Digital frequency discriminator

Frequency discriminator has five integrated circuit chips interconnected to provide a divide function, exclusive OR function, phase shifting, and holding so that a single binary output signal results. The state of the binary signal indicates which one of the two input signals has a lower frequency than the other

Electronic frequency discriminator

Digital comparator permits discrimination at accuracy of reference frequency. The compare circuit is a shift register element

Digital frequency discriminator Patent

Describing frequency discriminator using digital logic circuits and supplying single binary output signa