| 摘要 |
PURPOSE:To detect the training signal for setting the characteristics of the automatic equalizer, by making effective the output of the level deciding circuit only when the reception signal level is higher than the prescribed level and then starting the detection for the fixed segment advised by CCIT. CONSTITUTION:The signal sent from input terminal 11 is demodulated at demodulator circuit 24, and the demodulated in-phase signal and the orthogonal signal are obtained at terminals 25 and 26 each. Then the square sum is produced through envelope signal producing circuit 27 for both the demodulated in-phase signal and the orthogonal signal. On the other hand, the reception signal from terminal 11 undergoes the level decision by reception signal level detector 12, and the logic product is obtained through AND logic circuit 29 between the above decision output and the output of level deciding circuit 28. Then the output of circuit 28 is made effective only when the reception signal level is higher than the prescribed value, and thus the detection is started for the fixed segment advised by CCIT. In this way, the training signal can be detected for setting the characteristics of the automatic equalizer. |
