| 摘要 |
PURPOSE:To attain equalization with high precision even when the kind, thickness, and ambient temperature of a line are changed by adjusting the slope characteristics of the equalizer automatically by a control circuit according to the detection output of a specific pattern as the tail of an output waveform. CONSTITUTION:A PCM signal is inputted to the 1st equalizer 71 which equalizes the slope characteristics of the loss of line characteristics in discrete steps at a reference frequency and its equalization output is inputted to the 2nd equalizer 12. The equalizer 12 removes a reflected wave caused by a bridged tap connected to the line and sends its output to a discriminating circuit 13, comparing circuit 73, and the 1st control circuit 14. The circuit 13 compares the input signal with a reference discrimination level VREG and discriminates and outputs ''1'' and ''0'' of the received PCM signal to the 2nd control circuit 72. The circuit 73 compares the signal from the equalizer 12 with a reference level signal VR and sends its output to the circuit 72. The circuit 14 controls the gain of the equalizer 71 according to whether the peak value from the equalizer 12 is larger than a reference value VP or not and the circuit 72 switches and control slope characteristics of loss to the frequency of the equalizer 71. |
