A Stabilized Frequency-Modulation System

A wide-band frequency-modulation system in which the center frequency is directly controlled by a single crystal is described. The stability obtainable is that of a single quartz-crystal oscillator. Further, a system of distortion correction in a phase modulator is described in which the maximum angle of phase shift may be 60 degrees or more with low attendant distortion. This is accomplished by modulation of both the carrier and sidebands.