An IF digitizing receiver for a combined GPS/GSM terminal

For the purpose of traffic telematics (route guidance, fleet management etc.) one needs terminals on the vehicle for the quasi-simultaneous reception of cellular phone (GSM) and satellite navigation (GPS). A conventional approach uses two complete receivers for these two tasks. We describe a cost-saving solution for a combined receiver which relies on the TDM structure of the GSM signal. Our solution is based on an bandpass-sigma-delta ADC for IF digitizing.