| 摘要 |
PURPOSE:To attain the transmission of other signal at a period when no voice signal is transmitted by transmitting a PCM signal while being substituted to a fixed pattern under prescribed conditions and allowing a reception side to detect the coincidence between an extracted signal and a stored pattern. CONSTITUTION:An output 101 of a PCMCODEC1 is fed to a code bit substituting circuit 4 via a 8-bit shift register 2 and a 4-word delay circuit 3. Then the output 101 shows + or -0 for consecutive 5 words during the non-talking period, a code bit control signal 109 goes to ''1'', a 5-bit fixed pattern 108 is substituted with a code bit of the output of the delay circuit 3 and the result becomes a transmission output. On the other hand, a reception signal is inputted to a PCMCODEC11 and a 40-bit shift register 12 at the reception terminal device, and 5 outputs per 8 bits are extracted at a register 12 and fed to a detection circuit 13. The circuit 13 compares the 5-bit fixed pattern stored in advance with the extracted 5-bit output to detect a 5-bit fixed pattern and a synchronizing signal 114 is fed to the CODEC11 based on the detected output. |
