Pulse ratio detector

Abstract

Abstract A frequency detection system provides a distinct output for each sinusoidal input signal represented by a selected frequency or combination of frequencies appearing on a common transmission line. Included are a frequency detector and a plurality of station selectors. The frequency detector comprises circuitry converting any input signal into a rectangular wave whose frequency and wave shape are related to that of the input signal. The rectangular wave is applied to a pulse ratio detector whose output normally blocks the rectangular wave from the frequency detector''s output. When a legitimate sinusoidal input signal is being received, as distinguished from noise, the rectangular wave has a unity ratio of positive-negative pulse widths and the pulse ratio detector is operative to allow the frequency detector to produce a pulse waveform whose pulse width is directly related to the input frequency. Each station selector initiates a reference pulse in synchronism with one of the output pulses from the frequency detector. The pulse waveform and the reference pulse are coupled to a coincidence circuit. The duration of the reference pulse is chosen to correspond with that of the pulse waveform, if an input signal having a frequency corresponding to that established for the particular station selector is being received. If the termination of the reference pulse and the pulse from the frequency detector coincide within narrow limits, an output signal is provided to station output device and additionally to a lock circuit in the frequency detector which blocks further operation until the input signal has been removed.

Inventors

• 👤 A Mcintosh
• 👤 M Smith

Bibliographic Details