To provide an automatic frequency control apparatus which ensures higher frequency compensation accuracy even in the highly noisy receiving environment and shorter pull-in time.
The automatic frequency control apparatus comprises a frame synchronization determining means 26 for generating the timing control signal synchronized with the synchronization code on the basis of the correlation detecting results of a plurality of correlation means 25; an inverse modulation means 17 for outputting the phase of signal by conducting inverse modulation using a series of codes obtained through ideal decoding or differential decoding of the synchronous signal, under the synchronization of the frequency-converted receiving signal or the signal outputted from a delay detecting means 13 to the timing control signal; a third error detecting means for detecting a third frequency error on the basis of the signal outputted from the inverse modulation means 17, and an error switching means 22 for selecting, in accordance with the timing signal control signal, a third frequency error in the section of the synchronous code of the receiving signal, and also selecting the first frequency error in the other section.
KOBAYASHI SEI
UEHA MASAZUMI
