| 摘要 |
PURPOSE:To make interception difficult by varying a rate of a time length of a telephone signal and a time length of pseudo noise depending on each frame under the condition that the total of both the time length of the telephone signal and the time length of pseudo noise is constant. CONSTITUTION:A pseudo telephone signal from a pseudo telephone signal generator 80 is applied to a switch SW 1-2 and it is controlled by an output of a cryptographic provision device 76 together with its time length. Each signal is led to cryptographic processing time chip signal synthesizers 78-1-1, 78-1-2 and phase shifters phi1, phi2 are inserted on the way and a delay time is adjusted so that an output of a pseudo telephone signal generator 80 subject to time chip processing is fed just after the telephone signal subject to time chip processing. Moreover, the total time length of the telephone signal subject to time chip processing to be synthesized and the pseudo telephone signal is constant as to all time slots by adjusting the switch SW 1-1 or a SW 1-2. |
