A common signal generating sub-system (CSGS) for a radio frequency (RF) receiver. The CSGS includes a down converter section and a digitizer section. The down converter section receives intermediate frequency (IF) signals and injection frequency signals from an RF/IF processing section of an RF receiver and translates the IF signals to analog intermediate frequency (IF) signals preserving the spectra thereof. The analog IF signals comprise analog in-phase IF signals and analog quadrature IF signals. The digitizer section utilizes a locally generated sampling rate signal (LGSRS) and converts the analog in-phase IF signals and the analog quadrature IF signals to a common digital in-phase IF signal and a common digital quadrature IF signal. The common digital IF signals can be subsequently processed by a digital processing section of the RF receiver. Implemented in a GPS system, by selecting the proper injection signals and A/D sampler rate, the L1, L2 and L5 signals can be converted to a single digital IF frequency for use with a common digital processing section.