Reception of DPSK signals by a DMSK demodulator

When implementing differential minimum shift keying (DMSK) satellite communications services, it is desirable to remain compatible with existing differential phase shift keyed (DPSK) services. The use of DMSK demodulators to receive DPSK signals is investigated. It is shown that a correctly designed DMSK demodulator is capable of demodulating DPSK signals at one half the DMSK channel rate. Expressions are presented for bit error rate (BER) performance of DMSK demodulators with DMSK and DPSK signals in additive white Gaussian noise (AWGN). It is shown that using DPSK cross support reduces the power efficiency of DPSK channels by 2 to 4 dB relative to DPSK demodulators, depending on required BER. For a small penalty in DMSK performance (≈0.2 dB), the cross support penalty on the BER range 0.05 10^-5 can be reduced to 1.5 to 2 dB