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Transcript 
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?


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

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

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

Dissecting the Signal

Downconverting TV signal process:
Assume nominal offset frequency
 Sample the frequency
 Create complex code signal


Compute Fourier Transform
Positioning

Device acquires signal

Triangulates latitude and longitude


Monitor unit tracks signals


Pseudoranges
No common clocks
Location server does computations

Sends data to chips
Positioning
Positioning

Message flow diagram
Conclusions

Positive:
Excellent positioning system when paired
with conventional GPS
 Robust, high speed, large coverage
 Many practical uses


Negative:

Location privacy
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
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