FREQUENCY SHIFT KEYED DEMODULATOR

摘要

A frequency shift keyed (FSK) modem (modulator and/or demodulator) utilizing a phase lock loop which modem may operate at any of several predetermined frequencies and whose output for the modulator section, is combined with a frequency shift keyed signal and the result passed through a low pass filter to provide a frequency shift keyed output. The phase lock loop also supplies signals to the receive or demodulation section. The use of a multiple frequency phase lock loop negates the requirements for a plurality of bandpass filters of different frequencies to be used with the frequency shift keyed source.