The Global Positioning System and Embedded Receiver Applications

The Global Positioning System and Embedded Receiver Applications Noah Wardrip CSE 237 A

Agenda l Introduction l Current Status and Operation of GPS l Future Direction of GPS l Embedded Receiver Applications

Introduction l Worldwide satellite positioning system l 24 l hours/day, all weather, receive-only GPS Military in Origin l Wide-scale l civilian adoption Comprised of three components: l Space l Control l User l Focus: Empower embedded receiver designer with current information

Current Status and Operation l Currently 31 Block II satellites in orbit l 6 orbital planes – Always ≥ 6 satellites in view l 12, 500 miles – Medium Earth Orbit l 12 monitoring stations around the world l Control and update with timing and orbit info

Current Status and Operation l 3 codes on 2 carriers l C/A code – course acquisition for civilian use l P/Y code – precision code (encrypted) l M code – military code with packet data l Codes modulated using CDMA technique l Receivers use trilateration to calculate position

Current Status and Operation l GPS has several drawbacks l Line-of-sight to satellite is required l Data rate low causing long first fixes l Several sources of error in measurement l Clock offset l Imperfect orbit information l Ionospheric effects l Receiver noise l Augmentation services developed l Require special receiver support

Future Direction of GPS l Block III Satellites will provide increased reliability and accuracy through: l Additional civilian signals l Additional military signals l Stronger “Safety-of-life” signal for aircraft l Compatibility with Galileo

Embedded Receiver Applications Hardware improvements are helping miniaturize receivers l Types of receivers include: l l Civilian l Surveying l Fixed installation l Military l All share similar building blocks

Embedded Receiver Applications l Examples include l Cell phones – location based services l Cameras – instant fix needed l Time-critical activities – networks l Non-GPS satellite orbit correction

Conclusion Possibilities with embedded GPS are limitless l Successful receiver design requires understanding entire system l Now more than ever are innovative solutions to GPS limitations l Questions? l