| 摘要 |
PURPOSE:To prevent the generation of a residual ripple component and to reduce the deterioration of picture quality by subjecting logarithmic amplitude demodulation to an RF video signal by using a decoding signal when descrambling a scrambled video signal. CONSTITUTION:At a transmission side 1, a horizontal synchronizing signal component is extracted from part of an RF video signal and, after its phase is adjusted, is applied to a logarithmic amplitude modulating circuit 6 composed of an element having exponential function characteristics, thereby scrambling the RF video signal by the circuit 6. The scrambled signal is transmitted to a reception side 2 through a repeating transmission line 12, and through a logarithmic amplitude demodulating circuit 13, only an RF audio signal is separated by a distributing circuit 14. The RF audio signal is amplified and detected, and the resulting signal is inputted to an amplitude demodulating circuit 13 to obtain a demodulated wave. |
