Effect of noisy phase reference on coherent detection of unbalanced QPSK signals
Abstract
A phase error in the reference signal used in coherent detection of PSK signals causes a degradation in performance; this effect on bit error probability has been much discussed in the literature for BPSK and balanced QPSK systems. For unbalanced QPSK (UQPSK) systems, where the power and data rates in the two channels are unequal, and where the channel data symbols might also be different, the problem of computing the error probability is more complex, and only approximate solutions have been previously given. In this paper, exact expressions are derived for the conditional probability of error for the I and Q channels as a function of the channel power and data rate ratio. This is done for all combinations of Manchester and NRZ signalling schemes, and it is shown that in some cases the low data rate channel can be more seriously affected by a phase offset. Numerical results are also given for the average probability of error, assuming a biphase Costas loop is used for carrier synchronization.
 Publication:

NTC 1978; National Telecommunications Conference, Volume 1
 Pub Date:
 1978
 Bibcode:
 1978ntc.....1....2O
 Keywords:

 Channels (Data Transmission);
 Error Analysis;
 Phase Error;
 Phase Shift Keying;
 Probability Theory;
 Signal Detection;
 Frequency Synchronization;
 Signal To Noise Ratios;
 Transmission Efficiency;
 Space Communications, Spacecraft Communications, Command and Tracking