| 摘要 |
PURPOSE:To decrease the noises and the waveform distortions and to improve the S/N by using plural low band elimination filters, a logarithmic amplifier having the rough logarithmic characteristics and connected in series with the low band elimination filters, and an adder which adds or subtracts the output signal of the logarithmic amplifier and the outputs of those low band elimination filters to or from the input signal. CONSTITUTION:The signals received from an input terminal 1 are inputted to an adder 9 as well as to the low band elimination filters 3-5. The outputs of filters 3, 4 and 5 are connected in series to the logarithmic amplifiers 6, 7 and 8 respectively. The output signals of the amplifiers 6-8 are inputted to the adder 9. In case a nonlinear amplifier circuit is used as a nonlinear emphasizer, the adder 9 performs the addition. While the adder 9 performs the subtraction in case the nonlinear amplifier circuit as a non-linear de- emphasizer. Thus it is possible to decrease the noises and the waveform distortions and to improve the S/N. |
