| 摘要 |
PURPOSE:To obtain a high speed digital transmission system with high security by rearranging a digital data of plural channels at each bit and multiplying the data and an M series signal whose initial value is changed at each prescribed time so as to transmit the result. CONSTITUTION:An analog signal from terminals 1-4 is subject to A/D conversion 7-10 and inputted to a multiplexer MPX12 together with a facsimile signal from a terminal 5 and a game software from a terminal 6. The MPX12 applies processing such as distribution to each channel, addition of an error check code and bit interleaving to the input signal and outputs the result to a multiplier 13. The multiplier 13 multiplies an output signal of the MPX12 with an M series sigal from an M series signal generator 14 and scrambles the multiplied result. The initial value of the generator 14 is set in synchronizing with a frame synchronizing signal by a controller 16 and changed at each prescribed time in order to improve the security. A synchronizing signal and a service bit are adeed to an output of the multiplier 13 by the generator 15, and control information is added further from memories 17-19 and outputted while being subject to AM modulation 21. |
