An improved quadraphase shift keyed (QPSK) adaptive demodulator includes a Costas loop modified to independently cross couple the inphase (I) and quadraphase (.phi.) channels so that minimum cross talk takes place between the I and Q channels. Advantageously, the improved QPSK adaptive demodulator separates...http://www.google.de/patents/US4085378?utm_source=gb-gplus-sharePatent US4085378 - QPSK demodulator
