A communication device (100) includes mixers (104) and (108) which mix a local oscillator (112, 106) with a received signal to produce in-phase (i) and quadrature (q) components. The direction of the phase of the signal is detected as it crosses the i and q axes. The direction of the phase rotation is...http://www.google.ca/patents/US5469112?utm_source=gb-gplus-sharePatent US5469112 - Communication device with zero-crossing demodulator
