| 摘要 |
PURPOSE:To always establish the reception synchronism at a high speed with a relatively simple constitution even in the case of frequent power-on/off. CONSTITUTION:Mixers 11 and 12 multiply a local oscillation signal Go and a reception input signal Sa to convert them to an I signal and a Q signal, and they are demodulated by a carrier reproducing circuit 15, and the reception synchronism is discriminated by a reception synchronism discriminating circuit 16. A synchronism discrimination signal St is outputted to an AFC circuit 18. In the case of a failure in reception synchronism, a frequency offset value estimating circuit 17 estimates a frequency offset value, and this operation is repeated until the reception synchronism is established by the change of an AFC voltage Sv based on this frequency offset value. The value of the AFC voltage Sv for establishment of the reception synchronism is written in a non- volatile memory 19. Thereafter, a local oscillator 13 is controlled by the value of the AFC voltage Sv read out from the nonvolatile memory at the time of power-on to start the initial operation with the local oscillation signal So in the operation before power-off where the reception synchronism is established. |
