OPTICAL TRANSMISSION METHOD FOR VIDEO AND AUDIO SIGNAL

摘要

PURPOSE:To prevent the deterioration in an S/N with respect to fluctuation of the amplitude in a color signal of a composite video signal after demodulation by applying frequency modulation(FM) to the color signal after frequency conver sion at transmission. CONSTITUTION:A composite video signal V is separated into a luminance signal and a color signal by a branching device 1, FM modulation is applied to the luminance signal at a carrier frequency fY by a luminance signal FM modulator 2. The color signal is converted at the outside of an occupied frequency band of the frequency modulation(FM) luminance signal by a color signal frequency converter 3 at first to form a color signal carrier frequency f'C after the conver sion. Then a color signal FM modulator 5 applies FM at a carrier frequency fC. If noise is invaded to the color signal subjected to FM modulation as the amplitude fluctuation component in the process of transmission, it is eliminated by a limiter 13 before demodulation and the deterioration in the S/N with respect to the fluctuation of amplitude of the color signal is prevented in the composite video signal after demodulation.