Localization

1

Location Based Services for

Mobile Devices

Embedded Computing Seminar

Shay Horovitz

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Technologies

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Location Technologies

• GPS - Global Positioning System• AGPS - Assisted GPS• Cell ID• Cell ID + Timing Advance• Signal Strength Based• AOA - Angle Of Arrival• TOA - Time Of Arrival• TDOA - Time Difference of Arrival• EOTD - Enhanced Observed Time Difference• Keypad based (click the address yourself)• Camera based (taking pictures of signs)• Hybrid solutions• RF Fingerprinting (on phones that will support WLAN)

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GPS

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History

• Mariners relied upon the sun for latitude, and clocks for longitude

• With the launch of Sputnik in 1957, radio-based global positioning became a (theoretical) possibility

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TRANSIT

• This was a very crude form of GPS using only one satellite (1960s)– Submarines used it– Could only be used every 35-45 minutes– Submarine had to be still

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TIMATION (1960s)

• Another satellite (TIMATION I) was launched to enhance the TRANSIT system

• Major innovation was the inclusion of an atomic clock

• Submarines could now be in motion and use the system

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NAVSTAR

• In 1973, NAVSTAR began research & development• 1978 – the first 4 satellites

were launched• Operated by the

Department of Defense– Primary mission is to

provide exact coordinates for land, sea & air-based military forces

– Cost about $18,000,000,000 to develop… so far

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There are three components of GPS

• 1.) Space (e.g. satellites)

• 2.) Control (i.e. a ground station at a known geographic location)

• 3.) User

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How it works

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Satellites

• The GPS receiver precisely measures the time it takes a signal to travel from a satellite to the receiver

• There are lots and lots of satellites

• Anyone want to guess how many?

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Details

• 6 orbital planes, included at 55 degrees to the equator, each with 4 satellites– 21 active satellites,

3 backups

• Orbit the earth at 12,541 miles and have an orbital period of 11 hrs. 56 min.

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Satellite Triangulation

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How many points do you need?

• Using one satellite narrows the distance to a sphere around the satellite

• Using two satellites, you’ll find your location within a circle (previous slide)

• Using three satellites limits your location to only 2 points– Usually, it is possible to determine which point

• Using four satellites confirms your location and gives you 2 readings for altitude– Usually you can determine which is correct

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The importance of time

• Both satellites and receivers generate Pseudo Random Noise (PRN)– A Link 1 (L1) carrier signal is generated at 1575.42

MHz and Link 2 (L2) carrier signal is generated at 1227.60 MHz

• Carrier signals are modulated to produce coded signals, such as C/A code (at 1.023 MHz) and the P code (at 10.23 MHz)

– The frequencies are frequency-modulated to produce step-functions

– The codes repeat every millisecond

• The satellites come with cesium or rubidium clocks

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Time lag

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Selective Acquisition

• The US military was concerned about the possibility of terrorists or other unfriendly people using GPS to precisely guide a missile (or other unfriendly device)

• The deliberately introduced errors in the time embedded in the signal

• This caused locations to be up to 100m off

• Turned off on 2 May 2000

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Selective Acquisition

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2010

• GPS III system will launch

• Should be even more accurate than the 8m accuracy limit currently in place

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Tech: AGPS

• GPS has a slow time to fix unless it is permanently tracking satellites

• To solve the inherent restrictions with GPS, Assisted GPS was proposed

• Assisted GPS is based upon providing GPS satellite information to the handset, via the cellular network

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Tech: AGPS

• Assisted GPS gives improvements in– Time to First Fix– Battery Life– Sensitivity– Cost

• Assistance Data– Satellite Position– Time information– Visible GPS List– Sensitivity

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Tech: Cell ID

• Cell ID: the cell that the mobile is connected to

• Operator’s know where their cell sites are

• Accuracy is dependent on cell density

• Can be implemented both network based or device based

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Tech: Cell ID

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Tech: Cell ID + Timing Advance (TA)

• TA is the time delay between the mobile and serving base station

• Resolution is 500 meters

• Serving cell identity and TA are available in networks

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Tech: Signal Strength Based

• Measure signal strength from the control channels of several Base Stations

• If signal levels from 3 different BSs are known, it’s possible to calculate the location

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Tech: Signal Strength Based

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Tech: AOA - Angle Of Arrival

• Measure the angle of arrived signal between base station and mobile station

• Location error increases as mobile is far from BSs

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Tech: TOA - Time Of Arrival

• Measure the time of arrived signal between base station and mobile station

• Mobile station locates at the intersection point which will be made by more than 3 circles

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Tech: TDOA – Time Difference Of Arrival

• Measure the time difference of arrived signal between base station and mobile station : Minimum three base stations

• Mobile station locates at the intersection point which will be made by more than 3 hyperbolas

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Tech: TDOA – Time Difference Of Arrival

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Tech: EOTD – Enhanced Observed Time Difference

• Added device, LMU (Location Measurement Unit), whose location is known

• LMU and mobile station measure the time difference of arrived signal from base station at the same time

• Mobile station locates at the intersection point which will be made by more than 3 hyperbolas

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Tech: EOTD – Enhanced Observed Time Difference

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Tech: Keyboard Based

• You set your location!

• Example: Navigation Software:

1. Manually set origin

2. Manually set destination

3. Approve when each step is completed to get the next step instructions

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Tech: Camera Based

• Take a picture of road signs and send by MMS to a server

• 2D Barcodes

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Tech: Lamposts Based

• Last Mile, a British company plans to offer Internet & LBS using street lampposts…

• A flash memory will be installed inside the lampposts and store info about local pubs, shops.

• Cost: about £500 per lamppost

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Tech: Hybrid Solutions Based

• Improve effectiveness• Extends the coverage of a solution e.g.

AGPS• Common Hybrids

– EOTD / AGPS– Cell ID / AGPS

• Benefits of both systems realized increasing the accuracy and availability of any single method

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Tech: RF Fingerprint Based

• Pinpointing wireless clients makes it easier to secure and manage wireless LANs

• WLANs typically have used closest access point (closest AP) or triangulation technologies to track location

• RF fingerprinting improves by taking into account the effects that a building or people will have on an RF signal - characteristics such as reflection, attenuation and multi-path

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Tech: RF Fingerprint Based

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Range Of Coverage

Cell ID

AGPS,GPS, GPS Hybrids

EOTD

TDOA, AOA

Cell ID + TA

1000+m

500 m

300 m

100 m

5 m

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Major Technologies Table

Technology Handset impact Accuracy

Cell ID none Depends on the size of the cell

100m-3km

Cell ID + TA none 500m

TDOA none 100-200m

AOA none 100-200m

EOTD yes 20-200m

GPS/AGPS yes 5-30m

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Applications

• Network Optimization• In-Car & Personal Navigation and wayfinding• Emergency (E911)• Monitoring traffic flow using device location & optimization• Automated Mapping• Family Tracking/ Find-A-Friend• Find the Nearest Store/place• Tourist Information/Automated Guide• Live public transport info• Games• Fleet Management• Location-based Billing• Demographic Statistics• Target Marketing• Other applications

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LBS based games

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Game: Glofun RayGun

- Location: US

- Target: Ghost-Hunting!

- Use of GPS for location of player

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Game: SS+K Conqwest

• Location: 5 cities in the USA• Team-based treasure hunt in the urban jungle• 5 teams searching for treasure in the form of

“printed codes” – 2d barcodes that can be captured by phonecam

• 1 code=1$. First team to find $5000 worth codes wins and earns a $5000 scholarship for their school…

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Game: Blisterent Swordfish

• GPS based game

• You play against a virtual school of Swordfish

• See where’s the nearest school of virtual fish

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Game: Blisterent Torpedo Bay

• A-GPS based game

• No GPS reception? - Predictive positioning…

• Use of real map

• 360 degrees view

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Game: NewtGames Mogi

• Location: Tokyo, Japan

• GPS based

• Pick up virtual items spread on the whole of Japan

• At a range of 400m, you’re able to collect an item

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Game: Mikoishi GunSlingers

• Location: Singapore

• Cell-ID based

• Multiplayer shooting game

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HP Labs City Tags

• Location: Bristol, UK

• iPaq PocketPC with GPS, Wifi needed

• Social interaction: Tag people

• When got tagged, need to find a friend to free you

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GeoCaching

• Take something from the cache

• Leave something in the cache

• Write about it in the logbook

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Geocaching

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Developer Toolkits

• Chips:– HammerHead– TI– Intel

• APIs:– Sun J2ME Location API– Qualcomm BREW LBS API

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Chips Market

"The mobile GPS semiconductor market is expected to exceed 180 million units in 2008 …" Will Strauss, president of Forward Concepts [http://www10.edacafe.com/nbc/articles/view_article.php?section=ICNews&articleid=223846 ]

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HammerHead: PMB 2520

• Single chip solution

• A-GPS Implementation

• Size: 80 mm2

• Low Power

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TI Chip: NaviLink 4.0 GPS5300

• Single chip solution

• Smallest A-GPS (50 mm2)

• Low Power, Power Management

• Production: 2Q, 2006

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TI Chip: NaviLink 4.0 GPS5300

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Intel’s Plans

• “Notebook chips will likely support location-based services by 2006, Intel says. “ PCWorld [http://www.itworld.com/Comp/2085/041025pentiumm/]

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SUN J2ME LBS

• Location API for J2ME (JSR 179)

• A set of generic APIs for developing LBS

• Can support GPS/A-GPS/Cell-ID/any other method [by implementing a location provider]

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SUN J2ME LBS sample

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Chips in detail

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Typical GPS Receivers Power Usage

Name CPUFab Process

Voltage

(volts)

Average Power Usage (mW) Average

SiRFstar IMotorola MC68330

at 19.1 mhz0.60 5

1,700 

SiRFstar I/LX

HitachiSH-1 7021 RISC at

12.2 mhz0.35 3.3

165 

SiRFstar IIe

ARM7/TDMI12.3 mhz   2.7

165 

SiRFstar IIe/lp

ARM7/TDMI12.3 (?) mhz

? 2.765

SiRFstar IItARM7/TDMI12.3 (?) mhz   2.7

45 

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Some interesting numbers…

• Most popular chipset – SiRF

• Smallest modules: – SyChip GPS2020: 13x15x3.8– Trimble M-Loc MPM: 25x25x6.5– Fastrax iTrax02: 26x26x6.5

• Smallest module with integrated Antenna – Axiom Swift A1: 41x41x11

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Use One?

• Ready made External boxes with integrated antennas or separate

• Support USB / RS232

• Available as both PCMCIA and Compact Flash cards

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Chip Sets 1

Company Product PictureDims.mm

Sup/Curr.V/mA

Analog Devices

NAV 2300 chipset. ADSSTRF2000 RF Down converterADSST NAV 2300 based Correlator and Navigation Processor

BethelTronix, Inc.BT1575 RF front end   QLP32 2.4-3/

Conexant (Rockwell)

Zodiac 2000 chip set Scorpio Baseband Processor and Monopac RF front endor CX74010 RF front end or CX76502 RF MCMCX11239 optional HW accelerator

 Monopac: PQFP80

EverMore BBP1202 baseband processor TQFP100 3.3/

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Chip Sets 2

Company Product PictureDims.mm

Sup/Curr.V/mA

MagellanG10 gps chip     3.3/115

Motorola

MG2000 Mixed mode GPS RF down-converter and 12-channel digital correlator

BGA64 2.7-3.6/20

GPS chip set. MRFIC1504 RF front endMMC2003 controller

 LQFP48LQFP144

2.7-3.3/273-3.6/

ParthusNavStream platform HW and SW

 24x40x10LQFP

3/3/

Phillips

UAA1570HL RF SAA1575HL

LQFP48LQFP100

2.7-5/603-5/50

SAF1576 single chip gps.

QUAD-44 3/?

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Chip Sets 3

Company Product PictureDims.mm

Sup/Curr.V/mA

RF Micro Devices, Inc.

RF2460 LNA/Mixer, EGR-X001, ACS-X001 transceivers

SiRF

SiRFstarI GSP 1/LX, GRF1/LX front end, GSW1/LX SW.

GRF1: LQFP32,GSP1: LQFP100BGA144

3.3/150

SiRFstarII GSP2e digital section, GRF2i RF front end, GSW2e SW.

GRF2i:LQFP48LPCC32,GSP2e:TQFP100BGA144,160LQFP144

3/160

SiRFstarIIt ext. host, GSP2t digital section, GRF2i RF front end, SiRFNav SW.

GRF2i:LQFP48GSP2t:LQFP48

3/57

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Chip Sets 4

Company Product PictureDims.mm

Sup/Curr.V/mA

Sony SemiconductorCXA1951AQ RF front endCXD2931R baseband processor

 QFP40LQFP144

2.7-5.5/303-3.6/55

STMicroelectronicsSTB5600 RF Front EndST20-GP6 Baseband Processor

TQFP32PQFP100

3.3-5.9/353.3/45

Trimble

FirstGPS (Infineon based)IO - PMB 2500 Baseband CorrelatorColossus -- PMB 3330 RF Front-end

TSSOP28TSSOP24

3.3/2.52.7/8

Valence Semiconductor VS7001 gps front end TQFP48 2.7-3.3/14

Zarlink SemiconductorGP2015 RF Front EndGP4020 Baseband Processor

TQFP48LQFP100

3-5/703.3/100

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Modules 1

Company Product PictureDims.mm

Sup/IidleV/mA

AirbiquityGPS accessory combined battery/gps for cell. phones (SiRF based)

103x46x193.7/1.4Ah LiIon

Analog Devices

NAV-2300 GPS receiver board   50x40x12 3.3/180

Ashtech

G8 oem receiver (8 chan. only)(Phillips based)

39x60x10.4

5/140

G12 oem receiver 108x57x? 5/360

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Modules 2

Company Product PictureDims.mm

Sup/IidleV/mA

Axiom Navigation Inc.

Swift A2 oem GPS receiver (SiRF based)integrated ceramic patch antenna

42x42x 3.3/150

Swift B2 oem GPS receiver (SiRF based)

25x32x7 3.3/150

Sandpiper oem GPS receivers (SiRF based)

CMC Electronics Inc. SUPERSTAR II gps oem receiver 46x71x13 3.3/150

Conexant (Rockwell)

TU70-D100 GPS sensor boardintegrated patch antenna

  61x54x14.5 3.3/

Jupiter receiver boards   71x41x11 3.3,5/130

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Modules 3

Company Product PictureDims.mm

Sup/IidleV/mA

EMTACCrux II GPS engine D154N (SiRF based)

41x52x? 3.3,5/160

EverMore

GM-X205 oem module w/antenna

55x40x20 3.8-8/105

EB-X305 oem module 70x40x10 3.3/130

Fastrax iTRAX02 GPS receiver 26x26x4 2.7-3.3/37

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Modules 4

Company Product PictureDims.mm

Sup/IidleV/mA

Garmin GPS 25 Series gps engine 46.5x70x11.4 3.6-6/115

Javad Navigation SystemsJGG20 GPS, INMARSAT, WAAS, and GLONASS

108x57x16 4-14/500

Laipac Tech

TF10 receiver module (SiRF based)

42x72x12 3.3,5/180

TF 30 receiver module (SiRF based)

30x40x7 3.3/140

TF 50 GPS and GLONASS module

71x51x12 3.3/180

UV-40 16-chan. receiver module

    3.3/?

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Modules 5

Company Product PictureDims.mm

Sup/IidleV/mA

Motorola

M12 Oncore GPS Receiver

40x60x10 2.7-3.2/75

SL Oncore GPS Receiver(8 chan. only)

40x80x12.2 5/150

GT Plus Oncore GPS Receiver(8 chan. only)

51x83x16.3 5/150

RF Micro Devices, Inc. RF8000 12-ch. module   38x38x9.8 3.3/100

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Modules 6Company Product Picture

Dims.mm

Sup/IidleV/mA

Rojone

Genius 3 (SiRF based) integrated antenna

66x66x7 5/180

Genius 4 (SiRF based) 66x66x7 5/180

Micro Genius 3 40x35x10 3.3/160

RoyalTek

REB-12R Series gps engine (SiRF based)

41x71x11.5 3.3(5)/180

REB-2101 gps board (SiRF based) 40x36x8 3.3/170

RGM-3000 gps board (SiRF based)

21x28x13 3.3/170

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Modules 7Company Product Picture

Dims.mm

Sup/IidleV/mA

Sena GPS SA

Albatros OEM gps receiver (SiRF based)

11x29.5x38 3.3(5)/135

Proteus OEM gps receiver (Mitel based)

50x120x19 9-32/220

Sigtec Navigation Pty Ltd

MG5001 OEM GPS Receiver

66x47x12 3.3/150

autoNAV MG5002 - Designed for external microprocessor.cellNAV MG5003 - Designed for use in cellphones.

microNAV MG5004 - General purpose, optimised for small size

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Modules 8Company Product Picture

Dims.mm

Sup/IidleV/mA

Sony Semiconductor

GXB2100 Module   36.5x25x? 3.3/?

GXB3000 Module 3.3/?

GXB3100 Module 3.3/?

SyChipGPS2020 receiver module (SiRF based)

13x15x3.8 3.3/145

Trimble

Lassen SK-II gps module 83x31x10.2 5/95

Lassen LP gps module 66x32x12 3.3/55

Lassen SQ gps module 26x26x6 3.3/30

M-Loc MPM gps module 25x25x6.5 3.3/10.5

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Modules 9

Company Product PictureDims.mm

Sup/IidleV/mA

u-blox

TIM gps module (SiRF based)

25x25x3 3.3/140

GPS-MS1E gps module (SiRF based)

30x30x7.7 3.3/140

GPS-PS1E gps module (SiRF based)

32x82x7.7 5/140

Valence SemiconductorVS7001-REF 3B/3D ref. module

    3.3/?

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Build your own ?

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GPS Building Blocks 1

• Antenna element – Cost: $3 to $300 (depends on single/double frequency reception & phase center

stability)– Diameter: 2cm to 15cm

• Low Noise Amplifier (LNA)– Amplifies GPS signals– Cost: $5 to $100 (depends on number of frequencies & quality of filters)– Power consumption: 20mW to 200mW

• RF section– Converts received signal to digital form– Cost: $5 to $200 (depends on number of frequencies & quality of filters)– Size: 2-20 cm– Power consumption 100mW to 1 Watt

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GPS Building Blocks 2

• Digital section– Processes the digital samples and provides tracking measures– Cost: $5 to $15

• Microprocessor– Control the tracking elements based on measurements and doppler

(range rate change)– Collects navigation data about the orbit and clock of each satellite– Compute position– Support interfaces to the user– Cost: $5 to $50– Power consumption: 200mW to 3W

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GPS Building Blocks 3

• Processor Peripherals– Provide memory for program and data storage– Cost: $5 to $100 (depending on capacity and speed)– Power consumption: 100mW to 2W

• I/O & Drivers– Serial/ Parallel/ USB/ Ethernet/ other comm ports– Cost: $2 to $20– Power consumption: 10mW to 100mW

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References• Ronald Azuma et el., “Recent Advances in Augmented Reality”, IEEE Computer Graphics

and Applications, vol.21, no.6, Nov/Dec 2001, pp.34-47• Mohammad S. Sharawi et el., “Investigation into the performance of EOTD for GSM users

in Telematics applications”, Proceedings of SPIE, vol. 5084, Aug. 2003, pp.6-18 • http://yona_n.tripod.com/gps/gps-survey.html#chips• EDN: http://www.edn.com/article/CA243219.html• GPSWorld: http://www.gpsworld.com/gpsworld/article/articleDetail.jsp?id=15100&pageID=1• HowStuffWorks: http://electronics.howstuffworks.com/gps.htm• http://www.symbian.com/developer/techlib/papers/messaging/LocalAwareness_LBS_01.pdf• http://www.terena.nl/conferences/tnc2005/core/getfile.php?file_id=453• LBS Market: http://www.trueposition.com/lrc/LBSLongTimeComing.pdf• LBS Forecast: http://mms.ecs.soton.ac.uk/mms2002/papers/4.pdf• Location Technologies:

http://developer.openwave.com/omdtdocs/location_studio_sdk/pdf/Intro_to_Location_Technologies.pdf

• GSM LBS: http://www.ftw.at/ftw/events/telekommunikationsforum/WS2001/WS01docs/020111.ppt

• E-911: http://www.sss-mag.com/e911.html• Solutions: http://www.wirelessdevnet.com/channels/lbs/features/mobilepositioning.html• GPS Based games: http://www.glofun.com/• LBS in Europe: http://www.hottelecom.com/berginsight-lbs.html

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Thank YouFor Listening