| 摘要 |
PROBLEM TO BE SOLVED: To conduct stable AGC by detecting a binary symbol area from a demodulation signal so as to generate an AGC signal based on a signal level of the demodulation signal obtained for a detection period of a binary symbol area. SOLUTION: Information data to be sent are converted into multi-value symbol series and a symbol resulting from adding periodically a binary symbol area HDP consisting of a binary symbol to the multi-value symbol series is subject to multi-value digital modulation by a 16-value VBS modulator 40 and the result is sent to a transmission line 15. The IF signal obtained by applying frequency conversion to the received multi-value digital modulation signal at a tuner 21 is given to a configuration consisting of an orthogonal detector 27 and a Nyquist filter 28, in which the signal is demodulated by demodulation processing corresponding to the multi-value digital modulation. Then the demodulated signal is given to a pilot component extract circuit 30, in which the binary symbol area is extracted and the gain of the IF signal is adjusted based on a signal level of the demodulation signal obtained for the detection period of the binary symbol area. |
