Application of Wagner coding method to multi-DPSK system

The Wagner coding method utilizing analog information of a received signal in the decoding of single parity check code is known to have a similar ability to that of single error correcting code. Also, it possesses a simple decoding operation. This paper proposes a concrete example of the Wagner coding method applicable to multi- DPSK system. Example solutions are shown to the problems such as in the parity check coding scheme which can be used in the DPSK channel, extracting scheme of the channel measurement information in the case of multi-DPSK system, and the error correcting scheme which can be applied after the differential decoder. Further, the theoretical analyses of BER (Bit Error Rate) performance are made for the case where white Gaussian noise is offered as a signal quality degradation factor and the case where phase jitter is contained in the recovered carrier. Consequently, it is clarified that by simply adding some peripheral circuits to the conventional DPSK modulator/demodulator, the proposed scheme compares favorably with the conventional 4-DPSK system by 2-dB improvement in the BER performance against white Gaussian noise and also offers considerable immunity against phase jitter. the equipment is actually fabricated in the case where the proposed method is applied to a 4-DPSK system and the effectiveness of the proposed method is confirmed through experiments.