TV-GPS

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 Doppler
• ionospheric propagation delays
• data 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/articleDe
  tail.jsp?id180165
• http//www.pcworld.com/news/article/0,aid,118031,0
  0.asp
• http//www.directionsmag.com/press.releases/index.
  php?dutyShowid11394trv1
• http//www.dailywireless.org/modules.php?nameNews
  filearticlesid782
• http//www.fcw.com/article88942-05-23-05-Print
• http//fleetowner.com/information_technology/paten
  tpending/fleet_tvgps/
• http//www.rosum.com/rosum_tv-gps_plus_indoor_loca
  tion_technology.html
• http//www.popsci.com/popsci/computerselec/7a924c3
  ee4d05010vgnvcm1000004eecbccdrcrd.html
• http//www.wipo.int/cgi-pct/guest/getbykey5?KEY01
  /43428.010614ELEMENT_SETDECL