A system for calibrating oscillators by trimming film resistors includes a network for energizing a film oscillator under simulated operating conditions, with a digital counter measuring the frequency of the active oscillator by counting with a zero axis register the number of times the oscillator signal waveform crosses the zero axis of a zero axis detector and thereafter converting to frequency by dividing the resulting count by the count of a simultaneously triggered time register, comparing this measured frequency to a predetermined frequency to be achieved, and physically modifying the film resistor in response to the frequency comparison to correct the frequency of the film oscillator.

Frequency calibrator for crystal oscillators

Citations

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