| 摘要 |
PROBLEM TO BE SOLVED: To shorten the pull-in time of a carrier frequency by demodulating an in-phase signal and a quadrature signal from a selected quadrature modulation wave, converting a digital signal, multiplying a delayed signal by an original signal, adding the output of a multiplier by prescribed time, controlling a gain, generating the timing of a valid symbol and executing discrete Fourier transformation. SOLUTION: A tuner 10 frequency-converts a desired frequency band into an intermediate frequency band. The frequency-converted signal is orthogonally demodulated by a quadrature demodulator 11 and I and Q signals are reproduced. A ground interval removal circuit 14 takes out only the valid symbol part of the digitized signals of the I and Q signals and it is transferred to an FFT processing part 15. A QAM demodulation circuit 17 demodulates data of the respective carriers and an error correction circuit 18 corrects errors and outputs the signal as demodulation data. The guard interval removal circuit 14 separates only the valid symbol with a synchronizing signal 6 from a synchronism processing circuit 22 as a reference and transfers it to the FET processing part 15. |
