| 摘要 |
PURPOSE:To correct the set error of an AGC for a demodulator which performs the AGC with a training signal by detecting the switching between an AB period (when data A and B are repeated regularly and alternately) and a CD period (when data C and D are repeated at random by a certain produced polynomial) respectively. CONSTITUTION:An input signal is received and demodulated via an AGC circuit 1, a demodulator 2, an LPF3 and an automatic equalizer 4. When a training signal is received, the level of the training signal is detected by a level detector 5. Then a high-speed AGC is applied by an AGC control circuit 6. When the training signal shifts to a CD period from an AB period, an AB/CD switching detector 7 detects this shift. Then a high-speed AGC is applied again by the circuit 6. |
