The Global Positioning System and Embedded Receiver Applications Noah Wardrip CSE237A

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

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

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

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

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

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

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

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

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