Phase velocity sign detector for frequency shift key demodulation

摘要

A frequency shift key receiver includes a phase velocity sign detector which detects whether a FSK modulated input signal has a frequency (fFSK) which is greater than or less than a reference frequency (f0) of a REF signal. The phase velocity sign detector includes a sequence generator which generates a two bit binary code which represents the phase angle between the FSK and REF signals. The sequence of the code indicates the sign of the phase velocity between the FSK and REF signals. The phase velocity sign detector includes a sequence detector which provides an output signal indicating whether the FSK signal has a frequency greater than or less than the REF signal based upon the sequence of the code from the sequence generator. The phase velocity sign detector demodulates the FSK signal in the digital domain using circuitry which is completely integrable on a monolithic integrated circuit chip.