FSK RECEIVER

摘要

PURPOSE:To improve the accuracy of an oscillation frequency of a fundamental frequency oscillator inexpensively. CONSTITUTION:An output of an oscillation frequency of a fundamental frequency oscillator 6 multiplied by a multiplier section 7 and an output of an RF section 1 are mixed to convert the signal into an intermediate frequency signal and after the intermediate frequency signal is amplified, the result is demodulated. A voltage controlled oscillator is adopted for the fundamental frequency oscillator 6. The oscillation frequency from the fundamental frequency oscillator 6 is multiplied by a multiplier section 8 and the intermediate frequency signal is frequency-divided by a frequency divider section 9. When a carrier signal representing no data is received and there is no deviation in the oscillation frequency of the fundamental frequency oscillator 6, the conversion is implemented to make respective conversion frequencies coincident with each other. The frequency of each output from the multiplier section 8 and the frequency division section 9 are compared by a frequency comparator section 10. An output of the frequency comparator section 10 is converted into a voltage signal by a low pass filter 11. A control section 5 corrects a deviation in the oscillation frequency of the fundamental frequency oscillator 6 by an output cancelling an output based on data of the low pass filter 11 by using data after demodulation.