| 摘要 |
PURPOSE:To attain signal reproduction without distortion by passing signaling information through a low pass filter to dull a leading/trailing edges of a rectangular wave of the signaling information to track an ADPCM coder and an ADPCM decoder. CONSTITUTION:A voice signal is sampled in 8kHz by a PCM coder 1 and transmitted in a signal of 64kbps by an 8-bit code. On the other hand, the signaling information such as off-hook, a dial signal and a charging is inputted to an AND circuit 5 and when the signaling information is at an H level, a digital code having a 8kHz frequency given in advance is outputted, added to the voice signal on the digital code by the adder 3 and the result is outputted via an ADPCM coder 4. The signaling information sampled by 8kHz is outputted through a low pass filter 12. |
