| 摘要 |
PURPOSE:To prevent a wiretapping fundamentally by converting a signal at the transmitting side and sending the converted signal to the exchange side on the basis of a fixed rule of a calling signal recognized mutually by speaker in respective telephone set. CONSTITUTION:A voice signal is separated into transmitting and receiving signals by HYB, the transmitting signal is converted from analog to digital signal by a COD and the digital signal is successively stored in a transmission memory M-S. The specification of writing addresses uses the output of the counter as it is and is constituted to increase the address No. one by one. On the other hand, the reading address of the transmitting memory M-S is designated by the specification of a jumper part JMP-S set up by a transmission mode A specified by SUBA. Transmitting signal read out from the transmission memory M-S in the order of address corresponding to the transmission mode A is converted into 65Kb/s by an INT and the converted signal is sent to the exchange side. The transmitted signal is received by an SUBB and reversely converted. |
