| 摘要 |
PURPOSE:To attain the privacy communication system with a very simple constitution by using the output noise of a noise generating circuit so as to modulate a main carrier. CONSTITUTION:The output of a noise generating circuit 5 is fed to the output of a submodulation circuit 2 to modulate the main carrier. A reception noise generating circuit 12 generates the noise of the same waveform synchronously with the transmission noise. A local oscillation circuit 11 whose oscillation frequency is modulated by the circuit 12 receives the oscillation signal modulated by the noise and the S/N is improved by the output of a MIX 10. The output level and the phase of the reception noise generating circuit 12 are adjusted to optimize the S/N of the output signal of the mixing circuit 10 by varying the oscillation frequency of the local oscillation circuit 11.
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