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TV-GPS

TV-GPS. Enhancing Global Positioning Systems Using Television Signals By Chris Lehnert. Overview. Introduction Dissecting the Signal Positioning Conclusions Resources. Introduction. What is TV-GPS?

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TV-GPS

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  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 • Higher bandwidth

  4. Introduction • Benefits • Compliments conventional GPS • No modifications to current TV signals • Works stand-alone or with regular GPS • Robust and jamming resistant • Low Horizontal Dilution of Precision (HDOP)

  5. Dissecting the Signal • TV signal bandwidth -> 6-8Mhz • Low frequency & high power signals • Synchronization signals • VSYNC, HSYNC • Keeps receiver in step with sender

  6. Dissecting the Signal • Frame: 626 segments, 832 symbols each • Segment: 4 symbols for synchronization • Segment types: Field synchronization, Data

  7. Positioning • Components required: • Mobile device equipped with TV tuner • Location server • Regional monitor • Steps to finding position: • Pseudo-range calculation

  8. Positioning

  9. Positioning • Message flow diagram

  10. Positioning • Pseudo-range Calculation: • A measure of apparent propagation time from transmitter to mobile unit expressed as a distance • Determined from difference between time received and time sent • Receive time is measured at mobile receiver • Send time is included in frame header • Requirements: • Needs 3 transmitters to form accurate horizontal measurements

  11. Positioning • Position signal error sources: • Multi-path • Transmitter clock instability • Multi-path • Line-of-sight is not the strongest signal • Transmitter clock instability • Fluctuations in oscillator

  12. Applications/Advances • Applications • People tracking • Mobile resource management • Public/Personal safety • National security/Warfare • Asset tracking • Advances • 3D positioning (TV-GPS Plus)

  13. Applications / Advances • TV-GPS Plus: • Uses portable pseudo TV transmitters (PTTs) • Can be used with existing TV-GPS and GPS infrastructures • Applications: • Emergency first responders – Firefighters, Police, etc. • Child safety

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

  15. 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 Questions?

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