| 摘要 |
PURPOSE:To tune the title receiver to an input frequency corresponding always to a tuning frequency data by comparing a measured data of a mixing frequency between a reference signal and a local oscillation signal from a reference signal oscillator of a local oscillator with the tuning frequency data so as to correct the tuning frequency data. CONSTITUTION:An input signal FI is mixed with an output (frequency FL) of a voltage controlled oscillator 1 by the first mixer 3 to form an intermediate frequency signal (frequency FIF). The output FL of the voltage controlled oscillator 1 is corrected in a way that the FIF is equal to a center frequency Fc of a band pass filter 4 when the frequency of the input signal FI is equal to the frequency of a tuning frequency data, then the input frequency corresponding to the tuning frequency data is selected at the center of the band pass filter 4. Then a signal turned and selected in this way is outputted to a frequency measuring circuit 6 through a signal switch 8 and a mixer 5.
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