Phase-Inversion Tolerant Coding for PRK Data Links

Phase reversal keying (PRK) with coherent detection is becoming increasingly popular for use in binary data communication systems. Coherent detection of double sideband-suppressed carrier signals requires precautions to avoid inadvertent reinsertion of the local carrier 180° out of phase with the suppressed carrier, as this would convert every demodulated 1 to a 0 and vice versa. Some of the previous solutions to this 1-0 ambiguity problem are reviewed and a new solution based on properties of error correcting codes is outlined briefly. It is shown that the performance penalty imposed by the coding solution is negligible. Performance curves are presented to illustrate the efficiency of the scheme.