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GPS Technology Tech Talk

This presentation by Chad Halvarson, from April 2008, explores the fundamentals of Global Positioning System (GPS) and Assisted GPS (AGPS). It discusses the operational requirements of GPS in open environments versus urban areas where signal blockage occurs. The presentation delves into the benefits of AGPS, which uses wireless carrier networks to enhance location services and is crucial for applications like E911 emergency services. Additionally, the presentation outlines the CDMA GPS service, detailing its advantages in affordability and the range of services it provides.

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GPS Technology Tech Talk

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Presentation Transcript

  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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