| 摘要 |
PURPOSE:To improve the secrecy of communication by ciphering and transmitting a control signal used for transmission control of information to be transmitted, decoding the control signal sent at the reception side and using it by reception control. CONSTITUTION:a voice signal having a predetermined channel CH number is inputted to a delay circuit 4 and a voice detector 5 through a line 3 in a transmission section 1 in a DSI device. The detector 5 checks the presence of a voice signal at each CH and a signal representing it is fed to a control circuit 6. The circuit 6 sends a control signal including output CH assignment information and time slot assignment information of an output signal frame to a buffer memory 7. The information of a required CH is written in the memory 7 from the circuit 4, the output CH is assigned and the result is sent to a multiplexer MUX9. The control signal from the circuit 6 is ciphered by a ciphering device 8, the result is sent to the MUX9 and sent together with the information from the memory 7. The control signal ciphered at the reception side is decoded by a decoder and used for the reception control. |
