The Effect of Carrier Phase Error on the Performance of a Duobinary Shaped QPSK Signal

An analysis is presented showing the effect of carrier phase error on the error-rate of a duobinary shaped, quaternary, phaseshift keying digital radio system. A simple upper bound on the probability of error as a function of phase error is derived and the results are compared to those obtained by computer simulation. The conclusion is reached that such a system exhibits approximately 1.0 dB degradation for a carrier phase error of 3° at an error-rate of 10^-5and a 10 dB degradation at a phase error of 15°.