| 摘要 |
<p>PURPOSE:To adaptively change the instantaneous dynamic range of a transmission system by constituting an arithmetic means so as to execute addition and subtraction of each sampled value of a PCM signal, and a value obtained by multiplying each sampled value with a coefficient. CONSTITUTION:The device is provided with an arithmetic means 11 for which a PCM signal is inputted and which outputs a continuous composite output signals for showing each sampled value of an analog signal. Also, the arithmetic means 11 is constituted so as to execute addition and subtraction of each sampled value of the PCM signal and a value obtained by multiplying each sampled value with a coefficient. For instance, usually the S/N of a low frequency is good by a difference PCM, transmission whose dynamic range is wide is executed and when high frequency signal power becomes large, linear PCM transmission is executed, by which the deterioration of S/N of a high frequency peculiar to the differential PCM, or the reduction of the dynamic range is compensated. In such a manner, the instantaneous dynamic range of a transmission system can be changed adaptively and accordingly, even in the transmission system of a low bit rate, the transmission of a high frequency signal can be executed with low S/N.</p> |
