A comparison of a limiter-discriminator, delay and coherent detection for pi /4 QPSK

A brief description is given of limiter-discriminator, delay, and coherent detection of pi /4 quadrature phase shift keying (QPSK). Simulated bit error rate (BER) performance of these detectors in static and Rayleigh faded fields is presented. Performance in delay spread faded fields is also given. Results of the use of an equalizer with the coherent detector in delay spread faded fields is evaluated. Three methods of detecting pi /4 QPSK are evaluated. A brief description of the operation and an estimate of implementation complexity is given for each detector. Simulated results of BER performance for each detector in static, Rayleigh, and delays spread faded fields are then presented. The use of an adaptive decision feedback equalizer with a coherent detector is then evaluated for use in delay spread faded fields.<>