| 摘要 |
PURPOSE:To enable to replace the coefficient of the low pass filter used for the estimation of the gain of communication line, by monitoring the frequency distribution given to the variation of communication line gain through the spectral analyzer. CONSTITUTION:The information signal via the communication line is analyzed for the frequency component of the reception information signal at the spectral analyzer 1; The output value of the spectral analyzer 1 is compared at the comparator 2 in comparison with the frequency reference value, and the cut-off frequency of the low pass filter 4 is changed with the filter coefficient selector 3 when it exceeds the threshold value. The low pass filter 4 is variable filter having the upper limit frequency of the frequency component given with the communiction line gain variation, the cut off frequency in matching with the communication line gain variation component is determined with the signal from the filter coefficient selector and the gain of communication line is estimated. In the transmission signal repoduction circuit 5, the information signal with distortion received via the communication line and the estimated value of the gain of communication line of the output of the filter 4 reproduce the transmission signal without distortion before the communication line 2. |
