Design and implementation of multifrequency front end using bandpass over sampling

Direct digitization front end using direct radio frequency (RF) sampling is useful in multifrequency application for its flexibility and minimization of problems resulting from analog components. In such front end, the sampling frequency is the most important factor. This paper proposes the constraints and steps to design the sampling frequency using bandpass over sampling which means over sampling is based on the signal bandwidth. A new direct digitization front end for GPS L1 and L2 is then designed, implemented and tested. The digital down converter in this front end mixes the two signals to the same intermediate frequency (IF) which will facilitate the post signal processing and benefit the coherence consideration between frequencies.