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GPS Technology Tech Talk

GPS Technology Tech Talk. April, 2008 Chad Halvarson. Agenda. Current GPS and Assisted GPS (AGPS) Overview CDMA GPS Service Conclusion Q & A. GPS Review. A GPS receiver determines the travel time of a signal from a satellite – Synchronization

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GPS Technology Tech Talk

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  1. GPS TechnologyTech Talk April, 2008 Chad Halvarson

  2. Agenda • Current GPS and Assisted GPS (AGPS) Overview • CDMA GPS Service • Conclusion • Q & A

  3. GPS Review • A GPS receiver determines the travel time of a signal from a satellite – Synchronization A Travel Time x c (Speed of Light ~ 3 x 109m/s) = Total Distance

  4. GPS Requirements • GPS is good for open field. • Less accurate for blocked or indoor areas (urban locations). • Requires line of sight to at least 3 satellites. • GPS Receiver requires high processing power. • Expensive GPS hardware and Pre-loaded software.

  5. AGPS Overview • Affordable solution • Uses an assistance server to calculate locations via Wireless Carrier Backbone • Commonly associated with Location Based Services (LBS) over cellular networks. • E911 – Mandated by FCC to provide emergency service • Mobile Tracking • Navigation • Ability to download specific information dynamically in real-time

  6. Assisted GPS Overview WEB for Operator or Customer Wireless Carrier Assistance Server Internet Data Communication to cellular IP

  7. CDMA GPS Service • Replaces expensive typical GPS receivers with inexpensive Handset • Provides various mobile services • Location Base Service (i.e. E911, Weather, POI etc.) • Tracking • Navigation

  8. CDMA Location Hierarchy AGPS Fix ... open sky AGPS Fix requires a minimum of three GPS measurements. “Assisted” because network resources are still required. Hybrid Fix … partial view of sky CDMA pilot phase measurements can be used as a virtual GPS to determine position. Advanced Forward Link Tri-lateration AFLT Fix … indoors AFLT is a “triangulation type” fix that requires contact with a minimum of three towers to establish a position. Cell Sector Fix … indoors, edge coverage Cell Sector location reports the center of the cell sector as the current position.

  9. CDMA

  10. R 1 R 1 R 1 CDMA - Network Initiated • Features: • First fix in tens of seconds • Very high accuracy • Available during a voice call • Fallback modes available • Limitations: • Each additional fix requires same time as initial fix • Limited to specific devices • Network resources needed for every location request Satellite Satellite Data No Ranging Raw GPS data collected & passed Mobile Station Base Station Satellite Acquisition and Sensitivity Assistance Data requested & passed Location Application Network HW Network does the math to calculate position

  11. CDMA

  12. Conclusion • Current GPS technology Overview • GPS vs. AGPS • CDMA GPS Service Offerings

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