| 摘要 |
In an automatic frequency control circuit, a circuit constitution thereof is simplified without decreasing performance of demodulation. In the control circuit, a frequency counter counts a number of regenerative intermediate frequency from an intermediate frequency or a wave detection circuit, then a magnitude comparator compares an output of the frequency counter with a prescribed comparison data, before a subtraction circuit subtracts the output of the frequency counter from the prescribed comparison data. An operation part implements required operation according to an output of the magnitude comparator and an output of the subtraction circuit. A D/A converter converts an output data of the operation part into an analog signal. A TCXO oscillates an oscillation frequency according to the analog signal of the D/A converter. A variable frequency demultiplier is connected to a stage in front of the frequency counter. Due to this constitution, it is capable of compensating a frequency deviation of the TCXO without in use of a divider.
|
