QPSK Demodulator with two-step quadrupler and/or time- multiplexing quadrupling

摘要

A QPSK demodulator apparatus utilizing a pair of doubling units in tandem but separated by a bandpass filter to remove any undesired cross products and to eliminate possible noise signal that may be applied to the second doubler. The use of two doubling units to provide a times 4 quadrupling allows the use of heterodyning in order to operate at a lower frequency.