the USA and Japan. Based on the status and planning of international C-ITS initiatives, it is expected that C-ITS enabled vehicles will be introduced to global markets from 2015. Austroads is taking a lead role in establishing a regulatory and operational framework that will enable C-ITS deployment in Australia. The required C-ITS framework will cover policy and regulation, spectrum management, technical standards, platform requirements and operational arrangements. To ensure the local C-ITS framework achieves the required interoperability, market access, and optimised transport outcomes, it is critical that it is harmonised with international standards and best practices where possible. KEYWORDS: Cooperative Intelligent Transport Systems (C-ITS), Connected Vehicles, Vehicle Positioning, Operational Framework, Regulatory Framework
GNSS Positioning Requirements for Cooperative Intelligent Transport Systems Matthew B Higgins (1) President of the IGNSS Society Manager Geodesy and Positioning, Department of Natural Resources and Mines, Brisbane, Australia Telephone: +61 7 389 63754 Facsimile: +61 7 3896 3697 Email: matt.higgins@qld.gov.au
Yanming Feng (2) Professor, Science and Engineering Faculty, Queensland University of Technology, Brisbane, Australia Telephone: +61 7 3138 1926 Facsimile: +61 7 3138 9390 Email: y.feng@qut.edu.au
ABSTRACT
Cooperative Intelligent Transport Systems (C-ITS) represent a very demanding suite of emerging application for precise positioning. This presentation will outline work undertaken recently for Austroads (via the Australian Roads Research Board) on the technical background and analysis of positioning requirements for C-ITS. Potential C-ITS applications range from simple alerts for a driver about problems on the road ahead to sophisticated automatic collision avoidance systems. A key piece of the work therefore was to develop a framework that can be used for characterising and describing the positioning requirements across that range of C-ITS applications. One example is the need to differentiate requirements across three positioning accuracy levels that we characterise as metre (for road-level positioning), sub metre (for lane-level) and decimetre (for where-in-lane-level). The work also examined issues such as the variation in timeliness requirements and found that road-level applications can typically tolerate about one second (1 Hz), while for lane-level and where-in-lane-level applications it is 0.1 second (10 Hz). The research also defined and then examined critical issues for a number of other vehicle positioning performance requirements such as continuity, availability, integrity and interoperability. Another important aspect of the work was to identify the need for the road transport sector to work more closely with other key sectors of positioning users to ensure that C-ITS requirements are factored into planning of initiatives like the National Positioning Infrastructure Plan and possible future Space Based Augmentations for GNSS users in Australia. KEYWORDS: Cooperative Intelligent Transport Systems C-ITS, GNSS, positioning requirements, accuracy, timeliness, continuity, availability, integrity, interoperability.
Technological Limits to Positioning Accuracy for C-ITS Andrew G Dempster Australian Centre for Space Engineering Research, School of Electrical Engineering and Telecommunications, University of New South Wales Ph: +61 2 93856890, a.dempster@unsw.edu.au
ABSTRACT Requirements and applications of Cooperative Intelligent Transport Systems (C-ITS) are becoming better defined. It is important that any assumptions regarding the accuracy, availability and integrity of positions used in C-ITS are well founded. This presentation examines the use of Dedicated Short-Range Communications (DSRC), the IEEE 802.11p standard operating at 5.9 GHz, to aid in delivering C-ITS goals. For the positioning requirements of C-ITS, DSRC can be used as a communications medium alone (i.e. reporting), as an enabler of vehicle ad-hoc networks – VANETs (using localisation techniques), or as a source of raw measurements for use in the position solution. The latter two can be considered separately and together as methods of improving positioning over, say, GPS. However, there are limits to the extra accuracy offered by these techniques, so it is possible that DSRC does not bring sufficient extra capability to support all of the C-ITS applications. KEYWORDS: Up to 5 key words in 11pt Times New Roman font, separated by commas; these will assist in the cross-indexing of the paper. Leave two line spaces before the Introduction below.
Session 6A:
Chinese SatNav
1110-1250
The BeiDou Navigation Message Oliver Montenbruck DLR, German Space Operations Center, Germany Phone +49(8153)28-1195, fax -1450, oliver.montenbruck@dlr.de
Peter Steigenberger Technische Universität München, Germany steigenberger@bv.tum.de
ABSTRACT With the disclosure of a public signal ICD in late Dec. 2012, worldwide users can now get access
to the broadcast navigation messages transmitted by the BeiDou satellites and employ them for real-time navigation. Following a summary of the BeiDou navigation message contents, its specific communalities and differences with respect to other GNSS constellations are highlighted. Based on BeiDou navigation data collected in the first quarter of 2013 by various reference stations in Asia, Australia and Europe, the accuracy of the provided orbit and clock information and the resulting impact on the achievable positioning accuracy are assessed. For comparison, precise orbit determination results for BeiDou MEO, GEO, and IGSO satellites are computed from observations of a globally distributed set of BeiDou-capable multi-GNSS monitoring stations of the MGEX and CONGO networks. While users close to the China mainland will generally benefit from a very low ephemeris age, the same cannot be guaranteed for remote regions in view of limited uplink stations. The resulting variation in ephemeris age and quality is evaluated for selected test sites inside and outside the Asia-Pacific region. Further attention is given to signal-specific group delays and their proper consideration in a multi-GNSS positioning solution. The Timing Group Delay parameters provided in the navigation message are compared with values derived from a monitoring stations and a thin layer ionosphere model. KEYWORDS: BeiDou, Broadcast Ephemeris, multi-GNSS positioning, TGD, MGEX
Analysing the Potential Benefits of Adding BeiDou/Compass Satellites to the Trimble CenterPoint RTX Service Herbert Landau, Markus Brandl, Xiaoming Chen, Ralf Drescher, Markus Glocker, Rodrigo Leandro, Markus Nitschke, Dagoberto Salazar, Ulrich Weinbach, Feipeng Zhang Trimble TerraSat GmbH, Germany Phone: +49 8102 7433 0 Fax: +49 8102 7433 131
ABSTRACT The Trimble CenterPoint RTX service provides real-time GNSS positioning with global coverage and fast initialization. The accuracy of kinematic positioning is better than 4 cm in horizontal (95%) at anytime, anywhere. It is achieved after a typical convergence time of 30 minutes or less. The CenterPoint RTX system is based on the generation of precise orbit and clock information for GNSS satellites. The CenterPoint RTX satellite corrections are generated in real time using data streams from approximately 100 globally distributed reference stations of Trimble’s tracking network. Since its introduction in 2011 the system has undergone two major releases in spring 2012 and spring 2013, which included the general performance improvement with respect to convergence time and the introduction of additional services like RangePoint RTX and features like xFill. The Trimble CenterPoint RTX service today supports GPS, GLONASS and QZSS signals. Recently emphasis was put on the evaluation of the possibility to include additional satellite systems into the service. The authors started to research the ability to integrate BeiDou/Compass into the RTX system. Results on the achievable orbit and clock quality for BeiDou satellites are presented using the Trimble CenterPoint RTX tracking network. The benefit of using BeiDou in RTX positioning was analysed and first results are shown using a prototype implementation KEYWORDS: BeiDou, Orbit and clock estimation, Real-time PPP, Trimble CenterPoint RTX
Variance Analysis of Pseudo-Range Noises of GPS and Beidou GNSS Signals Lei Wang Science and Engineer Faculty Queensland University of Technology, Australia (+61) 0416892716 I62.wang@qut.edu.au
Charles Wang Science and Engineer Faculty Queensland University of Technology, Australia (+61) 0410060668 cc.wang@qut.edu.au
Yanming Feng Science and Engineer Faculty Queensland University of Technology, Australia Phone: 07 3138 1926 Fax: 07 3138 9390 email y.feng@qut.edu.au
ABSTRACT Observation weighting strategy is one of the challenging issues in processing of multi-GNSS signals. False or simple variance settings between measurements from two systems can cause degraded navigation solutions instead of improving the solutions. Furthermore, reasonable prior code variance settings between systems and satellites can improve ambiguity resolution and positioning accuracy as well. This paper presented a new code variance estimation method based on time-differenced (TD) observations, which enables real time and single-receiver code variance estimation. The challenge of code variance estimation is how to separate random noise from systematic bias and how to evaluate the variance of random noises objectively. Current prior code variance estimation method relies on single difference observations between two receivers to reduce the effects of systematic biases. This method may perform well in the short baseline or zero baseline scenarios. However, it is not applicable for data processing with zero differenced measurements. The proposed method can eliminate the effects of the major systematic biases in the time differenced code-phase observations. It can estimate the variance components of code measurements over a moving observation window in real time manner, suitable for real time data processing. The experimental results indicate that the time differenced code observation errors can be treated as normally distributed white noises, although the time correlation between undifferenced code noises are of concerns. Code observations from three types of GPS/Beidou receivers collected over many hours are analysed using the proposed approach. The results show that the behaviour of code noises depends on the signal tracking method. Not all code variances generally depend on elevation angle and the code variances for different satellite systems are different as well. Hence, a receive-specified code variance model is generally recommended in the processing of multi-GNSS signals. KEYWORDS: Stochastic model, Multi-GNSS, Variance Estimation, GNSS observables, time correlation
The Current ARAIM Availability According to LPV-200 Using GPS and BeiDou in Western Australia Ahmed El-Mowafy Dept. of Spatial Sciences, Curtin University of Technology Tel: +61892663403, Fax: +61892262703, a.el-mowafy@curtin.edu.au
Balwinder Arora Department of Applied Physics, Curtin Institute of Radio Astronomy, Curtin University of Technology Tel: +61 08 9266 9899, Fax: +61 08 9266 9246, B.arora@postgead.curtin.edu.au
ABSTRACT The Localizer Performance with Vertical guidance at 200 feet (LPV-200) is a set of procedures for aircraft precision approaches down to 200 feet (61 metres). With the modernised GPS and emerging GNSS constellations, it is targeted to globally fulfil requirements of LPV-200 by the years 2020-2025. Fulfilment of LPV-200 with integrity monitoring will support the use of GNSS as a
supplementary/primary means for aircraft navigation. In this investigation, availability of the Advanced Receiver Autonomous Integrity Monitoring (ARAIM) approach will be investigated according to LPV-200 requirements in Western Australia (WA). Two cases will be considered, firstly using GPS alone and secondly when augmenting GPS satellite observations with the current regional BeiDou constellation of 15 satellites. Australia enjoys an excellent location in receiving BeiDou signals, which may help in improving integrity monitoring due to unavailability of traditional SBAS service over Australia that includes integrity information. In this paper, the LPV-200 requirements will first be reviewed. Next, the ARAIM method will be discussed including the airborne error model, satellite integrity failure model, and assumptions on allocations of the different cases of integrity faults using GPS alone. The impact of using BeiDou satellites will be addressed. Assumption on its error model and allocations of probability of integrity faults when integrating BeiDou with GPS will be discussed. The data used in this study were collected at six IGS stations, well-distributed across WA, and are close to main airports in the region. Due to BeiDou data availability, testing of its actual data integrated with GPS was only performed at one site (Perth). Results show that the current GPS constellation alone does not fulfil LPV-200 requirements in WA, with an average ARAIM availability of 99.9% across the study area. However, using GPS with the BeiDou dramatically improves availably of ARAIM. KEYWORDS: Integrity Monitoring, ARAIM, LPV-200, GPS, BeiDou.
Quality Analysis of a Combined COMPASS/BeiDou-2 and GPS RTK Positioning Model Robert Odolinski (1) GNSS Research Centre, Curtin University of Technology, Australia +61 8 9266 3157 & +61 8 9266 2703, email: robert.odolinski@curtin.edu.au
Peter J.G. Teunissen (2) GNSS Research Centre, Curtin University of Technology, Australia, and Delft University of Technology, the Netherlands +61 8 9266 7676 & +61 8 9266 2703, email: P.Teunissen@curtin.edu.au
Dennis Odijk (3) GNSS Research Centre, Curtin University of Technology, Australia +61 8 9266 3157 & +61 8 9266 2703, email: D.Odijk@curtin.edu.au
ABSTRACT The Chinese COMPASS (BeiDou-2) Navigation Satellite System attained initial regional operational status in the end of December 2011, and can provide Positioning, Navigation and Timing (PNT) services in the whole Asia-Pacific region. The COMPASS full constellation is expected by year 2020 with more than 30 satellites, and will provide global coverage. Australia is already a beneficiary of the regional COMPASS system as enough satellites are available for positioning. A combined COMPASS-GPS system increases the redundancy, which allows for higher accuracy and improved integrity. In this contribution we will compare the combined system performance with the COMPASS- and GPS-only systems. The comparisons will be made on measures of precision of the estimated GNSS parameters and their reliability, formally as well as empirically. Reliability is a measure of robustness of the underlying model, and can be categorized into internal and external reliability. Internal reliability concerns the ability of the system to test the observations for modelling errors, and external reliability is referred to as the consequences on the estimated parameters when such model misspecifications are left undetected. Comparisons will involve single-frequency vs. multiple-frequencies. KEYWORDS: COMPASS/BeiDou-2, GPS, RTK, precision, variance matrix, reliability, Minimal Detectable Bias (MDB)
Session 6B
Inertial Navigation System
1110-1250
Zero Velocity Update with Stepwise Smoothing for Inertial Pedestrian Navigation Yan Li Faculty of Engineering and Information Technology, University of Technology, Sydney, Australian (02) 9514 3148 Yan.Li-11@student.uts.edu.au
Jianguo Jack Wang Faculty of Engineering and Information Technology, University of Technology, Sydney, Australian (02) 9514 2634 Jianguo.Wang@uts.edu.au
ABSTRACT Zero velocity update (ZUPT) is an effective way to correct low cost inertial measurement unit (IMU) errors when it is foot-mounted for pedestrian navigation. The stance phase in steps provides zero velocity measurement for inertial sensor error correction. During this integrative and recursive scheme, the errors of estimated position and velocity grow with time rapidly, thus ZUPT applied at each step leads to sharp corrections and discontinuities in the estimated trajectory. Rauch-Tung-Striebel (RTS) smoother is commonly used for bridging GPS outages. RTS is a two pass filter operated in post processing mode which can get an optimal estimate of the filter states. The forward pass runs as a standard Kalman filter but store all the filter states while the backward pass running in a reverse time fashion uses the stored states to compute smoothed states. In this paper, we propose a closed loop RTS smoothing filter, which can achieve near real-time based on a 24 error states extended Kalman filter (EKF). Unlike common RTS smoother, a stepwise backward filter is implemented to eliminate the sharp corrections over the steps. The impact of the near real-time smoothing filter for different step manners (walk and run) is illustrated and analysed. Experimental results show that the proposed method can dramatically improve pedestrian navigation solutions. A prototype is developed for demonstration. The method can also be used in sports and body art etc. researches when precise trajectory of foot movement is required. KEYWORDS: Pedestrian navigation, INS, ZUPT, RTS smoothing.
Implementing Quaternion Based AHRS on a MEMS Multisensor Hardware Platform Gang Sun 1. School of Mechanical Engineering/ Nanjing University of Science and Technology/ China 2. School of Surveying and Geospatial Engineering/ University of New South Wales/ Australia T: 86-025-8431-5471, F: 86-025-8431-5471, E: sg_nj@hotmail.com
Yong Li School of Surveying and Geospatial Engineering/ University of New South Wales/ Australia T: 61-2-9385-4173, F: 61-2-9313-7493, E: yong.li@unsw.edu.au
Jiawei (Steven) Xie School of Surveying and Geospatial Engineering/ University of New South Wales/ Australia T: 61-2-9385-4173, F: 61-2-9313-7493, E: stevenxie@live.cn
Matthew Garratt School of Engineering and Information Technology/ University of New South Wales/ Australia T: 61-2-6268-8267, F: 61-2-6268-8581, E: m.garratt@adfa.edu.au
Changming Wang School of Mechanical Engineering/ Nanjing University of Science and Technology/ China T: 86-025-8431-5471, F: 86-025-8431-5471, E: wangchangming@mail.njust.edu.cn
ABSTRACT
Over the last decade or so micro-electromechanical system (MEMS) technology has been widely used in many navigation applications such as pedestrians, aircraft, land vehicles and robots, because of its advantages in terms of price, accuracy and size. This paper presents a novel lowcost multisensor hardware platform known as “NAVCON�, which is designed for navigation and control of quad-rotor unmanned aerial vehicles. It is a smart board with GPS, MEMS accelerometer and gyroscope, magnetometer, barometer and a rich set of peripheral interfaces. One significant function of this platform on UAV is the attitude and heading reference system (AHRS), which outputs the pitch, roll and yaw in real time to assist the control unit to balance the aircraft or to perform specific actions. But, the low-cost inertial sensors usually have large biases and nonlinear characteristics in their outputs. To correct the errors of the NAVCON, error modelling and calibration are very essential. The general calibration method usually has strict requirements on experimental environment and equipment. For calibrating such low-cost sensors more conveniently, the auto-calibration strategy based on ellipsoid fitting for accelerometer and magnetometer is presented. Test result shows that the auto-calibration strategy can obtain the same accuracy as the traditional method, but it is simpler and more efficient. A quaternion based extended Kalman filter (EKF) is also proposed for implementing the AHRS function on the NAVCON. In addition to the online sensor bias estimation and compensation by EKF, the measurement noise covariance matrix R is set adaptively in consideration of the dynamic disturbance in both accelerometer and magnetometer. Moreover, a new variable monitoring the long term change on magnetic field strength is introduced to improve the robustness of magnetic disturbance detection strategy. In the tests, proposed AHRS algorithm on NAVCON is compared with the Xsens’ AHRS product MTi directly. The result shows a good accuracy. And the improved disturbance detection strategy can identify the body motion and detect the magnetic disturbance correctly. KEYWORDS: MEMS; AHRS; quaternion; EKF; multisensor platform.
Real-time Nonlinear Complementary Observer for Low-cost Inertial Attitude System Dafizal Derawi Malaysia-Japan International Institute of Technology, Universiti Teknologi Malaysia dafizal2@live.utm.my
Jonghyuk Kim Research School of Engineering, The Australian National University jonghyuk.kim@anu.edu.au
ABSTRACT This paper addresses the real-time implementation of a nonlinear complementary attitude observer on a low-cost Inertial Measurement Unit (IMU) system aiming built in-house for small-scale flying robots. We propose a new approach for attitude estimation in real-time system on embedded hardware by using a nonlinear complementary observer on the special orthogonal group of rotation matrices SO(3), rather than conventional Extended Kalman Filter, to exploit the near-global convergence property of the observer. The proposed nonlinear complementary observer combines the positive features of inertial sensors where the gyroscope is used as the main source of shortterm orientation information of the vehicle, whilst accelerometer and magnetometer are used to correct long-term drift error in gyroscope and errors in computations. A los-cost embedded IMU board has been built in-house costing less than $50, aiming for future integration with GPS and vision sensors. The experimental results, both in indoor and outdoor flying environment will be presented showing the proposed system performs reliable real-time attitude estimation with excellent convergence. KEYWORDS: Nonlinear complementary implementation, small-scale flying robots.
observer,
attitude
estimation,
IMU,
real-time
Separability Analysis for Multiple Faults in GNSS/INS Integration Jinling Wang, Youlong Wu and Muwaffaq Alqurashi School of Surveying and Geospatial Engineering University of New South Wales Sydney, NSW 2052
Australia Email: Jinling.Wang@unsw.edu.au Fax: +61 2 9313 7493 ABSTRACT Global Navigation Satellite System (GNSS) sensors have been widely used for many applications to provide position, velocity and timing (PNT) information with high precision. However, under harsh operating environments, due to the signal strength attenuation or even temporary losses of ranging signals especially in urban and vegetative environments, GNSS sensors cannot provide reliable and continuous PNT information at any time. In contrast, without external signals, an Inertial Navigation System (INS) sensor is able to offer a full navigation in terms of position, velocity, and attitude. However, the accuracy of inertial navigation solutions decreases significantly with time. Thus, an integrated GNSS/INS system can overcome the shortcomings of each individual sub-system to improve the availability and reliability of the full navigation solutions for a variety of user platforms in such areas as machine guidance, control, autonomous driving, as well as geospatial mapping. In the integration of GNSS and inertial sensors, any potential sensor failures or faulty measurements due to harsh operating environments or malfunctions of sensor components may result in poorly estimated navigation parameters. If the sensor component failures or faulty measurements occur and cannot be detected immediately, overall system performances will de degraded. Thus, real time detection of failures in estimations system is critically important, particularly for some safety or liability-critical applications. Therefore, it is certainly necessary to implement an online fault detection and isolation (FDI) algorithm. Various approaches of fault detection and isolation have been proposed and implemented, and at the same time, the Minimum Detectable Biases (MDBs) in the GNSS/INS integration and the impact of these MDBs on the estimated navigation parameters can also be defined. However, in order to identify and remove the specific faulty measurements, the system should have the ability to separate these faults. Such fault separability analysis for single fault scenario has been extensively investigated, while the the multiple fault separability analysis is still lacking. The recent studies have shown that, compared with the situation in single fault scenarios, the correlation relationships between the detection/ identification statistics for two groups of multiple faults are quite complicated and relatively less understood. This paper will present the latest separability analysis for multiple fault scenarios within the GNSS/INS integration, which is of importance in developing future robust positioning and navigation systems with the fault detection and isolation procedures. KEY WORDS:, Quality Control, GNSS, INS, Integration, Fault Detection and Isolation
Session 6C
Land Navigation
1110-1250
Performance of GNSS Speed Measurement for Evidentiary Purposes Andriy Dyukov (1) Transport Certification Australia +61 3 8601 4600 andriyd@tca.gov.au
Shaun Talko (2) Transport Certification Australia +61 3 8601 4600 shaunt@tca.gov.au
ABSTRACT
Global Navigation Satellite Systems (GNSS) in particular the Global Positioning System (GPS) are core positioning technologies used in telematics applications. GNSS is being used beyond the traditional positioning, navigation and timing domains and is emerging as a system for determining vehicle speed. However not all GNSS based systems perform equally and the accuracy in determining vehicle speed is not consistent across different telematic platforms especially for evidentiary purposes. Transport Certification Australia (TCA) tests GNSS-based telematics solutions for the performance of speed against national standards to provide users with the consistency and confidence in the reporting of speed. This paper explores the measurement and use of speed based on GNSS. KEYWORDS: Global Navigation Satellite Systems (GNSS); Global Posiitioning System (GPS); Speed; Transport Certification Australia; Regulatory Telematics; evidentiary; certification.
Improving the Low Cost INS/GNSS Solution Using Cooperative Positioning and Robust Dynamic Modelling Techniques Azmir Hasnur Rabiain (1) The University of Melbourne, Australia +614 31729103 azmirhr@unimelb.edu.au
Allison Kealy (2) The University of Melbourne, Australia +613 83446804 a.kealy@unimelb.edu.au
Mark Morelande (3) The University of Melbourne, Australia +613 83444672 mrmore@unimelb.edu.au
ABSTRACT Maintaining the availability of a position solution is a significant challenge for many applications such as intelligent transportation systems (ITS), location based services (LBS) and collision avoidance system. Global Navigation Satellite Systems (GNSS) are the primary technology for meeting positioning requirements for many applications. GNSS enable users to solve for their positions at a global scale but its availability can be limited in urban and other environments where satellite visibility is partially or completely obscured. To provide for continuous positioning, low cost MEMS Inertial Navigation System (INS) can be employed to bridge GNSS gaps. However, MEMS INS are known to produce large errors when GNSS gaps occur over even short time periods (more than 30 seconds for example), to the point that it is meaningless for critical applications such as collision avoidance and hazard warning systems. This paper proposes two techniques to tackle this issue. The first, is by employing the Cooperative Positioning (CP) technique where vehicles within a vehicular ad hoc network (VANET) are able to share relative positioning information which would in turn, improve their positioning solutions. Secondly, this paper presents a new dynamic model for combining GNSS and INS measurements, specifically for land based vehicles. The new model is able to provide better positioning estimates and is computationally less expensive compared to conventional Kalman filter techniques. Datasets obtained from a practical experiment coordinated under the International Association of Geodesy - Commission 4 and the International Federation of Surveyors – Commission 5 have been used to validate the aforementioned techniques. The results indicate the proposed technique outperforms the conventional standalone INS/GNSS integrated system, particularly during long (a few minutes) GNSS outages, which is beneficial particularly in GNSS denied areas. KEYWORDS: INS/GNSS integrated system; Cooperative Positioning; INS Modelling; Ubiquitous Positioning; Land Mobile Applications
Field and Lab Test Results of Vehicle Positioning Systems in Weak GNSS Signals Environments Using a Multi-channel Signal Generator Oliver Michler, Chair of Transport System Information Technology / Full Professor, TU Dresden, Germany oliver.michler@tu-dresden.de, Tel. +4935146336841, Fax. +493514636782
Robert Richter, Chair of Transport System Information Technology / Research Assistant,, TU Dresden, Germany robert.richter@tu-dresden.de, Tel. +4935146336842, Fax. +493514636782
Georg Förster Fraunhofer IVI, Locating, Information and Communication, Dresden georg.foerster@ivi.fraunhofer.de, Tel. +493514640682, Fax. +493514640803
ABSTRACT For international transport systems, vehicle localization based on GNSS is becoming more and more essential. Particularly for the two primary freight transport carriers railway and waterway transport the accuracy of GNSS is sufficient, but for other purposes, such as safety-relevant applications, inner-terminal logistics and digitalization of infrastructures, more sophisticated systems capable of track-sharp locating are necessary. In future, those systems will seamlessly combine GNSS with infrastructure-based localization. If such systems are going to be introduced, one problem will be the need for valid and reliable test and evaluation procedures. It is particularly difficult and extensive to perform reproducible field trials for that. In PiLoNav (Precise and integer Localization and Navigation) – a project funded by the German government – this problem is addressed. It deals with the evaluation of GNSS-based locating systems in the railway and inland shipping sector using a multi-channel radio frequency (RF) signal radio recorder and generator system. This RF-test environment can be used to record or to generate, respectively, various GNSS antenna signals (e.g. GPS, GLONASS, partially Galileo) synchronously. This allows storing characteristic GNSS RF environments of typical scenarios as an IQ-Database and reproducing them for laboratory GNSS receiver tests any number of times. The railway field trials addressed weak satellite navigation signals in environments like one sided/two sided shadowing through forests, buildings and cliffs or passing of bridges, tunnels, rock galleries and train stations. In comparison to that the inland water field trials addressed weak satellite navigation signals like passing of bridges, using locks and landing in ports. Additionally, inertial sensor data and video data can be stored within the same process. This makes it very efficient to evaluate new technologies (e.g. receivers, locating data fusion methods, track matching approaches). The contribution to the conference will focus on the experimental design, the technical configuration and statistically evaluating positioning results regarding to field trials in the European railway and waterway networks. KEYWORDS: GNSS field test, GNSS multi-channel signal generator, receiver evaluation
A Design of Carrier-Smoothed GPS/DR Integration System for Two-Dimensional Precise Vehicle Trajectory Estimation Kyu-Jin Lee Department of Information and Communication Engineering Chungnam National University, Korea Tel:+82-42-821-6807, Fax:+82-42-824-6807, likebasic@naver.com
Jeong-Min Lim Department of Information and Communication Engineering Chungnam National University, Korea Tel:+82-42-821-6807, Fax:+82-42-824-6807, likebasic@naver.com
Tae-Kyung Sung Division of Electric and Computer Engineering Chungnam National University, Korea Tel:+82-42-821-5660, Fax:+82-42-824-6807, tksaint@cnu.ac.kr
ABSTRACT
Using carrier phase as well as code measurements from GPS satellites, we can obtain a precise position or smoothed trajectory. If the real-valued integer ambiguities in carrier measurements are estimated using single epoch code measurements at the initial state, precise trajectory with bias can be obtained assuming that cycle slips do not take place and satellite set is unchanged. Therefore, in order to get precise trajectory in real application using CSGPS (Carrier-Smoothed GPS), the change in position bias should be carefully monitored and compensated. On the other hand, DR (dead reckoning) navigation has an excellent short-term accuracy to provide precise relative position and attitude. But DR sensor errors are accumulated in the computation. As a result, the position and attitude errors increase exponentially if it is not properly calibrated. If the CSGPS and DR are integrated together, real-time precise trajectory estimation is possible even when cycle slips exist in carrier measurements. This paper presents a CSGPS/DR integration system for two-dimensional precise vehicle trajectory estimation. MEMS gyro, accelerometer, and odometer are used for DR system. Using the DR measurements, cycle slips in carrier measurements are monitored and compensated if they happen. Moreover, when the visible satellite set is changed, real-valued integer ambiguities are recomputed to guarantee the trajectory continuity. Also, DR sensor errors as well as vehicle position and heading are estimated using carrier measurements conversely. By field experiments, performance of the proposed integrated system will be verified. KEYWORDS: Carrier-Smoothed GPS, Dead reckoning, Cycle-slip, Vehicle trajectory,
Session 7A
GNSS Receiver Hardware 1 – Developments
1350-1530
Monolithic Integrated RF Front Ends for Multi-GNSS Receivers K. J. Parkinson (1) E. Glennon (2) Nagaraj C. Shivaramaiah (3) Andrew G. Dempster (4) Chris Rizos (5) School of Surveying and Spatial Information Systems, University of New South Wales, Sydney, 2052, Australia Email for corresponding author: k.parkinson@student.unsw.edu.au
ABSTRACT The continuing expansion of available GNSS signals is an increasing challenge for receiver designers. New signals with expanded bandwidths are demanding greater sampling rates that require careful design of the receiver RF section to maximise performance tradeoffs. A high level of integration is required to preserve signal path integrity and minimise noise while keeping power consumption to a minimum. The design of the frequency plan and the choice of IF bandwidth are critical to overall receiver performance. This paper describes the development of the monolithic RF front end chips used in the new Namuru multi-GNSS receivers at UNSW. Analysis of the system requirements and architecture design are discussed including the LNA, Mixer, IF Amplifier through to the A/D converter. The re-configurable design provides frequency plan and signal selection flexibility using an integrated synthesiser and programmable bandwidth filter. The design challenges of the new front end chips are discussed including features aimed at delivering greater performance and flexibility. KEYWORDS: Namuru, Receiver, FPGA, RF FE
Project Biarri and the Namuru V3.2 Spaceborne GPS Receiver Eamonn P. Glennon (1), Kevin J. Parkinson (2), Mazher Choudhury (3), Joseph P. Gauthier (4), and Andrew G. Dempster (5) School of Surveying and Geospatial Engineering, The University of New South Wales e.glennon@unsw.edu.au, kevin@dynamics.co.nz, joseph.gauthier@student.unsw.edu.au; a.dempster@unsw.edu.au
ABSTRACT The Namuru V3.2 GPS receiver is an Australian developed FPGA-based GPS receiver designed specifically for the Biarri Project; a multi-lateral Colony 2 cubesat defence project that Australia is participating in via the Defence Science and Technology Organisation. In this paper a brief introduction to the Biarri mission requirements is provided, as are the various design features of the receiver that has been developed to satisfy those requirements. In particular, we focus on describing the features relating to operation of the receiver in low-earth orbit, in-orbit reprogramming of the receiver, high accuracy relative positioning using carrier phase and the provision of precise timing signals. GPS simulator test results using the latest generation of Namuru V3.2 receiver are also presented. KEYWORDS: Cubesat, GPS receiver, FPGA, Colony 2
Namuru GNSS Receiver Development at UNSW K. J. Parkinson (1) E. Glennon (2) Nagaraj C. Shivaramaiah (2) Andrew G. Dempster (3) Chris Rizos (4) School of Surveying and Spatial Information Systems, University of New South Wales, Sydney, 2052, Australia Email for corresponding author: k.parkinson@student.unsw.edu.au
ABSTRACT The UNSW Namuru Field Programmable Gate Array (FPGA) based GPS receivers, developed originally in 2004, have been deployed into many organisations worldwide and used as a valuable open source GNSS research platform. Originally designed for the L1/L2 signals, the Namuru receivers have continued to develop further as GNSS research has progressed. With the availability of new GNSS signals and augmentation systems new multi-GNSS versions of the receiver have been developed at UNSW to access those signals. The receiver designs consist of custom designed RF front end chips, printed circuit boards, base-band logic in an FPGA and application firmware. This paper describes the direction and development path of the Namuru receivers, including an insight into the RF front ends designed to expand receiver bandwidth and signal access. The architecture and design challenges of the new receiver models are discussed with features aimed at delivering greater performance and flexibility. KEYWORDS: Namuru, Receiver, FPGA, Base-band, RF FE
Galileo IOV Satellites Receiver Development Jinghui Wu* Mazher Choudhury Joon Wayn Cheong Nagaraj C Shivaramaiah Andrew G Dempster Australian Centre for Space Engineering Research, UNSW, Australia Ph: +61(2)93854206 / Fax: +61 (2) 9313 7493/ email: jinghui.wu@unsw.edu.au
ABSTRACT The first four operational Galileo satellites were launched on 21 October 2011 and 12 October 2012 and will play an important role as a kernel of the full Galileo satellite constellation. The success of receiving and decoding the real Galileo IOV PFM satellite signals along with the GPS signals enables the use of GPS+Galileo integrated receivers. This paper shows how our Galileo E1 receiver has been developed to process the real-time Galileo signals broadcasted from the operational IOV PFM satellites. The Navigation Message was correctly decoded from the live Galileo signals which enable GPS/Galileo integration positioning in real time. A Matlab software version and an FPGA-based real-time receiver have been used for simultaneous acquisition and tracking of GPS+Galileo signals. The performance in static mode was demonstrated through codephase measurement as well as zero-baseline double difference carrier-phase measurements. KEYWORDS: Galileo+GPS, Acquisition, Tracking, Decoding, Measurement
Session 7B
Indoor Positioning 1
1350-1530
A New Approach to Model Wi-Fi Signal Strength Lina Chen College of Mathematics, Physics and Information Engineering , Zhejiang Normal University, China; School of Surveying and Geospatial Engineering, UNSW +86-579-82282501, chenlina@zjnu.edu.cn
Binghao Li School of Surveying and Geospatial Engineering, UNSW +61-2-93854189, Binghao.li@unsw.edu.au
Andrew Dempster School of Surveying and Geospatial Engineering, UNSW +61-2-93856890, a.dempsteri@unsw.edu.au
ABSTRACT Fingerprinting is a widely used technique for indoor positioning, especially for Wi-Fi positioning systems. It is essential to create the fingerprint database in training phase. A quick survey can save labour effort and time; however it normally means the sacrifice of the positioning accuracy since a small number of measurement the signal strength can’t represent the real signal distribution well with current models at each reference points. In order to achieve high accuracy, a better model is required. A new model is proposed in this paper using the Double-Peaks Gauss function to approximate the Wi-Fi signal strength distribution in the offline training phase. The model was created based on the analysing of large amount measurement during the intensive experiments. Testing shows this model worked well even the samples changed from 10000 to 100. The model can be used to improve the efficiency to generate the radio map. The new model can possibly be applied to other types of wireless signal. KEYWORDS: fingerprinting; radio map; signal strength
A Outlier Detection algorithm for RSSI-based ML estimation in Wireless Sensor Networks Wonju Lee Department of Electrical Engineering, Korea Advanced Institute of Science and Technology, Republic of KOREA Phone: +82-42-350-7522, Fax: +82-42-350-7622, Email: na5208@kaist.ac.kr
Joonhyuk Kang Department of Electrical Engineering, Korea Advanced Institute of Science and Technology, Republic of KOREA Phone: +82-42-350-7522, Fax: +82-42-350-7622, Email: jhkang@ee.kaist.ac.kr
ABSTRACT In these days, target localization is important application in wireless sensor networks. Several location estimation methods; time of arrival-, time difference of arrival-, angle of arrival-based location estimation methods, perform good estimation accuracy, however, these methods become worse as the number of moving object increasing. Therefore, the received signal strength indicatorbased (RSSI) localization scheme with maximum likelihood (ML) estimation technique is proposed, and which has good localization performance even though multipath fading and shadowing effects exist. In other hand, when there are some outliers over anchor node, it is well known that the localization performance becomes poor. In order to improve the estimation accuracy, the proposed algorithm efficiently detects the outlier over each anchor node by using extreme studentized deviate test and estimates the target node location. From simulation results, we show the estimation accuracy of proposed algorithm is better than that of conventional localization algorithm. KEYWORDS: Wireless sensor networks, Localization, RSSI-based ML estimation, Outlier detection,
Extreme studentized deviate test.
Using Barometer to Determine the Height for Indoor Positioning Binghao Li School of Surveying and Geospatial Engineering, UNSW +61-2-93854189, binghao.li@unsw.edu.au
Bruce Harvey School of Surveying and Geospatial Engineering, UNSW +61-2-93854178, b.harvey@unsw.edu.au
Thomas Gallagher School of Surveying and Geospatial Engineering, UNSW +61-2-93854208, t.gallagher@unsw.edu.au
ABSTRACT It has been observed that atmospheric pressure decrease when the altitude increases. Models have been created to relate height to pressure. A barometer can measure the air pressure and then the altitude can be calculated. Before the era of GNSS, barometer was widely used to determine heights outdoors. The invention of GNSS was a revolution in positioning and navigation. However, it does not work in indoor environment. Alternative technologies have been developed such as Wi-Fi fingerprinting mainly for 2D positioning and navigation. In some of the applications, 3D or 2.5D (the level of the building) is required. Using barometer is a possible solution and some new mobile phones have a build in pressure sensor. But there too many issues should be considered. Is height determined from barometer accurate enough? Is there a latency problem? Does the air conditioning in an almost sealed building significantly affect height readings? This paper discusses the necessary considerations to use barometers for indoor applications based on experiments. Possible solutions are suggested. KEYWORDS: Barometer; Indoor positioning; Altitude
Hyperbolic Positioning with Proximate Multi-channel Pseudolite for Indoor Localization Yoshihiro Sakamoto Dept. of Modern Mechanical Engineering, Waseda University, Japan phone: +81-3-5286-3264, fax: +81-3-5272-0948, email: yoshi@aoni.waseda.jp
Hiroaki Arie Dept. of Intermedia Art and Science, Waseda University, Japan phone: + 81-3-5286-2742, fax: + 81-3-5286-2742, email: arie@aoni.waseda.jp
Takuji Ebinuma Dept. of Aeronautics and Astronautics, the University of Tokyo, Japan phone: +81-3-5841-6972, fax: +81-3-5841-6976, email: ebinuma@nsat.t.u-tokyo.ac.jp
Kenjirou Fujii Hitachi Industrial Equipment Systems Co., Ltd., Japan phone: +81-3-4345-6011, fax: +81-3-4345-6913, email: fujii-kenjirou@hitachi-ies.co.jp
Shigeki Sugano Dept. of Modern Mechanical Engineering, Waseda University, Japan phone: +81-3-5286-3264, fax: +81-3-5272-0948, email: sugano@waseda.jp
ABSTRACT The carrier-phase-based positioning with GPS pseudolites has potential to achieve centimetrelevel positioning accuracy. However, since it has several innate problems such as the near-far problem, synchronization, and integer ambiguity resolution, it is difficult to use pseudolites for practical applications, especially in narrow indoor environments. In the present work, in order to avoid these problems, a novel use of pseudolite is introduced. Three pseudolite antennas are located at intervals of 95 mm (half wavelength of the GPS L1 carrier wave) similar to an antenna array, and those antennas transmit carrier waves that are synchronized to each other. The receiver (an off-the-shelf GPS receiver whose firmware is modified) detects the phase differences between the carrier waves, and calculates its position using a hyperbolic positioning method. Positioning experiments to evaluate the proposed method are conducted in two different indoor places. The results of the experiments show that positioning accuracy of less than one metre is possible if the distance between the receiver and pseudolite antennas is less than about three metres. Although this accuracy is worse than the centimetre-level accuracy aimed at (but practically not achieved) by conventional pseudolites, the proposed method can avoid major problems of pseudolites; that is, it opens up new possibility for indoor positioning applications KEYWORDS: hyperbolic positioning, pseudolite, indoor GPS
Session 7C
Datums and Geodesy
1350-1530
Monitoring Station Movement using a State-Wide Simultaneous ‘Adjustment of Everything’− Implications for a Next-Generation Australian Datum Joel Haasdyk Survey Infrastructure and Geodesy, Land and Property Information NSW Department of Finance & Services, Bathurst NSW 2795, Australia Tel: +61 2 6332 8485, Fax: +61 2 6332 8479, Email: Joel.Haasdyk@lpi.nsw.gov.au
Craig Roberts School of Surveying and Geospatial Engineering, University of New South Wales, Sydney NSW 2052, Australia Tel: +61 2 9385 4464, Fax: +61 2 9313 7493, Email: c.roberts@unsw.edu.au
ABSTRACT The establishment of a next-generation Australian datum is currently being investigated. Such datum update is required to accommodate the increasing accuracy and improved spatial and temporal resolution available from modern positioning technologies to an ever-broadening user
base. While the spatial community debates the costs, benefits and optimum implementation of a new datum, each Australian state and jurisdiction is currently preparing a dataset containing all available geodetic measurements from their archives. New computing technologies mean that state-wide and even nation-wide adjustments are now routinely possible with an essentially unlimited number of stations and measurements, while new measurements can be incorporated immediately when they are available. This study discusses the opportunities and limitations of a simultaneous adjustment of all available GNSS measurements for monitoring the movement of geodetic survey stations. Two case studies in NSW are presented to highlight the different implications of land movement versus station instability on potential datum deformation models in the vicinity of these stations. Additional measurements via ‘crowd-sourcing’ methodologies would help to maintain the currency and relevance of the datum, while traditionally non-geodetic techniques such as DInSAR would be invaluable in defining the extent of any detected deformation. The results presented here are preliminary and aim to highlight areas of potential research, and promote discussion regarding datum update in the wider spatial community. KEYWORDS: data-mining, Datum, deformation, geodesy, GNSS
Determining National Vertical Datum by GPS Buoy Po-Hsien Hsu (1) Department of Applied Geoinformatics , Chia Nan University of Pharmacy and Science,Taiwan R.O.C. 6-2664911 & 6-2666114, phhsu1688@mail.chna.edu.tw
Ching-Liang Tseng (2) Department of Earth Sciences, National Cheng-Kung University, Taiwan R.O.C. 6-2613614 & 6-2666114, tsengcl1155@gmail.com
ABSTRACT Usually, to maintain the national vertical datum of Taiwan is based on the support of tidal gauge that provides an accurate and precise height record. Ideally, the height of the primary tidal bench mark located on the stable solid earth is based on the result obtained from the long term tidal gauge record and it can be referred to all bench marks around the island. However, the height difference between the tidal gauge and primary tidal bench mark is relative. On the other hand, the height is referred to local datum. From global point of view, it should be transformed to global coordinate system by satellite geodesy or physical geodesy. Since the technique of space geodesy has been developed rapidly, it can achieve absolute sea level accurately. Therefore, a suitable GPS buoy was designed. It was drift on the sea surface near tidal gauge to monitor the height of sea surface in global coordinate system. It can solve the problems of local datum and unstable tectonic plates and subduction zones. Since the antennas of GPS cannot continuously perpendicular to the sea surface due to up and down of the wave, the buoy gesture must be solved out. According to the result collected from the harbor near tidal gauge for three days, the accuracy of the zero point of the sea level is about 5mm～7mm. It is clear that GPS buoy can be a useful tool to achieve the vertical datum in global point of view. KEYWORDS: tidal gauge, GPS buoy, ellipsoid height, TGGS station, altitude angle
Victoria's Geodetic Strategy – Ongoing Developments in Light of Geodetic Infrastructure Priorities, Challenges and Opportunities Dr Roger Fraser Department of Environment and Primary Industries, Victoria, Australia +61 3 8636 2551, roger.fraser@dse.vic.gov.au
Hayden Asmussen Department of Environment and Primary Industries, Victoria, Australia +61 3 8636 2374, hayden.asmussen@dse.vic.gov.au
ABSTRACT Fundamental to the sustainable development of Victoria is the availability of a reliable, high accuracy geodetic referencing system upon which spatial information can be based. The authoritative referencing system in Australia is the National Geospatial Reference System (NGRS). Like other fundamental infrastructure, the NGRS requires ongoing development and maintenance to ensure that it continues to meet the purpose for which it has been established. In the Victorian context, the development and maintenance of the NGRS stands upon several critical infrastructure components including an integrated network of Global Navigation Satellite System (GNSS) Continuously Operating Reference Stations (CORS) and conventional survey control marks; a large number of geodetic measurements; a vast amount of information about GNSS CORS, marks and measurements; hardware, database management systems and software; and various policies, standards and guidelines. In response to recognised trends in various societal, environmental, scientific and economic priorities and challenges, DEPI is pursuing a number of strategic objectives for the maintenance of Victoria’s geodetic infrastructure over the next five years. This presentation reviews these strategic objectives and discusses some opportunities for the way in which Australia’s geodetic datum is maintained. KEYWORDS: Geodetic strategy, GNSS, datum, infrastructure, information.
Session 8A
GNSS Receiver Hardware II – Performance
1600-1740
Performance Evaluation of a GPS Receiver with VDFLL in Harsh Environments Deok Won Lim Satellite Navigation Team, Korea Aerospace Research Institute, Korea +82-42-870-3978, +82-42-860-2789, dwlim@kari.re.kr
Heon Ho Choi Department of Electronics Engineering, Chungnam National University, Korea +82-42-825-3991, +82-42-823-4494, heonho@cnu.ac.kr
Sang Jeong Lee Department of Electronics Engineering, Chungnam National University, Korea +82-42-825-3991, +82-42-823-4494, eesjl@cnu.ac.kr
Moon Beom Heo Satellite Navigation Team, Korea Aerospace Research Institute, Korea +82-42-860-2266, +82-42-860-2789, hmb@kari.re.kr
ABSTRACT The problem of designing robust architectures to track global navigation satellite system (GNSS) signals in harsh environments has gained high attention. The classical closed loop architectures such as delay locked loops (DLL) and frequency locked loops (FLL) have been used for many years for tracking, but in challenging applications such as blockage of signals and the presence of multipath, their design procedure becomes intricate. As one of the alternative architecture, there is the vector tracking technique which is able to improve the GNSS availability in such signal environments. This paper, therefore, describes an approach to implement a vector delay and frequency locked loop (VDFLL) in a conventional GPS receiver. The architecture of this approach will be described in detail and the potential capabilities will be shown by the results of experiments in urban and suburban areas. For these experiments, a pair of low cost GPS receivers was also deployed to assess the accuracy in commercial domain. The data from these receivers was post-
processed for further reasoning and conclusions. The analysis of this data demonstrated that the performance of the proposed architecture has been improved for the harsh signal conditions due to the blockage of signals and the presence of multipath. KEYWORDS: GNSS, Vector Tracking, Signal Blockage, Multipath
Analysis of Performance Degradation Due to RF Impairments in Quadrature Bandpass Sampling GNSS Receivers Vaidhya Mookiah, Ediz Cetin, Andrew G. Dempster University of New South Wales, Australia Tel: +61415823738 e-mail: v.mookiah@student.unsw.edu.au, e.cetin@unsw.edu.au, a.dempster@unsw.edu.au
ABSTRACT Radio receiver architectures with Analog to Digital Converter (ADC) close to the antenna can perform reconfigurable band selection in the digital domain, improving performance. Techniques such as Bandpass Sampling (BPS) require a sampling rate of at least twice the bandwidth of signal to sample and downconvert the received signal, whereas Quadrature Bandpass Sampling (QBPS) accomplishes this with half the sampling rate, but for two sample sequences. QBPS achieves frequency downconversion and digitisation eliminating the need for expensive analog mixers, filters and the Radio Frequency (RF) impairments associated with them. QBPS operates on the received RF signal and using two ADCs with sampling clocks separated by one quarter of the signal carrier period (1/fc4) relative to one another. For GPS L1 signals this delay corresponds to 158.69 ps which is not trivial to generate accurately. Impairments associated with generating this delay and the signal paths between the ADCs results in performance degradation in the receiver. This paper will investigate the influence of the RF impairments associated with the QBPS scheme and will compare its performance with different classical RF front-end architectures for generating in-phase and quadrature signals in terms of Image Rejection Ratio (IRR) and Bit Error Rate (BER). A quantitative comparison of architectures will be performed using simulation case studies in a MATLAB environment. The proposed QBPS architecture performance with respect to RF impairment is better than other architectures as it eliminates power hungry and non-linear analog components. In addition, the feasibility of QBPS for frequency translation and digitising multiband GNSS signals will also be explored. KEYWORDS: software radio, bandpass sampling, RF impairment, image rejection ratio, quadrature sampling.
Initial Test Results of Namuru Dual-GNSS Spaceborn Receiver Mazher Choudhury (1)* Joon Wayn Cheong (2)* Jinghui Wu (3)* Nagaraj C Shivaramaiah (4) * Andrew G Dempster (5) * *Australian Centre for Space Engineering Research, UNSW, Australia Ph: +61(2)93856702 / Fax: +61 (2) 9313 7493/ email: (1) mohammad.choudhury@unsw.edu.au
ABSTRACT This paper analyses the test results of the performance evaluation of the Namuru dual-GNSS integrated receiver capable of handling both GPS and Galileo simultaneously. The Namuru is a dual-RF frontend FPGA hardware platform developed by University of New South Wales (Sydney, Australia) and General Dynamics (New Zealand) to support various research projects that requires access to the signal-processing level of a GNSS receiver – a feature that is not available in any Commercial Of The Shelf (COTS) GNSS receiver. Recent improvements made to the Namuru receiver enable it to process not only GPS signals but also QZSS and Galileo signals. The Namuru receiver that is still under development specifically targets space operations such as an orbiting satellite at Low Earth Orbit. The space scenario considered is a realistic set of formation-flying LEO satellites where accurate relative position information is crucially required. The tests performed include a single-spacecraft single-antenna case for absolute positioning, a single-spacecraft multi-antenna case for attitude determination and a dual-spacecraft case for relative positioning. To satisfy both attitude determination and relative positionng cases, carrier phase positioning algorithms are employed, whereas pseudorange-derived position solution is used to achieve absolute positioning. The evaluation was performed using a Spirent simulator (GSS8800). The NMEA output stream from the receiver was processed using MATLAB and RtkLib to produce position solutions that will be compared against Spirent-derived truth data. Preliminary test results in orbit scenario exhibits the navigation accuracy of 0.2±10m, 0.60±5 and 2±7m for X,Y and Z respectively. On the other hand, baseline solution presents accuracy of 0.20±0.8m for 3D position. Further improvement on pseudorange as well as carrier phase measurements are under development. KEYWORDS: Namuru, GPS-Galileo receiver, dual-GNSS.
Initial Assessment of BeiDou Augmented GNSS Thomas Morley NovAtel, Inc. +1-403-730-4641 thomas.morley@novatel.com
Rod MacLeod NovAtel Australia Pty Ltd +61 400 883 601 rod.macleod@novatel.com
ABSTRACT The recent release of the BeiDou ICD has allowed GNSS receiver manufacturers to integrate BeiDou signals into their tracking and positioning algorithms. This presentation will provide an overview of NovAtel’s initial observations of the BeiDou signal performance and characteristics. Additionally, this presentation will review real-world results of BeiDou augmentation of GNSS position solutions. Data were collected at various locations within the area covered by the regional component (geostationary and inclined geosynchronous satellites) of the BeiDou constellation. The BeiDou signals were found to be reasonably compatible to GPS signals in terms of pseudorange and carrier phase quality. Performance deltas due to the inclusion of BeiDou information are noted for various positioning modes including single point, GL1DE and RTK
modes. Improvements to solution accuracy and availability are demonstrated, particularly for users operating in an obstructed environment, such as surface mining. This presentation concludes that, when properly integrated, the BeiDou signals will be a valuable enhancement to augmented GNSS positioning. KEYWORDS: BeiDou, RTK, accuracy, availability
Session 8B
Indoor Positioning II
1600-1740
A Comparison of Algorithms Adopted in Fingerprinting Indoor Positioning Systems Zhao Kai Li Binghao School of Surveying and Spatial Information Systems University of New South Wales Sydney, Australia +61 424420022 kai.zhao@unsw.edu.au
ABSTRACT Fingerprinting technology has been widely used in indoor positioning systems such as Wi-Fi positioning systems. Its performance depends on not only the measurement of signal strength, but also the algorithm used. In this paper, an overview is given of the current popular algorithms adopted in Wi-Fi indoor positioning system, including deterministic method (K nearest neighbour, K weight nearest neighbour), probabilistic method and neural network. In order to get reliable and representative result, two different set of data were tested. Comprehensive comparisons were made with respect to positioning accuracy, computing power requirement and the complexity of creating the database. Furthermore, details of choosing parameters and implementation of these algorithms are discussed. KEYWORDS: Indoor positioning, Fingerprinting Method, Algorithm
Using Geomagnetic Field for Indoor Positioning Binghao Li School of Surveying and Geospatial Engineering, UNSW +61-2-93854189, binghao.li@unsw.edu.au
Thomas Gallagher School of Surveying and Geospatial Engineering, UNSW +61-2-93854208, t.gallagher@unsw.edu.au
Chris Rizos School of Surveying and Geospatial Engineering, UNSW +61-2-93854205, c.rizos@unsw.edu.au
Andrew G. Dempster School of Surveying and Geospatial Engineering, UNSW +61-2-93854205, c.rizos@unsw.edu.au
ABSTRACT Geomagnetic field variations for indoor positioning and navigation has attract attentions recently because of the advantage that no infrastructure needs to be pre-deployed. Test using delicate magnetometers has shown it is possible to use geomagnetic field for positioning purposes. However, there are still issues to be addressed for real applications. For instance, are the low cost built-in magnetometers in mobile phones good enough for positioning purpose based on fingerprinting technology? Is the geomagnetic field stable for a very long term? Further tests were carried out using the latest smart phones. As using geomagnetic field alone for positioning may have difficulties, integration with other method is necessary. Wi-Fi is one of the obvious options. There are two possible ways to combine these two methods: one is a two steps process, using WiFi to estimate the approximate position first, and then apply geomagnetic filed to refine the estimation; the other is creating a fingerprinting database including Wi-Fi signal strength elements
and geomagnetic field elements, a combined fingerprint is used to estimate the position directly. Algorithms were developed and tested. KEYWORDS: Geomagnetic; Indoor positioning; Fingerprinting
“Simon says”: Mobility and Indoor Navigation for persons who are Blind or Vision Impaired Euan Ramsey-Stewart Ramsey Stewart Industrial Design (RSID) Sydney, Australia P: +612 8958 4774 E: euan@unsw.edu.au
Binghao Li School of Civil and Environmental Engineering, UNSW Sydney, Australia P: E: binghao.li@unsw.edu.au
Thomas Gallagher School of Civil and Environmental Engineering, UNSW Sydney, Australia E: t.gallagher@unsw.edu.au
Chris Rizos School of Civil and Environmental Engineering, UNSW Sydney, Australia E: c.rizos@unsw.edu.au
Hoechee Yam School of Civil and Environmental Engineering, UNSW Sydney, Australia E: yam.hoechee@gmail.com
ABSTRACT People who are Blind or Vision Impaired (BVI) are arguably a part of the world community that could benefit most from using navigation and location technologies. Such technologies are able to change a person’s quality of life in many ways; providing health, social interaction employment and economic opportunities. .. All too often this community is forgotten or given inadequate consideration when designing navigation or way finding systems. This is evidenced by minimal navigation systems use, amongst BVI persons. Almost 80% percent of our lives are spent indoors and GPS only provides accurate positioning outdoors. There is a void to be filled; the indoor environment. We have yet, to develop a truly lowcost, usable and commercially viable solution to the problem of indoor navigation and positioning. The BVI Project team at the University of New South Wales (UNSW) has been addressing this situation. The team set out to deliver a low cost solution to the indoor navigation problem. By hypothesising, “If BVI persons can safely navigate through an unfamiliar indoor environment, then almost anyone could.” The team used the information needs as well as the many mobility and orientation perspectives of BVI persons, in the overall design and system solution called SIMO (Simplified Information for Mobility and Orientation). The UNSW team conducted research through, interviews with BVI persons and Orientation and Mobility experts, surveys, phone questionnaires and prototype/user testing. The team has uncovered a non-traditional way of expressing spatial information and provides a solution using a new Smart Phone APP, internal IMU’s and Wi-Fi detection. From the start the BVI community was consulted by the team who
through user experience
design and incorporation of inclusive design principles at all times, enabled a better understanding of specific and particular orientation and mobility needs. “Thinking outside the box�, the UNSW BVI Project team have provide a unique solution to the problem of Indoor Navigation and Positioning and interface design. KEYWORDS: SIMO, Indoor Navigation, Indoor Location, Blind or Vision Impaired, BVI, User Interface, User Experience, Inclusive Design Indoor GPS, Simplified Information, Mobility, Orientation.
Integration of Pedestrian DR and Beacon-AP based Location System for Indoor Navigation Jeong-Min Lim Department of Information and Communication Engineering Chungnam National University, Korea Tel:+82-42-821-6807, Fax:+82-42-824-6807, likebasic@cnu.ac.kr
Sang-Hoon Yoo Department of Information and Communication Engineering Chungnam National University, Korea Tel:+82-42-821-6807, Fax:+82-42-824-6807, hoonkko@hanmail.net
Kyu-Jin Lee Department of Information and Communication Engineering Chungnam National University, Korea Tel:+82-42-821-6807, Fax:+82-42-824-6807, lkj0136@cnu.ac.kr
Tae-Kyung Sung Division of Electric and Computer Engineering Chungnam National University, Korea Tel:+82-42-821-5660, Fax:+82-42-824-6807, tksaint@cnu.ac.kr
ABSTRACT Though the global navigation satellite systems (GNSS) are widely used in various location based services (LBS), it can hardly be used indoors due to signal blocking or multipath fading. For indoor LBS, various location systems have been developed and examples include WiFi multilateration, RF fingerprint, UWB WPAN, and pedestrian dead reckoning (PDR). Owing to rapid deployment of the smartphone, WiFi location systems and PDR are more highlighted as a candidate of indoor location solution recently. Because WiFi multilateration utilized received signal strength indicator (RSSI) measurement in ranging, its positioning accuracy is somewhat poor. Though the performance of RF fingerprint is better than that of WiFi multilateration, its performance is sensitive to RF environment. Moreover, if many access points (AP) are installed to improve their location performance, interference between APs becomes critical in data communication. In the PDR, pedometer is commonly used to measure distance and the heading direction is found using magnetometer and/or gyroscope. Because dead reckoning (DR) sensor errors are accumulated in the computation, location error of PDR increases cumulatively as time goes if the position and heading are not calibrated peoperly. This paper presents a novel indoor navigation system integrating beacon-type AP and PDR. To minimize the interference and to find user position with high accuracy, we developed a beacontype AP that has a small footprint. When the beacon-type APs are installed at the crossroad and the footprint of each AP covers each direction of corridor, smartphone users can easily obtain their precise position and moving direction. Because beacon-type AP has a small footprint, PDR is used to compute user position between the footprint coverage of beacon-type AP. Comparing the AP position and the output of PDR, user position and heading are calibrated. Moreover, pedometer scale factor and gyro bias are estimated to improve the performance of PDR. By field experiments, performance of the proposed indoor navigation system will be verified.
KEYWORDS: Pedestrian DR, Beacon-type AP, Indoor navigation
A Performance Evaluation of the RFID Method in Indoor Positioning Fingerprinting Database Collection and Maintenance Zhao Kai Li Binghao School of Surveying and Spatial Information Systems University of New South Wales Sydney, Australia +61 424420022 kai.zhao@unsw.edu.au
ABSTRACT Fingerprinting technology has been widely used in Wi-Fi indoor positioning systems. However, the major disadvantage of this technology–the requirement to generate and maintain the location fingerprinting database remains. We have proposed an approach to use Radio Frequency Identification (RFID) technology to significantly simplify the process of location fingerprinting collection. In this method, we use the RFID tags to mark and represent the reference points. An electronic device can be used to collect fingerprinting data automatically while people carry it walk around. Thus, the process of fingerprinting data collection can be done by the staffs like security guards in their common patrol. We have developed an experimental system called Geni Wi-Fi, to test the proposed method. In this system, RFID tags were designed to be deployed in the target environment in advance. The portable fingerprinting data collector, which is the main part of this system, contains a RFID reader, a Wi-Fi scanner, a processor chip and a memory bar. When people carry such collector and pass by the RFID tag, the reader scans the tag and triggers the Wi-Fi scanner to record the Wi-Fi signal strength. Data are saved in the memory bar and uploaded to the server via either a Wi-Fi connection or a serial port later. The data are post processed to generate or update the fingerprinting database. Geni Wi-Fi was tested in common indoor environment. We analysed the impact of different factors to the positioning performance and tested some potential solutions which could improve the accuracy. The issues of compatibility with the current fingerprinting positing systems are also discussed. KEYWORDS: Geni Wi-Fi, indoor positioning, RFID, Fingerprinting method
Session 8C
GNSS Infrastructure I
1600-1740
National Positioning Infrastructure: Where are we now? Grant Hausler Cooperative Research Centre for Spatial Information The University of Melbourne, Australia Tel: +61 3 9035 3223 Email: g.hausler@student.unimelb.edu.au
ABSTRACT Spatial organisations across Australia have been leading the push to develop a National Positioning Infrastructure (NPI) that will deliver uniform access to reliable and accurate Position, Navigation and Timing (PNT) information. The NPI will be based on the acquisition, processing and distribution of Global Navigation Satellite System (GNSS) data through a network of Continuously Operation References Stations (CORSs). CORS infrastructure is currently deployed and operated independently on an ad-hoc basis by governments and industry across Australia.
Australia’s spatial community has identified and responded to the need for more efficient and costeffective management of PNT infrastructure by defining agreed principles and strategies for the NPI. Collectively, the Spatial Information Council’s (ANZLIC’s) NPI Policy, the Australian Spatial Consortium’s (ASC’s) Strategic Plan for GNSS, and the NPI Infrastructure Plan prepared by Geoscience Australia identify objectives and priority actions aimed at limiting infrastructure duplication and over-investment; implementing data and service standards; improving quality control measures; extending user access; providing redundancy through non-GNSS technology; and designing a NPI that supports the diverse PNT needs of all industry sectors. This paper provides a summary of past and present work towards establishing the NPI and indentifies future challenges for communicating and realising its benefits. PNT initiatives that aim to improve user access and service performance both domestically and internationally are identified to justify why the NPI will ensure Australia remains competitive in a multi-GNSS future. KEYWORDS: National Positioning Infrastructure (NPI); Global Navigation Satellite System (GNSS);
Continuously Operating Reference Station (CORS); Position, Navigation and Timing (PNT); Service Level Management (SLM).
Architecture Proposal for the Open Source GNSS Reference Server v4 Ali Sarwar School of Surveying and Geospatial Engineering, University of New South Wales, Australia Phone : +61 2 9385 4185, Fax : +61 2 9313 7493 Email: ali.sarwar@student.unsw.edu.au
Chris Rizos School of Surveying and Geospatial Engineering, University of New South Wales, Australia Phone: +61 2 9385 4205, Fax: +61 2 9313 7493, Email: c.rizos@unsw.edu.au
ABSTRACT Mobile communications network architecture is changing rapidly, leading to changes in end-user access, core and positioning network elements. For example, cellular network carriers may be increasingly constrained to providing transmission carriage pipes. This means that mobile location based server technologies will need to evolve. The scalable Open Source GNSS Reference Server (OSGRS) is an implementation of a continuously operating location based reference server operating at the University of New South Wales. It is based on the following elements: GNSS Reference Interface Protocol (GRIP), Extensible Mark-up Language (XML), Novatel OEM4 chipset, Networked Transport of RTCM (Radio Technical Commission for Maritime Services) over Internet Protocol (NTRIP), Long Term Evolution (LTE) Positioning Protocol and its extensions (LPP/e). The OSGRS system development timeline (2007-2013) is presented. This paper proposes a future architecture of OSGRS that will source NTRIP information over a different underlying network. The network sub-system core which contains the positioning units of Serving Mobile Location Centre (SMLC) and Gateway Mobile Location Centre (GMLC) in the Radio Access Network (RAN) will merge with General Packet Radio Switching (GPRS). The SMLC-GMLC together serve the localisation requests of end-users through LPP/e where the GPRS network provides OSGRS the connection to the global localisation caster network such as NTRIP. The new architecture is referred to as OSGRS version 4. Possible network configurations suited to different scenarios are presented. Open source software architecture and its multi-GNSS assistance model can provide coarse and fine acquisition and data processing assistance to GNSS receivers operating in weak signal environments such as those encountered inside buildings. GNSS availability and accuracy can be improved without the use of proprietary protocols and licensing costs. KEYWORDS: OSGRSv4, LPP, NTRIP, Availability, Accuracy
Ensuring the Quality of the Australian National GNSS Infrastructure Guorong Hu Geospatial and Earth Monitoring Division, Geoscience Australia Tel: 02-6249 9884; Fax: 02-6249 9969; Email: Guorong.Hu@ga.gov.au
John Dawson Geospatial and Earth Monitoring Division, Geoscience Australia Tel: 02-6249 9028; Fax: 02-6249 9969; Email: John.Dawson@ga.gov.au
Bob Twilley Geospatial and Earth Monitoring Division, Geoscience Australia Tel: 02-6249 9066; Fax: 02-6249 9969; Email: Bob.Twilley@ga.gov.au
Nicholas Dando Geospatial and Earth Monitoring Division, Geoscience Australia Tel: 02-6249 9552; Fax: 02-6249 9969; Email: Nicholas.Dando@ga.gov.au
ABSTRACT The Australian National GNSS Infrastructure consists of the Continuously Operating Reference Stations (CORS) of the Australian Regional GNSS network (ARGN), operated by Geoscience Australia (GA), and the AuScope network operated collaboratively by GA and the State and Territory geodetic agencies. Developed to support the geospatial sector and Earth science applications, this national infrastructure underpins the national datum, the Geocentric Datum of Australia (GDA), and contributes to the Global Geodetic Observing System (GGOS) products and services, which includes the International Terrestrial Reference Frame (ITRF). To ensure this infrastructure meets the needs of its users a quality management system has been developed that includes procedures for site selection, monumentation design, routine data management, and data fitness-for-purpose assessment. This presentation overviews Geoscience Australia’s approach to quality management including our approach to monitoring the impact of: equipment configuration changes; antenna malfunctions; crustal deformation; and processing strategy and modelling changes. Some examples are given based on experience within the Asia Pacific Reference Frame (APREF) community. KEYWORDS: CORS, GNSS, National Datum, ITRF.
Development of a Test System for GNSS Receiver Performance Ahmad Ridhwanuddin Tengku The University of Melbourne, Australia / CRCSI (61) 4 3145 2766 teng@student.unimelb.edu.au
Associate Professor Allison Kealy The University of Melbourne, Australia akealy@unimelb.edu.au
Dr. Mark Morelande The University of Melbourne, Australia mrmore@unimelb.edu.au
ABSTRACT The Global Navigation Satellite System (GNSS) industry is experiencing rapid growth with new signals and constellations being actively deployed. Availability of additional signals and satellites will benefit its users with better coverage and improved integrity, but it does not necessarily guarantee the quality of the derived positioning output. As such, it is integral to ensure that a GNSS receiver system is performing according to its expected statistical values. A problem often encountered is the inability to identify the actual cause of positioning degradation with users having almost complete trust on the GNSS receiver system. The proposed test system attempts to define these boundaries by determining the root cause of the issue – whether it is receiver or externally dependent. In conceptualising the physical and functional foundations of the test system, this paper will address the issues from both theoretical and practical perspectives. From a practical perspective, a
GNSS simulator will be used to examine the consistency of GNSS receivers to process signals under different modelled conditions. These individual raw measurements will be the basis of developing an undifferenced stochastic model which will effectively be used as a benchmark for a GNSS receiver performance. A user needs analysis will also be presented, highlighting the specific issues faced by different manufacturers and end users. KEYWORDS: GNSS Receiver Performance, GNSS Test System, GNSS Simulation, Undifferenced
Stochastic Modelling, User Needs Analysis
Monitoring in Estuaries and Rivers with GNSS Floaters Charles Wang, Richard Brown and Yanming Feng Queensland University of Technology, Australia
ABSTRACT Buoys equipped with GPS receivers have been used to measure water levels, atmospheric parameter and other physical conditions in oceans for the purposes of navigation, tide correction, the altimeter range calibration and as part of tsunami warning systems. In recent years, some studies have emerged to apply a similar technology to smaller bodies of water such as estuaries and rivers in for hydraulic monitoring purposes, such as determination of water levels in rivers. This paper presents the preliminary results of new GPS experiments that measure the river flow field in three-dimensions by deploying a free-floating GPS capsule. The water proof circular cylinder capsule was designed and developed to allow for simplified analysis of the drag characteristics and interacts with flow in the same manner regardless of direction. Additionally, GNSS antenna was mounted on top compartment to minimize interference with GNSS signals. The capsule incorporated a dual frequency GNSS receiver, miniature computing and storage platform and battery to last for a 12 hours mission. The field experiments were conducted on the 20th October 2012. The GPS capsule was deployed in a local estuary, Eprapah Creek River, South East of Brisbane. Multiple tests were conducted during different tidal conditions. The kinematic GNSS data obtained from the capsule was compared with the velocity data from a fixed Acoustic Doppler Velocemeter (ADV) system and the river height measurements. The capsule performed as expected during testing. The capsule was able to provide cm-level positioning accuracy with the use local SunPOZ reference station while free flowing in the river. The performances were degraded when the capsule was moving close to the river bank due to signal blockages by trees. Finally, the height measurements from the capsule aligned well with ADV site recorded height. The GNSS monitoring system developed in this research provides a flexible, low maintenance and cost effective alternative to current fixed stations. With the ability to provide 3D Lagrangian measurements, the additional information may be useful to improve the water modelling for estuaries and rivers in the case of climate changes and the flood events. Keywords: GNSS, real-time kinematic positioning, free-floating GPS buoy and fluid dynamics.
Oral Presentations Abstracts – Thursday 18 July, 2013 Session 9A
QZSS
0900-1020
Performance Evaluation of the Japanese Quasi-Zenith Satellite System (QZSS) LEX Signal in Australia Shaocheng Zhang SPACE Research Centre/RMIT University/Australia (03) 99253709 shaocheng.zhang@rmit.edu.au
Suelynn Choy SPACE Research Centre/RMIT University/Australia (03) 99252650 suelynn.choy@rmit.edu.au
Kefei Zhang SPACE Research Centre/RMIT University/Australia (03) 99253272 kefei.zhang@rmit.edu.au
Suqin Wu SPACE Research Centre/RMIT University/Australia (03) 99252114 suqin.wu@rmit.edu.au
ABSTRACT The Quasi-Zenith Satellite System (QZSS) is a Japanese regional satellite navigation system. The constellation currently (in 2013) consists of one highly inclined geosynchronous orbit satellite and three more satellites by 2018. It aims to augment the current GPS service over Japan and provide Japanese users with at least one QZSS satellite located at high elevation angle, which gives rise to the term of ‘quasi-zenith’. The QZSS orbit coverage map shows that the Asia Oceania region including Australia is covered by the QZSS service and thus users will not only benefit from having additional navigation satellites, but also having access to the high accuracy GNSS satellite orbits, clocks, and regional ionosphere model transmitted by the LEX signal. However, as the LEX service is originally developed for Japanese users, it is necessary to validate the usability and feasibility of this service in Australia. In this research, the GPS satellite orbits, clocks and ionosphere model transmitted from the LEX signal are compared with the IGS precise products. Data collected at several Australian CORS stations are then post-processed using Precise Point Positioning (PPP) to validate the quality of the estimated point positions. The results show that the GPS satellite orbits and clocks transmitted by the LEX signal have an accuracy of less than 1 metre and 2 nanoseconds, respectively. The positioning results from the dual-frequency (ionosphere-free) PPP processing are accurate to sub-metre level; and the single frequency users cannot benefit the ionospheric correction parametres as the model is generated for Japanese regional. It can be concluded that the current QZSS LEX orbits and clocks service can provide sub-metre point positioning service in Australia, however the ionosphere correction parametres from LEX service cannot be used in Australian area, the future Australia ionospheric grid will be a necessary supplement for QZSS LEX service. KEYWORDS: GNSS, QZSS, Satellite Orbits and Clocks, Ionospheric Delay, Precise Point Positioning.
Kinematic Estimation of QZSS Orbits with Triple Frequency Measurements Yongchao Wang (1) Cooperative Research Centre for Spatial Information, Queensland University of Technology, Australia
Charles Wang (2) Cooperative Research Centre for Spatial Information, Queensland University of Technology, Australia
Yanming Feng (3) School of Electrical Engineering and Computer Science, Queensland University of Technology, Australia
ABSTRACT The existing GNSS orbital solutions, regardless of broadcast orbital and precise orbit solutions, are derived from dual-frequency code and phase measurements collected over data arcs of 24-48 hours. However, some operational satellites of different GNSS constellations, such as GPS IIF, QZSS MICHIBIKI and several recent Compass satellites have been able to transmit code and phase ranging signals at three or more frequencies. A straightforward question is how three triple or multi-frequency signals can contribute to GNSS orbits solutions. This paper presents kinematic orbit estimation algorithms using QZSS triple frequency phase and code measurements over several minutes collected from about ground GPS/QZSS stations in the Asia-Oceania region. The key is to estimation of ionosphere-free narrow-lane phase biases to the accuracy of about 10 centimetres every few minutes, which can be used to replace the ionospherefree code measurements usually used in the orbit estimation. Another important strategy is use of GPS measurements and precise orbits/clocks to estimate the receiver clocks and zenith delays. With known ground clocks, precise undifferenced ionosphere-free range measurements, the QZSS states are be determined every epoch and improved over minutes. QZSS orbit estimation experimental results from 20 stations equipped with Trimble R9 receivers will be analysed and compared with QZSS broadcast orbits and JAXA precise orbit solutions. It preliminarily demonstrates that the kinematic QZSS orbital solutions can achieve sub-metre orbital accuracy, which is expected to be further improved through the usual orbit improvement procedures to the accuracy of better than 10 centimetres in the future. KEYWORDS: QZSS, Precise Orbit Determination, Triple frequency, kinematic orbit estimation.
QZSS LEX Receiver Design Bin Lei School of Electrical Engineering and Telecommunications The University of New South Wales Sydney NSW 2052, Australia
Jinghui Wu Australian Centre for Space Engineering Research at the University of New South Wales/Australia +61 2 93854206/ jinghui.wu@unsw.edu.au
Andrew G. Dempster Australian Centre for Space Engineering Research at the University of New South Wales/Australia +61 2 93856890/ a.dempster@unsw.edu.au
Chris Rizos School of Surveying and Geospatial Engineering at the University of New South Wales/Australia +61 2 93854205/ c.rizos@unsw.edu.au
ABSTRACT Since the first GPS satellite was launched in the 1970s, several satellite-based navigation systems have been deployed globally or regionally. In the meantime, researchers are still trying to develop innovative systems which can provide high-accuracy positioning, navigation, time (PNT). To enhance positioning performance, the Japanese augmentation satellite system QZSS (Quasi Zenith Satellite System) broadcasts a unique LEX Open Service signal from the QZSS satellite “MICHIBIKI� to support precise point positioning (PPP) or differential GNSS. It is compatible and
interoperable with the European Union’s Galileo signals. Australian researchers and users can take advantage of the QZSS to enhance PNT results. In this project, the L-band LEX signal is the research focus using a software approach based on Matlab simulation of the tracking receiver. The aim was to modify existing software used for GPS L1 C/A processing so that it would be suitable for LEX signal processing. Design challenges such as CSK ddemodulation and de-multiplexing of the Short and Long Code were tackled so that new acquisition and tracking approaches could be proposed for the LEX signal. KEYWORDS: GPS, GNSS, QZSS, Galileo, LEX
Real-time Precise Point Positioning Utilising the Japanese Quasi-Zenith Satellite System (QZSS) LEX Corrections Suelynn Choy School of Mathematical and Geospatial Sciences, RMIT University, Australia Phone: +61 3 9925 2650 Fax: +61 3 9663 2517 Email: suelynn.choy@rmit.edu.au
Ken Harima School of Mathematical and Geospatial Sciences, RMIT University, Australia Phone: +61 3 9925 3775 Fax: +61 3 9663 2517 Email: ken.harima@rmit.edu.au
Yong Li School of Surveying & Geospatial Engineering, University of New South Wales, Australia Phone: +61 2 9385 4173 Fax: +61 2 9313 7493 Email: yong.li@unsw.edu.au
Yaka Wakabayashi Satellite Application and Promotion Centre, Space Applications Mission Directorate, Japan Aerospace Exploration Agency, Japan Phone: +81-50-3362-3558 Fax: +81-29-868-5987 Email: wakabayashi.yaka@jaxa.jp
Hiroaki Tateshita Satellite Application and Promotion Centre, Space Applications Mission Directorate, Japan Aerospace Exploration Agency, Japan Phone: +81-50-3362-3361 Fax: +81-29-868-5987 Email: tateshita.hiroaki@jaxa.jp
Satoshi Kogure Satellite Application and Promotion Centre, Space Applications Mission Directorate, Japan Aerospace Exploration Agency, Japan Phone: +81-50-3362-2456 Fax: +81-29-868-5987 Email: kogure.satoshi@jaxa.jp
Chris Rizos School of Surveying & Geospatial Engineering, University of New South Wales, Australia Phone: +61 2 9385 4205 Fax: +61 2 9313 7493 Email: c.rizos@unsw.edu.au
ABSTRACT The Quasi-Zenith Satellite System (QZSS) is a Japanese regional satellite navigation system (when fully deployed) consisting of several QZSS satellites in highly inclined elliptical orbits. This means that at least one satellite is constantly located at a high angle of elevation, which gives rise to the term ‘quasi-zenith’. QZSS is a satellite-based augmentation system for GPS and Galileo, capable of transmitting navigation signals that are compatible and interoperable with both of these Global Navigation Satellite Systems (GNSS). In addition to the navigation signals, QZSS also transmits augmentation signals, e.g. the L-band Experimental (LEX) signal on the E6b frequency. The LEX signal is unique for QZSS delivers correction messages – such as orbits and clock information – that enable Precise Point Positioning (PPP) for real-time applications. The aim of this research is to evaluate the QZSS LEX signal and the quality of the broadcast correction messages on the LEX for real-time PPP. The system will be tested in both static and kinematic positioning mode in Melbourne in early March 2013; and the results will be presented and compared to positioning solutions derived from conventional positioning techniques, e.g. Real-Time Kinematic (RTK). This will be the first attempt in Australia at evaluating the feasibility of using the QZSS LEX signal to deliver a high accuracy real-time positioning service to Australian GNSS users. This is a collaborative research project between the Cooperative Research Centre for Spatial Information (CRCSI) and the Japan Aerospace Exploration Agency (JAXA). KEYWORDS: GPS, QZSS, LEX, PPP, GNSS.
Session 9B
Orbit Determination
0900-1020
Impact of Orbit Dynamics on GPS-Based Satellite Orbit Determination Li Qiao Australian Centre for Space Engineering Research, School of Surveying and Geospatial Engineering, University of New South Wales, Australia 61(2)93856705 & 61(2)93137493 l.qiao@unsw.edu.au
Chris Rizos School of Surveying and Geospatial Engineering, University of New South Wales, Australia 61(2)93854205 & 61(2)93137493 c.rizos@unsw.edu.au
Andrew Dempster Australian Centre for Space Engineering Research, School of Surveying and Geospatial Engineering, University of New South Wales, Australia 61(2)93856890 & 61(2)93137493 a.dempster@unsw.edu.au
ABSTRACT Due to the success of GPS space applications more and more space missions are now replying on GPS technology. A commonly used approach to GPS-based satellite orbit determination is to use filtering algorithms such as a batch estimator or Kalman filter to blend on-board orbital GPS observations with orbit dynamics. In some situations when the geometry of GPS satellites is poor, the orbit dynamics algorithm can predict the orbit trajectory with the required level of accuracy. Considering the on-board computational workload, the orbit dynamics algorithm could account for all the perturbations. But to what extent the orbit dynamics model can be reduced without introducing too much error in orbit determination/prediction is worthy of study. This paper reviews the orbit dynamics models for various satellite missions from Low Earth Orbit to High Earth Orbit. Then the paper discusses the impact of gravitational and non-gravitational forces, and the integration method on the orbit determination/prediction performance. An assessment tool has been developed using STK and Matlab to assist in evaluating orbit dynamics performance under different mission scenarios. KEYWORDS: orbit dynamics, on-board GPS, orbit determination
Analysis of Regionally Enhanced GPS Orbit and Clock Solutions for Supporting Real-Time Positioning Charles Wang and Yanming Feng Queensland University of Technology, Australia, cc.wang@qut.edu.au
Shengfeng Gu and Chuang Shi Wuhan University, China
ABSTRACT Currently, several IGS Analysis Centres, such as GFZ and CODE, are generating ultra-rapid GPS orbit and clock solutions from approximately 80 ~ 120 global CORS in supporting real-time application. Such solutions are typically accurate to approximately 3cm and 150ps for observed orbit and clock solution and approximately 5cm and 3ns for predicted orbit and clock solution. Although, the predicted orbits are of high quality, large error of more than 10cm can sometimes occur and can impact on the quality of positioning (PPP in particular), downgrading accuracy and increasing initialisation times. This work explores the benefits of using a regionally enhanced CORS network to derive GPS orbit and clock solutions for supporting real-time application. The regionally enhanced network is comprised of a global evenly distributed CORS network with addition of a densely distributed network in Australia and New Zealand region. A series of computational schemes were performed to demonstrate the benefits of such network on the GPS orbit and clock solutions.
Gamit and PANDA software were used to compute daily GPS orbit solutions from different network configurations of global networks (G35, G65, G84 and G100) and regional network (A20, A50, A80). The solution performances were analysed based on the orbital differences with respect to the IGS final orbit solution. The result shows overall improvements (up to 14%) in the regionally enhanced orbit solutions, for both Gamit and Panda POD processing, compared to the solutions derived from global network. When comparing to SIU hourly ultra-rapid solutions, QUT Gamit derived regionally enhanced orbit can provide improvements of 15~28% in the estimated orbit solution and 12~ 26% in the predicted (24hr) solution. Additionally, the orbital differences over GPS satellite arcs that are visible by any of the five chosen Australian CORS stations (ALIC, DARW, TOW2, HOB2 and YAR3) shows higher percentage of improvements compared to satellite arcs not visible within Australian region. Finally, it is noted that the use of more regional stations (>20) does not necessarily offer additional benefits, it is more important to keep use of well distributed and high quality stations. The recommended configuration for generating regionally enhanced orbit solutions is a well distributed 100 to 120 stations of which a total of 20 to 30 stations chosen from Australian and New Zealand region. The regionally enhanced clock solutions were computed with PANDA software using a combination of G65, G100 and A50 network configurations for 30 days duration. Analysis have shown improvements in the regionally enhanced clock solutions where RMS for G65, G65+A50, G100 and G100+50 network configurations are 0.113ns, 0.090ns, 0.073ns and 0.070ns respectively. KEYWORDS: GPS, regional enhancement, precise orbit determination and clock estimation.
Estimation of Initial State and Model Parameters for Autonomous GNSS Orbit Prediction Juha Ala-Luhtala Tampere University of Technology/Finland Phone: +358456509464, juha.ala-luhtala@tut.fi
Mari Seppänen Tampere University of Technology/Finland mari.j.seppanen@tut.fi
Henri Nurminen Tampere University of Technology/Finland henri.nurminen@tut.fi
Simo Ali-Löytty Tampere University of Technology/Finland simo.ali-loytty@tut.fi
Robert Piché Tampere University of Technology/Finland robert.piche@tut.fi
ABSTRACT In self-assisted GNSS the orbit of a satellite is predicted by solving the differential equation that models its motion. The equation of motion consists of accelerations due to different forces. Our model includes the most important of these forces: Earth's gravity, Lunar and Solar gravity and Solar radiation pressure. The effect of unmodeled forces is taken into account by using Gaussian white noise with covariance matrix estimated from historical orbital data. The estimation of model parameters (Solar radiation pressure and Earth Orientation parameters) and initial state for the prediction is conducted in two steps. First, the parameters that are expected to stay unchanged for long periods of time are estimated using the precise orbits generated by the International GNSS Service (IGS). In the second step, the satellite’s broadcast ephemeris is used to estimate the initial state and dynamic model parameters. The estimation steps are formulated as non-linear continuous-discrete time filtering problems. The filtering equations are integrated numerically and the performance of different numerical integration methods (Extended, Cubature and Unscented Kalman filters) is compared. Using the estimated initial state and model parameters the satellites orbit is predicted 5 days into the future. The accuracy and consistency of the predicted orbits is
analysed using the IGS precise ephemerides. In this paper only GPS satellites are considered, but the method can be extended to other satellite systems. KEYWORDS: Satellite orbit prediction; Gaussian filtering; Estimation
Session 9C
GSNSS Infrastructure II
0900-1020
Designing and Implementing a Successful GNSS Infrastructure Project Neil Ashcroft, Leica Geosystems, Singapore Joël VAN CRANENBROECK, Leica Geosystems, Switzerland Vincent LUI, Leica Geosystems, Hong Kong
ABSTRACT Most of the GNSS Network RTK projects have been developed by the economical justification that an active geodetic network would reduce the cost of maintaining a traditional (passive) geodetic network where the maintenance of the benchmarks and the control survey were a significant part of the owner’s budget. A GNSS Network RTK can also be justified where there was no geodetic network to assist the creation and the maintenance of a Spatial Data Infrastructure to support land governance and cadastre operations. We also have seen the decision to deploy such technology as part of prestige from governmental organizations but without a clear analysis of user’s need and business plan leaving such positioning infrastructure with only few users and a request to re-engineer the approach. The authors have been in charge of both the development of the technology and also on the promotion, the design and the implementation of numerous GNSS Network RTK positioning infrastructures worldwide. This paper is dealing with the reasons the authors have identified to make such project a success or a failure. KEYWORDS: : GNSS Infrastructure, GPS, GLONASS, COMPASS, GALILEO, GNSS, RTCM, RTK, NTRIP, Business Model
Investigation of Virtual RINEX Data Performance Volker Janssen Survey Infrastructure and Geodesy, Land and Property Information NSW Department of Finance & Services, Bathurst NSW 2795, Australia Tel: +61-2-6332 8426, Fax: +61-2-6332 8479, Email: Volker.Janssen@lpi.nsw.gov.au
ABSTRACT Network Real Time Kinematic (NRTK) Global Navigation Satellite System (GNSS) technology is increasingly being utilised for a wide range of positioning applications. The advantage of NRTK is its ability to provide corrections (accounting for atmospheric and satellite orbit errors) that are based on a Continuously Operating Reference Station (CORS) network rather than a single reference station. While most users employ NRTK for real-time applications, it is also possible to benefit from network-based GNSS corrections for post-processing applications. This is achieved through the provision of Virtual RINEX data, i.e. data that would have been observed at an invisible, unoccupied (i.e. virtual) GNSS reference station specified by the user. This paper investigates the performance of Virtual RINEX data compared to observed data. An extensive 3day dataset is used to compare static positioning results obtained with Virtual RINEX data generated by CORSnet-NSW and RINEX data observed at three test sites (incorporating small and large NRTK cells) in New South Wales, Australia. At each test site, data are analysed in three ways: (1) ‘zero’ baseline processing between virtual and observed data for session lengths ranging from 24 hours to 10 minutes, (2) AUSPOS processing using virtual and observed data for 24-hour,
6-hour and 2-hour sessions, and (3) baseline processing relative to four surrounding CORS using virtual and observed data for session lengths of 24 hours, 1 hour and 10 minutes. It is found that ‘zero’ baselines vary from 1 mm (hz) and 2 mm (vt) for long observation sessions in a small NRTK cell to 15 mm (hz) and 40 mm (vt) for all observation windows investigated in a large NRTK cell. 24-hour AUSPOS solutions based on Virtual RINEX data agree with those using observed data at the 10 mm level or better, while 2-hour solutions show differences of up to about 20 mm (hz) and 40 mm (vt). Baseline processing to surrounding CORS reveals differences ranging from the fewmm level for short (10 km) baselines in a small NRTK cell to the few-cm level for long (60 km) baselines in a large NRTK cell. These results indicate that Virtual RINEX data can be comparable to observed data for some applications, provided NRTK cell size, observation length and baseline length are taken into consideration. KEYWORDS: GNSS, Virtual RINEX, Network RTK, CORSnet-NSW.
Victoria's GNSS CORS infrastructure – Current Status and Application to Reference Frame Maintenance and Research Dr Roger Fraser Department of Environment and Primary Industries, Victoria, Australia +61 3 8636 2551, roger.fraser@dse.vic.gov.au
Hayden Asmussen Department of Environment and Primary Industries, Victoria, Australia +61 3 8636 2374, hayden.asmussen@dse.vic.gov.au
ABSTRACT The Department of Environment and Primary Industries (DEPI) in Victoria continues to maintain a statewide Global Navigation Satellite System (GNSS) Continually Operating Reference Station (CORS) network known as GPSnet. Since its initial establishment in 1996, GPSnet has been used in a wide array of applications including engineering and cadastral surveying, mining, rail and port operations, precision agriculture, vegetation mapping, environmental science and asset management. In response to factors such as consumer expectation and technological evolution, GPSnet has seen considerable expansion and enhancement over the last decade. This presentation provides an overview of the current status of GPSnet, including a summary of various issues relating to the operation of a statewide CORS network. This presentation also summarises the application of GPSnet to Australian and regional reference frame maintenance, and its contribution to GNSS related research activities in the Australian context. KEYWORDS: Network Real-Time Kinematic, GNSS, CORS, reference frame, research.
Estimating Coordinate Uncertainty in AUSPOS Minghai Jia Geoscience Australia Phone: +61 2 62499045 Fax: +61 2 62499999 Email: minghai.jia@ga.gov.au
John Dawson Geoscience Australia Phone: +61 2 62499028 Fax: +61 2 62499999 Email: john.dawson@ga.gov.au
ABSTRACT AUSPOS is Geoscience Australia’s on-line static GPS positioning service, providing user access to a state-of-art analysis system via a simple web-interface. AUSPOS delivers ITRF2008, GDA94 and AHD coordinates to Australian users and ITRF2008 coordinates to international users by simultaneously processing up to 7 days of user-supplied GPS data from up to 20 sites. Like other GPS data processing systems, the internal coordinate uncertainty of AUSPOS solutions is typically optimistic. In this paper, we report on a more realistic uncertainty estimation method for AUSPOS. Test results using this method show that uncertainties of AUSPOS solutions vary from several millimetres to several centimetres, with respect to ITRF2008, depending on the duration of data
sets and their global location. KEYWORDS: AUSPOS; GPS; Uncertainty
Session 10A
Precise Point Positioning and GNSS Meteorology
1050-1230
Real-Time Precise Point Positioning – Are We There Yet? Thomas Grinter University of New South Wales, Sydney, Australia Phone: (02)63328211 Email: Thomas.Grinter@lpi.nsw.gov.au
ABSTRACT The concept of Precise Point Positioning (PPP) using Global Navigation Satellite System (GNSS) technology was first introduced in 1976, however it took until the 1990s for PPP to generate interest amongst the greater GNSS community. Over the last two decades, dual-frequency PPP has been extensively researched, culminating in the availability of PPP post-processed correction products from organisations such as the National Aeronautics and Space Administration (NASA) Jet Propulsion Laboratory (JPL), the International GNSS Service (IGS) and Natural Resources Canada (NRCan). With the advent of cost-effective, accurate, Real-Time Kinematic (RTK) positioning provided by an increasing number of Continuously Operating Reference Station (CORS) networks around the world, the focus of PPP has shifted to real-time or near real-time solutions. A real-time or near realtime PPP solution would potentially allow for a viable alternative to RTK solutions in some circumstances, while maintaining the advantages of PPP over differential real-time products. However, several limitations still remain, primarily the long convergence times needed to resolve ambiguities, currently restricting the use of PPP for real-time applications. This paper provides a brief history of the development of PPP and reviews the advances made in PPP in the last two decades with an emphasis on the development of a real-time or near real-time PPP solution. KEYWORDS: Precise Point Positioning, GNSS, CORS, Real-Time Kinematic, IGS.
A Reference Station-based GNSS Computing Mode to Support Unified Precise Point Positioning and Real Time Kinematic Positioning Services Yanming Feng and Charles Wang Queensland University of Technology, Australia,y.feng@qut.edu.au
Shengfeng Gu and Chuang Shi Wuhan University, China
Chris Rizos The University of New South Wales, Australia
ABSTRACT Currently, the GNSS computing modes are of two classes: user receiver-based processing and network-based data analysis. A GNSS reference receiver station essentially contributes raw measurement data in either the RINEX file format or as real-time data streams in an RTCM format. Very little computational effort is done by the reference station. This paper describes a new GNSS computing framework that incorporates three GNSS modes: reference station-based, user receiver-based and network-based data processing. It is proposed that raw data streams from each GNSS reference receiver station be processed in a distributed manner, i.e, at either the station itself or at a hosting data server/processor, to generate station-based solutions (and perhaps additional useful information). The station-based processing referred to here is similar to the “precise point positioning” (PPP) technique. PPP processing estimates a number of “local” parameters but keeps the satellite orbits/clocks and the reference receiver station coordinates
fixed. The estimated reference receiver-specific parameters include precise receiver clock, zenith tropospheric delay, and differential code biases, as well as line-of-sight information such as ionospheric delays, L1 and L2 ambiguity parameters, azimuth and elevation angles. In such a mode not only can the nearby positioning users directly apply some of the corrections from the reference station(s) for enhanced real-time precise positioning, but also various network-based users can form linear observation equation systems directly from each reference station solution to support commercial services and scientific data analysis. At the user receiver, PPP and real-time kinematic (RTK) modes are unified under the same observation models, and the distinction is how the user receiver software deals with corrections from the reference station solutions and the ambiguity estimates in the observation equations. Preliminary numerical tests demonstrate that the reference station-based solutions, such as the convergence of ambiguity estimates, can stabilise within 4 hours of receiver operation. With station-based solutions from three reference stations within distances of 20 to 100km the user receiver positioning results with various schemes were analysed, showing accuracy improvement of the proposed station-augmented PPP solutions with respect to the traditional PPP solutions. KEYWORDS: GNSS, station-based processing, precise point positioning, network-based analysis, and real-time kinematic positioning.
Comparing GPS Radio Occultation Observations with Radiosonde Measurements Over Antarctica R. Norman1, J. Le Marshall1,2, B.A. Carter1, K. Zhang1, G. Kirchengast3, S. Alexander4 , C-S.Wang1 and Y. Li1 1
Satellite Positioning for Atmosphere, Climate and Environment (SPACE) Research Centre, RMIT University, Melbourne, Australia, Tel: 99256735, email: robert.norman@rmit.edu.au 2 Centre for Australian Weather and Climate Research (CAWCR), Bureau of Meteorology, Melbourne, Australia 3 Wegener Center for Climate and Global Change (WEGC), University of Graz, Graz, Austria 4 Australian Antarctic Division, Hobart, Tasmania, Australia
ABSTRACT GPS Radio Occultation (RO) is a space-based technique for sounding the Earth’s atmosphere. This technique has been shown to significantly improve weather forecasting and climate monitoring over many regions of the Earth. The GPS RO technique uses specially-designed GPS L-band frequency receivers on-board Low Earth Orbit (LEO) satellites to receive signals from GPS satellites. The Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) is a joint Taiwan and USA satellite program and was launched into orbit in April 2006. GPS RO data from this constellation of six FORMOSAT-3 (Formosa Satellite Mission #3), LEO (800 km altitude) micro-satellites provides an observational data type for operational meteorology and significant information on the thermodynamic state of the atmosphere. In the Antarctic region there are only 18 radiosonde (RS) weather stations mainly distributed along the coastal fringe. As such this RS network is far from ideal for studying the atmosphere, meteorology and climatology in the Antarctic region. It does however provide excellent reference stations to test and validate the GPS RO technique as a suitable meteorological data type in the Antarctic region. In this study the COSMIC GPS RO temperature and pressure profiles are compared to those measured using radiosondes in the Antarctic region. Yearly and seasonally, weighted area average temperature profiles from the Antarctic region are also presented. KEYWORDS: Radio Occultation, Antarctica, radiosonde, satellites, COSMIC
A New Australian GNSS Radio Occultation Data Processing Platform Kefei Zhang SPACE Research Centre/RMIT University/Australia (03) 99253272 kefei.zhang@rmit.edu.au
Shaocheng Zhang SPACE Research Centre/RMIT University/Australia (03) 99253709 shaocheng.zhang@rmit.edu.au
John Le Marshall The Australian Bureau of Meteorology
Robert Noman, Ying Li, Congliang Liu and Brett Carter SPACE Research Centre/RMIT University/Australia
ABSTRACT GNSS Radio Occultation (RO) is a robust space-borne technology for sounding the Earth’s atmosphere with global coverage. The data retrieved using GNSS RO has been demonstrated with unprecedented advantages and used to improve operational weather analysis and forecasting and to assist in regional reanalysis and climate monitoring. This technology has been considered as a new avenue for profiling the atmosphere with a high accuracy and high vertical resolution that is not subject to biases and instrument drifting and has heralded a new era of climate, weather and severe weather forecasting systems. Most recently, GNSS RO profiles from COSMIC, MetOp and GRACE have been successfully used operationally in Australia and eight-hour improvement has been demonstrated. In 2010, a prestigious Australia Space Research Program (ASRP) project was awarded to an international consortium led by the SPACE Research Centre in RMIT University. The aims of this multi-million dollar ASRP project are to develop platform technologies for Space, Atmosphere and Climate. A number of software platforms in the areas of GPS radio occultation, space tracking and atmosphere modelling have been developed since being awarded the ASRP project. This contribution introduces the new GNSS data processing platform developed including its rationale, main functionalities, processing engine and algorithm used etc. The system is developed based on a customized Bernese GPS software platform with selected processors from both EGOPS and ROPP. The current version of the system is able to carry out extensive data processing from Level 0 LEO on-board receiver raw observations to the Level 2 atmospheric profiles of bending angle, refractivity, temperature and pressure. This new GNSS RO platform consists of several major modules, i.e. LEO satellite precise orbit determination module, GNSS RO excess phase data processing module, quality control module and atmosphere parameter retrieval module. Various results from this new system have been compared with other independent RO data processing products (e.g. UCAR) and consistent results have been obtained. It is anticipated that the new GNSS RO system will provide an important research platform for our research and a valuable contribution to the international community in GNSS RO. This system can be a very useful tool for the operational usage of the GNSS RO in Australian NWP models, severe weather and climate research. This will also be an important step forward for future Australian GNSS satellite remote sensing programs. KEYWORDS: GNSS radio occultation, Platform Technology, Bernese, Atmosphere.
Improved Real Time Ionospheric Scintillation and TEC Monitoring Using All GNSS Constellations Rod MacLeod NovAtel Australia Pty Ltd Sydney, NSW, Australia
ABSTRACT Given the predictable impact of the Ionosphere on the GNSS signals, these signals provide an excellent tool for ionospheric monitoring on a global and continuous basis. The presentation discusses how Ionospheric disturbances induce rapid fluctuations in the phase and the amplitude of received GNSS signals and the short comings of previous ionospheric monitoring that used GPS only Semi-codeless L2 tracking dual frequency receivers. These receivers greatly limited the accuracy, robustness and utility of the TEC measurements and were useless for scintillation measurements on L2. It provides real time results of NovAtel’s GPStation-6 receiver with the ability to now track multi-frequency measurements, for all GPS+GLONASS+GALILEO+BEIDOU+QZSS satellites by using a new specialized receiver design that provides robust and less noisy real time ionospheric measurements. KEYWORDS: ionosphere; GNSS; amplitude scintillation; phase scintillation; total electron content (TEC); space weather; monitoring.
Session 10B
Network and Signal Processing
1050-1230
Mixed Signals DOA Estimation Method in the Presence of Nonuniform Noise Yuexian Wang School of Electrical and Electronic Engineering, University of Adelaide, Australia jwang@eleceng.adelaide.edu.au
Matthew Trinkle School of Electrical and Electronic Engineering, University of Adelaide, Australia mtrinkle@eleceng.adelaide.edu.au
Brian Ng School of Electrical and Electronic Engineering, University of Adelaide, Australia brian.ng@adelaide.edu.au
ABSTRACT A new estimation method combining oblique projector and space-time matrix algorithm is proposed when uncorrelated and coherent sources coexist．With this algorithm，the coherent and incoherent sources are estimated separately. The coherent sources are estimated by exploring the symmetry of array geometry to avoid the significant loss of array aperture and high computation of the conventional smoothing method．The oblique projector instead of differencing method is used to make the algorithm work without the restriction of Toeplitz configuration. Therefore，the algorithm is suitable for arbitrary array structure．This method can obviously improve the overload capability to resolve sources，and along with the processing of time-space matrix reconstruction， the nonuniform noise is transformed to white noise．As a result，the method discussed can fully eliminate nonuniform noise. KEYWORDS: centre-symmetric virtual array; direction of arrival (DOA); coherent signals; nonuniform noise
Design of Network Architecture for Routing in Terrestrial and Satellite Network Kwang-Chun Go School of Electrical and Computer Engineering, Ajou University, Korea +82-31-219-2474, xaviersr@ajou.ac.kr
Jae-Hyun Kim School of Electrical and Computer Engineering, Ajou University, Korea
ABSTRACT In a terrestrial network interworking with satellite networks, it is important to design the optimal network architecture for selection of efficient routing paths. Especially, the satellite network has different characteristics compared with the terrestrial network. Thus, the characteristics of satellite networks should be considered to design interworking network architecture. In this paper, we design network architecture by considering the characteristics of the terrestrial network interworking with the satellite networks. We introduce several design criteria such as AS separation, NCC configuration, topology of satellite link, and etc. Then, we consider all combinations of the criteria to design the routing scenarios on the network architectures and evaluate the advantages and disadvantages between routing scenarios. Finally, we propose efficient network architecture of the terrestrial network interworking with a satellite network and evaluate the end-to-end delay and packet error rate performance for the proposed network architecture. KEYWORDS: Routing, Network architecture, Terrestrial network, Satellite network
DOA Estimation for Uncorrelated and Coherent Signals with Centre-symmetric Virtual Array Yuexian Wang School of Electrical and Electronic Engineering, University of Adelaide, Australia jwang@eleceng.adelaide.edu.au
Matthew Trinkle School of Electrical and Electronic Engineering, University of Adelaide, Australia mtrinkle@eleceng.adelaide.edu.au
Brian Ng School of Electrical and Electronic Engineering, University of Adelaide, Australia brian.ng@adelaide.edu.au
ABSTRACT A new direction of arrival (DOA) estimation method for the uniform linear array is proposed to cope with the scenario where both uncorrelated signals and coherent signals are presented. By constructing a centre-symmetric virtual array manifold and exploiting its properties coherent signals can be decorrelated and then estimated without the interference of uncorrelated signals, while the uncorrelated signals are estimated by utilising the uniqueness condition of array manifold. The twostage estimation method is simple but effective. It expands the aperture of array and can estimate more DOAs with less antennas than traditional spatial smoothing methods. It has higher estimation precision. Simulation results demonstrate the effectiveness and efficiency of the proposed method. KEYWORDS: centre-symmetric virtual array; direction of arrival (DOA); coherent signals; real
signals
Simulation and Analysis of Time Synchronization Based on Inter-satellite Link Xuhai YANG Key Laboratory of Precision Navigation and Timing Technology/National Time Service Center， Chinese Academy of Sciences / China, Email: yyang@ntsc.ac.cn +86-29-83890424 & +86-29-83892309
Lin Fang Key Laboratory of Precision Navigation and Timing Technology / University of Chinese Academy of Sciences / China +86-18292485175
BaoQi Sun Key Laboratory of Precision Navigation and Timing Technology/National Time Service Center， Chinese Academy of Sciences / China +86-15249092933
ABSTRACT The inter-satellite link is one of key techniques in the autonomous operation of satellite navigation system. Inter-satellite two-way time transfer calculation formula is built in this paper by adopting asynchronous two-way satellite time transfer technology in GPS constellation. Corrective method of main systematic error is proposed. Inter-satellite asynchronous two-way time synchronization is simulated on the basis of IGS precise ephemeris and on-board clock. We analyze the impact of epoch domestication of asynchronous link pseudo-range, initial orbit, and other main systematic error on satellite time synchronization. Simulation results show that epoch domestication of asynchronous link pseudo-range and initial orbit have little impact on satellite clock-error, and thus it needn’t be taken into account. The error caused by relativity theory effect and multi-path have large impact on satellite clock-error, and those should be corrected with theory formula. KEYWORDS: inter-satellite link，time synchronization，GPS
Low Cost Adaptive Array Signal Processing by Subarray Selection Xiangrong Wang (1) University of New South Wales/Australia Email: x.r.wang@unsw.edu.au
Andrew Dempster (2) University of New South Wales/Australia Email: a.dempster@unsw.edu.au
Elias Aboutanios (3) University of New South Wales/Australia Email: elias@unsw.edu.au
ABSTRACT Adaptive antenna arrays have been proposed to mitigate strong interference and multipath in Global Navigation Satellite Systems (GNSS) receivers. However, the high cost of an entire frontend and limited signal processing resources make large antenna array a luxury for GNSS receivers. Therefore, we propose in this work a low cost adaptive array processing strategy by subarray selection, while with maximum preserved performance. There are only K front-ends installed in the receiver, thus the hardware cost is reduced dramatically. Then we adaptively select an optimum K-antenna subarray from N candidates using switches and then connect them to the following signal processing network. A parameter defined as Spatial Correlation Coefficient (SCC) is introduced to characterise the spatial separation between the satellite signal and the interference and used as a cost function to calculate the optimum subarray. The relationship between the effective C / N 0 and the SCC is expressed as a closed formula as well. This formula shows that the effective C / N 0 depends on both the number of selected antennas K and the SCC value, thus there is no linear relationship between the effective C / N 0 and K. The optimum K-antenna subarray can guarantee negligible performance loss when the satellite signal and the interference are close in
space and no more than 10log10 N / K when they are well separated. An 8-antenna circular array is used to collect the data in our experiment and only the data received from selected antennas is processed. Experimental results show that (1) SCC is an effective parameter for characterising the effect of array configuration, with the smallest value denoting the best performance under the fixed subarray size; (2) the optimum subarray can reduce the hardware cost dramatically with maximum preserved performance; (3) given the fixed hardware cost, the optimum subarray can achieve the best performance. KEYWORDS: adaptive array processing, subarray selection, low cost, spatial correlation coefficient, effective carrier to noise density ratio
Session 10C
GNSS Software Receivers
1050-1230
A High Accuracy Reconfigurable Platform of Multi-mode Navigation Signal Simulator based on SNWA Feng Xuzhe (1) College of Mechatronics Engineering and Automation, National University of Defense Technology ,China
0731-84575313/0731-84576475/kd805fxz@163.com
Chen Jianyun (2) College of Mechatronics Engineering and Automation, National University of Defense Technology ,China
0731-84575313/0731-84576475/kdcjy@sina.com
Lin Jinmao(3) College of Mechatronics Engineering and Automation, National University of Defense Technology ,China
0731-84575313/0731-84576475/kd805fxz@163.com
ABSTRACT This paper represents a high accuracy reconfigurable platform of multi-mode navigation signal simulator based on SNWA(Software Navigation Waveform ArchitectureďźŒSNWA). Navigation signal simulator, as the resource standard, can provide a real-like signal environment for the research and test of navigation receiver. What’s more, it can shorten the development cycle and lower the research risks. With a adaptability to different navigation systems and signal forms, the navigation signal simulator should be multi-mode and reconfigurable, so it can satisfy the demand of compatibility and renewal. That is to say, multi-mode navigation signal can be generated on same hardware platform by software reconfiguration. Furthermore, these signals which in different mode and different frequencies can be switched rapidly and easily. The paper introduces the principle of SNWA at first, and then studies the architecture of reconfigurable navigation signal simulator based on SNWA, some reconfigurable designs for important modules are also stated, such as precise time delay, navigation signal generator, interference signal generator, et al. A high resolution signal delay algorithm based on multilevel re-construct delay filters is investigated, test method and result are also given in this paper. In addition, the system performance evaluation, algorithm of high accuracy delay and parameter estimation validation are listed at last. The navigation signal simulator has high adaptability to different navigation systems, such as Beidou, GPS, GLONASS and Galileo. Its main performances are as follows, pseudorange uncertainty is 1mm, zero stabilization is 1cm, interchannel bias is 1cm, coherence between different frequencies is 2cm. KEYWORDS: navigation signal simulator; multi-mode; reconfigurable; high precision; SNWA
GNSS Software Receiver Sampling Noise and Clock Jitter Performance and Impact Analysis Chen JianYun (1) College of Mechatronics Engineering and Automation National Univ. of defense Technology China 13974980956 kdcjy@sina.com
Fen XuZhe (2) College of Mechatronics Engineering and Automation National Univ. of defense Technology China 13974980956 kdcjy@sina.com
ZhouYonBin (3) College of Mechatronics Engineering and Automation National Univ. of defense Technology China 13974980956 kdcjy@sina.com
ABSTRACT In the design of a multi-frequency multi-constellation GNSS software defined radio receivers is becoming more and more popular due to its simple architecture, flexible configuration and good coherence in multi-frequency signal processing. It plays an important role in navigation signal processing and signal quality monitoring. In particular, GNSS software defined radio receivers driving the sampling clock of analogue-to-digital converter (ADC) by FPGA implies that a more flexible radio transceiver design is possible. According to the concept of software defined radio(SDR), the ideal is to digitize as close to the antenna as possible. Whereas the carrier frequency of GNSS signal is of the frequency of GHz, converting at this frequency is expensive and consumes more power. Band sampling method is a cheaper, more effective alternative. When using band sampling method, it is possible to sample a RF signal at twice the bandwidth of the signal. Unfortunately, as the other side of the coin, the introduction of SDR concept and band sampling method induce negative influence on the performance of the GNSS receivers. ADCs suffer larger sampling clock jitter generated by FPGA; and low sampling frequency introduces more noise to the receiver.Then the influence of sampling noise can not be neglected. The paper analyzes the sampling noise, presents its influence on the carrier noise ratio, and derives the ranging error by calculating the synchronization error of the delay locked loop. Simulations aiming at each impact factors of sampling-noise-induced ranging error are performed. Simulation and experiment results show that if the target ranging accuracy is at the level of centimeter, the quantization length should be no less than 8 and the sampling clock jitter should not exceed 60ps. KEYWORDS: GNSS software receivers, band sampling, sampling noise, clock jitter, ranging error.
Analysis of Receiver Observables to Spoofing Attacks Using Software Receivers. Ryan J. R. Thompson, Ediz Cetin, Andrew G. Dempster University of New South Wales, Australia. Tel: +61293854184 E-mail: r.thompson@unsw.edu.au, e.cetin@unsw.edu.au, a.dempster.@unsw.edu.au
ABSTRACT Spoofing attacks, where false satellites signals are broadcast to trick the operation of a GNSS receiver, present a serious threat to GNSS security. There are a number of receiver observables, such as C/No, correlator function shape, pseudo-range, and clock offset, to name a few, which will show variations during spoofing attacks. The aim of this work is to investigate the response of these observables, using a commercial and a MATLAB based software receiver, to different types of spoofing attacks. This work will make use of the Texas Spoofing Test Battery, a collection of scenarios for evaluating spoofing detection techniques, provided by the Radionavigation Laboratory at the University of Texas at Austin. The first part of this work is concerned with the conversion of these datasets, which are at high sampling and bit rates, for use in software receivers using open source tools such as gnuradio. The second part of this work looks at the response of the receiver observables and how receiver settings, such as correlator spacing,
integration times, tracking loop bandwidths and bit-rates, affect their response to spoofing. The results of the analysis will provide insights into the ability of an autonomous GPS receiver to detect spoofing using only the observables generated during the normal navigation process. The datasets will also be converted for use with a commercial GNSS replay unit to analyse and quantify the effect of quantization and up-conversion operations when replaying the scenarios to a software receiver connected to a RF front-end operating in real-time. KEYWORDS: spoofing, software receivers, C/No, clock offset, tracking loops.
Multi-processor Architectures for FPGA-based Multi-GNSS Receivers Nagaraj C Shivaramaiah Andrew G Dempster Australian Centre for Space Engineering Research, UNSW, Australia Ph: +61(2)93856702 Fax: +61 (2) 9313 7493 email: nagaraj@unsw.edu.au
ABSTRACT This paper analyses multi-processor architectures for software defined GNSS receivers implemented using FPGA-based SoC technology. Several design architectures are studied in the paper starting from a single high-end processor based solution on one end of the spectrum to a coarse-grained architecture with multiple low-end soft-core processors on the other end. Considering the availability of the range of processors in the current FPGA devices, the challenges and the feasibility of these design architectures are discussed. While the horse-power of the FPGA-based high-end processors becomes a challenge for simultaneous processing of multiple GNSS signals, the architecture intricacies pose other interesting challenges for the coarse-grained architectures. The inter-signal and inter-processor interaction and related intricacies in the multiprocessor architectures needs a thorough analysis of the debating design partition methodologies. The paper will touch on these topics and provide recommendations based on initial results and use-cases. KEYWORDS: Multi-GNSS, Receiver design, Multi-processor.
Mitigation of Standing Multipath Based on Adaptive Filtering Xuanying Zhou School of Science, National University of Defense Technology, China Phone: +86-731-84573260, Fax: +86-731-84574234, email address: djulia1020@gmail.com
Bo Chen School of Science, National University of Defense Technology, China Phone: +86-731-84573260, Fax: +86-731-84574234, email address: chenbo0354@yahoo.com
Jing Yao School of Science, National University of Defense Technology, China Phone: +86-731-84573260, Fax: +86-731-84574234, email address: isabellayj@gmail.com
Jiying Liu School of Science, National University of Defense Technology, China Phone: +86-731-84573260, Fax: +86-731-84574234, email address: gene0572@163.com
ABSTRACT GEO satellites have been used in satellite navigation systems such as Beidou and augmentation systems of GPS. Because GEO satellites are almost stationary relative to the Earth, some multipath signals are varying very slowly. This causes the “standing multipath�, which dramatically decreases the accuracy of positioning. Some approaches combined by radio frequency and postprocessing methods have been proposed to mitigate the standing multipath. The post-processing methods can be classified into two types: the time-domain and frequency-domain processing. While the frequency of multipath of the GEO satellite is low, which may lap over those of ionosphere, troposphere and so on, they are difficult to separate in frequency domain. It also needs the data in at least one period to calculate its spectrum. For the multipath of one-day period, the frequency domain method needs a whole day to initialization. The time domain processing can
be done in a way called code noise and multipath (CNMP), which was proposed for real time processing in Wide Area Augmentation System (WAAS). Because multipath in the carrier-phase measurement is quite small, the multipath in pseudorange can be cancelled in the similar way as pseudorange smoothing. Unfortunately, in our experiments it is found that the smoothed code in CNMP still has some error left, which has the same periods as standing multipath. As an improvement, we proposed a coefficient-adaptive filter. The coefficients of this filter are estimated according to the modeling of standing multipath data by methods of time series analysis. A numerical verification was carried out by using WAAS data. The results indicate that the proposed method can significantly suppress the standing multipath and improve the rate of filtering convergence. KEYWORDS: standing multipath, adaptive filtering, GEO satellites, time-frequency analysis
Session 11A
Multi GNSS Data Processing
1330-1530
Improved High Precision GNSS Positioning with New Satellites and Signals Nicholas Talbot Research Fellow, Trimble Navigation, Australia Ph: +61 (0)3 9518 7464; Fax: +61 (0)3 9518 7401; nick_talbot@trimble.com
Timo Allison Engineering Manager, Trimble Navigation, UK timo_allison@trimble.com
Kendall Ferguson Software Engineer, Trimble Navigation, USA kendall_ferguson@trimble.com
Rodrigo Leandro Engineering Manager, Trimble Navigation, Germany rodrigo_leandro@trimble.com
Gang Lu Development Engineer, Trimble Navigation, USA gang_lu@trimble.com
Stuart Riley Research Fellow, Trimble Navigation, USA stuart_riley@trimble.com
Stephan Seeger Development Engineer, Trimble Navigation, Germany stephan_seeger@trimble.com
Ralf Stolz Development Engineer, Trimble Navigation, Germany ralf_stolz@trimble.com
ABSTRACT The world is on the cusp of a significant enhancement to the constellation of Global Navigation Satellite Systems. By 2015, approximately 90 navigation satellites will be in orbit around the earth; by 2020, the number of satellites will increase to 120 or more. Today, in the Asia-Pacific region, 30 or more GNSS satellites are routinely in view above the local horizon – this provides an opportunity to explore the benefits of using signals from the Chinese BeiDou; Japanese QZSS; Russian GLONASS; and US GPS constellations, for precise positioning. Precise GNSS positioning techniques that deliver centimetre-level accuracy are now widely used across a broad spectrum of applications, among the many are: precision agriculture, construction, machine control, and surveying. The performance of high-precision, Real-Time Kinematic (RTK) positioning is often measured in terms of initialization time, accuracy and solution reliability, and these parameters are strongly related to the prevailing satellite geometry. This paper examines the benefits and challenges of using the latest Global Navigation Satellite signals for precise positioning. Several RTK tests were conducted with and without the inclusion of
new satellite measurements. The results indicate that additional satellites produce substantial improvement in the standard deviation and range of the position errors. The inclusion of new satellite system measurements is shown to particularly strengthen the height component estimates and the solution integrity. Furthermore, the spatial distribution of the satellites increases the ability of users to operate in challenging tracking environments where parts of the sky are obstructed. KEYWORDS: RTK, Precise-Positioning, BeiDou, QZSS, GLONASS
GNSS Satellite Selection With Integrity Consideration: A Case Study in the Differential Positioning Mode Liang LI Academy of Opto-electronics, Chinese Academy of Science, Beijing, China, 100094 (+86)-010-82178653, lilianghrb@gmail.com
Hong YUAN Academy of Opto-electronics, Chinese Academy of Science, Beijing, China, 100094 (+86)-010-82178851, yuanh@aoe.ac.cn
Chao YUAN, Dongyan WEI, Ruidan LUO Academy of Opto-electronics, Chinese Academy of Science, Beijing, China, 100094 (+86)-010-82178653, yuanchao_yx@aoe.ac.cn
ABSTRACT With the promising future of Global Navigation Satellite System (GNSS), the high precision Location Based Services (LBS) based on differential positioning in high density urban area is more enviable than ever. As tracking all available satellites simultaneously in the user receiver leads unacceptable computation burden. Satellite selection therefore were proposed to release the computation limitation with selecting the minimum operation satellites set to maintain endurable positioning accuracy under the least Dilution of Precision (DOP) loss criterion. Most of the existing satellite selection methods are based on single-point positioning model. As the differential residual errors vary with time, measurement quality should therefore be considered in the selection criterion. Furthermore, another challenge for satellite selection is the signal interference/deformation in the urban area as multipath error will be dominant, the integrity monitoring need to be used in such case. A novel satellite selection algorithm with using total weighting score method is presented to select the optimal satellites set with satisfying the requirement from both accuracy and integrity. The selection threshold values for weighted DOP and integrity is deduced from the Required Navigation Performance (RNP). The performance of the proposed method was validated with using the real-world data which was collected in Beijing. The experiment results demonstrate that weighted satellites selection method could provide not only the minimum accuracy and integrity loss, but also with a reasonable computation burden, and thus could be an edge option for the differential positioning in the urban canyon area. KEYWORDS: GNSS; differential positioning; satellite selection; accuracy; integrity
Effect of Satellite Selection of GPS and GLONASS by High Accuracy Positioning with Roving Antenna Takahiro Ikeda Transportation Engineering and Socio-Technology, Graduate School of Science and Technology /Nihon University/Japan Phone&Fax: +81-47-469-8147 Email:ikeda.takahiro@trpt.cst.nihon-u.ac.jp
Tatsunori Sada Department of Transportation Engineering and Socio-Technology, Science and Technology / Nihon University /Japan Phone&Fax: +81-47-469-8147 Email:sada@trpt.cst.nihon-u.ac.jp
Tetsuhiro Ishizaka Department of Transportation Engineering and Socio-Technology, Science and Technology / Nihon University /Japan Phone&Fax: +81-47-469-8147 Email:ishizaka.tetsuhiro@nihon-u.ac.jp
ABSTRACT GLONASS and other satellite systems was launch to operate and has come to be used in recent years, although GPS had mainly used. Therefore, the improved availability of high accuracy positioning is expected in urban and mountainous areas by using GLONASS with GPS. However, the increase of satellites may cause the increase of multipath; it is required to beforehand select the GNSS without multipath by checking the status of satellite radio. The authors proposed the selection method of satellite signal with multipath using the distance change of the carrier wave L1 and L2, in addition to the signal strength of the satellite. The effect of high accuracy positioning was verified by the satellite selection to be used for positioning. In the experiment, GNSS satellite signal were received. And its observation points were set on the course for moving in order to observe the various ambient conditions. As a result, satellite signal affected by multi-path was confirmed by efficient combination of distance and signal strength of the carrier wave changes. In addition, positioning ratio of fixed solution was improved by the satellite selection. KEYWORDS: GPS，GLONASS，high accuracy positioning，multipath，carrier wave L1 and L2
Receiver Inter-Channel Bias Search Technique for Real-Time Kinematic GPS/GLONASS Hee Sung Kim School of Electronics, Telecomm., and Computer Eng./Korea Aerospace University/Korea 82-2-300-0148, hskim07@kau.ac.kr
Je Young Lee School of Electronics, Telecomm., and Computer Eng./Korea Aerospace University/Korea 82-2-300-0148, jeylee@kau.ac.kr
Kwang Ho Choi School of Electronics, Telecomm., and Computer Eng./Korea Aerospace University/Korea 82-2-300-0148, sahnhara@kau.ac.kr
Hyung Keun Lee School of Electronics, Telecomm., and Computer Eng./Korea Aerospace University/Korea 82-2-300-0131, hyknlee@kau.ac.kr
ABSTRACT It is anticipated that the number of visible navigation satellites would increase dramatically in the near future by multiple GNSS constellations. Currently, most representative examples of multiple constellations include GPS and GLONASS. However, it is not easy to integrate the two different systems since they have different time references, coordinate systems, and signal characteristics. Especially, signal generation technique known as FDMA (frequency division multiple access) utilized in GLONASS causes receiver ICBs (inter-channel biases). ICBs vary among the receivers from different manufacturers and vary among the different channels of a receiver. This paper investigates receiver ICB search technique based on LAMBDA (least-squares
ambiguity resolution decorrelation adjustment) method for RTK (real-time kinematic) GPS/ GLONASS. Although receiver ICB which exists in each GLONASS channel are within one wavelength, it can cause degradation of positioning performance and prevent ambiguity resolution in RTK .To search receiver ICBs, the decorrelated integer ambiguity estimation method is utilized. Next, the performance of ICB search and ambiguity resolution is further improved utilizing correlated integer ambiguity estimations. To evaluate the performance of the proposed technique, static and kinematic experiments are performed between heterogeneous GNSS receivers in realtime mode. KEYWORDS: GPS/GLONASS, RTK, Inter-Channel Bias, Ambiguity Resolution, LAMBDA
A Generalised Formation of GNSS Observational Models for Multi-Constellation and Multi-frequency Data Processing Shengfeng Gu, Chuang Shi, Yidong Lou Wuhan University, China; emails: gsfjay@163.com; shi@whu.edu.au
Yanming Feng Queensland University of Technology, Australia, email: y.feng@qut.edu.au
ABSTRACT The existing GNSS data processing models and methods are predominately based dual-frequency code ad phase signals. For instance, by default, dual-frequency code and/or phase GPS measurements are linearly combined to eliminate the effects of ionosphere delays in precise orbit determination (PPP) and precise point positioning (PPP). This traditional treatment exhibits limitations when processing signals of three or more frequencies and from multiple constellations. This paper explores a generalised formation of GNSS observational models that are applicable for any navigation systems and any number of carriers and can suit both single and multi-site data processing. For the synchronization between different systems and signals, uncalibrated signal delays (USD) are more generally defined to compensate the signal specific offsets in code and phase signals respectively. In addition, the ionospheric delays are included in the parameterization with an elaborate consideration. Based on the analysis of the algebraic structures, this generalized model is further refined with a set of constrains to regularize the datum deficiency of the observation equation system. With this new model, uncalibrated signal delays (USD) and ionosphere delays are derived from a large set for GPS and COMPASS data. Numerical results demonstrate that, with a limited number of stations, the uncalibrated code delays (UCD) are determined to a precision of about 0.1ns for GPS and 0.4ns for COMPASS signals, while the uncalibrated phase delays (UPD) for L1 and L2 are generated with 37 stations evenly distributed in China for GPS with a consistency of about 0.3 cycles. Additional experiments concerning the performance of this novel model in point positioning with mixed-frequencies of mixed-constellations are analysed, in which the USD parameters are fixed with the generated values from the network. The results are evaluated in terms of both positioning accuracy and convergence time. KEYWORDS: Multi-GNSS; Multi-frequency; Uncalibrated Signal Delay; Ionospheric delay, Precise Point Positioning
Session 10B
Non GNSS Positioning
1330-1530
Locata, a Non-GNSS Positioning Technology: From Mines to the Masses Chris Rizos School of Surveying & Geospatial Engineering, UNSW, Australia +61-2-93854205(T), +61-2-93137493(F), c.rizos@unsw.edu.au
ABSTRACT Until recently there have been no viable alternatives to GNSS that provide the combination of high accuracy positioning (centimetre-to-several-decimetre), good coverage, low receiver cost, and ease of use. Locata is an Australian positioning technology solution that is a promising option to either augment GNSS with extra terrestrial signals where the skyview is limited as in the case of deep open-cut mines, or to replace GNSS altogether in indoor and urban environments. UNSW has been conducting Locata research for over a decade in a variety of sensor scenarios, from GNSS+Locata, multi-sensor modes, and Locata-only. Locata appears assured of a future as a commercial positioning technology, now integrated within Leica’s mining positioning products. Although Locata has now demonstrated its capability, and despite it having several very innovative features, the transition from being a positioning system for niche applications (such as for open-cut mines) to being able to address the “ubiquitous positioning” market is an extremely difficult one. First steps in promoting Locata as a viable positioning technology for use in urban/indoor environments were taken in October 2012 when UNSW, LPI and Locata cooperated in a Sydney Harbour experiment. The next step is to build a permanent test network to service the Sydney downtown area. The fundamental obstacle in Locata becoming accepted as an augmentation/ alternative to GNSS is the classic “chicken-and-the-egg” challenge. No service provider will invest in deploying the Locata signal transmitters unless there are users; yet commercial user devices will not be developed unless there is pre-deployed Locata signal transmission infrastructure. This paper discusses the Locata technology from the perspective of mass market applications, including the notions of a Locata “ecosystem”, the value of technology demonstration platforms, and the respective roles of technology pioneers (or early-adopters), government agencies (through R&D policies and incentives) and research institutions (both in progressing fundamental research and providing independent assessment of the technology). KEYWORDS: Locata, alternative PNT, GNSS, indoor positioning, positioning infrastructure
A Novel Deformation Monitoring System Based on Pseudolite Technology Tao Wang, Qiu Wu (1) Centre of Communication and TT&C/Chongqing University/China 023 65105925-614 wt1977@cqu.edu.cn
Andrew G Dempster (2) ACSER/UNSW/Australia 02 9385 6890 a.dempster@unsw.edu.au
ABSTRACT This paper puts forward a novel deformation monitoring system based on pseudolite technology. This system consists of one reference station, three pseudolites and many observation points installed on the structure. The reference station radiates two radio frequency spread spectrum signals modulated by the same pseudo noise signal. The pseudolites are active delay-repeaters. The amplifier of the pseudolite is used to adjust the amplitude of the signal arrived at the observation point to eliminate the influence of far-near effect existed in CDMA system. The delay line of the pseudolite is used to make the pseudo noise code phase difference between any two signals arrived at the observation point larger than one chip width in order to distinguish them from each other. The observation point received one pure low frequency spread spectrum signal and one high frequency spread spectrum signal which is a mixed signal of four signals coming from reference station and three pseudolites. The observation point uses carrier recovering circuit such
as square loop to recover the carrier of the low frequency spread spectrum signal and then uses this carrier to mix with the spread spectrum to recover the pseudo noise code. Then we can delay this recovered pseudo noise code and mix it with the received high frequency spectrum signal to recover the carrier signals from the reference station and three pseudolites. We can use phase detectors to calculate out the phase difference between any pseudolite and reference station. We can construct one linear equation group to use the phase difference variations to calculate out the three dimensional deformation of observation. Compared with Locata Pseudolite positioning technology, there’s no need of clock synchronization circuit and pseudolite noise code acquisition and tracking loop, and also the pseudolite’ circuit is relatively simplified. In short, this system is more robust but the cost has decreased sharply. KEYWORDS: Pseudolite, deformation monitoring, pseudolite noise code, active repeater
Cooperative Wireless Sensor Nodes based Acquisition for Mobile Location Services (MLoC) Ali Sarwar School of Surveying and Geospatial Engineering, University of New South Wales, Australia Phone : +61 2 9385 4185, Fax : +61 2 9313 7493 Email: ali.sarwar@student.unsw.edu.au
Chris Rizos School of Surveying and Geospatial Engineering, University of New South Wales, Australia Phone: +61 2 9385 4205, Fax: +61 2 9313 7493, Email: c.rizos@unsw.edu.au
ABSTRACT Positioning based on Wireless Sensor Nodes (WSNs) has proven effective for assisting GNSS operations in indoor environments. Based on the received signal strength indicator, link quality indicators and individual fixed node location “slices” (contained in a cumulative signature indices database at each node) can supply frequency offset, range and coordinate assistance for location based services for indoor coverage or outdoor (GNSS) coverage scenarios, through periodic transmission to surrounding nodes. Since each node stores a database of its own as well as neighbouring node location “slices”, a cumulative output stream containing location coordinates of a mobile node of interest is calculated and input through a dynamically chosen point of interconnect into the rover node for location determination. The rover node is a smartphone interfaced to a WSN, displaying the location information and providing assistance parameters to the inbuilt GNSS chipset. However problems such as misaligned transceiver time-syncing, thermal noise and broadcast error, incorrect parameter decoding and processor initialisation delay at a fixed or mobile sensor node can introduce arbitrary errors in GNSS calculations. This can adversely affect the resultant localisation performance. In this paper the different error types, their respective effects and resource constraint considerations are discussed. To address such problems a system comprising seven fixed stand-alone WSN is proposed for indoor positioning and compared against traditional GNSS, Assisted-GNSS (AGNSS), and WSN-AGNSS techniques. This paper presents test results demonstrating cm-level accuracy, and discusses response sensitivity and reliability in the event of partial node malfunction. Empirical measurements based on received signal strength (RSS) (neighbor-to-neighbour), link quality indications (in overlapping coverage) with diverse geographical geometry are presented. System architecture, code processing workflow and RSS-based localisation methods are described. Technical details of the IEEE 802.15.4d protocol, physical and medium access control layers with respect to MICAz WSNs are briefly discussed. Rover tracking experiments were conducted in an enclosed building corridor simulating a difficult indoor GNSS environment and results are presented. Signal attenuation and absorption parameters subject to different materials are analysed. The system demonstrates slightly improved time-to-first-fix, time-syncing and clocking information without the processing cost associated with aforementioned techniques. WSN network can be rapidly deployed and can efficiently track a mobile rover node. Applications of interest will be discussed. KEYWORDS: WSN, MLoC, TTFF, Sensitivity, Accuracy, Availability
Performance Enhancement of MEMS Navigation System based on ANFIS Inference System Ling Zhang (1) Navigation Research Center, Nanjing University of Aeronautics and Astronautics, China +86 25 84892304-810& +86 25 84892304-819, zhanglingsnowman@nuaa.edu.cn
Zhi Xiong (2) Navigation Research Center, Nanjing University of Aeronautics and Astronautics, China +86 25 84892304-804& +86 25 84892304-819, Xznuaa@nuaa.edu.cn
Jianye Liu (3) Navigation Research Center, Nanjing University of Aeronautics and Astronautics, China +86 25 84892304-801& +86 25 84892304-819, ljyac@nuaa.edu.cn
Jizhou Lai (4) Navigation Research Center, Nanjing University of Aeronautics and Astronautics, China +86 25 84892304-807& +86 25 84892304-819, laijz@nuaa.edu.cn
ABSTRACT Characterized by small volume, low cost and low power, MEMS inertial sensors are widely concerned and applied in navigation research, environmental monitoring, military and so on. Especially in indoor and pedestrian navigation, its easily-portable feature seems particularly indispensable and important. However, MEMS inertial sensor is inborn low-precision and impressionable, and sometimes goes against accurate navigation or even become seriously unstable when working for a period of time and the initial alignment and calibration are invalid. A thought of adaptive neuro-fuzzy inference system (ANFIS) is relied on, and an assistive control modulated method is presented in this paper, which is newly designed to improve the inertial sensor performance by black box control and inference. The repeatability and long-time tendency of the MEMS sensors are tested and analyzed by ALLAN method. The parameters of ANFIS models are trained using reasonable fuzzy control strategy, with high-precision navigation system for reference as well as MEMS sensor property. The MEMS error nonlinearity is measured and modulated through the peculiarity of the fuzzy control convergence, to enhance the MEMS function and the whole MEMS system property. Performance of the proposed model has been experimentally verified using low-cost MEMS inertial sensors, and the MEMS output error is well compensated. The test results indicate that ANFIS system trained by high-precision navigation system can efficiently provide corrections to MEMS output, and meet the requirement on navigation performance. KEYWORDS: MEMS, adaptive neuro-fuzzy inference system (ANFIS), fuzzy control strategy, error
modulation
6U CubeSat satellite for GNSS Radio Occultation Andrew Dempster Australian Center for Space Engineering Research, University of New South Whales, Australia Email:a.dempster@unsw.edu.au
Lily Qiao Australian Center for Space Engineering Research, University of New South Whales, Australia Email:l.qiao@unsw.edu.au
Sebastian Chaoui Australian Center for Space Engineering Research, University of Technology Sydney, Australia Email:sebastian.chaoui@hotmail.com
ABSTRACT GNSS Radio Occultation (RO) is a remote sounding technique which utilises radio waves emitted by GNSS satellites that become occulted through the ionosphere. GPS receivers in LEO satellites could receive these signals and process them for the retrieval of key atmospheric/climate parameters. Recent technological developments permit highly miniaturised receivers that provide high quality scientific data for ionospheric studies, these receivers are compatible with the CubeSat
form factor. The aim of the study is to verify whether a large number of CubeSats that are cheap to produce but yield less accurate results could compete with a smaller constellation of larger, more expensive satellites that were able to produce more accurate data sets. The QB50 program's UNSW ECO 2U CubeSat is designed by ACSER and is planned to fly a RO payload in 2015. ECO will be a prototype that aids the development of a constellation of larger 6U CubeSats. KEYWORDS: CubeSat Constellation, GNSS RO, GPS receiver
Session 11C
Interference + Aviation and Avionics
1330-1530
GNSS Signal Cancellation for Enhanced Interference Detection and Localization Giulio Gabelli University of Bologna, Italy Tel: +390512093396 e-mail: giulio.gabelli2@unibo.it
Ediz Cetin, Ryan J. R. Thompson, Andrew G. Dempster University of New South Wales, Australia Tel: +61293854206 e-mail: e.cetin@unsw.edu.au, r.thompson@unsw.edu.au, a.dempster@unsw.edu.au
Giovanni E. Corazza University of Bologna, Italy Tel: +390512093054 e-mail: giovanni.corazza@unibo.it
ABSTRACT A plethora of services and applications rely on the Global Navigation Satellite Systems (GNSS) positioning and synchronization capabilities. GNSS signals, however, are susceptible to interference due to their weak power levels. The GNSS Environmental Monitoring System (GEMS) II provides the capability to detect and geo-locate interferers in real time in a given area. It consists of a network of spatially separated time-synchronized sensor nodes connected to a central processing unit. Interference localization is achieved by hybrid Angle-of-Arrival (AOA) and Time Difference of Arrival (TDOA) techniques. In order to calculate the TDOA, data collected at different sensor nodes are cross-correlated. This however limits the level at which the actual interferers can be detected since the cross-correlation not only contains peaks due to the interferers but also peaks due to the GPS satellites themselves. These unwanted peaks could be mistaken for weak interferers hence degrading the interference detection and localization performance. In this paper, a novel solution for the elimination of the cross-correlation peaks due to the GNSS signals is proposed. A complete analysis of the crosscorrelation between the GNSS signals at different receivers is provided, and different solutions to the interference correlation estimation problem are proposed. The cross-correlation of the interfering signal is estimated by adaptively cancelling the correlation due to the GNSS signals, which is continually estimated until the interference is detected. A complete analysis of the proposed solutions is carried out by means of theoretical as well as numerical simulations based on Spirent data. Results in terms of cross-correlation function and TDOA estimation accuracies are provided. It is shown how the performance of the proposed algorithm depends on the Jammer-toNoise Ratio (JNR), on the Interference-to-GNSS-Signal Ratio (JSR), and on the interference signal dynamics. Finally, recommendations for real-time implementation are also provided in order to maximize the system computational efficiency. KEYWORDS: interference, localization, TDOA, cross-correlation.
Application of Collective Detection in Spoofing Scenarios Joon Wayn Cheong Australian Centre for Space Engineering Research at the University of New South Wales/Australia +61 2 93856702/ cjwayn@unsw.edu.au
Li Li College of Electronic Engineering at the Tianjin University of Technology and Education + 61 4 51387618/ lili7312@gmail.com
Jinghui Wu Australian Centre for Space Engineering Research at the University of New South Wales/Australia +61 2 93854206/ jinghui.wu@unsw.edu.au
Andrew G. Dempster Australian Centre for Space Engineering Research at the University of New South Wales/Australia +61 2 93856890/ a.dempster@unsw.edu.au
Chris Rizos School of Surveying and Geospatial Engineering at the University of New South Wales/Australia +61 2 93854205/ c.rizos@unsw.edu.au
ABSTRACT Collective Detection is an algorithm typically used in the field of weak signal acquisition to enhance the signal detection rate. The core idea of Collective Detection is to project correlation values in the code phase domain onto the position domain such that the correlation values from various satellite channels are combined to form a stronger peak with respect to the cross-correlation noise floor. Many existing considerations of spoofers typically involve a repeater or a "record and replay" attack on the victim receiver. Many simple workarounds have been proven to mitigate these primitive attacks. However, it has come to light in recent years that modern spoofers can be much more sophisticated such that many of these existing workarounds are no longer effective in defending the victim receiver against spoofing. This paper specifically targets such sophisticated attacks for investigation. The main aim of this paper is to discuss the possible amalgamation of Collective Detection with a conventional spoofing detection technique to achieve higher rates of detection of a spoofing signal. In addition, this paper will also discuss the adaptation of the Collective Detection concept for spoofer localisation. Some preliminary experimental results show the feasibility of some of the proposed methods. KEYWORDS: Collective Detection, Anti-Spoofing, Spoofer Localisation, Spoofing Detection
UAS Photogrammetry using Real Time Precise GNSS Camera Locations Gavin Docherty Position Partners/Australia Ph:0400354873 email: gdocherty@positionpartners.com.au
ABSTRACT The concept of photogrammetry has been around since the advent of modern photography and can be dated back to the mid nineteenth Century. Analytical photogrammetry has been used to accurately model and map the Earths terrain since the nineteen sixties. Only recently has digital “Soft Copy� photogrammetry come of age which has allowed practitioners to produce point clouds of millions of points that represent the three dimensional geometry of the features captured in the photography. Typically, this type of photogrammetry would be carried out by full size manned aeroplanes with special mounted cameras and up until now it has been necessary to use well-coordinated photo control points positioned strategically on the ground surface to allow for feature matching and accurate modelling of the surface. Modern Surveyors are now opting for more control over their
own surveying missions by using Unmanned Aerial Systems (UAS’s) where they have the advantages of low level flight (below clouds) and relatively quick mobilisation times. This paper examines the principles of development of Real Time Kinematic (RTK) positioning of the UAS’s camera location during flights negating the need for ground control points. KEYWORDS: UAV, UAS, NTRIP, CORS, RTK
Aircraft Detection Experimental Results for GPS Bistatic Radar using Phased-array Receiver Chow Yii Pui School of Electrical & Electronic Engineering, University of Adelaide Gate 5, Frome Rd, SA 5005 Tel: +61 8 8303 8314 Email: mpss@eleceng.adelaide.edu.au
Matthew Trinkle School of Electrical & Electronic Engineering, University of Adelaide Gate 5, Frome Rd, SA 5005 Tel: +61 8 8303 4708 Email: mtrinkle@eleceng.adelaide.edu.au
ABSTRACT A study has been made into using GPS signal as the illuminator of opportunity of a passive bistatic radar for target detection. Due to the low transmission power level of GPS signal, it can only be used to detect target of large size such as aircraft, assuming the system utilises high sensitivity receiver that uses large scale antenna arrays and sufficiently long integration periods. A phasedarray receiver that consists of 32 dual polarised elements was developed for the radar system to increase the detection performance and search for aircraft reflections across all direction-of-arrivals using the conventional beamforming technique. An initial aircraft detection experiment has been previously made into investigate techniques such as array orientation and channel phase calibration using GPS signals as the calibrating sources and also direct path and multipath interference mitigation technique using Weiner filter. The detection process will also be involved with using the correlation between data that is digitised by the front-ends and the PRN code that is directly acquired by the phased-array receiver instead of the locally generated PRN code. Further aircraft detection experiment will be conducted before the end of March to study the performance of using GPS signal for aircraft detection and the results will be presented. KEYWORDS: Passive Bistatic Radar, Phased-array, Aircraft Detection
Sensitivity Analysis of the Airborne CCD Monitor for GAST-D Youngsun Yun Korea Aerospace Research Institute Phone: 82-42-860-2798, Fax:82-42-860-2789, Email:ysyun@kari.re.kr
Jeongho Cho Korea Aerospace Research Institute Phone: 82-42-860-2407, Fax:82-42-860-2789, Email:jcho@kari.re.kr
Moon-Beom Heo Korea Aerospace Research Institute Phone: 82-42-860-2266, Fax:82-42-860-2789, Email:hmb@kari.re.kr
Gi-Wook Nam Korea Aerospace Research Institute Phone: 82-42-860-2365, Fax:82-42-860-2789, Email:gwnam@kari.re.kr
ABSTRACT Recently, many airports worldwide have installed the GBAS ground stations and been pursuing
Category-I precision approach services, GAST(GBAS Approach Service Type)-C, based on them in the near future. The next goal of GBAS is providing the CAT-II/III level precision approach service, which is called GAST-D. Since the GAST-C and D user avionics utilize only L1 signal, they should mitigate the anomalous ionospheric gradients properly to protect the user integrity. Since GAST-C avionics do not take any responsibility on integrity monitoring including ionosphere anomaly detection, the ground stations should consider all the worst case conditions of ionosphere threats which made the user protection levels become too conservative. On the other hand, GASTD avionics have been decided to take charge of some of the monitors, so those are required to perform various monitor algorithms to exclude measurements under threat: airborne CCD (Code Carrier Divergence) monitor, dual smoothing iono gradient monitor algorithm, geometry screening and so on. The airborne CCD among the monitors is employed to detect and exclude the range measurements affected by the large stationary ionosphere gradients, so the detection performance of the monitor impacts on the system availability. The airborne CCD monitor algorithm is defined as a series of two linear time invariant filters with a time constant of 100 seconds and a sample interval by RTCA DO-253C. Therefore, the monitor performance is expected to be dependent on the constants, which has been hardly researched before. The long time constant of the filter reduces the multipath and noise contribution of the pseudorange measurements but leads slow response to the divergence change. The authors’ previous research showed that the short time constants could improve the divergence detection performance under multipath limited environments. And the different sample intervals can cause different filter inputs, which is the difference between the code minus carrier measurements in successive epochs. The filter inputs with shorter sample intervals have less multipath induced errors since the multipath errors are highly correlated in a short time period, which leads lower detection thresholds. On the other hand, those inputs have only a small fraction of the ionosphere induced divergence rate, so the outputs could not reveal the divergence effects clearly out of the noise errors. For these reasons, the paper investigates the performance sensitivity of the airborne CCD monitors with different time constants and sample intervals with a consideration of the airborne multipath characteristics and the magnitude of the code carrier divergence rate. For the investigation, the paper analyzes the response of the airborne CCD monitors with different constants with regards to the multipath and the divergence characteristics theoretically. And the simulated data with various multipath conditions are processed to show the performance sensitivity. Based on the results, the paper suggests the optimal time constant and sample interval configurations of the airborne CCD monitor under different environments to obtain higher detection performance than the legacy one. KEYWORDS: GBAS; GAST-D; Code Carrier Divergence; Sensitivity; Airborne
Session 12A
Embracing the Multi-GNSS Era Invited Speaker Session
1540-1700
The Multi-GNSS Experiment of the International GNSS Service Oliver Montenbruck DLR, German Space Operations Center, Germany Phone +49(8153)28-1195, fax -1450, oliver.montenbruck@dlr.de
Chris Rizos University of New South Wales, Australia c.rizos@unsw.edu.au
Urs Hugentobler Technische Universität München, Germany urs.hugentobler@bv.tu-muenchen.de
ABSTRACT The International GNSS Service (IGS) has, over many years, set the gold standard for highprecision GPS and GLONASS measurement modeling and analysis. To pave the way for a future provision of high-quality data and products for all constellations, the IGS has initiated the MultiGNSS Experiment (MGEX – http://igs.org/mgex). It serves as a framework for increasing the overall awareness of multi-GNSS within the scientific and engineering communities, as well as to familiarize IGS participants and users with the new navigation systems.
The presentation describes the MGEX multi-GNSS network, which has by now grown to more than 70 stations around the globe and provides free access to new constellations and signals for all interested users. Most of the MGEX stations also provide real-time observations and thus assist the early incorporation of all constellations into real-time IGS services. First products derived from the MGEX network include Galileo-IOV and QZSS orbit and clock data as well as cumulative multiGNSS broadcast ephemerides. The quality of these products is presented and plans for new products are highlighted. KEYWORDS: GNSS, IGS, MGEX, Network, real-time, ephemeris products
What are the Issues with Multi-GNSS Enabling the National Positioning Infrastructure? Dr John Dawson, Geoscience Australia, Canberra, Australia Abstract not Provided
Multi-GNSS and the Research Agenda Professor Peter Teunissen, Curtin University, Perth, AUSTRALIA Abstract not Provided
Session 12C
Ionosphere
1540-1700
Ionospheric Path Delay Modelling for Spacecraft Formation Flying Yang Yang (1) Northwestern Polytechnical University; School of Surveying & Geospatial Engineering/University of New South Wales/Australia +61 416980313 & yiyinfeixiong@gmail.com
Yong Li (2), Andrew G. Dempster (3) School of Surveying & Geospatial Engineering/University of New South Wales/Australia +61 2 93854173 & yong.li@unsw.edu.au, a.dempster@unsw.edu.au
ABSTRACT Apart from absolute orbit determination information, many current and future space missions require relative navigation solutions to be available on board the spacecraft. GNSS is ideal to meet with such requirements because of its long-term stable accuracy and global availability. It is well known that of the various error sources in the GNSS observables, the ionospheric path delay is one of the largest. Even though common mode GNSS errors can be mitigated to a large extent by double-differencing observables, residual effects due to ionospheric delay may still be significant when spacecraft separation is large. Hence accurate modelling of ionospheric delays will improve relative navigation accuracy. This paper describes a method to solve the zero-differenced ionospheric delay making use of dual-frequency measurements. Then the double-differenced ionospheric delay errors can be determined, and subsequently eliminated from the observables. A new pseudorange measurement was first formed by differencing the L1 and L2 measurements,
which were also smoothed using the carrier phase measurements. In this measurement equation, the ionosphere error was transformed into a function of the vertical total electron content (VTEC), using the modified Lear mapping function. Then the differential code biases (DCBs) of all the GNSS satellites and the receivers were estimated by a least squares method on the basis that the VTEC was modelled using the spherical harmonic function. Once the DCBs were obtained using a long GNSS observation arc (for instance 1 hour of data), they were substituted into the new observable equation to calculate the ionospheric delay. A set of Gravity Recovery and Climate Experiment (GRACE) flight data were used to test the proposed method. The estimates of the DCBs and ionospheric path delay will be presented. KEYWORDS: relative navigation, modified Lear model, differential code biases, ionospheric path delay
Ionosphere Data Assimilation Capabilities for Representing the High-Latitude Geomagnetic Storm Event in September 2011 Dmitry Solomentsev (1) Central Aerological Observatory/ Dolgoprudny, Russia Phone/Fax: +7 495 408 62 21, e-mail: d.solomentsev@gmail.com
Knut Stanley Jacobsen (2) Norwegian Mapping Authority/ Hønefoss, Norway Phone: +47 32 11 83 81, e-mail: knut.stanley.jacobsen@kartverket.no
Boris Khattatov (3) Fusion Numerics LLC, Boulder, Colorado, USA Phone: +1-720-938-2184, e-mail: boris@fusionnumerics.com
Anton Titov (4) Central Aerological Observatory/ Dolgoprudny, Russia Phone/Fax: +7 495 408 62 21, email: anton@ionosphere.ru
ABSTRACT Severe geomagnetic storms have strong impact on space communication and satellite navigation systems. Forecasting appearance of geomagnetically induced disturbances in the ionosphere is one of the urgent goals of the space weather community. The challenge is that the processes, governing the distribution of the crucial ionospheric parameters are poorly known and the models, built using the empirical parameterizations have limited capabilities for operational purposes. On the other hand, data assimilation techniques are becoming more and more popular for nowcasting the state of the large- scale geophysical systems. We present an example of the ionospheric data assimilation system performance assessment during a strong geomagnetic event, which took place on 26 September 2011. The first-principle model has assimilated slant Total Electron Content measurements from a dense network of ground stations, provided by the Norwegian Mapping Authority. The results have shown rather satisfactory agreement with independent data (e.g. Tromso ionosonde measurements) and demonstrate that the assimilation model can be used for operational purposes in high-latitude regions. The operational system performance assessment is the subject of future work. KEYWORDS: ionosphere, geomagnetic storm, data assimilation model, space weather nowcasting
Comparing GPS Radio Occultation Observations with Radiosonde Measurements Over Antarctica R. Norman1, J. Le Marshall1,2, B.A. Carter1, K. Zhang1, G. Kirchengast3, S. Alexander4 , C-S.Wang1 and Y. Li1
1
Satellite Positioning for Atmosphere, Climate and Environment (SPACE) Research Centre, RMIT University, Melbourne, Australia, Tel: 99256735, email: robert.norman@rmit.edu.au 2 Centre for Australian Weather and Climate Research (CAWCR), Bureau of Meteorology, Melbourne, Australia 3 Wegener Center for Climate and Global Change (WEGC), University of Graz, Graz, Austria 4 Australian Antarctic Division, Hobart, Tasmania, Australia
ABSTRACT GPS Radio Occultation (RO) is a space-based technique for sounding the Earth’s atmosphere. This technique has been shown to significantly improve weather forecasting and climate monitoring over many regions of the Earth. The GPS RO technique uses specially-designed GPS L-band frequency receivers on-board Low Earth Orbit (LEO) satellites to receive signals from GPS satellites. The Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) is a joint Taiwan and USA satellite program and was launched into orbit in April 2006. GPS RO data from this constellation of six FORMOSAT-3 (Formosa Satellite Mission #3), LEO (800 km altitude) micro-satellites provides an observational data type for operational meteorology and significant information on the thermodynamic state of the atmosphere. In the Antarctic region there are only 18 radiosonde (RS) weather stations mainly distributed along the coastal fringe. As such this RS network is far from ideal for studying the atmosphere, meteorology and climatology in the Antarctic region. It does however provide excellent reference stations to test and validate the GPS RO technique as a suitable meteorological data type in the Antarctic region. In this study the COSMIC GPS RO temperature and pressure profiles are compared to those measured using radiosondes in the Antarctic region. Yearly and seasonally, weighted area average temperature profiles from the Antarctic region are also presented. KEYWORDS: Radio Occultation, Antarctica, radiosonde, satellites, COSMIC
Posters – Tuesday & Wednesday Lunchtime Ionospheric Delay Estimation Using the Modified IDW Grid Model Jungmin Joo (1) Satellite Navigation Team/Korea Aerospace Research Institute/South Korea Phone: +82-42-860-2554 Fax: +82-42-860-2789 Email address: jmjoo@kari.re.kr
Moonbeom Heo (2) Satellite Navigation Team/Korea Aerospace Research Institute/South Korea Phone: +82-42-860-2266 Fax: +82-42-860-2789 Email address: hmb@kari.re.kr
ABSTRACT The largest source of positioning error for single-frequency users of the GPS is typically the radio delay caused by the ionosphere. Up to now, even though several analytic function based models are available for ionospheric error corrections, grid based models are preferred due to their greater estimation accuracy and less complexity. One of the ionospheric grid models used for the US WAAS is the Inverse Distance Weighted (IDW) model weighted with Klobuchar ionospheric model. In this paper, we propose a modified IDW estimation method using adaptive cut-off radius and optimal distance weighting for the high-resolution ionosphere grid based service. If target service area is local relatively, smaller grid size is appropriate to improve the integrity performance of system level. Our proposed method also use the linear combination model of Klobuchar and Galileo NeQuick model as a nominal ionospheric delay model instead of Klobuchar model to improve estimation accuracy. In previous research results, for middle-latitude geographic region, the NeQuick model is offering better behavior than the Klobuchar model except for active ionospheric activity state. When we simulated in 1x1 degree grid resolution condition over the Korean service region, IPP density at any IGP was 10 and less and IPP densities at other IGPs were enough to compute the delay. When the number of reference stations and their coordinate are restricted, proper IPP densities at all IGPs is required to meet the accuracy and availability performance requirements of system. Our proposed method is the function of the IPP density and its variation rate and controls the cut-off radius until proper IPP density is maintained and then set up IPP’s optimal distance weighting in the cut-off radius. In the various simulation results, it demonstrated that the proposed scheme is able to meet the expected performance on the grid model with high grid resolution. KEYWORDS: Ionospheric Delay Estimation; Inverse Distance Weighted (IDW) Model; NeQuick Model; Klobuchar Model; Adaptive Cut-off Radius
Timing Performance of V2R3 Namuru Operating in Position-Hold Mode Joseph P. Gauthier University of New South Wales +61416028286, joseph.gauthier@student.unsw.edu.au
Eamonn P. Glennon University of New South Wales +61293137493, e.glennon@unsw.edu.au
Andrew G. Dempster University of New South Wales +61293856890, a.dempster@unsw.edu.au
ABSTRACT One of the primary outputs from GPS receivers is a pulse per second (PPS) signal that is aligned
with GPS time. Whereas nonstationary receivers typically operate in 3D mode, calculating a position-velocity-time (PVT) solution at each epoch, stationary receivers typically have a priori knowledge of their position and velocity, thereby enabling a more specialized mode of operation: position-hold mode. In this paper, the solution method for position-hold mode is derived, and a performance comparison between it and 3D mode is made. The experiments were performed with an Agilent 53230A Universal Frequency Counter/Timer and a Spirent GSS6560 signal simulator. The results show that the V2.3 Namuru achieves its best timing performance when operating in position-hold mode; this agrees with prior research by others on different GPS receivers. KEYWORDS: GPS, timing, position-hold, PPS, sawtooth
Modified Indoor Positioning Method Using WLAN RSSI Measurements and AP Configuration Information JunGyu Hwang School of Electronics Engineering/Kyungpook National University/Korea Fax: +82-53-950-5505, Phone: +82-53-950-7567, Email: cjstk891015@naver.com
Joon Goo Park School of Electronics Engineering/Kyungpook National University/Korea Fax: +82-53-950-5505, Phone: +82-53-950-7567, Email: jgpark@knu.ac.kr
ABSTRACT Researches on WLAN(Wireless Local Area Network) indoor positioning method of mobile device for its cost effectiveness and high positioning accuracy are hot topics in network based indoor positioning area. General WLAN based positioning methods are focused on establishing more accuracy relationship between true location and RSSI(Received Signal Strength Indication)’s from AP(Access Point)’s. In this process, there is no enough consideration for the configuration information of AP’s. When AP’s are concentrated in a certain area from target mobile device, calculated positioning error usually increases. To overcome this problem, this paper proposes an enhanced indoor positioning method by considering the configuration information of AP’s, additionally. For this purpose, we adopt dilution of precision (DOP) for reflecting AP configuration selection criteria. This proposed method selects an AP combination using DOP information and calculates the position of target mobile device using the RSSI information from the selected AP’s. Simulation and experimental results show that the proposed method can improve positioning accuracy significantly. KEYWORDS: Indoor positioning, WLAN, RSSI, Dilution of Precision (DOP).
Analysis of the Integration of Differential GNSS System (VRS/RTK) with a SBAS System Phd. Israel Quintanilla (1) Department of Cartographic Engineering/Technical University of Valencia/Spain Mobile Phone 0034630228230 & Fax 0034963877559. email: iquinta@cgf.upv.es
Phd. Jose Luis Berné Valero (2) Department of Cartographic Engineering/Technical University of Valencia/Spain Mobile Phone 0034630228230 & Fax 0034963877559. email: jlberne@cgf.upv.es
Mr. Jesus Olivares (3) Department of Cartographic Engineering/Technical University of Valencia/Spain Mobile Phone 0034630228230 & Fax 0034963877559. email: jlolivares@cgf.upv.es
Mr. Kevin Franquin (4) Department of Cartographic Engineering/Technical University of Valencia/Spain Mobile Phone 0034630228230 & Fax 0034963877559. email: kevin.franquin@gmail.com
ABSTRACT The aim of this article is to conduct an analysis of the integration of differential GNSS system
(VRS/RTK) with a SBAS system (more specifically the European air navigation system EGNOS). To do so, a practical analysis study of those different systems and on the corresponding air standard will be carried out. Then practical tests will be executed to compare the precision and continuity of the above systems, SBAS GNSS receivers onboard helicopter. To this end there have been four trials; two on the ground to check the correct operation of the receivers, and two with helicopters, one to test the accuracy VRS/RTK/EGNOS, and the other to study the integration EGNOS/VRS/RTK with ILS from the helicopter. We will show the analysis to compare the accuracy and continuity between SBAS system and differential GNSS and propose a system complement to improve the landing system. KEYWORDS: SBAS, RTK, VRS, EGNOS, Navigation.
Precipitable Water Vapour Estimation using Observations from the Australian Regional GNSS Network for Climate Monitoring Suelynn Choy School of Mathematical and Geospatial Sciences, RMIT University, Australia Phone: +61 3 9925 2650 Fax: +61 3 9663 2517 Email: suelynn.choy@rmit.edu.au
John Dawson National Geospatial Reference Systems, Earth Monitoring and Hazard Group, Geoscience Australia, Australia Phone: +61 2 6249 9028 Fax: +61 2 6249 9999 Email: John.Dawson@ga.gov.au
Minghai Jia National Geospatial Reference Systems, Earth Monitoring and Hazard Group, Geoscience Australia, Australia Phone: +61 2 62499045 Fax: +61 2 6249 9999 Email: Minghai.Jia@ga.gov.au
Yuriy Kuleshov National Climate Centre, Bureau of Meteorology, Australia Phone: +61 3 9669 4896 Email: Y.Kuleshov@bom.gov.au
ABSTRACT Atmospheric water vapour is a critical component of the greenhouse effect and plays a significant role in the global climate system. The knowledge of the long-term spatial and temporal variability of water vapour is vital for understanding climate change. The Global Positioning System (GPS) has long offered the prospect of retrieving column integrated Precipitable Water Vapour (PWV) profiles from the time-varying tropospheric Zenith Path Delay (ZPD), which can be retrieved by stochastic filtering of the GPS measurements. However, observing GPS-PWV for climate studies requires a homogenous and long-term time series of GPS data. We present a regional reanalysis of GPS data focussing on the Australian Regional GPS/GNSS Network stations from 1997 to 2012 (15 years). These stations are selectively chosen to provide a representative regional distribution of GPS sites on the Australian continent while ensuring conventional meteorological observations (surface-based data) are available for PWV conversion and other PWV sensors (e.g. upper-air data from radiosondes) for validation purposes. The research work is divided into three components: 1) estimation of homogenous long-term tropospheric ZPD from GPS measurements that are accurate, stable and consistent; 2) conversion of tropospheric ZPD to PWV estimates given surface temperature and pressure readings, and 3) intertechnique comparison and validation of the GPS-derived PWV. The derived data will be used to investigate the secular trend and seasonal variation PWV time series and its implications for climate application. This research represents the first attempt to utilise the Australian regional network of GPS stations to study the climate processes and variations from the long-term time series of GPS-PWV. KEYWORDS: GPS, PWV, ARGN, Climate.