Improved zero-IF zero-crossing demodulator for Gaussian minimum shift keying signals in land mobile channels

A baseband receiver, called zero-intermediate frequency zero-crossing demodulator (ZIFZCD), was developed for the implementation of a digital-FM receiver. The ZIFZCD offers increased battery life and simpler implementation. However, the bit error rate (BER) performance of the ZIFZCD is inferior to those of conventional schemes. An objective of this paper is to improve the BER performance of the ZIFZCD. Two postprocessors, a decision feedback (DF) and a sliding window (SW) of multiple symbol observation are employed to improve the BER performance of the ZIFZCD. The additional complexities of the DF and SW are insignificant when the size of the multiple symbol observation is small such as three symbols. Compared with no postprocessing, the ZIFZCD with either SW or DF shows significant BER improvement for a Gaussian minimum shift keying signal, under both static and Doppler frequency shifted Rayleigh fading environments