OFFSET QUADRATURE PHASE COMPARISON MODULATION SCHEMES FOR LOW CROSSTALK COMMUNICATION.

The authors exhibit offset quadrature constant envelope modulation schemes, called Phase Comparison Continuous Shift Keying (PCCSK), for achieving efficient, low cross-talk data communication when a coherent phase reference is unavailable at the receiver. PCCSK has particular application in the detection of unsynchronized, closely packed, frequency division multiplexed signals accessing a processing communications satellite. Consider the demodulation of a desired signal in the presence of receiver noise and an interfering signal having the same modulation format but arbitrary frequency and symbol timing offsets and received power level. Crosstalk is defined as the demodulator output induced by the interfering signal. With PCCSK, cross-talk performance is far superior to that with DQPSK, for example, in the sense that the center frequency spacing between PCCSK signals is several times smaller for a given level of crosstalk.