| An efficient baseband receiver, called zero-intermediate frequency (IF) zero-crossing demodulator (ZIFZCD), was recently developed for digital demodulation of the digital frequency modulation (FM) signals, e.g., minimum shift keying (MSK) and Gaussian minimum shift keying (GMSK) signals. The ZIFZCD is simpler than the conventional digital receivers, and easily implementable using digital integrated circuits. Perfect symbol synchronization was assumed in the previous studies for the ZIFZCD [1], [2]. However, symbol timing is jittering in practice. Therefore, symbol synchronization should be acquired and tracked before information bit decision at the receiver.; This dissertation proposes a symbol synchronization scheme for the ZIFZCD and analyzes its performance. The discrete time output of the ZIFZCD is converted into a rectangular pulse stream. Then, the early-late gate symbol synchronizer is applied. Analytic and simulation results show acceptable performance for this scheme. In other words, we will show that the steady-state bit error rate of the ZIFZCD employing the symbol synchronizer with overall loop gain K 0.1 is close to that of the ZIFZCD with perfect symbol synchronization under static and mobile fading environments. We also show that the steady-state bit error rate of the ZIFZCD with symbol synchronizer can be improved under static and mobile fading environments by employing decision feedback post processing. |
