| 摘要 |
PURPOSE:To constitute a complete two-way privacy call circuit by inputting simultaneously a transmission/reception signal to a single time axis compressing and stretching circuit to apply the compressing and stretching processing to each signal thereby attaining simultaneously the privacy call modulation of the transmission signal and the demodulation of the reception signal. CONSTITUTION:A reception voice signal and a transmission voice signal from an input terminal 12 of a privacy call communication system are inputted to an analog shift register 17 via BPFs 13, 14 and analog switches 16, 15. The register 17 consists of a charge transfer element and a clock output from clock circuits 18, 19 is applied to the register 17 via an OR gate 21. Further, the output of the gate 21 is applied to a 2N frequency division circuit 24; and outputs Q2, Q2' are outputted alternately at each count of 2N. Analog switches 25, 26 inputting the output of the register 17 are controlled alternately by the outputs Q2, Q2' and the result is outputted from a transmission circuit 30. Further, the receiving signal is applied to a receiving circuit 36 from an antenna 35, the compressing and expanding processing is applied to the respective transmission and reception signals to constitute the two-way privacy call circuit. |
