INVESTIGATION OF TELEMETRY AND GPS COMPATIBILITY

Abstract

Several test programs have reported degraded Global Positioning System (GPS) performance when L-band (1435-1535 MHz) telemetry is used while other test programs have had acceptable GPS performance with L-band telemetry. Most test programs seem to have minimal problems with S-band telemetry interfering with GPS performance if a bandpass filter is used between the GPS antenna and the low noise amplifier (LNA). This paper will present measured data on GPS performance with L- and S-band telemetry and explain what must be done to minimize interference to GPS. The paper will present both GPS signal-to-noise ratio (S/N) values as well as measured spectra from telemetry transmitters. System design guidelines for compatible operation will be presented.