| 摘要 |
PROBLEM TO BE SOLVED: To adjust the frequency of an intermediate-frequency signal to a nearly center value in the tuning range of the normal intermediate frequencies if the frequency of the intermediate frequency signal deviates from the tuning range by finding a value which is a half of the difference value of the number of steps until the deviation of the frequency of the intermediate-frequency signal from the tuning range and finding the frequency of the intermediate-frequency signal from it. SOLUTION: When the frequency of the intermediate-frequency signal deviates from the tuning range of normal intermediate frequencies, the frequency of the intermediate-frequency signal is increased or decreased by turns in AHz steps of the frequency of the intermediate-frequency signal to enter the tuning range. Then the frequency of the intermediate-frequency signal is increased or decreased alternately in BHz steps. The frequency is increased or decreased by increasing or decreasing the oscillation frequency of a VCO 9 by a CPU 10. In this increase or decrease, the numbers SQ and SR of steps until the deviation of the frequency of the intermediate- frequency signal from the tuning range are found, and the value which is a half as large as the difference value between the SQ and SR is found and multiplied by BHz to find the frequency of the intermediate frequency signal from the multiplication result.
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