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 2015 Book of Abstracts For Oral and Poster Presentations
www.ignss.org
Oral Presentations Abstracts – Tuesday 14 July, 2015 Session 1B:
Plenary Session GNSS System Providers
0900-1020
GPS Civil Service Update and U.S. International GNSS Activities David A Turner Deputy Directory Office of Space and Advanced Technology, Department of State, USA
Abstract Not Provided Glonass Status and Performance Improvement Professor Victor Kosenko, First Deputy Director General, ISSC ReshetnevCompan, RUSSIA Dr Sergey Revnivykh Deputy Director General, Head of PNT Information Navigation Centre, Central Research Institute of Machine Building, RUSSIA ABSTRACT After completion of the restoration in 2011 the GLONASS system obtained worldwide recognition as an essential part of the global satellite navigation infrastructure. The most of high accurate navigation solutions cannot be achieved based on the only one GNSS, involving both GPS and GLONASS. For reliability of most applications at least two GNSS has to be used. During the last decade the GLONASS accuracy has been improved by factor of ten. The GLONASS Evolution Program adopted in 2012, envisages the further accuracy improvement applying advanced techniques. New satellites Glonass-K with better atomic clock, new CDMA signals, cross-link with data and range capability, deep modernization of ground control segment shall provide for users the sub-meter level of positioning in nearest future and new services. Involving the augmentations GLONASS will submit opportunity for global real time navigation with centimeter level of accuracy. Existing capabilities of GLONASS satellites which all equipped with laser retroreflectors, provide extreme benefit for global scientific community for Earth model improvement. New technique combining two way and one way laser ranging should provide the remote clock synchronization on the sub-nanosecond level. GLONASS as a global utility is open for international cooperation. Compatibility and interoperability among GNSS shall provide benefits for all user community worldwide. The Russian state policy declares the open GLONASS service available for all users without direct fees and any restrictions. KEYWORDS: GLONASS, Satellite, Navigation, Utility, Evolution
Session 2B:
Plenary Session GNSS System Providers
1045-1230
BeiDOU Mr Jianguang Feng, Program Manager, China Satellite Navigation Office, CHINA Abstract Not Provided The European Union's GNSS Programmes, Galileo and EGNOS Dominic Hayes European Commission/European Union +32 2 29 56077 dominichayes@ec.europa.eu
ABSTRACT Galileo has been in various European pipelines for many years. After initial difficulties agreeing financial and political aspects, the programme is now well on track to provide a free to use global PNT service. Although Galileo will provide a range of standalone services using its own satellites and ground infrastructure, it also provides signals designed to be fully interoperable with GPS, thus making combined GPS/Galileo PNT solutions easier. With an ambitious schedule of launches in 2015 and 2016, initial Galileo services are planned to be available by the end of 2016, with full service in the 2018/19 timeframe. The EU’s other GNSS programme EGNOS, the European Geostationary Navigation Overlay Service, is already in full operation, augmenting GPS over Europe since 2011 and enabling GNSS to be used for safety critical applications. European aviation is one such sector benefiting greatly from its GPS integrity information.
KEYWORDS: Galileo, EGNOS, European Union (EU), Cospas-Sarsat, European Space Agency (ESA)
The Current Status of QZSS Program Satoshi Kogure Japan Aerospace Exploration Agency, JAPAN Abstract Not Provided
Session 3C:
QZSS LEX Demonstration
13:30 – 13:45
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
Session 4C:
Multi GNSS 1
13:45 – 15:25
QZSS Based Augmentation for PPP/PPP-AR Applications Satoshi Kogure
Mission Manager/Japan Aerospace Exploration Agency/Japan Phone: +81-50-3362-2456 Fax: +81-29-868-5687 E-mail address: kogure.satoshi@jaxa.jp
Tomoji Takasu Tokyo University of Marine Science and Technology, Lighthouse Technology and Consulting Co. Ltd./Japan Phone:+81-3-3353-4668 E-mail address: tomoji.takasu@lighthousetc.jp
Tomoya Osawa Tokyo Electronic Systems Corporation/Japan Phone: +81-44-820-8191 FAX: +81-44-820-8180 E-mail address: tomoya.osawa@toshiba.co.jp
Hirofumi Okubo FUJITSU LIMITED/Japan Phone: +81 3-5809-3682 E-email address: okubo.hirofumi@jp.fujitsu.com
ABSTRACT The utilization of multiple GNSS constellation is expected to resolve one of the drawbacks of satellite navigation which is difficult to use in dense urban area. Especially, carrier phase positioning in urban canyon is still big challenge, since surrounding building can easily block satellite signals, cycle slip and signal loss occur frequently. However, multi-GNSS signals can facilitate to get positioning solution even in the such severe condition. Combining use some relative sensors like IMU, Rader scanner and imaging sensor, with PPP/PPP-AR are to be essential for mobile applications. If reliable and continuous PPP solution could obtain even in urban area, the reliability of autonomous driving vehicle can be improved, and more cost effective composition can be found. "Multi-GNSS Advanced Demonstration tool for Orbit and Clock Analysis" (MADOCA) as well as user PPP technology with using precise orbit and clock offset estimated by MADOCA, which we call "MADOCA-PPP" have being developed. JAXA is routinely generating error correction message for MADOCA-PPP, broadcasting it via LEX signal and evaluating its performance. Current performance of MADOCA-PPP is sub-decimeter accuracy (RMS) for both horizontal and vertical direction in real time processing. Several applications using MADOCA-PPP was demonstrated including autonomous driving conducted at ITS World Conference 2013 in Tokyo. There are major two technical challenges on current MADOCA-PPP, one is more precision and the other is convergence time. Some applications like farming robot control require centimeter level accuracy. To realize this accuracy, Ambiguity Resolution (AR) is requested. In addition, the biggest challenge is convergence time reduction under limiting transmission data volume. Considering the limited satellite bandwidth, LEX message should be used for broadcasting globally applicable error corrections like satellite orbit, clock offset, code bias as well as FCB (Fractional Cycle Bias). It is the effective way to transmit error corrections for ionospheric delay and tropospheric delay, which depend on local environment, via ground based local area network (3G/4G cell phone network or WiFi). In this paper, the latest status of the MADOCA and MADOCA-PPP development is described with performance test results. In addition, current technical challenges are introduced and how to resolve them are also discussed in the paper. KEYWORDS: Quasi-Zenith Satellite System(QZSS), multi-GNSS, Presice Point Positioning (PPP), PPP-Ambiguity Resolution (AR),.and Convergence time
Pilot Study on the use of Quasi-Zenith Satellite System as a GNSS Augmentation System for High Precision Positioning in Australia 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
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
Mohammad Choudhury School of Civil and Environmental Engineering, University of New South Wales, Australia
Phone: +61 2 9385 4173 Fax: +61 2 9385 5657 Email: mohammad.choudhury@unsw.edu.au
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 Civil and Environmental Engineering, University of New South Wales, Australia Phone: +61 2 9385 4205 Fax: +61 2 9385 6139 Email: c.rizos@unsw.edu.au
ABSTRACT The Quasi-Zenith Satellite System (QZSS) is a Japanese regional satellite navigation system covering East Asia and Oceania. QZSS is designed as a satellite-based augmentation system to improve the availability and performance of Global Navigation Satellite Systems (GNSS) in the region. QZSS transmits augmentation signals such as the LEX (L-band Experimental) signal, which is capable of transmitting precise navigation messages for high accuracy point positioning. A joint project between the Australian Cooperative Research Centre for Spatial Information (CRCSI) and the Japanese Aerospace Exploration Agency (JAXA) aims to assess the feasibility of using the LEX signal to potentially deliver a precise positioning service in Australia. This paper presents the results of a pilot study for the use of the LEX signal to transmit navigation messages for Precise Point Positioning with Ambiguity Resolution (PPP-AR). LEX correction messages based on the available real-time products were transmitted from Australia to the QZS master control station in Japan and broadcasted on the LEX signal. The messages were decoded on different points regions in Australia and used to compute real-time PPP-AR solutions. Positions solutions were obtained for both fixed receivers and vehicle mounted receivers. A comparison with Position solutions obtained using real-time streams directly shows that latency and outages product of the satellite transmission don’t have significant effects in ambiguity resolution nor positioning accuracy.
KEYWORDS: Real-time PPP, Ambiguity resolution, QZSS, GNSS Augmentation On the multi-GNSS RTK positioning performance in New Zealand Robert Odolinski (1) School of Surveying/University of Otago/New Zealand +64 3 479 5401 & +64 3 479 7586, robert.odolinski@otago.ac.nz
Paul Denys (2) School of Surveying/University of Otago/New Zealand +64 3 479 7596 & +64 3 479 7586, paul.denys@otago.ac.nz
ABSTRACT With the advent of new Global Navigation Satellite Systems (GNSSs), multi-system, multifrequency precise real-time kinematic (RTK) positioning can potentially be possible anywhere, at any time. Some of these satellite constellations are the European Galileo and the Chinese BeiDou Navigation Satellite System (BDS), the regional constellation of Japan’s Quasi-Zenith Satellite System (QZSS) and the modernized American Global Positioning System (GPS). Preliminary positioning results when combining satellites from these systems have been obtained in Australia. However, the multi-GNSS positioning performance in New Zealand has not yet been investigated. This contribution aims to give an initial overview of the single-baseline RTK positioning performance achievable in the South Island of New Zealand, a region with a good visibility of all these constellations. Comparisons will be made to the positioning performance obtained in Australia that has a better visibility of the Asia-Pacific regional systems. The between-receiver differential code and phase inter-system biases (ISBs) on the overlapping frequencies will be analysed and used as a-priori corrections on an independent baseline, in order to maximize the redundancy of the multi-GNSS RTK functional model. It will be shown that if the ISBs are neglected there can be a serious effect on the ambiguity resolution performance and thus the positioning results. It will also be illustrated that by combining all four-systems the RTK positioning results will be significantly improved in comparison to using GPS as a stand-alone system, which has the potential to further advance applications which require high precision positioning for GNSS users in New Zealand.
KEYWORDS: Multi-Global Navigation Satellite System (GNSS), real-time kinematic (RTK), integer ambiguity resolution, inter-system biases (ISBs), New Zealand
Utilisation of the Japanese Quasi-Zenith Satellite System (QZSS) Augmentation System for Precision Farming in Australia 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
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
Hideshi Kakimoto Hitachi Zosen Corporation, Tokyo, Japan Phone: +81 3 6404 0813 Fax: +81 3 6404 0869 Email: kakimoto_h@hitachizosen.co.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
Phillip Collier Cooperative Research Centre for Spatial Information, Australia Phone: +61 3 8344 8125 Emaill: pcollier@crcsi.com.au
ABSTRACT Delivery of real-time centimetre-level positioning accuracy using GNSS in remote and rural parts of Australia is crucial to the widespread adoption and long term productivity of precision farming. Presently only 9% of the country is served by network real-time kinematic positioning (NRTK) services, leaving remaining users in remote parts of the country to either build, operate and maintain their own ad-hoc system or to continue working without the gains and benefits real-time GNSS precise positioning can provide. To overcome the significant barriers to adoption that emerge in a vast and sparsely populated country like Australia, an alternative mode of positioning is required and the associated augmentation message must be made uniformly and consistently available. One potential solution is to utilise a satellite-based communications infrastructure such as the Japanese Quasi-Zenith Satellite System (QZSS) to deliver precise positioning augmentation message across Australia. This paper describes a collaborative project between Australia and Japan aimed at evaluating and demonstrating key attributes and benefits of the QZSS augmentation system, in particular the L-band Experimental (LEX) signal, for robotic tractor guidance in Australia. Different Precise Point Positioning (PPP) augmentation corrections including an Australian generated correction were transmitted via the QZSS LEX signal. The positioning solutions were compared with NRTK and evaluated in terms of positioning accuracy and time of convergence.
KEYWORDS: QZSS, Precise Point Positioning, Real-Time, Precision Farming An Adaptively Filtering Approach for Autonomous Orbit Determination of Constellations Wende Huang (1) College of Mechatronics Engineering and Automation, National University of Defense Technology, China Phone: +86 135 7481 0984, Email: nn_hwd@126.com
Wei Wang (2) College of Mechatronics Engineering and Automation, National University of Defense Technology, China Phone: +86 135 0848 6238, Email: wangwei4213440@163.com
ABSTRACT This paper discussed the adaptive techniques for autonomous orbit determination of
constellations through inter-satellite links (ISL). Though there are two modes are used to achieve this task: concentricity and distribution, we just address the latter to take advantage of implement on-board rather easy than the former. In this case, a satellite (refer to as local satellite) determination its orbit on the assumption that the orbits of the others (refer to as remote satellites) were determined and thus can be attained by ISL communication. Because there may be outliers or abnormal observations in inter-satellite ranging (ISR) measurements and imprecise force models or orbit dynamics information both of local and remote satellites, the results of autonomous orbit determination may deserve large errors and even fail to converge. A multifactor adaptive technique was employed to restrain the effect of abnormal observations and imprecise orbit dynamics on the basis of covariance components estimation, in which the effect of the two were assessed. The numerical simulations show that, the approach proposal was able to reduce the effect of abnormal observations and imprecise orbit dynamics. Consequently, an improvement can be obtained for autonomous orbit determination of constellations both in precision and robustness. KEYWORDS: constellations, autonomous orbit determination, adaptive filtering, covariance components estimation, weighted balance
Session 5C:
Testing & Calibration
15:55-17:15
Geoscience Australia’s GNSS Antenna Calibration Facility: Initial Results Anna Riddell Geoscience Australia, Australia +61 2 6249 5840 Anna.Riddell@ga.gov.au
Michael Moore Geoscience Australia, Australia +61 2 6249 9884 Michael.Moore@ga.gov.au
Guorong Hu Geoscience Australia, Australia +61 2 6249 9884 Guorong.Hu@ga.gov.au
ABSTRACT A GNSS antenna calibration facility has been established at Geoscience Australia, for determining individual antenna calibrations as well as aiding the establishment of type mean calibrations as used by the International GNSS Service. Studies have highlighted the importance of accounting for the variation in individual antenna calibrations for high precision positioning applications. In order to use individual antenna calibrations reliably, the repeatability of the calibration needs to be well understood. In this paper, we give an overview of the repeatability of calibrations for different antenna types. We also present a case study on the application of an individual GNSS antenna calibration in Australia and its effect upon positioning. KEYWORDS: GNSS antenna, calibration, robot, positioning.
Test report of L1-SAIF experiment Mazher Choudhury (1)* Yong Li(2)* Chris Rizos(3)* * Surveying and Geospatial Engineering, School of Civil & Environmental Engeneering, UNSW, Australia Ph: +61(2)93854173 / Fax: +61 (2) 9385 5657 email: (1) mohammad.choudhury@unsw.edu.au
Ken Ito(4)^ Takeyasu Sakai(5)^ ^ Electronic Navigation Research Institute 7-42-23, Jindaiji-higashi-machi, Chofu, Tokyo 182-0012 Japan
ABSTRACT The MICHIBIKI satellite transmits the L1-SAIF signal. Since 2014, UNSW has hosted an L1-SAIF receiver (provided by the Electronic Navigation Research Institute, Japan) in order to collect continuous L1-SAIF data over a three month period. In this paper, a report on the L1-SAIF enabled positioning accuracy is presented. Kinematic or static real-time position estimation could not be executed as the ionospheric correction is only valid for Japan. However, epoch-by-epoch postprocessed solutions could verify the positioning accuracy. For this paper, 90 days of observation and navigation data from an MGEX station located in Japan, named CHOF, was used. Results indicate that there is up to 60% improvement of the position solution when using the correction information broadcasted by the L1-SAIF signal. For example, the single point positioning solution from DOY 320 shows that, GPS-only solution has a 2D RMS of 4.322m whereas by using the L1-SAIF the 2D RMS comes down to 1.582m. Similarly, the height estimate is improved by 40%. RMS of the pseudorange residuals is 0.628m (using L1-SAIF) whereas GPS-only solution has 1.187m. Similar results have been observed for the days when L1-SAIF was transmitted. These results indicate that the L1-SAIF enabled solutions can be used when there are no other position solutions possible. KEYWORDS: QZSS, L1-SAIF, single point positioning.
Results from Kea V4.1 FPGA-based GPS Receiver Performance Testing Eamonn P. Glennon Australian Centre for Space Engineering Research (ACSER), School of Electrical Engineering and Telecommunications, University of New South Wales, Australia +61 2 9385 4173, e.glennon@unsw.edu.au
Kevin J. Parkinson General Dynamics Pty Ltd, New Zealand kevin@dynamics.co.nz
Andrew G. Dempster Australian Centre for Space Engineering Research (ACSER), School of Electrical Engineering and Telecommunications, University of New South Wales, Australia +61 2 9385 6890, a.dempster@unsw.edu.au
ABSTRACT The Kea V41 FPGA-based GPS receiver is a successor to the Namuru V32R3 GPS receiver that has been designed specifically for flexibility in order to support a variety of applications. In this paper we first provide a brief overview of the receiver hardware and its capabilities, showing how the design represents an evolution of the proven Namuru V32R3 design. This is followed by test results in which the receiver performance is validated using Spirent GPS simulator scenarios, with particular emphasis on results relating to operating the receiver in lowearth-orbit, high precision timing and the output of L1 carrier-phase. Significant improvements in performance compared with previous generations will be demonstrated, especially with regard to power consumption and acquisition time. The performance of the pulse-width-modulation (PWM) control of the voltage-controlled temperature compensated crystal oscillator (VC-TCXO) will also be reported as this directly impacts the synchronisation and syntonisation capabilities of the receiver. KEYWORDS: FPGA based GPS receiver, cubesats, timing, low earth orbit
Oral Presentations Abstracts – Wednesday 15 July, 2015 Session 6B:
Plenary Session
0900-1030
Secure Perception for Autonomous Systems Todd Humphreys Assistant Professor/The University of Texas at Austin/USA 210 E. 24th St. Stop C0600 Austin, TX 78712-1221 Office: 512 471 4489 todd.humphreys@mail.utexas.edu
ABSTRACT The next few decades will see pervasive autonomous control systems become critical to the world economy—from autonomous cars and aircraft to smart homes, smart cities, and vast energy, communication, and financial networks controlled at multiple scales. Protecting these systems from malicious attacks is a matter of urgent societal interest. The study of secure control has made important advances over the past few years, but these constitute not solutions so much as problem framing and an emerging consensus that traditional fault detection and mitigation fails when confronted with a deliberate attacker: outlaws are different from outliers; fraud is different from faults. Moreover, the majority of this early literature focuses on standard cyber attacks—those that entail infiltration of communications networks or computer systems within which sensor measurements and control commands are conveyed or calculated. This presentation focuses on an emergent category of cyber-physical attack that has seen little scrutiny in the secure control literature. Like cyber attacks, these attacks are hard to detect and can be executed from a distance, but unlike cyber attacks, they are effective even against control systems whose software, data, and communications networks are secure, and so can be considered a more menacing long-term threat. These are field attacks: attacks on the physical fields— electromagnetic, magnetic, acoustic, etc.— measured by system sensors. My students and I in the UT Radionavigation Laboratory have demonstrated the surprising potency of a field attack targeting the GPS sensor of an autonomous helicopter: in a live demonstration the target helicopter became remotely controllable almost as if caught in a tractor beam. More recently, we launched a field attack against the semi-autonomous navigation system of an $80M superyacht, driving it several km off course without raising alarms.
KEYWORDS: Navigation security, timing security, GNSS signal authentication eLoran Initial Operational Capability in the United Kingdom Dr. Paul Williams Mr. Chris Hargreaves Mr. George Shaw Dr. Nick Ward Mr. Martin Bransby The Research and Radionavigation Directorate The General Lighthouse Authorities of the United Kingdom and Ireland Trinity House, Harwich +44(0)1255-245000
ABSTRACT GNSS, in particular GPS has become the de-facto world standard for high-accuracy, highavailability radio-navigation services. Its success has led to GNSS becoming ubiquitous for positioning, navigation and timing across all sectors of industry, transport, emergency services and the military. Of late there has been some concern raised about the over-reliance many critical systems now place on GPS, and the need for a backup. The General Lighthouse Authorities of the UK and Ireland have studied several potential backup systems to augment GPS to provide reliable positioning and navigation for the mariner at sea. The most promising, and cost-effective of these is to update the Loran-C radio-navigation service to eLoran. This has the capability to meet the IMO’s standards for positioning Accuracy, Availability, Continuity and Integrity. The paper will present the rationale and technical details of the UK General Lighthouse Authorities’ implementation of eLoran Initial operational Capability (IOC). This system uses the existing network of Loran transmissions in Northwest Europe together with the addition of differentialLoran Reference Stations installed at 7 major ports on the east coast of the United Kingdom. The system provides a complementary backup to GPS capable of supporting Maritime Port Approach operations at the 10 m (95%) accuracy level, using a prototype multi-source Resilient PNT receiver. Techniques and methods to employ eLoran in the Coastal Voyage phase, between Port Approaches, are also discussed, in addition to the process of developing new and updated technical standards.
Session 8B:
NPI Workshop
1330-1510
NPI: Background and Current Progress Gary Johnston Geoscience Australia, Canberra, ACT
ABSTRACT NOT PROVIDED
Jurisdictional Updates on Positioning Infrastructure & Services across Australia Paul Harcombe, ICSM ABSTRACT The Intergovernmental Committee on Surveying and Mapping (ICSM) is the peak body for surveying and mapping in Australia. ICSM provides leadership, coordination and standards for surveying, mapping, charting and national datasets. ICSM membership is comprised of senior representatives of surveying and mapping agencies from the Commonwealth, State and Territory jurisdictions of Australia and New Zealand. ICSM is a Standing Committee of ANZLIC – the peak intergovernmental body responsible for spatial information in Australia and New Zealand. This presentation will outline the current status of positioning programs across the jurisdictions of Australia, with a view to identifying common issues and opportunities for developing the National Positioning Infrastructure (NPI). Jurisdictional updates will primarily focus on current and future plans for Continuously Operating Reference Station (CORS) infrastructure, including station numbers, service coverage, partnerships, and data access/licensing models. These updates will
inform a coordinated view on key issues to consider as part of planning and development of the NPI, including data and service standards, End User needs, business models for infrastructure supply and maintenance, and whole-of-nation drivers for strengthened capability, resilience and adoption from an ICSM perspective.
Enabling Connected and Automated Vehicles Stuart Ballingall Austroads, Australia Ph: +61 (3) 9229 6095, E: stuart.ballingall@roads.vic.gov.au
ABSTRACT Smart technologies are increasingly being deployed within our transport systems, with the promise of delivering not only convenience and infotainment services to end users, but also significant societal outcomes in the form of safety, mobility and environmental benefits. A connected vehicle ecosystem is emerging in which vehicles will share data wirelessly with other vehicles, with infrastructure, with transport management systems, and with mobile devices. Commonly referred to as Cooperative Intelligent Transport Systems (C-ITS), the emerging ecosystem will enable a wide range of vehicle and transport applications to be deployed and cooperatively work together. There is also significant development occurring towards increasing levels of automation in vehicles. Vehicles are already available that enable the driver to be relieved of the driving task in limited scenarios, and the automotive industry are informing that this trend will continue towards highly and fully automated vehicles that can drive themselves for extended periods. While connected and automated vehicle systems are often spoken about separately, we are seeing a convergence occur between the two. Many of the same smart technologies, and also regulatory and operational frameworks, will be required to support both. This will include positioning systems. This presentation will provide an overview of connected and automated vehicles, discuss their emerging positioning requirements, and highlight some of the key challenges that will need to be addressed to enable their deployment. KEYWORDS: Connected vehicles, intelligent transport systems, cooperative systems, C-ITS, automated vehicles.
Agriculture Tim Neale PrecisionAgriculture.com.au, Brisbane, AUSTRALIA ABSTRACT NOT PROVIDED
Equipment Manufacturer Rod MacLeod,
NovAtel Inc, Sydney AUSTRALIA
ABSTRACT NOT PROVIDED
Aviation Ian Mallett Civil Aviation Safety Authority, Canberra, AUSTRALIA
ABSTRACT NOT PROVIDED
Session 8C:
Interference
1330-1350
Detecting the Presence of Spoofers using Multipath Detection Techniques Laure Demicheli ENAC, France Tel: +33 5 62 17 45 58 E-mail: laure.demicheli@eleve.enac.fr
Ryan J R Thompson, Ediz Cetin, Andrew G Dempster Australian Centre for Space Engineering Research (ACSER), UNSW Australia, Australia. E-mail: r.thompson@unsw.edu.au, e.cetin@unsw.edu.au, a.dempster.@unsw.edu.au
ABSTRACT A significant threat to the integrity of systems that rely on Global Navigation Satellite System (GNSS) receivers is spoofing, where an attacker transmits counterfeit satellite signals to deceive the operation of a receiver. During sophisticated spoofing attacks where the spoofer attempts to closely match the power of the authentic signals there will be significant distortion in the receiver’s correlator outputs as the two signals overlap and interfere with each other. The aim of this work is to examine statistically the response of different Signal Quality Monitoring (SQM) techniques, originally devised for detecting the presence of multipath and other signal faults, in the presence of different spoofing attacks. The results will demonstrate that the Early Late Phase (ELP) metric, which differs from traditional SQM metrics in that it looks at the Quadrature-Phase correlator outputs as well as the In-Phase, can detect subtler distortions caused by the spoofer than the others. For analysis 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. Other locally recorded datasets will be used to study the behaviour of the SQM metrics under spoofer free conditions, as well as data from GNSS simulators to analyse simpler spoofing scenarios. KEYWORDS: spoofing, multipath, signal quality monitoring
Commercialisation and large area field trial results of the GNSS Environmental Monitoring System (GEMS) - A jammer/spoofer detection and localisation system . Ryan J R Thompson GPSat Systems Australia ryant@gpsatsys.com.au
Graeme Hooper GPSat Systems Australia
graemeh@gpsatsys.com.au
ABSTRACT After five years of research and several past technical papers presented at GNSS conferences, the GEMS2 project for developing RF Interference, Spoofing Detection and Geo-location technologies, has now transitioned from past academic research into initial production and customer focused open space field trials. Specifically designed for detecting weak interference or spoofing signals at long “stand-off� distances, (several kilometres) the technology is designed to deliver regional static GNSS spectrum protection against all forms of jamming and spoofing for mission critical GNSS infrastructure users, such as defence facilities, airports and future industry automation customers. Reliant on several diverse technology advancements, including, multi element electronic beam steering antenna arrays for highly accurate Angle of Arrival (AOA) targeting and precision time synchronising for Time Difference of Arrival (TDOA) correlation processing, the presentation delivers updates on both commercial product developments and actual field performances achieved over large areas.
KEYWORDS: Interference, jammers, spoofing, localisation. Unambiguous s-curve shaping for multipath mitigation for MBOC modulated signals in GNSS Zhe Liu (1) National University of Defence Technology/China 073184576542 & 073184576537
Baiyu Li (2) National University of Defence Technology/China 073184576542 & 073184576537
Xiaomei Tang (3) National University of Defence Technology/China 073184576542 & 073184576537
Feixue Wang (4) National University of Defence Technology/China 073184576542 & 073184576537
ABSTRACT A novel multipath mitigation algorithm for multiplex binary offset carrier (MBOC) signals in the global navigation satellite system (GNSS) is presented. On the base of the W2 code correlation reference waveform (CCRW) structure, a series of bipolar reference waveform (BRW) is introduced, aiming to shape the unambiguous s-curve. The shaped s-curve has a single stable zero-crossing point, and the problem of unambiguous tracking in MBOC signals is solved. Multipath mitigation capability has also been improved. The performance of multipath mitigation is similar to W2 CCRW. This method could be used in GPS L1 and Galileo E1. KEYWORDS: Multipath mitigation, MBOC, unambiguous tracking
Network Joint Clock Synchronization and Ranging: Linear Bayesian Solution Xiaobo Gu School of Electronic and Information Engineering, Beihang University, China +86 10 82317800, xiaobo.gu@buaa.edu.cn
Qing Chang School of Electronic and Information Engineering, Beihang University, China +86 10 82317800, changq@263.net
Eamonn P. Glennon Australian Centre for Space Engineering Research (ACSER), School of Electrical Engineering and Telecommunications, University of New South Wales, Australia +61 2 93854173, e.glennon@unsw.edu.au
Andrew G. Dempster Australian Centre for Space Engineering Research (ACSER), School of Electrical Engineering and Telecommunications, University of New South Wales, Australia +61 2 93856890, a.dempster@unsw.edu.au
ABSTRACT Time synchronization and ranging are two critical issues for time of arrival (TOA) based localization systems such as the wireless sensor networks (WSNs), indoor positioning systems and pseudolite systems. In order to jointly estimate the clock skews, clock offsets and fixed relative distances, a two-way timing stamp exchange mechanism to collect the necessary time information is first discussed. Second, a network wide observation formula is derived, according to which, the implementation conditions and restrictions of the existing algorithms apply. Finally, a novel global linear Bayesian (GLB) estimation algorithm is presented in this paper. Unlike the other existing solutions, the proposed algorithm could compute the desired unknown parameters in a recursive, rapid and low-complexity way, and also free the restrictions of symmetric and synchronous communications. The Monte Carlo experiments shows that the GLB estimator achieves the best performance compared with the other existing estimators. KEYWORDS: Time synchronization, two-way communication, clock model, Bayesian estimation, joint estimation
Session 9B
NPI Workshop continued
1540-1700
New Zealand National Positioning Infrastructure Graeme Blick Chief Geodesist National Geodetic office Land Information New Zealand 64 4 4983833 gblick@linz.govt.nz
ABSTRACT Land Information New Zealand is responsible for the provision of the geodetic system (the national positioning infrastructure) in New Zealand. We provide an accurate geodetic system that enables geospatial datasets to be accurately integrated with each other. Historically there has been a strong focus on the provision of physical geodetic marks and data in support of the cadastral system in New Zealand. However with the increasing use of location based information and GNSS positioning systems by a wider range of users, we are changing our focus from the provision of vast networks of control points to the active maintenance of the models that define our datums. We are also placing a greater emphasis on supporting and maintaining global and regional reference frames which we in turn rely on to ensure accuracy of our geodetic system. This talk will describe the changing focus of the geodetic system in New Zealand and the current and proposed national positioning infrastructure.
KEYWORDS: New Zealand, geodetic system, national positioning infrastructure, GNSS National Positioning Infrastructure Advisory Board Presentation on maritime perspective Nick Lemon BSurv, Grad Dip Business Admin, Grad Dip Hydrography, member of the Hydrographic Society and the Nautical Institute Australian Maritime Safety Authority Phone: + 61 2 6279 5656 Fax: + 61 2 6279 5966 E-Mail: nsl@amsa.gov.au
ABSTRACT The presentation will highlight the diversity inherent in international shipping industry and its centrality to Australia’s trade and prosperity. The growing use of GNSS on board ships and its vulnerability to intentional and unintentional interference creates potential to jeopardise maritime operations, trade and impact negatively on maritime safety and environmental protection. There are several new initiatives underway, such as the International Maritime Organization led concept of e-navigation, wherein GNSS will play a key role. Broadly, e-navigation aims to integrate new and existing navigational equipment on board ships, improve the interaction of humans with equipment and join ship and shore to enhance the safety of navigation and improve supply chains. Innovations such as the Maritime Cloud and Sea Traffic Management, which are set to radically alter the way mariners exchange information, will also be outlined. GNSS will also play a major role in the conduct of marine spatial planning (MSP). Efforts to develop marine spatial plans for many waters of the world are already underway. UNESCO and peak mariner professional organisations such as the Nautical Institute have led the way by providing early guidance. Resilient positioning, navigation and timing (PNT) services will also be vital to support any government efforts for governance and preservation of the world’s oceans, while also promoting the blue economy.
KEYWORDS: maritime, shipping, MSP, resilient PNT Research Suelynn Choy RMIT University, Melbourne, AUSTRALIA Abstract not Submitted
Spatial/Construction Martin Nix Position Partners, Sydney, AUSTRALIA Abstract not Submitted
US PNT Advisory Board/ IGNSS Society Matt Higgins Department of Natural Resources and Mines, Brisbane, AUSTRALIA Abstract Not Submitted
Session 9C
Multi GNSS II
1540-1700
An efficient secondary code transition cancellation correlator for fast multi-GNSS acquisition Vinh T Tran Australia Centre for Space Engineering Research University of New South Wales, Sydney, Australia
Nagaraj C Shivaramaiah Australia Centre for Space Engineering Research University of New South Wales, Sydney, Australia
Andrew G Dempster Australia Centre for Space Engineering Research University of New South Wales, Sydney, Australia
ABSTRACT The involvement of secondary code in modern GNSS signals brings advantages and additional performances, especially for acquiring weak signals. However, it also makes the acquisition more difficultly. Unlike the acquisition of legacy GPS signal, the presence of secondary codes allows the polarity of the transmitted signal to change each primary code period. The unknown secondary code phase prevents the receiver from performing a longer integration. Fortunately, the secondary code transition only happens at the beginning or ending of each primary code period. Therefore, if the start bit of the primary code in the received signal is detected, the secondary code transition
problem can be eliminated. This paper proposes a configurable acquisition engine architecture which not only can handle the secondary code transition but also extends integration period by a suitable combination of coherence and non-coherence integration. FPGA implementation issues are presented and analysed in term of configurability and resource utilisation. The result reveals that the proposed engine can be flexibly configured across GNSS signals and consumes lowest resources. KEYWORDS: Secondary code, transition cancellation, multi-GNSS, fast acquisition, FPGA
Exploring the contributions of multi-GNSS constellations to Precise Point Positioning (PPP) solutions with raw single-frequency and dual-frequency measurements models Fu Zheng GNSS Research Center, Wuhan University, China Tel.: + 86-27-68778241; Fax: + 86-27-68778890; guntherdoit@163.com
Yidong Lou GNSS Research Center, Wuhan University, China Tel.: + 86-27-68778241; Fax: + 86-27-68778890; ydlou@whu.edu.cn
Shengfeng Gu GNSS Research Center, Wuhan University, China Tel.: + 86-27-68778241; Fax: + 86-27-68778890; gsf@whu.edu.cn
Charles Wang Science and Engineering Faculty, Queensland University of Technology, Australia cc.wang@qut.edu.au
Hailin Guo GNSS Research Center, Wuhan University, China Tel.: + 86-27-68778241; Fax: + 86-27-68778890; hailingG@whu.edu.cn
Yangming Feng Science and Engineering Faculty, Queensland University of Technology, Australia y.feng@qut.edu.au
ABSTRACT The emerging multiple satellite navigation systems, including BDS (C) and Galileo (E), modernized GPS (G) and GLONASS (R) systems, bring great opportunities and challenges for Precise Point Positioning (PPP). This paper studies the contributions of various GNSS combinations to PPP performance based on zero-combined (ZC) observation models, in which the ZC signal delay biases and ionosphere-delays must be considered. The model is more generally suitable for single, dual or multi-frequency data processing and for any single or combined multi-GNSS systems. Another advantage of the ZC-PPP models over the conventional ionosphere-free PPP models (IFPPP) is that ZC-PPP observations avoid noise amplification by linear combinations. Additionally, a priori ionosphere-knowledge, such as regional or global models can be used in estimation of ionosphere-related parameters, which potentially improves the positioning performance. Extensive performance evaluations were conducted with multi-GNSS data sets collected from 105 MGEX stations over the whole July of 2014. Dual-frequency PPP results from each single constellation show that the ZC-PPP solution convergence time is normally shorter than that of the IF-PPP solutions, while the positioning accuracy of the ZC-PPP shows more evident improvement for the GLONASS system. In addition, the GLONASS ZC-PPP results demonstrate evident performance enhance in the high latitude area, while this impact is less obvious in the GPS/GLONASS combined configuration. The results have also indicated the BDS GEO satellites have negative impacts on the ZC-PPP performance based on the current orbit and clock knowledge of the GEO satellites. More generally, the multi-GNSS ZC-PPP results have shown improvements in the convergence time by more than 60% in both the single- and dual-frequency PPP results, while the positioning accuracy after convergence indicates no significant improvements for the dualfrequency PPP solutions, but an improvement of about 25% on average for the single-frequency PPP solutions. KEYWORDS: Multi-GNSS; ZC-PPP; MGEX; convergence time
Programmable custom multi-core architectures for multi-constellation GNSS receiver Vinh T Tran Australia Centre for Space Engineering Research University of New South Wales, Sydney, Australia
Nagaraj C Shivaramaiah Australia Centre for Space Engineering Research University of New South Wales, Sydney, Australia
Andrew G Dempster Australia Centre for Space Engineering Research University of New South Wales, Sydney, Australia
ABSTRACT A programmable baseband signal processor is one of the essential facilitators of software-defined radios in general, and for software-defined multi-GNSS receivers in particular. As many new GNSSs evolve, the flexibility and processing power needed for baseband processing increases dramatically. Also, the underlying hardware needs to cope with various modulation standards and possibly simultaneously maintaining signal processing from several different GNSS. Meanwhile, the maximum power and resource consumption for a single-chip receiver is still limited. These challenges require both system and architecture level innovations. In this paper, we present our analysis on custom multicore architectures based on the following aspects. First, the dependency of the baseband channel design on the GNSS signal types (constellation, frequency bands). Second, the dependency of the baseband channel design on the signal processing design decisions (coherent and non-coherent integration time etc.). Third, the inter-core interconnects features that allow implementing a seamless three dimensions Frequency-Time-PRN search. Besides that, FPGA platform has been used to examine proposed architectures in regard to resource, power consumption and configurability. KEYWORDS: Programmable baseband, custom multi-core. multi-GNSS, FPGA
An Effective Use of Radio Altimeter to GPS/DME Integration System Moonsuk Koo Department of Electronics Engineering/Chungnam National University/Korea +82-42-821-7709 & +82-42-823-5436, koomoonsuk@cnu.ac.kr
Sun Yong Lee Department of Electronics Engineering/Chungnam National University/Korea +82-42-821-7706 & +82-42-823-5436, sy_lee@cnu.ac.kr
Hyoungmin So 3-4/Agency for Defence Development/Korea +82-42-821-4463, hmso@add.re.kr
Sang Heon Oh Integrated Navigation Division/Navcours Co., Ltd./Korea +82-42-363-9249 & +82-42-363-9240, laborosh@navcours.com
Dong-Hwan Hwang Department of Electronics Engineering/Chungnam National University/Korea +82-42-821-5670 & +82-42-823-5436, dhhwang@cnu.ac.kr
Sang Jeong Lee Department of Electronics Engineering/Chungnam National University/Korea +82-42-821-6582 & +82-42-823-4494, eesjl@cnu.ac.kr
ABSTRACT In order to overcome vulnerability of GNSS, lots of researches on use of ground navigation systems have been found. An effective use of an altimeter is proposed in an integration of GNSS/DME integration system. A weighted DOP which is based on statistics of measurement error, is derived for a given vehicle motion trajectory. From the derived DOP, the vertical error is estimated. By comparing the estimated vertical error with error specification of the altimeter, use of the altimeter is determined in the integrated navigation system. In order to show efficiency of the proposed method, 50 times Monte-Carlo simulations were performed for a GPS/DME integrated navigation system. KEYWORDS: GNSS, Ground Navigation, Integrated Navigation, Altimeter, DOP
Oral Presentations Abstracts – Thursday 16 July, 2015 Session 10C
Ionosphere and GNSS Meteorology
0900-1030
Ionospheric Corrections for Precise Positioning with Single-Frequency GNSS Receivers, a Long Distance Away from the Nearest Network Receiver Oscar L. Colombo Goddard Space Flight Center, Greenbelt, MD 20771, USA Tel: +1-301-614-6102, Fax: +1-301-614-6522, Oscar.L.Colombo@NASA.gov
Manuel Hernandez-Pajares Universitat Politècnica de Catalunya, UPC-IonSAT, Mod. C3 Campus Nord, E08034-Barcelona, Spain Tel: +34-93-4016029, Fax: +34-93-4015981, manuel@ma4.upc.edu
Volker Janssen NSW Land and Property Information, Bathurst NSW 2795, Australia Tel: +61-2-6332 8426, Fax: +61-2-6332 8479, Email: Volker.Janssen@lpi.nsw.gov.au
ABSTRACT We intend to present results of a study where precise ionospheric corrections have been generated and then used to assist Global Navigation Satellite System (GNSS) positioning with data
from high-end single-frequency receivers. The data used in the tests were from CORSnet-NSW (Australia) and from the NGS CORS (USA). The motivation has been twofold: (a) to use new techniques for estimating corrections for the ionospheric delay in L1, with moderate levels of scintillation and travelling ionospheric disturbance (TID), and test them in single-frequency positioning solutions; (b) to help make the most of good L1-only receivers that can be considerably less expensive than dual-frequency ones. The emphasis is on wide-area L1-only applications, such as point positioning, supported by a sparse CORS-type network where the stations are separated by distances of up to several hundred kilometres. In order to maximise the accuracy and consistency of the ionospheric corrections for single-frequency precise GNSS users, the following approach will be considered: the TOMION tomographic model of the ionospheric electron content, which simultaneously solve the main model unknown parameters in a wide area GNSS network (like carrier phase ambiguities and zenith tropospheric delays). This will be adopted in order to provide the main “lineal” ionospheric corrections to the users (following e.g. Colombo O.L., Hernandez‐Pajares M., Juan J.M. & Sanz J. (2002) Wide‐area, carrier‐phase ambiguity resolution using a tomographic model of the ionosphere, Navigation, 49(1), 61-69). Moreover, the potential benefits for single-frequency precise GNSS users of adapting existing models of the predominant ionospheric waves (the Medium Scale Travelling Ionospheric Disturbances, MSTIDs) will be specifically assessed in this work taking into account recent findings (Hernandez-Pajares M., Wielgosz P., Paziewski J., Krypiak-Gregorczyk A., Stepniak K., Bosy J., Kaplon J., Hadas T., OrusPerez R., Monte-Moreno E., Yang H., Garcia-Rigo A. & Olivares-Pulido G. (2015) New approaches in Medium Scale Travelling Ionospheric Disturbances modelling, Geophysical Research Abstracts, Vol. 17, EGU General Assembly 2015). KEYWORDS: Ionospheric corrections, single-frequency receivers, CORS.
Positioning Performance Evaluation of Regional Ionospheric Corrections with Single Frequency GPS Receivers W Liu, H Zhang,C Wang, Y Feng Queensland University of Technology, Australia
S Gu Wuhan University, China
ABSTRACT Low-cost single frequency (SF) GPS receivers have the potential to become an accurate alternative to medium- to high- end dual frequency receivers for many applications such as GIS data collections, vehicle positioning for lane-level safety applications and entertainment. For a single frequency receiver to achieve positioning precision of decimetre level, ionosphere delay is the main bottleneck among all error sources. The IGS-released Global Ionospheric Map provides for ionosphere corrections. However, the GIM corrections neither are available for real time applications, nor provide sufficient accuracy for areas without high density stations. With around 200 reference stations, Australian Regional Ionospheric Map (AUSRIM) is generated with high temporal and spatial resolution vertical slant total electron contents (TEC). This paper describes the station-based PPP ionosphere estimation method, which preserve the integer nature for carrier phase ambiguity resolutions. In order to achieving decimetre or higher precision, error sources including DCB, earth ocean tide, phase centre offset and windup are taken into consideration, in addition to adoption of precise orbits and clocks. Their effects on positioning performance are studied numerically in detail. With the AUSRIM generated for the January 1 2014, the evaluation is performed with both SF-SPP and SF-PPP modes, based on the modification to the RTKLIB software platform. The SF-SPP solutions from 40 selected reference receivers prove the decimetre RMS accuracy, which is better than 20 cm for East/North directions and 60 cm for Up-component. With the same data sets and receivers, the SF-PPP mode yields the RMS accuracy of better than 15 cm and 40 cm in the two directions. With a low-cost U-blox SF receiver, the RMS accuracy of East/North and Up components are degraded, but still reaches to 0.5 m and 1 m respectively. Overall, this work demonstrates the promising potential for the Australia GNSS network to offer decimetre positioning
services with single-frequency low-cost GNSS receivers, supporting many new applications such as transport safety over Australia. KEYWORDS: Regional ionospheric corrections, single frequency PPP, single frequency SPP, decimetre positioning
Real-time High Accuracy Retrievals of Precipitable Water Vapour from GNSS Precise Point Positioning Yubin Yuan SPACE Research Centre, School of Mathematical and Geospatial Sciences, RMIT University, Melbourne, VIC 3001, AUSTRALIA yubin.yuan@rmit.edu.au
Kefei Zhang SPACE Research Centre, School of Mathematical and Geospatial Sciences, RMIT University, Melbourne, VIC 3001, AUSTRALIA kefei.zhang@rmit.edu.au
Suelynn Choy SPACE Research Centre, School of Mathematical and Geospatial Sciences, RMIT University, Melbourne, VIC 3001, AUSTRALIA suelynn.choy@rmit.edu.au
Witold Rohm Institute of Geodesy and Geoinformatics, Wroclaw University of Environmental and Life Sciences, Norwida 25, 50-375 Wrocław, Poland witold.rohm@igig.up.wroc.pl
ABSTRACT This study investigates the real-time retrieval of zenith total delay (ZTD) and precipitable water vapour (PWV) using the precise point positioning (PPP) approach, which is implemented using a modified version of the BKG Ntrip Client. The software modifications include more accurate error corrections in terms of tropospheric delay, antenna phase centre offset and variation, solid Earth tides and ocean tide loading. In a GPS-only scenario, observations in a 1-month period from 20 globally distributed stations are selected for testing. The derived real-time ZTDs at most stations agree well with the tropospheric products from the International Global Navigation Satellite Systems Service and the root mean square (RMS) errors are <13 mm. The RMS errors of the retrieved PWVs in comparison with the radiosonde-derived values are â&#x2030;¤3 mm, which is the threshold value of PWVs as inputs to weather nowcasting. The theoretical accuracy of PWVs is also discussed and 3 mm quality of PPP-PWVs is proved to be achievable in different temperature and humidity conditions, even if empirical models are used. In a multi-GNSS scenario, the adding of GLONASS observations can significantly increase the number of visible satellites and improve the Dilution of Precision indices. However, the atmospheric retrievals at 12 global IGS stations show that adding GLONASS data slightly degrades the accuracies of PPP-ZTDs. This is likely caused by deficiencies in the functional model as extra GLONASS clock parameters are required, the introduction of new GLONASS ambiguity parameters weakens the benefits brought by more measurements and less accurate corrections of GLONASS orbits and clocks are unavoidable. KEYWORDS: precise point positioning, GPS meteorology, multi-GNSS, zenith total delay, water vapour
Space situational awareness - a new horizon of Australian space research Zhang K. (1) The SPACE Research Centre, RMIT University, GPO Box 2476V, Australia Tel: 99253272, Email: kefei.zhang@rmit.edu.au
Bennett J. C. (2) The SPACE Research Centre, RMIT University, GPO Box 2476V, Australia
Sang J. (3) The SPACE Research Centre, RMIT University, GPO Box 2476V, Australia
Smith C. (4) The SPACE Research Centre, RMIT University, GPO Box 2476V, Australia
Norman R. (5) The SPACE Research Centre, RMIT University, GPO Box 2476V, Australia
Carter B. (6) The SPACE Research Centre, RMIT University, GPO Box 2476V, Australia
Zhao Y. (7) The SPACE Research Centre, RMIT University, GPO Box 2476V, Australia
Wu S. (8) The SPACE Research Centre, RMIT University, GPO Box 2476V, Australia
ABSTRACT The Space Environment Research Centre (SERC) is a consortium to pursue research and development of technologies and capabilities that will help to preserve the orbital space environment. The consortium includes Electro Optics Systems, RMIT, The Australian National University, Lockheed Martin, Optus Satellite Systems and National Institute of Information and Communications Technology of Japan. SERC is a recipient of an Australian Government grant through the establishment of the Cooperative Research Centre for Space Environment Management (CRC-SEM). SERC will pursue a wide range of research tasks including technologies to improve tracking capability and capacity, orbit determination and orbit propagation algorithms, conjunction analysis and collision avoidance. All of these technologies will contribute to the flagship program to demonstrate active collision avoidance by remotely manoeuvring space debris using photon pressure delivered from a ground-based laser. This project joins the proposed NASA LightForce concept with extra infrastructure and capabilities provided by SERC. This contribution will introduce the newly established 5-year CRC-SEM, its rationale, partnership, research roadmap, expected outcomes and progress to date. The new CRC-SEM will build upon Australian expertise in measurement, monitoring, analysis and management of space debris to develop new technologies, new algorithms and strategies to preserve the space environment, especially robust solutions to help remediate the proliferation of debris objects caused by a collisional cascading phenomenon. This initiative is regarded as a new dimension of geodesy. It is argued that geodesists should play a major new role in space environment management and help with preserving our very valuable assets in space. KEYWORDS:.Space Situaltional Awareness, precise orbit determination, space environment management, debris objects, conjunction analysis
Session 11C
Multii GNSS III
1100-1220
RTX positioning using BeiDou geostationary satellites Carlos Rodriguez-Solano, Feipeng Zhang, Markus Nitschke, Xiaoming Chen, Victor Gomez, Herbert Landau, Markus Brandl, Ulrich Weinbach, Fabian Pastor Trimble TerraSat GmbH, Germany Carlos_Rodriguez-Solano@Trimble.com
ABSTRACT The Trimble CenterPoint RTX service provides real-time GNSS positioning with global coverage and fast initialization, it is based on the generation of precise orbit and clock corrections for GNSS satellites. The Trimble CenterPoint RTX positioning technology supports five satellite navigation systems: GPS, GLONASS, Galileo, QZSS and BeiDou. However, from the BeiDou satellite constellation the GEO (geostationary) satellites are not supported until now, i.e. only the MEO (medium earth orbit) and IGSO (inclined geosynchronous orbit) satellites are currently used. The main reason for this is that the precise orbit determination of the GEO satellites has proven to be a
big challenge. The GEO satellites have a weak (almost invariable) tracking geometry w.r.t. ground stations which causes a strong correlation of the solved-for parameters in the process of precise orbit determination. After overcoming the main challenges the RTX development team has achieved an accuracy of ~5 cm in radial and cross-track components, and ~1.5 m in along-track in the sense of orbit overlap errors. With precise satellite orbits and clock corrections for BeiDou GEO satellites, the satellites can be used for real-time RTX positioning on the Earth at the few centimeter level. In addition to the orbit quality, the improvements in the rover positioning performance are assessed in this paper in terms of position accuracy and convergence time. KEYWORDS: Trimble RTX, multi-GNSS, precise orbit determination, BeiDou, geostationary satellites,
Processing strategies and performances analysis for Beidou precise orbit determination based on GAMIT C Wang, Y Feng Queensland University of Technology, Australia
ABSTRACT The Chinaâ&#x20AC;&#x2122;s Beidou navigation satellite system currently consists of 14 satellites providing initial navigation and positioning services over the Asia-Pacific region. Unlike the GPS constellation, Beidou is made up of three types of satellites: geostationary orbit (GEO) satellites, inclined geosynchonous orbit (IGSO) satellites and medium orbit (MEO) satellites. The characteristics of these satellites, data quality and modelling uncertainties are some of the challenges faced by the researchers in deriving Beidou precise orbit for supporting precise positioning. This work explores the processing strategies of dealing with Beidou observation data and presents the preliminary results of Beidou precise orbit determination (POD) based on the modification to the GAMIT software. The current GAMIT version available only processes GPS data. The modification for Beidou data processing is based on the exiting framework and data structure and processing options. Changes include the signal frequencies, time conversion, GEO satellite position calculation from the broadcast navigation message and yaw attitude control. Furthermore, we investigate effects of various force models and different processing strategies for Beidou POD, against GPS satellites. The 3D RMS performance of the derived Beidou precise orbit solutions with the MGEX network of 40 stations is proven to be 1m, 0.2m and 0.1m for GEO, IGSO, and MEO satellite types, comparing with external solutions. The accuracy in the radial and cross-track direction are much better than the along-track direction for GEO satellites. The results have also shown better performances with GPS-assisted Beidou POD processing and impacted by the station quality and distribution. Lastly, tests with various solar radiation pressure models shows that the extended CODE model (BERN2) yields better results than the rests. KEYWORDS: GAMIT, BeiDou system, POD
Multi-Constellation GNSS Precise Point Positioning using GPS, GLONASS, Galileo, BeiDou and QZSS Suelynn Choy School of Mathematical and Geospatial Sciences, RMIT University, Australia Phone: +61 3 9925 2650 Email: suelynn.choy@rmit.edu.au
Xiaodong Ren School of Geodesy and Geomatics,Wuhan University, China Phone: +8613260587947 Email: xdren@whu.edu.cn
Xiaohong Zhang School of Geodesy and Geomatics, Wuhan University, China Phone: +8613396091378 Email: xhzhang@sgg.whu.edu.cn
Ken Harima School of Mathematical and Geospatial Sciences, RMIT University, Australia Phone: +61 3 9925 3775 Email: ken.harima@rmit.edu.au
ABSTRACT GNSS Precise Point Positioning (PPP) is a promising approach to high accuracy (centimetre to decimetre-level) positioning with a single receiver without the constraints of traditional precise positioning technique such as differential positioning. The advent of multi-constellation satellite systems, such as Chinaâ&#x20AC;&#x2122;s BeiDou and European Unionâ&#x20AC;&#x2122;s Galileo, offers additional satellites and observables, which can strengthen the positioning model thereby improving the accuracy and convergence time of PPP. This paper describes the prospects and challenges in combining multiple GNSS systems such as GPS/GLONASS/ BeiDou/Galileo/ QZSS in a PPP model. In particular, it aims to assess the performance of the combined system in terms of satellite availability, satellite geometry, positional accuracy, reliability and time of convergence. The system will be tested by comparing the performance of a combined system with respect to a stand-alone GNSS system in static and kinematic PPP modes, as well as in different environments. The effect of inter-system biases on the position estimates will also be analysed. KEYWORDS: Precise Point Positioning (PPP), multi-constellation, GNSS, BeiDou, Galileo, QZSS
Evaluation on the Multi-GNSS Precise Orbit and Clock Products: GPS, GLONASS, Galileo and BeiDou Fei Guo (1) School of Geodesy and Geomatics, Wuhan University, China School of Civil and Environment Engineering, University of New Southwales, Australia (+61) 0404198224 fguo@whu.edu.cn
Xingxing Li (2) German Research Centre for Geosciences (GFZ), Germany Lxl109121@gmail.com
Xiaohong Zhang (3) School of Geodesy and Geomatics, Wuhan University, China xhzhang@sgg.whu.edu.cn
Jinling Wang (4) School of Civil and Environment Engineering, University of New Southwales, Australia Jinling.wang@unsw.edu.au
ABSTRACT This contribution first provides an overview of the Multi-GNSS Experiment (MGEX), and then performs a comprehensive assessment of the multi-GNSS (including GPS, GLONASS, Galileo, and BeiDou) precise orbit and clock products from MGEX covering a time span of one and a half years. Orbit comparisons show a consistency of about 1-2 cm for GPS, 3 cm for GLONASS, and 10 cm for Galileo in general, whereas the orbit consistency of BeiDou range from a few centimeters to several meters depending on individual orbit types (GEO, IGSO, and MEO) in different components. Clock comparisons show that, the clock consistency is on the 0.1 ns level for GPS, 0.2 ns for GLONASS, Galileo and BeiDou MEOs. The clock quality of BeiDou IGSOs is slightly worse than that of MEOs, with a consistency of 0.3 ns, while the consistency of BeiDou GEO clocks reaches up to 0.5-0.6 ns. However, the MGEX products from different Analysis Centers (ACs) have inconformity of quality due to different quality control and processing strategies adopted by individual AC. To further verify the quality of the MGEX precise satellite orbit and clock products, kinematic Precise Point Positioning (PPP) tests are conducted with different observation sampling intervals using products from different ACs. Results show that the positioning accuracy of the solutions with different products agrees well with each other, and the fusion of multi-GNSS has advantage over single system for the PPP convergence. Finally, some suggestions are made for the MGEX and the multi-GNSS Positioning, Navigation, and Timing (PNT) users.
KEYWORDS: Multi-GNSS Experiment (MGEX), Precise satellite orbit and clock products, Orbit quality, Clock quality, Precise Point Positioning (PPP)
Session 12B
GNSS Infrastructure
1320-1500
CORSnet-NSW: State Infrastructure for GNSS Applications and Applied Research Volker Janssen Survey Infrastructure and Geodesy, Land and Property Information NSW Department of Finance, Services & Innovation, Bathurst NSW 2795, Australia Tel: +61-2-6332 8426, Fax: +61-2-6332 8479, Email: Volker.Janssen@lpi.nsw.gov.au
Joel Haasdyk Survey Infrastructure and Geodesy, Land and Property Information NSW Department of Finance, Services & Innovation, Bathurst NSW 2795, Australia Tel: +61-2-6332 8485, Fax: +61-2-6332 8479, Email: Joel.Haasdyk@lpi.nsw.gov.au
Simon McElroy Survey Infrastructure and Geodesy, Land and Property Information NSW Department of Finance, Services & Innovation, Bathurst NSW 2795, Australia Tel: +61-2-6332 8300, Fax: +61-2-6332 8479, Email: Simon.McElroy@lpi.nsw.gov.au
ABSTRACT The introduction and expansion of Global Navigation Satellite System (GNSS) Continuously Operating Reference Station (CORS) networks across Australia and internationally has greatly improved access to positioning infrastructure for a wide range of GNSS applications and related research. Benefits include datum definition, rationalisation of infrastructure, establishment of multiuser systems, positioning services that are similar across and between networks, consistent and reliable connectivity to the national datum, and the ability to provide some degree of legal traceability for satellite-based positioning. This paper outlines the current status of CORSnet-NSW and the impact it has on providing first-class state infrastructure for GNSS users in New South Wales, Australia. Now comprising more than 165 CORS, CORSnet-NSW has revolutionised LPI GNSS operations, supported innovations in the surveying and spatial information profession and continues to make important contributions to national and regional geodesy. The present difference between datum realisation via SCIMS and via CORSnet-NSW is explained, and efforts undertaken at LPI to rectify this situation by contributing to the modernisation of Australia’s datum are discussed. Finally, it is outlined how LPI supports the surveying profession and the wider spatial community in regards to GNSS. The State’s CORS infrastructure has become crucial in catering for an increasing demand for accurate, reliable and easily accessible GNSS positioning information in today’s society. In Australia, state jurisdictions provide the essential link between national initiatives and academia on the one hand and the profession on the other, e.g. via maintaining positioning infrastructure and conducting applied research that informs legislation and best practice guidelines. KEYWORDS: CORSnet-NSW, GNSS, CORS, positioning infrastructure, applied research.
SBAS for Australia/New Zealand Jack Scott Thales Australia 7 Murray Rose Avenue, Sydney Olympic Park NSW 2127, Australia
Email: jack.scott@thalesgroup.com.au
ABSTRACT Productivity in Europe, the US, Japan and India is being boosted by enhancing GPS signals through the Space Based Augmentation System, SBAS. Several other countries
are soon to follow, because SBAS substantially increases GPS accuracy, availability and provides integrity consistent with safety of life operations. The European SBAS, called EGNOS, is European wide infrastructure generating economic advantages amongst many sectors through productivity improvements and more efficient use of resources while creating environmental, safety and other social benefits. Thousands of aircraft are successfully using SBAS for precision flight approaches with no other infrastructure. Beyond aviation EGNOS is improving safety and efficiencies to transport systems including roads, rail, maritime and intelligent transport systems. 80% of European farmers use SBAS for precision farming. The mapping and surveying community is another large user base benefiting from the increased accuracy and lower cost commercial equipment. KEYWORDS: SBAS, GNSS, Integrity, aviation: approach with vertical guidance, precision farming, surveying and mapping
Topcon Fully Enables Multi-GNSS Infrastructure James Millner Positioning Infrastructure Manager, Position Partners, Australia Phone: +61 (0) 3 9930 7118 Fax: +61 (0) 3 9930 7170 jmillner@positionpartners.com.au
Gary Penno Topcon Positioning Systems, Inc. Livermore, California, USA Phone: +1 403 450 4256 Fax +1 403 450 4250 gpenno@topcon.com
Luis Elneser Project Services, Position Partners, Australia Phone: +61 (0) 3 9706 9966 Fax: +61 (0) 3 3 9701 7360 LElneser@positionpartners.com.au>
ABSTRACT Topcon Positioning Systems has integrated Multi-GNSS into new and existing infrastructure products including reference station receivers, antennas and its network RTK software. This complete system will support a wide range of new and existing multi-GNSS capable product applications. Results from Australian based testing and development are presented to demonstrate the impact and benefits that can be expected in regions (such as Australia) where multi-GNSS coverage has significantly increased. KEYWORDS: Multi-GNSS Infrastructure, Network RTK, GNSS Reference Station
A Conceptual Geodetic Coordinate System Model Peter Morgan University of Canberra Voice: 61262540137, Email: petermorgan@grapevine.net.au
ABSTRACT
KEYWORDS: GDA94, GDA2020, GDA2022020, Datums, Coordinate systems Real-time IGS in Support of Tsunami Modelling Professor Chris Rizos University of New South Wales, Sydney, AUSTRALIA
The IGS real-time GNSS network consists of over 180 GNSS instruments and has been generating satellite orbit and clock products since 1 April 2013. The RT-IGS supports a large variety of geoscientific and geospatial applications. In particular the RT-IGS initiative addresses many applications that include the mitigation of and response to natural hazards and natural disasters. For example, numerous studies have demonstrated the utility of real-time GNSS geodesy in the first identification of slow slip seismic events at fault zones and the rapid estimation of earthquake moments and associated ionospheric response for ground motion, tsunami prediction and tracking. A proposal for a prototype rapid (i.e. near-real-time) service to determine the time-varying coordinates of permanent GNSS receivers using the precise point positioning (PPP) technique is the Asia-Pacific region has been developed. It is intended that this service be used to detect changes in GNSS receiver coordinates, and ionospheric disturbances, in response to earthquake activity. These derived parameters can then be input into a tsunami modelling software to determine if there will be an associated tsunami generated by the seismic activity. An alert can then be sent to the appropriate disaster management authorities. Simulations have indicated that such a system based on the RT-IGS would be more accurate, and identify tsunami danger much faster than traditional techniques based on seismograph data.
Session 12C
Algorithms and Methods
1320-1500
A Real-time Cycle-slip Detection Method for CDGPS Yun Sub Choi (1) Department of Electronics Engineering/Chungnam National University/Korea 82-10-4096-4676, djurit@cnu.ac.kr
Sun Yong Lee (2) Department of Electronics Engineering/Chungnam National University/Korea 82-42-825-3991, sy_lee@cnu.ac.kr
Sung Lyong Cho (3) Department of Electronics Engineering/Chungnam National University/Korea 82-10-4096-4676, djurit@cnu.ac.kr
Moon Beom Heo (4) Korea Aerospace Research Institute/Korea hmb@kari.re.kr
Chansik Park (5) Department of Electronics Engineering/Chungbuk National University/Korea chansp@cbnu.ac.kr
Sang Jeong Lee (6) Department of Electronics Engineering/Chungnam National University/Korea 82-42-825-3991, sjlee@cnu.ac.kr
ABSTRACT Recently, GNSS (Global Navigation Satellite System) has been widely used in the ITS (Intelligent Transportation System), AVLS (Automatic vehicle location system), PDM (Physical Distribution Management), train operation control system as the ground transportation environment. In these applications, the CDGPS (Carrier phase Differential GPS) technique is frequently applied because of it can determine accurate position in cm-level by using the carrier phase measurement. But, in order to apply the CDGPS technique for the ground transportation environment, several critical problems have to solve. These problems include the multipath mitigation and the correction of other abnormal effects on the carrier phase measurement and code phase measurement. And, there are many studies about the multipath mitigation technique. Also in our priori study, the impact of multipath is effectively mitigated by applying the adaptive filtering technique in (Cho, S. L. et al, 2012) and (Cho, S. L. et al, 2013). However, other abnormal effect issues are still unsolved. In the presence of abnormal effects, measurement quality of GPS is decreased or measurement is shut out, then the performance of CDGPS is heavily degraded. And the performance of our adaptive filtering technique degraded too. Therefore, in order to apply our adaptive filtering technique to ground transportation environment, we introduce some techniques to detect the abnormal effects(cycle slip, jump). If the abnormal effect is occurred, impaired measurements are have not to use in solve the navigation solution or have to correct the characteristics of measurement. Especially in the ground transportation environment, it is important that these detection and correction process are performed in real-time. We apply the proposed method to the CDGPS technique, and then analyze the performance improvement in the ground transportation environment. KEYWORDS: CDGPS, Cycle-slip, Cycle-slip Detection References Cho, S. L., Choi, Y. S., Yeo, S. R., Heo, M. B., Park Chansik, and Lee, S. J., 2013, Adaptive Filter Design of the float solution in the presence of multipath, The European Navigation Conference 2013.
Cho, S. L., Han, Y. H., Heo, M. B., Park Chansik, and Lee, S. J., 2012, Design of the float solution considering the noise characteristics in the presence of multipath, International Symposium on GPS/GNSS 2012.
Adaptive Observation Error Modelling in Multi-Constellation RTK Engine Richard Deurloo, Andrew Simsky, Frank Kleijer Septentrio/Belgium +32(0)16300800, richard.deurloo@septentrio.com
Evan Bollard Globalpos/Australia +61(0)429342498, evan@globalpos.com.au
ABSTRACT The ongoing deployment of BeiDou and Galileo brings about significant increase in availability and reliability of RTK positioning. It has been demonstrated that BeiDou is already now of particular benefit to RTK users in the South Pacific region. In this paper we present our multi-GNSS RTK engine, which combines the use of new constellations with adaptive error modelling. It is shown that the use of BeiDou and Galileo, when coupled with adaptive modelling of multipath noise and ionospheric delays, results in significant improvement of time-to-fix and reliability of RTK solution in challenging highly masked and multipath-intensive urban and forested environments, as well as in the presence of ionospheric disturbances. In our RTK engine, the statistical properties of multipath and ionospheric delays are continuously monitored in separate pre-processing filters. Estimated noise levels are used to fine-tune the noise models and to optimize the performance of the RTK engine. Ionospheric disturbances present a particularly serious challenge for RTK operations, especially in ionospherically active regions, which occupy a great part of South Pacific region. The new engine is capable of estimating differential ionospheric delays in real time, taking into account the baseline, geographical position and time of day and also the pre-processing assessment of ionospheric activity. Owing to the realtime modelling of ionospheric delays, the accuracy of our RTK positional solution is almost insensitive to the baseline length and stays on the level of 1-2 cm even for baselines of about 50 km. KEYWORDS: BeiDou, RTK, multipath, ionosphere, modelling.
Geometry-free combinations of GPS triple frequency signals for effective integer ambiguity resolutions over several hundreds of kilometres Yanming Feng, Yongchao Wang and Charles Wang Queensland University of Technology, Australia
Qile Zhao Wuhan University
ABSTRACT In this paper, a geometry-free approach is proposed for effective modelling and estimation of the satellite- and receiver- specific uncalibrated signal delays (USD) using five linearly independent geometry-free combinations. The sixth combination is a geometry-based/ionosphere-free (GB/IF) observable that is required to set a boundary condition in order for all USDs in six original signals to be resolved. Of these combinations, ambiguity parameters of two wide-lane observables are resolved with the Melbourne-W端bbena combinations. The phase-only narrow-lane observables has the noise level of about 2 cycles, thus allowing their doubled differenced (DD) integer ambiguities to be reliably fixed as well. The known DD wide-lane and narrow-lane integers are then used as constraints for estimation of the receiver- and satellite-specific USDs in the network and time domains, setting one USD parameter as the necessary datum to overcome the rank deficiency. This geometry-free estimation does not require any knowledge of satellite and receiver
states, thus not being affects by uncertainty of these states parameters. Consequently, the geometry-based processing for satellite and receiver states of the network can be performed without need of estimation of ambiguity parameters. Numerical studies are performed with data sets from a regional network of nine receivers tracking PRN24 and PRN25, and PRN6 and PRN9 over two 3.3 h periods. In this example, the DD narrow-lane ambiguities of eight baselines of up to 1400 km in length are fixed to their integers by rounding at the success rates of over 97%. Analysis indicates that the four GF/IF measurements are as precise as the GPS wide-lane observable. It is expected that all the GF/IF USD solutions can reach the precision very much similar to that of the wide-lane Fractional-Cycle Bias (FCB) products currently generated with the dual-frequency GPS signals. KEYWORDS: GPS, triple frequency, geometry-free/ionosphere-free, uncalibrated signal delays (USD), Ambiguity resolutions
Kinematic GPS orbit determination with a global network of hundreds of stations Yongchao Wang , Yanming Feng and Charles Wang Queensland University of Technology, Australia
Xiatao Li and Qile Zhao Wuhan University
ABSTRACT This work presents the methods and results of the Kinematic Orbit Determination (KOD) of GPS satellites. The KOD procedure estimates the orbit derivations with respect to a nominal orbits epoch by epoch, contrasting the standard precise orbit determination (POD) that gives the orbit parameters at a specific epoch within a data arc of tens of hours. KOD is similar to single-receiver positioning, just being performed in the reverse manner. Therefore, the station coordinates, clocks and station-specific parameters such as troposphere-delays have to be given to support the KOD estimation. In general, KOD is performed for selected satellites in a constellation in the cases where these satellites perform orbit or attitude maneuverers, their antenna offsets are unknown etc. We give the detailed descriptions of the KOD models, algorithms, and procedures of processing for two basic KOD approaches: single point orbit estimation (SPOE) and precise point orbit estimation (PPOE). In both cases, receiver clocks and troposphere zenith delays of all the stations are determined by the rest of the satellites or other constellations, such as GPS constellation for BDS satellites. Another key issue is the high correlation between the satellite position states and clock parameters. We introduce a two-state Kalman filter for clock estimation in order to strengthen the geometry. We provide extensive verification of the SPOE and PPOE results with a network of globally distributed 350 stations. Based on phase-smoothed ionosphere-free code PC measurements, the SPOE orbital RMS uncertainties are 1.1m, and 0.8m, and 0.4 metres for along-track, cross-track and radius directions, respectively. The PPOE solutions can improve the radial accuracy to better than 20 cm in all directions after convergence. Overall, KOD approaches demonstrate the potential for precise orbit determination without knowledge of orbit dynamics. KEYWORDS: Kinematic Orbit Determination, Precise Point Orbit Estimation.
The effect of decorrelation on the success rate bounds of ambiguity estimation Lei Wang Science and Engineer Faculty Queensland University of Technology, Australia Phone: (+61) 0416892716 I62.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
Jiming Guo School of Geodesy and Geomatics, Wuhan University, China Phone: (+86) 027 68778807 email jm.guo@sgg.whu.edu.cn
Charles Wang
Science and Engineer Faculty Queensland University of Technology, Australia (+61) 0410060668 cc.wang@qut.edu.au
ABSTRACT The success rate is an important reliability measure of ambiguity estimation. However, the success rate of integer rounding (IR) estimator and integer least-squares (ILS) is difficult to be calculated directly. Thus, the upper and lower bounds of success rate are often used as a practical way to assess the ambiguity estimation reliability. On the other hand, the ambiguity components are highly correlated in fast ambiguity resolution case (e.g. RTK), which makes the searching space extremely elongated and degrades the ambiguity searching efficiency. The decorrelation procedure is widely used to improve the ambiguity searching efficiency. The impact of the decorrelation procedure on the integer estimators has been well-documented, while the impact on the success rate bounds is still less understood. In this study, the methodologies of bounding IR and ILS success rate are reviewed and the decorrelation effect on these bounds is examined based on simulated data. The analysis results indicate that some of the success rate bounds remain invariant during the decorrelation, e.g. the ellipsoidal upper and lower bound of the ILS success rate and the ADOP based approximation of the ILS success rate. Some of the bounds become tight after decorrelation, e.g. the lower bound of IR success rate, the Integer bootstrapping (IB) based ILS success rate lower bound. Additionally, the decorrelation procedure may also adversely impact on the success rate bounds e.g. the band intersection based ILS success rate upper bound. In addition, the decorrelation-dependent success rate bounds would be non-unique since there are several different decorrelation methods. It is important to be aware that some of the success rate bounds perform well only before or after the decorrelation procedure. This study provides a guide on how to reasonably use the success rate bounds in ambiguity estimation. KEYWORDS: ambiguity estimation, success rate, decorrelation, reliability, upper and lower bound
Session 12D
Co-operative Positioning and LBS
13:20-1500
An Appeal to Discuss Ethical Issues in Context with Cooperative User Localization Guenther Retscher Department of Geodesy and Geoinformation, Vienna University of Technology, Austria +43 1 58801 12847, +43 1 58801 12894, guenther.retscher@tuwien.ac.at
Franz Obex Freelancer, Vienna, Austria +43 650 5210486, obex@chello.at
ABSTRACT Rapid technical developments in GNSS and other ubiquitous positioning methods led to new applications and technical possibilities. Technical researchers and developers mostly imply that it is mainly about further enhancing localization technologies and algorithms including the development of new advanced Apps for Location-based Services (LBS). They are aiming to deliver personal navigation with a higher availability, integrity and reliability in any environment. Hence, localization technologies have become very powerful tools when tracking an individual or a group of users. As meanwhile LBS influences every individualâ&#x20AC;&#x2122;s life there is a need that ethical and political issues have to be addressed within our research community. Although there is a lot of research going on in developing algorithms to keep ones data and LBS search request in private, researchers can no longer keep their credibility without cooperating with ethical experts or an ethical committee. From our point of view, we should include the issue of the userâ&#x20AC;&#x2122;s privacy and ethical implications in mind from the very beginning of our research process. At the Department of Geodesy and Geoinformation of the Vienna University of Technology cooperation with social scientists in this
respect started recently. A study for the acceptance and user needs in a new project proposal dealing with cooperative positioning was initiated. In this project a mobile LBS user is guided with an App and located with assistance of the whole user group. Then users can help each other to find their way through complex environments such as multimodal public transport junctions, airports, shopping malls, etc. Users of such services should get the right to withdraw their consent for transferring location based and other personal data at any time. They also should get clear and comprehensive information when and for what they give away their personal data and location and its further use. KEYWORDS: Cooperative Positioning, LBS, Privacy, Ethical Thinking.
Modelling and Mitigating Multipath and NLOS for Cooperative Positioning in Urban Canyons Joon Wayn Cheong, Eamonn Glennon, Andrew G. Dempster Australian Center for Space Engineering Research School of Electrical, Electronics and Telecommunications Engineering University of New South Wales, Sydney 2052 Australia Phone: +(61) 2 93856702 Email: cjwayn@unsw.edu.au
Damien Serant, Thibaud Calmettes Thales Alenia Space, France 26 avenue J.F. Champollion BP 33787 31037 Toulouse Cedex 1 Email: damien.serant@thalesaleniaspace.com
ABSTRACT Existing investigations into integrating GNSS and Vehicle-to-Vehicle (V2V) ranging systems for Cooperative Positioning (CP) has evidenced its superiority in enhancing positioning accuracy. However, the ramifications of multipath – especially in terrestrial V2V measurements – have typically been neglected. This paper seek to effectively minimise the positioning error particularly in such circumstances using a modified particle filter technique. The development of a scenario-based multi-sensor time-series simulator is described. The simulator simulates the multipath/NLOS errors for GPS and V2V measurements based on the location of the vehicles and GPS satellites and the interaction of GPS and V2V signals with a predefined virtual environment. The simulation is made even more realistic by using NetLogo to simulate each vehicle's motion. The INS measurement of each vehicle is also simulated based on the vehicle’s motion. This software package thus provides a complete set of simulated measurements for V2V, GPS and INS. By adopting this method of simulating sensor outputs, arbitrary assumptions of multipath/NLOS simulation parameters can be avoided. An estimation filter based on a modified particle filter that integrates GPS+V2V+INS sensors is implemented. This estimator is specifically designed to mitigate multipath/NLOS. Experiment result shows that the modified particle filter can still achieve Root Mean Squared Error (RMSE) of approximately 3m despite the presence of multipath/NLOS errors of up to 90m. In the same scenario, the conventional particle filter produced RMSE of approximately 13m. In more extreme cases of NLOS, the conventional particle filter has failed to produce valid estimates entirely whereas the modified particle filter can still maintain a RMSE of approximately 3m. KEYWORDS: Multipath, Non-Line-Of-Sight (NLOS), Cooperative Positioning, C-ITS
A Framework for Efficient Cooperative Localization with Non-Gaussian Ranging Error Distributions Shenghong Li (1)
CSIRO, Australia (+61) 2 9372 4629 shenghong.li@csiro.au
Mark Hedley (2) CSIRO, Australia (+61) 2 9372 4136 mark.hedley@csiro.au
Iain B. Collings (3) Macquarie University, Australia (+61) 2 9850 9068 iain.collings@mq.edu.au
ABSTRACT Cooperative localization takes advantage of the range measurements between neighbouring agents to improve both the availability and accuracy of positioning systems. Distributed belief propagation is a promising technique for data fusion in cooperative localization. Difficulties with belief propagation lie in reducing the required communication overhead and computational complexity. Most of the existing works on this subject are based on Gaussian ranging error models, which are fine for outdoor applications but not suitable for indoor environments. In this paper we propose a framework for efficient cooperative localization, which can be applied to system with various types of non-Gaussian ranging error distributions. The communication and computational cost is reduced by passing approximate beliefs represented by Gaussian distributions between neighbours and by using an analytical approximation to compute peer-to-peer messages. The proposed scheme is validated by both simulation and experiments on a deployed indoor localization system, and is shown to achieve high accuracy with low communication and computational cost. KEYWORDS: cooperative localization, belief propagation, indoor positioning, ranging error distribution
Real-time position tracking via Internet communication protocols in LBS. I Idris, C Wang, Y Feng Queensland University of Technology, Australia
ABSTRACT The most enticing feature of a location based service (LBS) system is the ability to distribute and personalise useful and relevant information to its subscribers with regards to their current spatial location. In order to sustain a responsive and an uninterrupted service, LBS system requires consistent, efficient and reliable network connectivity between the central server and mobile devices. Currently, most of the connectivity is done through wireless mobile Internet connection which is not resistance to known issues such as service outages, limited bandwidth and intermittent signals. The connectivity in LBS is also impacted by the Internet communication protocols used in different applications. LBS system generally requires frequent message transmissions between the subscribers and the central server via Internet communication protocols particularly where real-time position tracking is required. Therefore, it is imperative for LBS applications to adapt to communication protocols that can optimise the connectivity performance particularly in wireless mobile Internet connection. In this paper, a study in the performance and agility of real-time Internet communication between mobile devices and a central LBS server is being carried out. The study is specifically focusing on how Internet communication protocols such as HTTP, TCP/IP and UDP, might affect the device connectivity in terms of data latency, transmission reliability and security, and system compatibility on wireless internet connection. Experiments in this study are conducted using a prototype vehicle monitoring platform utilising Open-Source GPS Tracking System (Open-GTS) as the central server and the on-board unit is equipped with a mobile computing unit and GNSS precise positioning system. Though HTTP based device communication server proved to be the simplest implementation in Open-GTS server, but the raw socket based device communication server utilising TCP/UDP proved to have better performance in data latency and higher success rate in data transmission.
KEYWORDS: LBS, Decimetre positioning, Communication Protocols
The Need for a Metadata Standard for global Geodesy Nicholas Brown Geoscience Australia (+61 2) 6249 9831 nicholas.brown@ga.gov.au
Roger Fraser Victorian Department of Environment, Land, Water and Planning (+61 2) 8636 2551 roger.fraser@delwp.vic.gov.au
ABSTRACT We live in an era when the geodetic community is being called upon to provide data, products and services in support of a broad sphere of Earth System Sciences. We are also seeing the ubiquitous uptake across society of accurate and reliable Positioning, Navigation and Timing (PNT) information. In order to service these user demands our geodetic data and the associated metadata need to be discoverable, authoritative and interoperable. The continual increase in the volume and complexity of data means we also need to generate, transfer and use data and metadata via a machine-readable form. In order to achieve these stated goals the geodetic community need a XML based standard for geodesy, which is easily transferable via web services, and based on internationally recognised data exchange methods. Representatives from Australian and New Zealand governments have been working together since 2004 to create the Geodesy Markup Language (GeodesyML) that fulfills these requirements. GeodesyML is a proposed Application Schema of the existing Geography Markup Language (GML), which is an ISO Standard. Being an Application Schema, GeodesyML extends GML to meet the specific needs of the geodetic community. GeodesyML has been designed to improve data discoverability and support information exchange within and between geodetic organisations (e.g. Data Centers, Analysis Centers etc.) and users of geodetic products and services. At the present time, GeodesyML is being considered by the IGS Data Centre Working Group and the Global Geodetic Observing System (GGOS) initiative of the International Association of Geodesy (IAG) as a viable alternative for the encoding and machine-to-machine transfer of geodetic data and metadata. KEYWORDS: Geodesy, Interoperability, Metadata, Exchange, Standards, XML Schema.
Session 13B
Precise Point Positioning
1530-1710
Precise Point Positioning from Combined GPS, GLONASS and BeiDou Mazher Choudhury (1)* Chris Rizos(2)* * Surveying and Geospatial Engineering, School of Civil & Environmental Engeneering, UNSW, Australia Ph: +61(2)93854173 / Fax: +61 (2) 9385 5657 email: (1) mohammad.choudhury@unsw.edu.au
ABSTRACT In this paper, the positioning model of Precise Point Positioning (PPP) combining GPS with GLONASS and BeiDou observations is introduced. This PPP model uses the combined precise orbit and clock data for GPS, GLONASS and BeiDou provided by the IGS analysis centre at Wuhan Universiy, China. Combining GPS with GLONASS (GLO) and BeiDou(BDS) also introduces additional inter-system biases (ISB) due to multi-GNSS signal processing within the receiver hardware. Without solving for ISB accuracy and precision of PPP will not be improved significantly. This ISB, with respect to GPS system time, is included in this contribution. Multi-constellation GNSS scenario, there could be some instances where gross errors in (assumed) known information and/or observation data may be present. These errors could be introduced by the receiver, or some unknown sources. To address this, and to guard against the position solution from diverging, statistical analysis of the residuals needed.
In this contribution a multi GNSSS PPP functional models is introduced which also takes account the gross error for ensuring better PPP result. Two IGS tracking stations’ multi-GNSS measurements were downloaded to investigate the performance of the combined PPP solution. The positioning accuracy and the convergence time of GPS-only, GLO-only, BDS-only, GPS+GLO, GPS+BDS and GPS+GLO+BDS are compared against the truth position. The results an improvement of up to 25% in GPS+GLO+BDS position accuracy and convergence time compared with GPS-only solutions. KEYWORDS: Multi GNSSS, PPP, ISB.
New Developments in real-time precise positioning Xialing Liu Fugro Intersite B.V. / Netherlands Phone: +31 70 31 11896 / m.goode@fugro.nl
Matthew Goode Fugro Intersite B.V. / Netherlands Phone: +31 70 31 11896 / m.goode@fugro.nl
Ole Oerpen Fugro Satellite Positioning A/S / Norway Phone: +47 21 50 14 31/ o.oerpen@fugro.com
Javier Tegedor Fugro Satellite Positioning A/S / Norway Phone: +47 21 50 14 31/ j.tegedor@fugro.com
Mark Hardman Fugro Satellite Positioning Pty Ltd / Australia Phone: +61 8 9445 0000 / m.hardman@fugro.com
ABSTRACT In recent years Global Navigation Satellite System (GNSS) based Precise Point Positioning (PPP) has become the de facto standard for precise real-time GNSS positioning applications. Up to now precision has been in the order of 3.0 – 5.0 cm horizontally, and twice this value vertically. The addition of new constellations have marginally increased accuracy and solution convergence times but have provided greater benefit to the user in availability & robustness of services in difficult areas of operation where obstruction have been an issue. In 2009 Fugro was the first company to offer a combined GPS & GLONASS global real time correction service G2 and in January of this year added Beidou orbit and clock corrections to its broadcasts introducing a new G4 service. Recent developments enable us to improve real-time precision to the level of 1.0-1.5 cm in horizontal and 2.5-4.0 cm in the vertical component, worldwide. There is an increasing requirement for increased real-time GNSS position accuracy whether it be driven by the increasing integration of survey sensors on offshore vessels or the need to place a towed seed drill in the correct position. Fugro, one of the world’s main providers of precise offshore real-time GNSS positioning services, has extended the PPP technique to utilize integer ambiguity resolution (IAR). This significant development enables the user to achieve the aforementioned increase in real-time accuracy. In addition our services have been expanded to include the Galileo and BeiDou constellations, which enhance convergence time, availability and precision. In this contribution we will show the results that are achieved by combining PPP and IAR at a selection of static sites and for a dynamic dataset. We will also present the result of multi-constellation PPP, using precise satellite orbit and clocks for GPS, Glonass, Galileo and BeiDou generated from Fugro’s tracking network. The strength of combining these two techniques will then be demonstrated by the case study of PPP-IAR in the Asia-Pacific region with ambiguity fixing for GPS and BeiDou. KEYWORDS: GNSS, Beidou, PPP, IAR, PPP-IAR
Advances in NovAtel’s Precise Point Positioning (PPP) solution for high accuracy kinematic applications. Sara Masterson NovAtel Inc. Calgary, AB, Canada sara.masterson@novatel.com
Thomas Morley NovAtel Inc. Calgary, AB, Canada thomas.morley@novatel.com
Rod MacLeod NovAtel Australia Pty Ltd. Sydney, NSW, Australia rod.macleod@novatel.com
ABSTRACT The logistical challenges associated with deploying and using RTK have meant that many user applications have not been able to reap the benefits of high-precision positioning. NovAtel CORRECT™ uses both real time PPP and Kinematic techniques within its GNSS hardware to provide users with globally or locally available centimetre-level positioning. Using NovAtel CORRECT™ with PPP expands the availability of centimetre-level positioning into many of these previously un-served applications. It combines globally valid and distributed corrections with advanced PPP algorithms, enabling cm-level GNSS positioning in harsher conditions for applications like precision agriculture and mobile mapping. This presentation will discuss the recent developments of NovAtel CORRECT™ PPP algorithm using the latest TerraStar correction data. The key algorithmic improvement in NovAtel CORRECT™ is the addition of PPP carrier-phase integer ambiguity resolution. Ambiguity resolution is necessary to unlock the full accuracy of carrier-phase positioning. From a user’s perceptive, the most important new feature is immediate re-convergence, in which the receiver can recover from short signal outages of up to at least 60 seconds, back to a similar level of position error as before the outage. Depending on the ionosphere and other observing conditions, even longer interruptions can be tolerated. The improved kinematic performance of NovAtel CORRECT™ PPP algorithm will be shown using agricultural-application field test data collected in Brazil and Canada. In addition, the initial convergence, re-convergence and final accuracy improvements will be discussed against other existing commercial PPP based services. KEYWORDS: GNSS, Precise Point Positioning (PPP), kinematic
Cycle Slip and Clock Jump Repair with Multi-Frequency GNSS data for improved Precise Point Positioning Manoj Deo PhD Candidate, Department of Spatial Sciences, Curtin University, GPO Box U 1987, Perth WA 6845, Australia Phone: +61 432163000 Email: manoj.deo01@gmail.com
Dr Ahmed El-Mowafy Associate Professor, Department of Spatial Sciences, Curtin University, GPO Box U 1987, Perth WA 6845, Australia Phone: +61 8 9266 3403 Fax: +61 8 9266 2703 Email: a.el-mowafy@curtin.edu.au
ABSTRACT Detecting and repairing cycle slips and clock jumps are crucial data pre-processing steps when
performing Precise Point Positioning (PPP). If left unrepaired, they can adversely affect PPP convergence time, accuracy and precision. The paper proposes algorithms for detecting and repairing cycle slips and clock jumps using multi-frequency and multi-constellation GNSS data. The cycle slip detection method uses the geometry-free measurement at a current and previous epoch to detect the occurrence of a cycle slip. Triple frequency data improves the reliability of the detection, since a cycle slip is detected on both the geometry-free measurements of the frequency on which the cycle slip occurred. The size of the cycle slip is determined using least squares fitting to a sample of geometry-free measurements immediately preceding the cycle slip, which is followed by repair of phase measurements after the cycle slip. A clock jump detection and repair technique procedure is also proposed and implemented, which uses a code-phase linear combination to test if a jump occurs on one or more frequencies. If a jump is detected at an epoch, it is tested if it exists in all (or majority) of satellites that are tracked at the time. The size of the clock jump is determined and validated to be 1 or multiple milliseconds. This is followed by repair of phase and code measurements after each clock jump occurrence. The algorithm is effective for single frequency, multi-frequency and multi-constellation GNSS data. The latter cases add redundancy, hence improves the reliability of clock jump detection. The significant impact of successful detection and repair of cycle slips and clock jumps on PPP convergence, accuracy and precision is demonstrated through processing one dayâ&#x20AC;&#x2122;s of static data. KEYWORDS: Precise Point Positioning, clock jump, cycle slip, linear combinations
Enhancing precise point positioning with external ionosphere constraint Peiyuan Zhou (1) School of Civil and Environmental Engineering University of New South Wales, Sydney, NSW 2052, Australia Phone:+61 2 938 54203 Fax:+61 2 9313 7493 Email: peiyuan.zhou@unsw.edu.au
Jinling Wang (2) School of Civil and Environmental Engineering University of New South Wales, Sydney, NSW 2052, Australia Phone:+61 2 938 54203 Fax:+61 2 9313 7493 Email: Jinling.Wang@unsw.edu.au
Shuyang Cheng (3) School of Civil and Environmental Engineering University of New South Wales, Sydney, NSW 2052, Australia Phone:+61 2 938 54203 Fax:+61 2 9313 7493 Email: csywhu2010@gmail.com
ABSTRACT In precise point positioning (PPP) applications, ionospheric errors must be accounted for. One popular way used in precise positioning is to form an ionosphere-free combination using measurements from two frequencies which can remove most of the ionospheric errors. The geometry strength is weakened by forming ionosphere-free combination with multi-frequency measurements, as some information is discarded when forming the combination. Furthermore, it still takes about several tens of minutes in order to obtain solutions with better than 10 cm accuracy. This prevents PPP from being widely used in real-time applications. One of the recent approaches is to strength the PPP model with precise external ionosphere information. The ionospheric delays and receiverâ&#x20AC;&#x2122;s Differential Code Bias (DCB) are estimated as unknown parameters in this method. In this paper, the impact of the quality of external ionosphere on the performance of PPP is evaluated using the global ionospheric map (GIM) with different temporal resolutions. Furthermore, the accuracy of estimated receiver DCB will be evaluated based on processing of a large amount of data. The results indicate that the quality of the a priori ionosphere delays plays a very important role in enhancing PPP performance. KEYWORDS: Precise Point Positioning, Raw observation, Ionosphere, DCB
Session 13C
Emerging and Enabling Capabilities
15:30-1710
Low-Cost cm-Accurate Mobile Positioning Todd Humphreys Assistant Professor/The University of Texas at Austin/USA 210 E. 24th St. Stop C0600 Austin, TX 78712-1221 Office: 512 471 4489 todd.humphreys@mail.utexas.edu
ABSTRACT GNSS technology is now ubiquitous in smartphones and tablets, yet the underlying positioning accuracy of consumer-grade GNSS receivers has stagnated over the past decade. The latest clock, orbit, and atmospheric models have improved receiver ranging accuracy to a meter or so, leaving receiver-dependent multipath- and front-end-noise-induced variations as the dominant error sources in current consumer devices. Under good multipath conditions, 2-to-3-meter-accurate positioning is typical; under adverse multipath, accuracy degrades to 10 meters or worse. Currently, the primary impediment to performing cm-accurate CDGNSS positioning on smartphones and other consumer handheld devices lies not in the commodity GNSS chips, which actually outperform survey-grade chips in some respects, but in the low-cost (e.g., a few cents to a few dollars), low-quality GNSS antennas, whose chief failing is poor multipath suppression. The time correlation of multipath errors, coupled with their relatively large magnitude, significantly increases the initialization period of GNSS receivers using low-cost antennas to achieve a cmaccurate CDGNSS positioning solution. This presentation will focus on receiver motion as a means of reducing the effects of multipath errors on carrier phase measurements in low-cost mobile devices. The motion may be unknown a priori, as in the case of a user moving a mobile device randomly in her extended hand, or may be strongly constrained a priori, as in the case of fusing carrier phase measurements with vision data to solve the joint mapping, positioning, and carrier phase ambiguity resolution problem. KEYWORDS: CDGNSS, mobile positioning, vision and GNSS integration
Space situational awareness - a new horizon of Australian space research Zhang K. (1) The SPACE Research Centre, RMIT University, GPO Box 2476V, Australia Tel: 99253272, Email: kefei.zhang@rmit.edu.au
Bennett J. C. (2) The SPACE Research Centre, RMIT University, GPO Box 2476V, Australia
Sang J. (3) The SPACE Research Centre, RMIT University, GPO Box 2476V, Australia
Smith C. (4) The SPACE Research Centre, RMIT University, GPO Box 2476V, Australia
Norman R. (5) The SPACE Research Centre, RMIT University, GPO Box 2476V, Australia
Carter B. (6) The SPACE Research Centre, RMIT University, GPO Box 2476V, Australia
Zhao Y. (7) The SPACE Research Centre, RMIT University, GPO Box 2476V, Australia
Wu S. (8) The SPACE Research Centre, RMIT University, GPO Box 2476V, Australia
ABSTRACT
The Space Environment Research Centre (SERC) is a consortium to pursue research and development of technologies and capabilities that will help to preserve the orbital space environment. The consortium includes Electro Optics Systems, RMIT, The Australian National University, Lockheed Martin, Optus Satellite Systems and National Institute of Information and Communications Technology of Japan. SERC is a recipient of an Australian Government grant through the establishment of the Cooperative Research Centre for Space Environment Management (CRC-SEM). SERC will pursue a wide range of research tasks including technologies to improve tracking capability and capacity, orbit determination and orbit propagation algorithms, conjunction analysis and collision avoidance. All of these technologies will contribute to the flagship program to demonstrate active collision avoidance by remotely manoeuvring space debris using photon pressure delivered from a ground-based laser. This project joins the proposed NASA LightForce concept with extra infrastructure and capabilities provided by SERC. This contribution will introduce the newly established 5-year CRC-SEM, its rationale, partnership, research roadmap, expected outcomes and progress to date. The new CRC-SEM will build upon Australian expertise in measurement, monitoring, analysis and management of space debris to develop new technologies, new algorithms and strategies to preserve the space environment, especially robust solutions to help remediate the proliferation of debris objects caused by a collisional cascading phenomenon. This initiative is regarded as a new dimension of geodesy. It is argued that geodesists should play a major new role in space environment management and help with preserving our very valuable assets in space. KEYWORDS:.Space Situaltional Awareness, precise orbit determination, space environment management, debris objects, conjunction analysis
Performance of GNSS speed measurement for evidentiary purposes Andriy Dyukov (1) Transport Certification Australia +61 3 8601 4600 andriyd@tca.gov.au
Ivan Enierga (2) Transport Certification Australia +61 3 8601 4600 ivane@tca.gov.au
ABSTRACT Global Navigation Satellite Systems (GNSS) and in particular to Australia, the Global Positioning System (GPS), are core positioning technologies used in telematics applications. GNSS is now being used beyond the traditional positioning, navigation and timing domains, and is being implemented as a system for determining vehicle speed. Transport Certification Australia (TCA), the national government body responsible for providing assurance in the use of telematics and related intelligent technologies, has evaluated the accuracy of GNSS based systems for determining vehicle speed, and whether it can be used for regulatory compliance purposes. TCA has developed unique test methodologies to conduct speed testing against national standards and specifications within the National Telematics Framework, to enable greater consistency and confidence in the reporting of speed through the use of GNSS-based telematics systems. TCA sought an independent assessment of its methodologies through National Association of Testing Authorities (NATA) and has continued to refine its test methodology to improve the uncertainty values. Testing of GNSS systems for speed accuracy with various test assets reveals that GNSS receivers have differences in their performance, and care should be taken when using GNSS reported speed to ensure it is done so in a manner fit for its purpose. KEYWORDS: Global Navigation Satellite Systems (GNSS), Global Positioning System (GPS), Speed, Regulatory, National Association of Testing Authorities (NATA).
Predictability of GNSS signal observations in support of Space Situational Awareness using passive radar Md. Sohrab Mahmud UNSW Canberra Australia s.mahmud@student.adfa.edu.au
Andrew Lambert UNSW Canberra Australia a.lambert@adfa.edu.au
Craig Benson UNSW Canberra Australia 0416 243231 c.benson@adfa.edu.au
ABSTRACT GNSS signals have been proposed as emitters of opportunity to enhance Space Situational Awareness (SSA) by tracking small items of space debris using bistatic radar. Although the scattered GNSS signal levels from small items of space debris are incredibly low, the dynamic disturbances of the observed object are very small, and the phase of the scattered signals is well behaved. It is therefore plausible that coherent integration periods on the order of many minutes could be achieved. However, even with long integration periods, very large receiver arrays with extensive, but probably viable, processing are required to recover the scattered signal. Such large arrays will be expensive, and smaller more affordable arrays will collect insufficient signal power to detect the small objects (relative to wavelength) that are necessary to maintain the necessary phase coherency. The investments necessary to build a large receiver array are unlikely without substantial risk reduction. Pini and Akos have previously reported on use of very large radio telescopes to analyse the shortterm modulation performance of GNSS satellite signals. In this work we report on tracking of GPS satellites with a radio-astronomy VLBI antenna system to assess the stability of the observed GPS signal over a time period indicative of that proposed for passive radar. We also confirm some of the processing techniques that may be used in both demonstrations and the final system. We conclude from the limited data set that the signal stability when observed by a high-gain tracking antenna and compared against a high quality, low phase-noise clock is excellent, as expected. We conclude by framing further works to reduce risk for a passive radar SSA capability using GNSS signals. KEYWORDS: GPS, temporal coherency, passive radar
New role of GNSS in Search-And-Rescue: Past, Present and Future of MEOSAR Jack Scott Thales Australia 7 Murray Rose Avenue, Sydney Olympic Park NSW 2127 Email: Jack.Scott@thalesgroup.com.au
Thibaud Calmettes, Michel Monnerat, Ana Petcu Thales Alenia Space, France 26 avenue J.F. Champollion, BP 33787 31037 Toulouse Cedex 1 Email: thibaud.calmettes@thalesaleniaspace.com
Yoan Grégoire Centre National d’Etudes Spatiales (CNES), France 18 Avenue Édouard Belin 31400 Toulouse, France Email: Yoan.Gregoire@cnes.fr
ABSTRACT Since its initial deployment in 1982, the Cospas-Sarsat system, based on LEO and GEO satellites, has provided valuable emergency distress and location information to worldwide search and rescue operators and teams. To improve performance, the system is now undergoing a profound evolution called MEOSAR, which will add SAR (Search And Rescue) capability to Middle Earth Orbit (MEO) satellites, namely GPS, Galileo and Glonass. The paper presents the main objectives and rationales of MEOSAR, in particular in terms of detection and location solutions. The paper focusses on the role of GNSS systems, as they are not only considered as platform opportunity for secondary payloads, but as contributor to the whole location and communication chain for distress, in particular through Galileoâ&#x20AC;&#x2122;s Return Link channel. The main technologies used in MEOSAR for signal processing and location are introduced, as a meeting point between GNSS and terrestrial mobile communication solutions. Finally, the paper presents the two major evolutions of MEOSAR in the coming years, which will extend its use to cover new challenges of recent distress situations: the new spread-spectrum waveform for a second generation of distress beacons, more suitable for MEO context on the one hand, and the in-flight activation and location of aircraft distress beacons capability on the other hand. KEYWORDS: MEOSAR, Localization, DTOA/DFOA, Galileo
Session 13D
Indoor Positioning
1530-1810
A Novel Approach for Wi-Fi Fingerprinting Using Logical Sequences of Intelligent Checkpoints Guenther Retscher Department of Geodesy and Geoinformation, Vienna University of Technology, Austria +43 1 58801 12847, +43 1 58801 12894, guenther.retscher@tuwien.ac.at
Hannes Hofer Vienna University of Technology, Austria +43 1 58801 12804, +43 1 58801 12894, h.hannes@gmx.at
ABSTRACT Commonly location fingerprinting is employed for Wi-Fi positioning. In the training phase RSSI scans have to be measured at known reference points (RPs) which are usually distributed in a grid within the area of interest. The grid has to be rather dense and therefore RSSI measurements are very labour consuming. The newly developed approach aims at a significant reduction of the number of required RPs. For that purpose particular points are selected which we call intelligent checkpoints (iCPs). To navigate a user to a certain room in a building certain iCPs have to passed on the way. Doors, stairs and corridors can serve as iCPs. Hence, a logical sequence can be derived due to the interdependence of these points along the way. iCPs are twofold intelligent, i.e., because of the fact that they depend on the selection of the points for the RSSI scans and because of the logical sequence in their correct order along the path. When navigating then always the following iCP is known due to the vector graph allocation in the fingerprinting database. Further constraints between the iCPs are definable, e.g. the heading of the moving user can be logically defined while walking along a corridor or even the step length while climbing stairs. Thus only a small limited number of iCPs needs to be tested when matching the current RSSI values. The required processing time is significantly reduced. Furthermore the scanned Wi-Fi Access Points can be weighted depending on their RSSI value level. From field tests in an office building it could be seen that the iCP approach achieves a higher success rate for correct matching of the RSSI fingerprints than conventional approaches. In average correct matching results of 90% were
achieved using a single Wi-Fi database including training measurements of all employed smartphones. An even higher success rate is achieved if the same mobile device is used in both phases. Thus the positioning accuracy can be crucially increased. KEYWORDS: Location fingerprinting, training phase, reference points, intelligent checkpoints (iCPs), logical sequence.
Vector Distance Measure Comparison in Indoor Location Fingerprinting Vahideh Moghtadaiee (1) School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, Australia v.moghtadaiee@unsw.edu.au
Andrew G. Dempster (2) School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, Australia a.dempster@unsw.edu.au
ABSTRACT Non-satellite-based technologies are important for indoor localization due to the difficulties that satellite-based technologies such as the Global Positioning System (GPS) experience operating in such areas, e.g. low received signal power and low visibility of satellites. The most popular positioning method indoors is fingerprinting, which is a technique that records vectors of received signal strength (RSS) from several transmitters at some reference points (RPs) into a database, and later for localization of the user, the users device records its own vector of signal strength and matches it against the pre-recorded database of vectors by applying pattern matching algorithms. In this work we deal with deterministic fingerprinting algorithms based on the nearest neighbour (NN) matching algorithm. For this purpose, similarity measurements between the recorded RSSs and the new measurements are necessary, which can be calculated using various signal distances. Manhattan and Euclidean distances are the most common. In this paper, however, responding to the lack of research on the performance of utilizing the other signal distances on indoor positioning, nine different types of similarity measures are investigated. The examined distances are Manhattan, Euclidean, Chebychev, Canberra, Cosine, Sorensen, Helinger, Chisquare, and Jeffrey. For this purpose, we employ an analytical framework for indoor positioning systems that enables us to analyse the accuracy performance of the system based on the probability of error, here defined as the chance of the distance between the RSS of the test point (TP) and the correct location fingerprint being larger than the distance between the RSS at the TP and an incorrect location fingerprint. Such similarity measures are compared in terms of the probabilities of error and the distance errors that they provide so that we can identify which provides least error. The results are presented for both a simulated environment and real experiments using Wi-Fi and FM (Frequency Modulation) signals. KEYWORDS: Indoor positioning, fingerprinting, vector distance measure.
Range Error Analysis of TDOA Based UWB-IR Indoor Positioning System Lian Zhang (1) School of Electrical and Electronic Engineering/Nanyang Technological University/Singapore (+65) 9059 7619; LZHANG025@e.ntu.edu.sg
Yanjia Luo (2) School of Electrical and Electronic Engineering/Nanyang Technological University/Singapore LUOY0012@e.ntu.edu.sg
Choi Look Law (3) School of Electrical and Electronic Engineering/Nanyang Technological University/Singapore (+65) 6790 5424; ECLLAW@ntu.edu.sg
ABSTRACT
The excellent performance of ultra-wideband (UWB) technology in indoor localization system has attracted increasing attention. As of today, most previous works focus on theoretical evaluation of the capabilities of UWB technology based on simplified simulations. The objective of this paper is to analyse how practically measured range using time-difference-of-arrival (TDOA) based UWB-IR positioning system deviates from the actual distance when the signal transmitter is located at various distances from the receiver. Empirical data of distances from 1m up to 35m are collected at INFINITUS lab, Nanyang Technological University, Singapore. A threshold-based estimator is used to compute the distance of flight. By investigating the mean and root mean square error (RMSE) of the estimated range, one constraint of indoor localization performance is found to be due to multipath propagation. Bias error is observed and is attributed to the front-end circuit delay due to near far signals. The study of range error suggests a more effective way to refine the position estimation algorithm and thus enhances the reliability of indoor localization technology. KEYWORDS: time-difference-of-arrival (TDOA), ultra-wideband (UWB), indoor localization, multipath propagation, range error
Posters – Tuesday & Wednesday Lunchtime RTK and NRTK: Observational Accuracy vs. Time Simon Conway Land Information New Zealand, National Geodetic Office, Wellington +64 04 4983524 sconway@linz.govt.nz
ABSTRACT The most timely and cost effective means of determining a 3-dimensional position is to use technologies such as GNSS. However, some instances require greater positional accuracy than others. Accuracy is often proportional to the length of observation and in a world where time is money it is of interest to explore this relationship further. Increasing productivity and reducing the cost while achieving the required outcomes will continue to be a goal for surveyors. This has led to the development of alternative observing techniques such as RTK, NRTK and VRS. Each of these methods has the potential to reduce the time in the field. However, thought must be given to ensuring sufficient data to obtain the required level of accuracy, without collecting more data than necessary (leading to losses in efficiency). These observing times are effected by many factors, such as; line lengths and observing conditions. This presentation investigates efficient observation periods, in order to determine optimal observation times for a range of observation techniques with variable line lengths. Finally, our findings will be used to recommend observation times to achieve various accuracy requirements. KEYWORDS: RTK, NRTK, GNSS, Accuracy, Time.
Performance Analysis of AOA-based Localization with Software Defined Radio Donggu Kim Department of Electrical Engineering Korea Advanced Institute of Science and Technology (KAIST), Korea Phone +82-42-350-7522 Fax +82-42-350-7622, kdg26@kaist.ac.kr
Seongah Jeong Department of Electrical Engineering Korea Advanced Institute of Science and Technology (KAIST), Korea Phone +82-42-350-7522 Fax +82-42-350-7622, seongah@kaist.ac.kr
Kwang Eog Lee Agency for Defense Development (ADD), Korea Phone +82-42-821-2136, kelee@add.re.kr
Joonhyuk Kang Department of Electrical Engineering Korea Advanced Institute of Science and Technology (KAIST), Korea Phone +82-42-350-7422 Fax +82-42-350-7622, jhkang@ee.kaist.ac.kr
ABSTRACT In this paper, we investigate angle of arrival (AOA) based estimation of a mobile station’s location by monitoring the AOA at multiple reference software defined radio (SDR) receivers. Each Universal software radio peripheral (USRP) device captures the AOA from the uplink transmission of a mobile via MUltiple SIgnal Classification (MUSIC), which is one of super-resolution techniques to estimate AOA by using pseudo-spectrum. Subsequently, a two-dimensional (2D) angulation is adopted for locating the mobile station based on AOA measurements and references’ positions.
We consider the various communication environments, such as i) outdoor area without obstacles, ii) outdoor area with only a few obstacles and iii) indoor area with many obstacles. In order to evaluate the performance of AOA-based localization, we evaluate and compare the mean-squared position error. Via experimental results, an impact of multipath on localization accuracy is verified. KEYWORDS: Angle of Arrival (AOA); MUltiple SIgnal Classification (MUSIC); Two-dimensional (2D) angulation; Universal Software Radio Peripheral (USRP)
A golden reviver used for GNSS satellite simulator time delay calibration Zhu XiangWei Department of Electronic Science and Engineering, National University of Defense Technology, China 18500644645 zhuxiangwei@nudt.edu.cn
Zhang Ke Department of Electronic Science and Engineering, National University of Defense Technology, China 13574826804 zhane0915@163.com
Liu ZengJun Department of Electronic Science and Engineering, National University of Defense Technology, China 13787209773 zjunliu@163.com
Sun Guangfu Department of Electronic Science and Engineering, National University of Defense Technology, China 13507315195 gfsun@nudt.edu.cn
ABSTRACT The time delay calibration of GNSS satellite simulator contains absolute channel time delay calibration and inter-channel time delay bias calibration, depends on the applications. For the case of positioning performance test of user equipment, the result is directly affected by the interchannel time bias difference. For the case of timing transfer performance test of reviver, the absolute time delay of the simulators must be calibrated firstly. Currently, the common used time delay calibration method is observing the signal envelope turning points with high rate oscilloscope. Usually, this method is suitalble for the BPSK or QPSK modulated signals. But it is hard to test the new modulation system, such as binary offset carrier modulation (BOC), which has no evident signal envelope turning points. In order to perform time delay calibration of satellite simulator with BOC modulation signals, a novel time delay measurement method based on “golden receiver” is proposed in this article, which aimed to realize absolute time delay calibration with high accuracy. The proposed method is based on software radio infrastructure. The direct RF sampling hardware platform with high fidelity and powerful computing ability has been developed and introduced in this article. The accuracy of the time delay measurement reaches the order of picosecond by use of all software architecture receiver and high precise signal processing algorithm. Because of the software radio infrastructure and all software processing characteristic, the time delay of such golden receiver can be treated as “zero” value, which can be used to satellite simulator calibration. The hardware platform can also be used for GNSS signal quality analyser, which can supported time domain, frequency domain and modulation domain signal analysis. KEYWORDS: satellite simulator; software radio; GNSS receiver; time delay calibration; interchannel bias
Linear combination ionospheric delay model of GPS and Galileo 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 ionospheric error is the major source of error faced by single-frequency GNSS users. The urgent need to eliminate the ionospheric error by single-frequency GNSS users creates the necessity of different options for different GNSS systems. Klobuchar and NeQuick are representative ionospheric delay models of GPS and Galileo, respectively. According to previous studies, for a middle-latitude geographic region such as the Korea peninsula, the NeQuick model is offering better behavior than the Klobuchar model as it provides range corrections more closely to the IGS-GIM’s corrections except for active ionospheric activity state. However for the active ionospheric state, the behaviour of Klobuchar model is better than the NeQuick model. In this paper, using the characteristic of Klobuchar model and NeQuick model in a middle-latitude geographic region, a novel linear combination of GPS and Galileo ionospheric delay estimation models is proposed to enhance the delay estimation accuracy of ionospheric error for GPS and Galileo single-frequency users in a middle-latitude geographic region regardless of the ionospheric activities. Our proposed scheme fundamentally uses the difference of ionospheric errors which are estimated from a few reference stations with dual-frequency GNSS receiver and Klobuachar and NeQuick models, respectively. In several estimation performance comparison test results for various ionospheric states, it demonstrated that our proposed model is capable of offering better ionospehric delay estimation performance than two models. KEYWORDS: Ionospheric delay; Klobuchar; NeQuick; Linear combination
Enhanced Indoor Positioning Method Using RSSI Log Model Based on IEEE 802.11s Mesh Network Jun-Gyu Hwang Graduate School of Electronics Engineering Kyungpook National University Daegu, Korea cjstk891015@naver.com
Joon-Goo Park Graduate School of Electronics Engineering Kyungpook National University Daegu, Korea jgpark@knu.ac.kr
ABSTRACT LBS(Location Based Service) is becoming popular. Location determination technologies are a core technology for LBS, because LBS based on a position of each device or user. In outdoor, GPS is used to get a position of device or user. But, in indoor, GPS is not available. Therefore, for ‘Indoor LBS’, an enhanced indoor localization scheme which produces a similar position accuracy to that of GPS is needed. In case, a wireless network, such as IEEE 802.11 a/b/g is available, a positioning method using RSSI(Received Signal Strength Indicator) from each AP may produce more positioning errors due to the limited number of available APs. In this paper, we will propose an enhanced indoor positioning method using mesh AP from IEEE802.11s that has mobility and can be changed from MS. KEYWORDS: LBS, mesh network, RSSI