| 摘要 |
PROBLEM TO BE SOLVED: To attain stable automatic phase control in which effect of fading is suppressed. SOLUTION: An IF-OFDM(intermediate frequency-orthogonal frequency division multiplex modulation) signal and a local intermediate frequency signal outputted from an IF-LO(intermediate frequency local oscillator) 1 are multiplied by mixers 5, 6, and outputted via A/D converters 9, 10, the resulting signals being output signals from orthogonal demodulation circuits 3, 4 are converted into a frequency region signal by an FFT device 11, the power spectrum level for each frequency band of the frequency region signal is calculated by a power spectrum calculation circuit 12. Then a frequency band component signal whose power spectrum level is a prescribed level or over is given to a feedback data selection circuit 13, where the signal is selectively outputted, a frequency control circuit 14 detects a mean phase difference of a phase error caused in each subcarrier of the IF-OFDM signal is detected from an output signal component of the feedback data selection circuit 13 and the frequency control signal based on the mean phase difference is given to the IF-LO1, which controls the local intermediate frequency signal to decrease the phase error. |
