| 摘要 |
PROBLEM TO BE SOLVED: To improve the equalizing characteristic of a radio demodulating device by removing a frequency deviation in a preamble section, through the use of a burst where a preamble signal for an AFC circuit is added before an equalizer training signal. SOLUTION: An AFC circuit 100-1 is provided with a phase difference detecting circuit 102, which uses an AFC non-modulating signal in preambling, receives a burst signal with a burst format where the equalizer training signal and a data signal are continued and detecting a phase fluctuated by a frequency deviation in a specified time interval, a noise removing circuit 103 which removes a noise component included in the signal and extracting only a phase change portion, a frequency deviation estimating circuit 104 which estimates the frequency deviation in the preamble section from the phase change, an oscillating circuit 105 which oscillates a sine wave of estimated frequency in a direction opposite to the phase change direction of the receiving signal and a compensating circuit 106 which executes the multiplication of the receiving signal by the output signal of the oscillating circuit to remove the phase fluctuation by the frequency deviation. |
