Tuning of oscillating circuits in closed filter circuit - compares outputs of equal amplitude inputs equally and narrowly spaced about resonant frequency

摘要

The system matches two oscillator circuits. Equal amplitudes of different frequencies, are applied alternately to the input and measured at the output and evaluated. The two frequencies, symmetrical w.r.t. the circuit resonant frequency, are spaced from it by less than 2%. Their output amplitudes are compared by a comparator amplifier whose output voltage is directly proportional to the oscilating circuit mistuning. The tuning device is operated until this output voltage disappears. The amplitudes compared may be received independently and compred simultaneously using a delay line for one or store for both.