Caribbean Green Team 2019
Doppler Shift Navigation
While the accuracy and reliability of GPS navigation systems makes them ideal for commercial use, GPS systems require four visible satellites and can be easily jammed, rendering them useless in remote locations and military applications. If the location and transmission frequency of one visible satellite is known, it is possible to obtain a position fix by tracking the Doppler shift of the satellite transmission. Doppler shift navigation has been explored in the past (eg. the Transit system), but initial developments were never expanded upon. We utilized recent developments in small, cheap, and easily accessible Software-Defined Radios to develop a signals of opportunity based navigation system. We accomplished this by recording a known satellite transmission using an SDR, tracking the Doppler shift of the signal, and using numerical optimization, along with the measurements, to obtain a position fix. The project required significant research on satellite constellations, software defined radios, carrier recovery, and numerical optimization.
Related Tech Notes
- United States Military Dependence on GPS and Vulnerability to Radio Frequency Interference by Jonathan Traester
- Carrier Frequency Shift Tracking for LEO Satellite Transmissions by Aji Sjamsu
- Celestial Body Position Tracking by Nate Krinsky
- Obtaining a Position Fix Using Doppler Shift Measurements by Tyler Klein
- Doppler Navigation by Elsa Ames
Caribbean Green Team Project Poster
