| 摘要 |
PURPOSE:To reduce noise modulation and to decrease the increase in noise and in distortion produced as the amplitude is compressed and expanded, by providing a frequency dependancy to an output of the 2nd D/A converting circuit and giving it to the 1st D/A converting circuit. CONSTITUTION:An input digital signal DX is given to the 1st D/A converting circuit 4 and also to the 1st converting circuit 7 functioning as an absolute value circuit. Further, a signal converted into an absolute value at the 1st converting circuit 7 is inputted to the 2nd D/A converting circuit, where the signal is converted into an analog signal, and the signal passes through the 2nd converting circuit 8 having frequency characteristics such as a high-frequency emphasis (low-frequency demphasis) circuit, is given to a multiplication terminal K of the 1st A/D converting circuit 4 so as to obtain the analog signal controlling the input digital information relating to the amplitude axis from the 1st D/A converting circuit. Thus, the noise modulation produced by the fact that the noise at a high frequency is subjected to the amplitude modulation with a low frequency component can be reduced. |
