Design of all channel ultra-stable FM discriminator

Axis crossings of the input wave are fed into a precision delay circuit, using a counted number of re-circulations through a quartz delay line. This delay controls the switching of a regulated current source producing a constant area pulse which is integrated in the output filter. Inverting the usual marked-space relationship provides a unique six-fold increase in stability of electrical parameters. The output filter is an active RC five-pole Tschebercheff. Remote switching between twenty-three channels is accomplished by changing the number of re-circulations and by relay switching the filter elements. A double servo permits setting the zero at 100% points to two initially injected frequencies to allow for individual transducer characteristics.