| 摘要 |
PURPOSE:To prevent the generation of noise at a descrambling time by changing the frequency of a carrier wave with a specific control signal synchronized with the carrier wave to obtain a voice scrambled signal and multiplexing and transmitting a reference clock signal and data which specifies the control signal and reproducing them in the reception side. CONSTITUTION:The voice band is limited to O-fc1 by an LPF22, and the carrier wave is defined as fc1 and fc2, and double balanced modulators 5 and 6 are balanced sufficiently for the carrier wave. The upper sideband of the signal except higher harmonic which appears in a terminal 20 has a phase opposite to that of the signal of a terminal 19, and they are added by an adder/subtractor 8 to obtain a voice scrambling signal f'SR which shifts the frequency-inverted voice signal. This signal f'SR is inputted to an LPF21 to remove higher harmonic and the upper sideband, and a reference clock signal f0 and scrambling modulation data fd, obtained by a data modulator 16 are multiplexed with the output of the LPF21 by a multiplexer 22, and the result is outputted as a voice scramble signal fSR from a terminal 24. |
