| 摘要 |
PURPOSE:To prevent a switching noise from being superimposed on an information signal by revising an equalization amount to a gain selection circuit of a variable amplifier section only when a pilot signal amplitude voltage is at the outside of a set variance range. CONSTITUTION:An information signal (a) and a pilot signal (b) are inputted to a buffer circuit 1 and the signal (a) is outputted from a high pass filter 2 and the signal (b) is outputted from a low pass filter 3. A peak hold circuit 5 holds the maximum amplitude voltage of the signal (b). Then an A/D converting circuit 8 digitized the voltage held by the circuit 5 in a rate according to a reference voltage of a reference voltage generating circuit 6. The result is inputted to registers A10, B11, each output is subtracted by a subtraction circuit, and the absolute value of the result and a reference variance from a reference variance setting circuit 14 are compared by a comparator 13. When the transmission line loss equalization variance is larger than the reference variance, a gate 7 is opened to revise the loss equalization of the transmission line of the variable amplifier section 4. |
