Sirf

Preliminary and Confidential

W HITE P APER

T HE S I RF STAR IV A DVANTAGE Breaking Through the GPS Performance-Power Compromise

Contributors: Sunil Gopinath, Dave Huntingford, Tim McCarthy, Dave Reid

Abstract

Consumer Global Positioning System (GPS) markets are transitioning from personal navigation devices (PNDs) to such low-power applications as cellular handsets, smartphones, games, cameras and even wristwatches. These new, lowpower applications are used in increasingly challenging environments, such as indoors -- away from open-sky view of GPS satellites -- and with limited available sources of power. These challenging environments can degrade the accuracy and robustness of GPS receivers.

This White Paper describes breakthrough

This White Paper describes breakthrough technologies that will enable consumer electronics device designers to incorporate SiRFstarIV technology to overcome these environmental challenges and provide consumers a high-quality GPS experience for numerous Location Based Services (LBS) applications that have previously not been available.

technologies that will enable consumer electronics device designers to incorporate SiRFstarIV technology to overcome these environmental challenges and provide consumers a high-quality GPS experience for numerous Location Based Services (LBS)

Introduction

applications that have previously not been

SiRFstarIV is a new generation of GPS technology and software that builds upon successful SiRF technologies, including the SiRFstarII and SiRFstarIII families of devices.

available.

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X

SiRFstarII architecture dramatically improved urban canyon navigation accuracy performance, but an external antenna was sometimes required to obtain satellite signals.

X

SIRFstarIII architecture offered pronounced increases in sensitivity and decrease in time to first fix (TTFF), enabling the use of an embedded GPS antenna in the product. Assisted GPS (A-GPS) which utilizes network aiding, adds additional sensitivity and fix speed. Together with the confluence of low cost color displays, the PND market grew at an explosive pace.

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The SiRFstarIV Advantage

Preliminary and Confidential

The new SiRFstarIV architecture uses four basic technological breakthroughs that open new frontiers of low power consumption and position awareness.

Fundamental to the SiRFstarIV story is the

In addition, SiRF has developed a software framework named SiRF Location Manager Software Suite, that makes possible enhanced multimodes of operation.

transition and growth in consumer electronics

This new set of features changes GPS reception from a single flat operating model -- where the receiver is either on or off -- to a more dynamic model able to make constructive use of periods between context switches, signals of opportunity, and available sensors.

currently the fastest growth market today.

from PNDs to wireless applications, which are

Future applications will include such devices as digital still-frame cameras, digital video cameras, games, and even wristwatches.

Changing Operating Environments Create Challenges

These products are used in more challenging

Fundamental to the SiRFstarIV story is the transition and growth in consumer electronics from PNDs to wireless applications, which are currently the fastest growth market today. Future applications will include such devices as digital stillframe cameras, digital video cameras, games, and even wristwatches. These products are used in more challenging environments.

environments.

PNDs normally have good, line-of-sight exposure to GPS satellites, and usually a steady power source, such as 12 V cigarette lighter adapter or ample batteries.

New applications, such as smartphones, cameras, and games, offer less available power. As users go indoors, there is less exposure to open sky.

Today’s GPS applications employ a very flat operating model where the receiver is either on, or the receiver is off to save power. Newer applications require a more dynamic model where the GPS receiver makes constructive use of the periods between condition changes, or context switches.

For example, if a user is in a car and walks to into a house, there is a brief opportunity to obtain GPS information during the exposure to open sky that will enable the receiver to obtain a location a fix when the user is inside the house.

Low

Portable Gaming Consoles

Location Power Budget

Figure 1 shows the relationship between supply of power versus exposure to open sky.

MIDs and UMPCs Cameras Handsets PNDs In-Dash NAV GPS

High Frequent

A-GPS

Exposure to Sky

SiRFaware Infrequent

Figure 1. Operating Environment Challenges

The following are the fundamental challenges when designing for devices used in dynamic operating environments: Challenges of Newer, Smaller GPS Devices Mixed indoor and outdoor use Navigation without network aiding Internal noise source design issues Tiny size Power consumption vs. performance Ease of use and integration

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The SiRFstarIV Advantage

Mixed Indoor and Outdoor Use

GPS receivers must be turned on when a fix is required. Performance is compromised to save power. Obtaining a fix indoors is difficult.

Navigation Without Network Aiding SiRFaware self-assisted mode makes

possible increased performance and reduced power usage. Beyond simply adding more correlators, SiRFaware technology includes innovations that meet the major technical challenges posed with smaller GPS devices.

Many portable products do not have broadband wireless network connectivity, and are typically limited to a small battery, limited sky view, and generally no assistance data.

Internal Noise Source Design Issues

Wireless and portable consumer electronics products are packed with a dense assortment of displays, touchscreens, backlights, radio transmitters, and other noise sources, oftentimes located very close to the GPS antenna, or even sharing the GPS antenna.

Small Size

Designers are continually challenged to pack more functionality into increasingly small packages.

Power Consumption vs. Performance

Wireless and portable consumer electronics usually operate on battery power alone. The typical design choice for powering a GPS receiver is either to turn it off until a location is needed in order to save power, which compromises location performance, or to leave it on for extended periods of time, which drains battery power.

Ease of Use and Integration

Consumer products are typically built on platforms, with many permutations for various market segments.

Meeting the Challenges With SiRFaware Technology

SiRFstarIV architecture is optimized for use indoors with short periods of good sky view

SiRFaware self-assisted mode makes possible increased performance and reduced power usage. Beyond simply adding more correlators, SiRFaware technology includes innovations that meet the major technical challenges posed with smaller GPS devices.

when moving from place to place. This new architecture can continually detect context,

Meeting the Mixed Indoor and Outdoor Use Challenge

motion, and satellite signal conditions,

SiRFstarIV architecture is optimized for use indoors with short periods of good sky view when moving from place to place. This new architecture can continually detect context, motion, and satellite signal conditions, remaining in a state of near continuous availability, and is easily augmented with sensors for faster response motion detection. SiRFaware technology can remain always aware of its location and context, taking advantage of short periods of strong signals to refresh its internal fine time, frequency, and ephemeris aiding, while consuming mere microwatts of battery power.

remaining in a state of near continuous availability, and is easily augmented with sensors for faster response motion detection.

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The SiRFstarIV Advantage

Preliminary and Confidential

Meeting the Navigating Without Network Aiding Challenge

SiRFstarIV architecture introduces a new self-assisted mode that captures satellite ephemeris when it has a sky view and retains fine time so a SiRFstarIV-powered product is always ready when an indoor location fix is required, at the highest rated acquisition sensitivity.

SiRFstarIV architecture introduces a new selfMeeting the Internal Noise Challenge

assisted mode that captures satellite ephem-

SiRFstarIV technology uses a Digital Signal Processor (DSP) that scans, detects, and removes carrier wave (CW) jammers, providing a cleaner signal into the location engine. It also informs the host of the frequency and strength of the jammers for subsequent design improvements.

eris when it has a sky view and retains fine time so a SiRFstarIV-powered product is always ready when an indoor location fix is required, at the highest rated acquisition

Meeting the Size Challenge

SiRFstarIV architecture occupies a tiny footprint due to its 65 nanometer process technology and innovative integration. The chip requires as few as six external passive components plus a single SAW filter for a complete location solution.

Meeting the Power Consumption vs. Performance Challenge

SiRFaware technology offers: X

Opportunistic ephemeris decode and advanced power management allowing the GPS chip to stay in a hot start condition nearly continuously.

X

Embedded ephemeris prediction enabling the capture of all ephemerides, so on day two and three, it can forward predict them.

X

Dynamic contextual awareness, through temperature change or movement detection with an appropriate sensor, benefiting from any sky view when moving from one location to another, whether walking or driving, without any user interaction.

SiRFstarIV architecture occupies a tiny footprint due to its 65 nm process technology and innovative integration. The chip requires as few as six external passive components plus a single SAW filter for a complete location solution.

Ease of Use and Integration

The SiRFstarIV silicon architecture is designed for maximum ease of use, minimizing engineering effort to integrate into multiple product platform variants.

Fewer external components are needed, resulting in easy integration, fast time-to-market, and low bill of material (BOM).

X

Flexible host transport of I2C, UART or SPI modes supported

X

Minimal interconnect of 2 wire UART and system reset, expandable to 3 or 4 wire UART for flow control or the use of preambles and handshakes in either direction to support host port sleep modes

X

Fail safe GPIO and RTC clock input to support simple integration

The SiRFstarIV Drive for Performance

Figure 2 shows the evolution of SiRF technology performance.

X X

SiRFstarII contains 2,000 correlators; acquisition sensitivity is at -142 dBm, and an external antenna is required.

SiRFstarIII contains 200K correlators; acquisition sensitivity is at -156 dBm, and an internal antenna can be used instead of an external antenna.

SiRFstarIV Navigation ≤160 dBm Works in pocket at shopping mall

Sensitivity

X

SiRFstarIII 200 K Correlators Navigation -156 dBm Antenna in PND

SiRFstarII 2 K Correlators Navigation -142 dBm Roof antenna required

Technological Advancements & Consumer Expectations

Figure 2. Performance Roadmap

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The SiRFstarIV Advantage

SiRFstarIV with SiRFaware technology boasts acquisition sensitivity of up to -160 dBm, bringing a PND-type experience to locations and applications not previously possible, such as a handset in a pocket; in a purse; or indoors.

Power Usage and Performance

Power Consumption

Figure 3 shows a comparison of energy use by each of the SiRFstarII, SiRFstarIII, and SiRFstarIV architectures.

SiRFstarII

SiRFstarIII SiRFstarIV

X

SiRFstarII consumes approximately 80 mW in TricklePower

X

SiRFstarIII consumes about 20 mW while in TricklePower mode, and about 40 mW in normal tracking mode.

X

SiRFstarIV consumes about 8 mW in TricklePower mode without the use of sensors. SiRFstarIV is able to use even less power with the aid of sensors, such as motion detectors, to indicate no movement. During these periods of no movement, the device saves power. By managing energy use, it’s possible to obtain even larger reductions in power usage, to far less than 8 mW.

Figure 3. Power Consumption

Breaking Through GPS Performance-Power Compromise

As shown in Figure 4, a GPS receiver in continuous tracking mode (top right) gives absolute best performance, with the highest coverage and the highest accuracy. In continuous tracking mode, TTFF is fast, but energy use is high.

In a trade-off mode, such as TricklePower, the receiver is off for about on- half of each second. Less energy is expended in TricklePower mode, but accuracy is slightly sacrificed. At a certain point, the receiver must be turned off. Turning off the receiver to save energy requires cold starts, which result in compromised sensitivity because ephemeris data must be decoded.

Figure 4. Performance-Energy Tradeoffs

SiRF self-assisted GPS pushes performance

Aiding from a network can increase performance slightly, but traditionally the tradeoffs are a choice between tracking modes (top right), and turning off the receiver (bottom left).

With SiRFaware technology, it is not necessary to turn off the receiver. Instead, background tasks that require only microamps of power allow the retention of aided hot-start performance with very fast fix speeds.

to new frontiers by employing SiRFaware

Self-Assisted GPS

features -- Active Jammer Remover, High-

Aided GPS (A-GPS) uses network aiding to push performance boundaries to use less power and require less sky view. However, since not all consumer products are connected, many cannot take advantage of network connectivity or use assistance data.

speed Location Engine, Adaptive Micropower Controller, and Smart Sensor Interface.

SiRF self-assisted GPS pushes performance to new frontiers by employing SiRF Always Aware Architecture features -- Active Jammer Remover, High-speed Location Engine, Adaptive Micropower Controller, and Smart Sensor Interface.

Self-assist methods allow the capture of useful pieces of information when in full sky view for use later to obtain a fix and retain fine time equivalent aided performance.

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SiRFstarIV Always Aware Architecture With the introduction of the benchmark SiRFstarIII platform, SiRF pioneered the multimode A-GPS system that can operate in different modes depending on available network features, bandwidth, GPS signals, and power. The benefits of multimode A-GPS include: X

Benefits of SiRF Always Aware Architecture

X

Supports all network connectivity standards.

X

Automatically switches between modes for optimum performance regardless of the type of network aiding available.

X

When roaming, or when network aiding is not available, the client can still get a fix.

X

Industry leading SiRFNav client software provides excellent urban canyon accuracy.

X

Aiding information can be reduced to manage network bandwidth or control costs.

X

Reverse aiding and network fingerprinting are supported.

X

Automatic mode switching responds to user quality of service settings

X

Location information can be “locked” to the handset and not sent back to the network for privacy reasons.

SiRF pioneered the multimode A-GPS system that can operate in different modes depending on available network features, bandwidth, GPS signals, and power.

SiRFstarIV self-assisted Always Aware Architecture builds on the success of SiRFstarIII by improving performance and reducing power consumption.

SiRFstarIV Architecture

The SiRFstarIV architecture, as shown in Figure 5, is highly integrated, with only a few external passive components and only one Surface Acoustic Wave (SAW) filter required.

SiRFstarIV self-assisted Always Aware Architecture builds on the success of SiRFstarIII by improving performance and reducing power consumption. The key to these improvements are the SiRFstarIV core.

Figure 5. SiRFstarIV Architecture

A Low Noise Amplifier (LNA) is built into silicon, and an external LNA is normally not required.

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There are four subsections that comprise the SiRFstarIV Always Aware Architecture, which is depicted in Figure 6. The four subsections are:

SiRFstarIV Lo

er

Active Jammer Remover, offering advanced DSP technology that actively searches for jammers prior to correlation for maximum GPS performance.

Jammer Remover

Location Engine

Sensor Interface

Micropower Controller

High-speed Location Engine, offering twice the search speed of industry proven, benchmark SiRFstarIII, resulting in enhanced sensitivity, reduced time-to-fix, and improved position accuracy.

ys

Sof

tware Suite tur tec

Awa

e

Al

wa

n catio Manag

The SiRFstarIV Advantage

re Archi

Figure 6. Multimode Location Architecture

Adaptive Micropower Controller, offering advanced power management with motion detection and integrated switch-mode regulation maintains hot start conditions with minimal energy.

Smart Sensor Interface, offering intelligent sensor support that improves the location experience, enables greater context awareness, and opens the door to superior indoor positioning accuracy.

The following describe the four subsections of the SiRFaware Architecture in detail.

Active Jammer Remover

Digital signal processing (DSP) methods are used to continuously and automatically

Figure 7. Active Jammer Remover

monitor amplitude and frequency to find up to eight carrier wave (CW) jammers and filter them out.

The Active Jammer Remover portion of the architecture is shown in Figure 7.

Active Jammer Remover Features Detects 8 strongest jammers Monitors amplitude and frequency Covers GPS band +/- 4MHz Excision of jammers to 80 dB/Hz Digital signal processing (DSP) methods are used to continuously and automatically monitor amplitude and frequency to find up to eight carrier wave (CW) jammers and filter them out. DSP does two things: X

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Issues to the host, via serial message, the location and strength of jamming signals.

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The SiRFstarIV Advantage

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Preliminary and Confidential

Describes to a second DSP block, offset Fast Fourier transform (OFFT) filter what to excise from the signal.

Typically, jamming signals drift as temperatures change. The system actively tracks jamming signals as they drift. This active technology can run continually in the background, tracking and removing unwanted signals.

Active Jammer Remover covers the entire GPS band, and can remove signals that exceed in strength those from GPS satellites. The scanner analyzes the signal ahead of removal. CW Detect gives signal size and position, while CW Removal removes the jamming energy. CW Detect and CW Removal are autonomous blocks in DSP. This technique is an improvement over other methods that use a single tunable notch filter. This automated jamming detection process reduces design cycle risk by eliminating signal noise problems before they crop up late in design validation and product validation

Active Jammer Remover covers the entire GPS band, and can remove signals that exceed in strength those from GPS satellites.

The scanner analyzes the signal ahead of removal. CW Detect gives signal size and position, while CW Removal removes the jamming energy.

High-speed Location Engine

High-speed Location Engine portion of the architecture is depicted in Figure 8.

Figure 8. High-speed Location Engine

The High-speed location engine improves on the performance of SiRFstarIII technology by doubling the size of DSP memory to allow

High-speed Location Engine Features 256K DSP memory, twice that of SiRFstarIII 109MHz operation, twice that of SiRFstarIII SBAS support

deeper and wider searches in a time frame, and by doubling speed at which the core runs to 109 MHz from a previous 50 MHz with SiRFstarIII

-163dBm tracking sensitivity There are two clear cut features of the enhanced High-speed Location Engine: X

Expanded DSP memory

X

Faster and higher sensitivity acquisitions

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The SiRFstarIV Advantage

The High-speed location engine improves on the performance of SiRFstarIII technology by doubling the size of DSP memory to allow deeper and wider searches in a time frame, and by doubling speed at which the architecture runs to 109 MHz from a previous 50 MHz with SiRFstarIII.

Tracking sensitivity has improved from -159 dBm to -163 dBm. Higher tracking sensitivity gives higher coverage in weak signal environments such as city centers and urban canyons. The added sensitivity allows the location engine to hold signals longer through difficult environments.

Full Satellite Based Augmentation System (SBAS) support has been added, including support for European Geostationary Navigation Overlay Service (EGNOS) and Wide Area Augmentation System (WAAS).

Tracking sensitivity has improved from -159 dBm to -163 dBm. Higher tracking sensitivity gives higher coverage in weak signal environments such as city centers and urban canyons. The added sensitivity allows the location engine to hold signals longer through difficult environments.

Other improvements include: X

Tracking signals using carrier aided smoothing techniques, resulting in fewer and shorter position excursions

X

Increased E911 sensitivity at -154 dBm for 19 seconds at 95% with coarse aiding.

The High-speed Location Engine pushes power/performance boundaries forward by providing higher coverage, accuracy, and availability in a 65 nm package.

Adaptive Micropower Controller

The Adaptive Micropower Controller portion is depicted in Figure 9.

The SiRFstarIV Adaptive Micropower Controller is highly advanced in terms of silicon design. The Adaptive Micropower Controller contains numerous power islands and power states.

Figure 9. Adaptive Micropower Controller

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Adaptive Micropower Controller Features Maintains Hot Start conditions Monitors temperature changes Calibrates TCXO and RTC curves Opportunistic Ephemeris decodes Motion detection interrupt handling

When Micropower is enabled, it runs a very low, continuous background task that stops

The SiRFstarIV Adaptive Micropower Controller is highly advanced in terms of silicon design. The Adaptive Micropower Controller contains numerous power islands and power states.

the growth of uncertainty to increase fine-time aided starts.

The Adaptive Micropower Controller controls the receiver from full-power tracking mode, to the TricklePower mode, and then down to a continuous availability mode.

When Micropower is enabled, it runs a very low, continuous background task that stops the growth of uncertainty to increase fine-time aided starts. Rather than on and off states, Adaptive Micropower Controller offers an intermediate state that consumes a very small amount of power --between 50 μA to 500 μA. The minor calibration measurement made in this low power state requires the reception of only one satellite signal. In addition, the Micropower mode can perform opportunistic ephemeris decode according to signal availability, with a corresponding increase in power consumption to 1 mA.

At the heart of this subsystem is SiRFaware technology, which ties together inputs and sensors running on power islands that consume no energy when not in use.

Even after a length of time of inactivity, full-rated -160 dBm sensitivity is achieved in 50 seconds when the device is re-activated. That compares to today’s standards that achieve only -147 dBm after periods of inactivity in autonomous modes.

At the heart of this subsystem is SiRFaware technology, which ties together inputs and sensors running on power islands that consume no energy when not in use.

An on-chip temperature sensor is included with logic that monitors for changes in temperature, creating wake-ups for the micropower mode. The temperature sensor absorbs only a few microamps of power in the RTC domain.

Also included is an interrupt input from a motion detector that can range in complexity from a simple device that detects vibration to highly complex MEMS sensors that create interrupt when boundary conditions are exceeded. Motion detection is useful in that the receiver can revert to a sleep mode until movement is being detected.

Overall, the Micropower Controller looks to maintain low uncertainty growth since the last position fix, enabling high sensitivity hot starts on demand.

Shown in the diagram are other components, including: X

Correlator sample and buffer

X

Switched mode regulator, regulation the 1.8 to 1.2 volt supply with ~ 90% efficiency.

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The SiRFstarIV Advantage

System management from the Adaptive Micropower Controller

Overall, the Micropower Controller looks to maintain low uncertainty growth since the last position fix, enabling high sensitivity hot starts on demand. In order to perform this function, the following technologies are operated together in close coordination in order to not waste any energy.

The architecture is optimized to detect

X

Clock calibration allows the retention of hot start conditions for long periods of time by learning clock behavior over temperature, enabling longer prediction of fine time conditions.

X

Opportunistic ephemeris decode allows the ability to stay in a hot start throughout the day. In cases where client generated extended ephemeris is available, ephemerides can be forward-predicted.

X

Contextual change can be detected either through temperature change or movement detection, depending on what resources are available.

X

Switched mode power supplies are more than 90 percent efficient.

X

Fast capture and correlate allows you to obtain a segment of signal, analyze it, and decide if there are any new data available, for example a satellite rising over the horizon.

context changes including mixed environments with extended periods of indoors, but with short bursts of time outdoors with a good sky view.

The architecture is optimized to detect context changes including mixed environments with extended periods of indoors, but with short bursts of time outdoors with a good sky view.

Smart Sensor Interface

The Smart Sensor Interface portion of the architecture is shown in Figure 10.

Smart sensors can be placed into a lowpower mode and programmed with an alarm level which will generate a hardware interrupt input which can be detected in the lowest power state.

Figure 10. Smart Sensor Interface

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The SiRFstarIV Advantage

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Smart Sensor Interface Features Supports smart I2C sensors with interrupt outputs Enables variety of applications - Heading - Point & Tell

By supporting these I2C bus and interrupt

- Context awareness

interfaces, the Smart Sensor Interface can

- Dead Reckoning

support a variety of applications, such as enhanced heading from a compass, point-

The Smart Sensor Interface contains: X

A single fully integrated temperature sensor

X

An I2C bus that allows connections of external sensors, such as a compass, gyro, or accelerometer

X

An interrupt that can be used to receive inputs from such MEMS sensors as motion detectors.

Smart sensors can be placed into a low-power mode and programmed with an alarm level which will generate a hardware interrupt input which can be detected in the lowest power state. For example, a smart accelerometer can be programmed with limits which if exceeded, an interrupt is generated. Many smart sensors offer this capability with a power budget in the tens of microamp range.

2

By supporting these I C bus and interrupt interfaces, the Smart Sensor Interface can support a variety of applications, such as enhanced heading from a compass, point-and-tell, and contextual awareness.

and-tell, and contextual awareness.

The SiRFstarIV High-speed Location Engine and Sensor Interface reside on a highly integrated system like a mobile handset. This requires a tremendous amount of connectivity...

Among the benefits of the I2C multi-master port is the ability to support existing smart sensors, such as a gyro, already designed into a camera for image stabilization. By utilizing existing device sensors, BOM costs can be reduced.

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The SiRFstarIV Advantage

Location Manager Software Suite The SiRF Location Manager Software suite, as depicted in Figure 11, residing on the host, is the management interface that delivers the power of the SiRFstarIV engine to the handset device and the location ecosystem.

SiRF has developed a extensive location framework that embeds these interfaces within the framework, thus accelerating time

Location Manager Software Suite

to market and reduced system integration

Software Managers

costs.

Context

Energy

Uncertainty

MEMS

Protocol

Figure 11. Location Manager Software Suite

At the core of the location manager architecture is an amalgamation of intelligent, collaborative software and system managers.

With this in mind, SiRF has developed a extensive location framework that embeds these interfaces within the framework, thus accelerating time to market and reduced system integration costs.

MEMS Manager and the GPS enable diverse power-saving scenarios such as turning off power to the host display when the device is stationary on a desk or if the device is in the user’s pocket.

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The SiRFstarIV High-speed Location Engine and Sensor Interface reside on a highly integrated system like a mobile handset. This requires a tremendous amount of connectivity, both to the wireless network as well as the rest of the handset resources, such as TCXO, 3G/2G Layer3, operating system resources, complementary wireless channels such as WiFi, power management, MEMS sensors, and third party applications.

The SiRFstarIV GPS receiver is a breakthrough piece of location hardware that can be left on continuously without burning up battery power. The flexibility of the new hardware is unprecedented. This unprecedented level of hardware flexibility requires a new software management system to enable its full capability. For example, the context detection logic of the Location Manager helps maximize accuracy when the SiRFstarIV detects the user is running or nearing a turn. It automatically helps minimize power when the chip detects the device is not moving, or is in a pocket by signaling the display unit in the handset.

At the core of the location manager architecture is an amalgamation of intelligent, collaborative software and system managers. The managers receive inputs from different system components and make real time decisions on a variety of tasks, such as the most efficient location algorithm or system resource to use or the lowest power location technology to fire-up based on application accuracy requirement. A central cortex coordinates the activities of the individual managers.

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Individual managers include: Context Manager

The Context Manager keeps track of device context. It determines whether the user is driving, walking, running, or engaged in some other activity, and optimizes the use of resources, navigation algorithms, and power by providing context input to various managers and applications.

Energy Manager always chooses the lowest energy fix for the accuracy requested. It

Energy Manager

The Energy Manager always chooses the lowest energy fix for the accuracy requested. It interacts with the Context Manager and the Uncertainty Growth Manager to choose the positioning technology that consumes the least amount of power based on numerous tunable parameters such as device battery level, energy-per-fix budget indicated by the host, always-on energy budget, and the application accuracy requirements. This provides the highest level of power optimization and configurability for the location application.

interacts with the Context Manager and the Uncertainty Growth Manager to choose the positioning technology that consumes the least amount of power

Uncertainty Growth Manager

Many LBS applications require GPS receivers to always maintain hot start condition for fast TTFFs. As the name suggests, the Uncertainty Growth Manager keeps track of the growth in uncertainty of the fix and starts the receiver when a threshold is reached to keep the uncertainty within limits to enable hot starts. The Uncertainty Growth Manager also monitors temperature changes and other uncertainty changes to decide necessity of calibrating the TCXO and downloading ephemeris. This function requires only microwatts of average power draw, thereby maintaining hot start conditions with very low battery power consumption.

Uncertainty Growth Manager keeps track of the growth in uncertainty of the fix and starts the receiver when a threshold is reached to keep the uncertainty within limits to enable hot starts.

MEMS Manager

The MEMS Manager provides a develop-and-go interface to the host system and applications. It discovers all available sensors in the system, calibrates them against all other location data, selects the best sensor for a task, arbitrates between sensors, and supports multiple simultaneous reporting streams at different data rates. Apart from providing a scalable interface for a high performance dead reckoning (DR) navigation solution along with the SiRF GPS Navigation engine, the MEMS Manager provides enhanced power management to the host system.

The highly sophisticated cocktail of SiRF Context Sensors, the MEMS Manager and the GPS enable diverse power-saving scenarios such as turning off power to the host display when the device is stationary on a desk or if the device is in the user’s pocket.

MEMS Manager and the GPS enable diverse power-saving scenarios such as turning off power to the host display when the device is stationary on a desk or if the device is in the user’s pocket.

Protocol Manager

The Protocol Manager abstracts the various A-GPS protocols (SUPL, Control Plane – RRC & RRLP, ASN.1 encoding/decoding) from the application, and provides a seamless interface to support A-GPS session management, including multiple simultaneous sessions. It also provides a platform abstraction layer (PAL) that abstracts various operating system specific primitives such as semaphores, threads, and timers.

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The SiRFstarIV Advantage

Conclusion The SiRFstarIV with SiRF Always Aware Architecture subsystems -- Active Jammer Remover, High-speed Location Engine, Adaptive Micropower Controller, and Smart Sensor Interface -- fused together and driven by SiRF Location Manager Software Suite, allow for always aware GPS experience.

The SiRFstarIV architecture packs better performance with breakthrough power consumption, allowing designers to enable true location awareness in a whole new class of consumer products such as digital

SiRFstarIV is simple to integrate and can be dropped into multiple platforms, lowering engineering investment. the small size, minimal footprint, and reduced power demand make the cost of adding location awareness to a device lower than ever before. The ability to detect and remove sources of jamming coupled with high 3GPP and E911 pass margins reduces risk and enables faster time to market.

The SiRFstarIV architecture packs better performance with breakthrough power consumption, allowing designers to enable true location awareness in a whole new class of consumer products such as digital still cameras, video cameras, and portable game consoles.

still cameras, video cameras, and portable game consoles.

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The SiRFstarIV Advantage

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©2009 SiRF Technology, Inc.

This document contains proprietary information to SiRF Technology, Inc. and shall not be reproduced or transferred to other documents or disclosed to others or used for any purpose other than that for which it was obtained without expressed written consent of SiRF Technology, Inc. All information in this document is preliminary and subject to change without notice.

All other products or company names mentioned herein are used for identification purposes only, and may be trademarks of registered trademarks of their respective owners.

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