| 摘要 |
PURPOSE:To achieve signal encryption, by multiplying a signal and reproduciable virtual random signal. CONSTITUTION:An objective signal inputted from a microphone MIC is applied to an adder SUM via an amplifier A1 and band pass filter BPF1, and a DC offset from a DC source VDCS is added at the adder SUM and applied to a multiplier MPY. On the other hand, a PN sequence is generated by using a shift register SR and an exclusive OR gate XOR and applied to the multiplier MPY. The result of multiplication is transmitted to a signal medium via a band pass filter BPF2 and an amplifier A2. A switch S1 transmits the start point of the PN sequence to the restoration side to quicken the job of finding of the phase synchronism of the PN sequence at the restoration side. |
