| 摘要 |
PURPOSE:To keep a prescribed frequency of a synthesizer output signal after the frequency conversion regardless of the variance of a SAW oscillator by outputting a signal to change the oscillation frequency of the 1st local oscillator from a frequency setting data generator so as to control the oscillation frequency of the voltage controlled reference oscillator. CONSTITUTION:The frequency of a voltage controlled reference oscillator 9' is changed minutely to change slightly the frequency of a voltage controlled oscillator 2 of a double superheterodyne type tuner 1 from the locked frequency substantially thereby cancelling the frequency variance of an intermediate frequency output signal 11. A control data in response to a frequency deviation DELTAf of the SAW oscillator 3 is written in a code converter 14. Since the deviation DELTAf depends on the individual component, the content of the code converter 14 is decided accordingly. Since the correction value of the reference frequency changes even in the same deviation DELTAf when the setting frequency is changed, the code converter 14 has a control data at each setting frequency. The output of the code converter 14 is converted into an analog voltage by a D/A comparator 13 and the result is fed to the voltage controlled type reference oscillator 9'.
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