A Servo System for Heterodyne Oscillators
Thaddeus Slonczewski · Transactions of the American Institute of Electrical Engineers · 1951
A constant rate of progression of frequency of a motor-driven heterodyne oscillator is obtained by comparing its output with a frequency standard. The result is fed into a servo loop which drives the motor at the proper speed. When used in connection with a level recorder a linear frequency scale is obtained which is more accurate than the static calibration of the oscillator.