Joint digitalization scheme for multiband GNSS receivers

A digitalization scheme for multi-band GNSS receivers employing a single A/D converter for all signals is presented. Theoretical analyses are carried out, to compute the degradation in post-correlation signal to noise ratio due to joint filter and digitalization, in comparison to a classic scheme with separate A/D converters for each band. As a case study, a GPS and GLONASS L1 receiver is considered. The intermediate and sampling frequencies and the number of bits for the converter are designed. Also, the loss analysis is extended to a scheme with digital filter and decimation followed by requantization, in order to reduce the sample rate and number of quantization bits to values that allow a simpler implementation of the following difital processing stages. The results show that with a sampling frequency slightly above the double of that necessary in a classic scheme, the losses of the single converter scheme proposed are of the order of 1 dB greater than those of the separate converters scheme.