Differential PSK System with Nonredundant Error Correction

Theoretical analysis and experimental results for a DPSK system with nonredundant error correction are described. The error correction capability of the proposed demodulation method is achieved without utilizing additional bandwidth. The demodulator utilizes outputs of differentially coherent detectors that employ the received signal delayed by two or more time slots as references. These outputs are shown to be the parity check sums of two or more conSecutive outputs of the conventional detector under noise-free conditions. The error rate performance of the proposed demodulation method is theoretically and experimentally studied for quaternary DPSK. Experimental results agree with the theory, which indicates that performance is superior to conventional DPSK by 1.2 dB, but poorer than coherent detection by 1.3 dB. This method can be applied effectively to TDMA communications and to on-board regenerative repeaters.