Phase error canceller for qpsk signals using unique word detectors

Abstract From the Canadian patent

In a circuit arrangement for correcting phase errors of P-channel and Q-channel baseband signals of a QPSK signal input registers are, provided corresponding respectively to possible bit patterns which the unique words of the P-channel and Q-channel baseband signals may assume. Each input register stores 2N bits of incoming unique words of the P- and Q-channel signals. Reference registers corresponding to the possible bit patterns are provided for individually storing 2N bits of a corresponding one of the possible bit patterns. Mismatches between the bits stored in each input register and the corresponding reference register are detected and compared with thresholds to produce a phase error …