| 摘要 |
An automatic frequency control apparatus includes a sampling portion for sampling the signal transmitted according to a phase-shift keying method, a phase difference detector for detecting the phase difference between the currently sampled signal and the immediately preceding sampled signal, and a phase bin comparator for determining which of a number of reference phases the phase of the transmitted signal is closest to, using a quantization characteristic of phase during transmission. The frequency offset generated by the distance between the frequency of a carrier wave and the local oscillation frequency of a receiver, or by the Doppler shift, in a MPSK communication method is determined as the phase difference between the detected phase difference information and the determined reference phase information. The apparatus can be used for the automatic frequency control of a modem using any type of MPSK modulation.
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