TV-GPSTV-GPS

Enhancing Enhancing Global Positioning Systems Global Positioning Systems

Using Television SignalsUsing Television Signals

By Chris LehnertBy Chris Lehnert

OverviewOverview

IntroductionIntroduction

Dissecting the SignalDissecting the Signal

PositioningPositioning

ConclusionsConclusions

ResourcesResources

IntroductionIntroduction

What is TV-GPS?What is TV-GPS? Positioning using synchronization signals Positioning using synchronization signals

that are broadcast by VHF and UHF that are broadcast by VHF and UHF frequenciesfrequencies

Why use TV transmitters?Why use TV transmitters? Higher power transmittersHigher power transmitters Lower broadcast frequencyLower broadcast frequency Number of different signalsNumber of different signals Higher bandwidthHigher bandwidth

IntroductionIntroduction

Benefits Benefits Compliments conventional GPSCompliments conventional GPS Not affected by:Not affected by:

• transmitter Dopplertransmitter Doppler• ionospheric propagation delaysionospheric propagation delays• data that is modulated into other signalsdata that is modulated into other signals

Low Horizontal Dilution of Precision (HDOP)Low Horizontal Dilution of Precision (HDOP) Superior triangulation of lateral positionsSuperior triangulation of lateral positions More accurate, reliable and rapid positioningMore accurate, reliable and rapid positioning

Dissecting the SignalDissecting the Signal

Focus on American Standards Television Focus on American Standards Television Committee (ASTC)Committee (ASTC)

Frame: 626 segments, 832 symbols eachFrame: 626 segments, 832 symbols each Segment: 4 symbols for synchronizationSegment: 4 symbols for synchronization Segment types: Field Synchronization, DataSegment types: Field Synchronization, Data

Dissecting the SignalDissecting the Signal

Downconverting TV signal process:Downconverting TV signal process: Assume nominal offset frequencyAssume nominal offset frequency Sample the frequencySample the frequency Create complex code signalCreate complex code signal

Compute Fourier TransformCompute Fourier Transform

PositioningPositioning

Device acquires signalDevice acquires signal

Triangulates latitude and longitudeTriangulates latitude and longitude PseudorangesPseudoranges

Monitor unit tracks signalsMonitor unit tracks signals No common clocksNo common clocks

Location server does computationsLocation server does computations Sends data to chipsSends data to chips

PositioningPositioning

PositioningPositioning

Message flow diagramMessage flow diagram

ConclusionsConclusions

Positive:Positive: Excellent positioning system when paired Excellent positioning system when paired

with conventional GPSwith conventional GPS Robust, high speed, large coverageRobust, high speed, large coverage Many practical usesMany practical uses

Negative:Negative: Location privacyLocation privacy

ResourcesResources A New Positioning System Using Television Synchronization SignalsA New Positioning System Using Television Synchronization Signals. Matthew Rabinowitz, James Spilker. ROSUM. Matthew Rabinowitz, James Spilker. ROSUM

http://www.gpsworld.com/gpsworld/article/articleDetail.jsp?id=180165http://www.gpsworld.com/gpsworld/article/articleDetail.jsp?id=180165

http://www.pcworld.com/news/article/0,aid,118031,00.asphttp://www.pcworld.com/news/article/0,aid,118031,00.asp

http://www.directionsmag.com/press.releases/index.php?duty=Show&id=11394&trv=1http://www.directionsmag.com/press.releases/index.php?duty=Show&id=11394&trv=1

http://www.dailywireless.org/modules.php?name=News&file=article&sid=782http://www.dailywireless.org/modules.php?name=News&file=article&sid=782

http://www.fcw.com/article88942-05-23-05-Printhttp://www.fcw.com/article88942-05-23-05-Print

http://fleetowner.com/information_technology/patentpending/fleet_tvgps/http://fleetowner.com/information_technology/patentpending/fleet_tvgps/

http://www.rosum.com/rosum_tv-gps_plus_indoor_location_technology.htmlhttp://www.rosum.com/rosum_tv-gps_plus_indoor_location_technology.html

http://www.popsci.com/popsci/computerselec/7a924c3ee4d05010vgnvcm1000004eecbccdrcrd.htmlhttp://www.popsci.com/popsci/computerselec/7a924c3ee4d05010vgnvcm1000004eecbccdrcrd.html

http://www.wipo.int/cgi-pct/guest/getbykey5?KEY=01/43428.010614&ELEMENT_SET=DECLhttp://www.wipo.int/cgi-pct/guest/getbykey5?KEY=01/43428.010614&ELEMENT_SET=DECL

http://www.embeddedstar.com/press/content/2003/2/embedded7435.htmlhttp://www.embeddedstar.com/press/content/2003/2/embedded7435.html

http://en.wikipedia.org/wiki/Pseudorangehttp://en.wikipedia.org/wiki/Pseudorange