PLURAL FREQUENCY SIGNALLING SYSTEM RECEIVER

摘要

A receiver for use in a signalling system of the kind in which data is conveyed by transmitting a signal having alternately first and second frequencies. The receiver has circuitry for providing in response to the received signal two trains of pulses with frequencies corresponding to that of the received signal. The trains of pulses are fed to delay and coincidence detecting circuits which are so arranged that a first coincidence gate circuit produces an output only when the received signal has its first frequency and a second coincidence gate circuit produces an output only when the received signal has its second frequency.