| 摘要 |
A system for determining the frequency of an oscillating signal is provided. The system can be used in the demodulating circuitry of an FM system for receiving binary information in the form of an FM signal. The frequency of the received FM signal is determined by transforming the FM signal into a series of pulses having voltage transitions occurring at a frequency determined by the received signal and by measuring the time lapse between successive voltage transitions in the series of pulses. The system is responsive only to frequencies in a predetermined frequency operating range, and produces a binary output signal to indicate the binary information represented by a received FM signal in the frequency operating range of the system.
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