1. TV-GPS Enhancing Global Positioning Systems Using Television Signals By Chris Lehnert

2. Overview  Introduction  Dissecting the Signal  Positioning  Conclusions  Resources

3. Introduction  What is TV-GPS?  Positioning using synchronization signals that are broadcast by VHF and UHF frequencies  Why use TV transmitters?  Higher power transmitters  Lower broadcast frequency  Number of different signals  Higher bandwidth

4. Introduction  Benefits  Compliments conventional GPS  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)  Superior triangulation of lateral positions  More accurate, reliable and rapid positioning

5. Dissecting the Signal  Focus on American Standards Television Committee (ASTC)  Frame: 626 segments, 832 symbols each  Segment: 4 symbols for synchronization  Segment types: Field Synchronization, Data

6. Dissecting the Signal  Downconverting TV signal process:  Assume nominal offset frequency  Sample the frequency  Create complex code signal  Compute Fourier Transform

7. Positioning  Device acquires signal  Triangulates latitude and longitude  Pseudoranges  Monitor unit tracks signals  No common clocks  Location server does computations  Sends data to chips

8. Positioning

9. Positioning  Message flow diagram

10. Conclusions  Positive:  Excellent positioning system when paired with conventional GPS  Robust, high speed, large coverage  Many practical uses  Negative:  Location privacy

11. Resources  A New Positioning System Using Television Synchronization Signals. Matthew Rabinowitz, James Spilker. ROSUM  http://www.gpsworld.com/gpsworld/article/articleDetail.jsp?id=180165  http://www.pcworld.com/news/article/0,aid,118031,00.asp  http://www.directionsmag.com/press.releases/index.php?duty=Show&id=11394&trv=1  http://www.dailywireless.org/modules.php?name=News&file=article&sid=782  http://www.fcw.com/article88942-05-23-05-Print  http://fleetowner.com/information_technology/patentpending/fleet_tvgps/  http://www.rosum.com/rosum_tv-gps_plus_indoor_location_technology.html  http://www.popsci.com/popsci/computerselec/7a924c3ee4d05010vgnvcm1000004eecbccdrcrd.html  http://www.wipo.int/cgi-pct/guest/getbykey5?KEY=01/43428.010614&ELEMENT_SET=DECL  http://www.embeddedstar.com/press/content/2003/2/embedded7435.html  http://en.wikipedia.org/wiki/Pseudorange