| 摘要 |
<p>PURPOSE:To automatically control a carrier frequency to a prescribed value without receiving interruption from an interleave channel by executing frequency calibrating operation only when interleave interfering quantity is smaller than the prescribed value. CONSTITUTION:Since a normal interleave channel interval DELTAf is set to be larger than the frequency deviation of a signal, which occupies a radio channel, for an instantaneous interleave channel interference detecting circuit 3, 2, a threshold is set to be smaller than a demodulating voltage corresponding to the DELTAf like levels 4 and 5 or 4 and 6. Then, by comparing this threshold and a demodulating signal, the inversion of the receiving levels of a desired wave (D wave) and an interrupting wave (U wave) in an IF band is detected. An interference quantity measuring circuit 3, 3 measures physical quantiity to the average power ratio of the D wave and the U wave from the output of the instantaneous interleave channel interference detecting circuit 3, 2 and detects that this physical quantity is at an ignorable level for frequency stabilizing operation. Then, this is announced to a reference oscillator control part 3, 4. Thus, without receiving the influence of the interference from the interleave channel, a high frequency stabilizing degree can be achieved.</p> |
