| 摘要 |
PURPOSE: To securely correct a large frequency offset at a high response speed even if the large frequency offset is generated by correcting the frequency offset quantity included in a subcarrier composite signal by using a calculated offset quantity. CONSTITUTION: The subcarrier composite signal outputted from a synchronous detecting circuit 12 is inputted to a frequency offset correcting circuit 13 and an offset frequency detection part 16. The detection part 16 consists of a phase detection part 17, a synchronous detection part 18, a memory 19, a phase difference calculation part 20, and an offset quantity calculation part 21. Then the detection part 17 detects the phase θof the composite signal consisting of an in-phase component and an orthogonal component outputted from the circuit 12 and sends it out to the calculation part 20 in sequence. Then a received signal (a) is synchronized with a reference phase waveform 25 stored in a memory 19, so the calculation part 20 calculates phase differences from respective reference phases in order and sends them out to the time differentiation part 22 of the calculation part 21. The differential values of the phase differences obtained by the differentiation part 22 are averaged by an averaging part 23 to correct the phase of the composite signal sent out of the circuit 12 by the circuit 13. |
