Doppler Collision and cross correlation interference in GPS receivers
Asghar Tabatabaei Balaei, DENNIS M. AKOS · 2009
Global Positioning System (GPS) receivers use Code Division Multiple Access (CDMA) modulation. Although this modulation is immune to interference, cross correlation interference is still a threat to this system. In the situation when the difference between the Doppler frequencies of the two satellite signals is within the bandwidth of the receiver tracking loop, cross correlation has a unique behaviour. In this situation, the two signals behave like multipath with respect to each other. Unlike normal cross correlation interference problems, this does not necessarily happen in the case of strong and weak signal. Although this situation is not too frequent in GPS satellites, it happens quite frequently in SBAS satellites. In this paper this behaviour is analytically and experimentally investigated