| 摘要 |
PROBLEM TO BE SOLVED: To provide a radio transmitter-receiver that can automatically control the frequency of an oscillated frequency signal of a voltage controlled oscillator in the radio transmitter-receiver with high accuracy and to provide an automatic frequency control method. SOLUTION: Whether automatic frequency control is started by time measurement or by temperature measurement is discriminated, and when the automatic frequency control is started, applied voltage data before starting automatic frequency control and applied voltage data are sequentially outputted to a voltage controlled oscillator in an initial application voltage data selection step, and when a best level exceeds a level reference value, the application voltage data resulting from outputting the level signal are selected as first application voltage data for automatic frequency control. Then the count of an intermediate frequency FSK is measured, and when a difference from a reference count is within a prescribed value, the frequency control is terminated (succeeded), and when the difference is higher than the prescribed value, the frequency deviation is calculated from the difference from the count, succeeding a plurality of voltage data are decided and the frequency is again counted.
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