Abstract: Signals to be transmitted through optical fibers either from a television camera to its control unit or vice versa are processed as follows. At first audio signal to be transmitted is amplitude modulated on a carrier. A second audio signal, which has a frequency range which does not include the frequency of the above-mentioned carried, and the amplitude modulated signal are frequency modulated onto a second carrier. The locally generated video signal, after passing through a digital data transmitter, as well as the frequency modulated signal are pulse modulated and the pulse modulated signal is used to modulate the light of a laser, the light in turn being transmitted by the optical fibers. At the receiving end a photo diode is provided to transduce the signal back into electrical signals and, after the demodulation in reverse order as the modulation, the desired signals are available at the receiving location.

Abstract: Superimposed pictures on the video outputs of cameras resulting from picking up stray transmitted television signals are eliminated by shielding the camera amplifier, and by insertion of inductances at the input of the amplifier and between the first two stages. The inductances combine with existing parasitic capacitances to create low-pass filters which pass the video signal from the camera but block the higher frequency transmitted television signals.