Optical-Fiber Video Transmission Using Analog Baseband Modulation

Optical-fiber technology provides a new medium for the transmission of video signals. Some of the advantages which optical fibers have over coaxial cables are: wide bandwidth without the need for equalization; freedom from RFI, crosstalk and loop problems; low attenuation; and small size and low weight. In this paper, an analog optical-fiber link was evaluated for the transmission of baseband video signals over a single fiber. It was found that studio-quality signal-to-noise ratios could be obtained for links up to 2.2 km in length if an optical fiber having an attenuation of 5 dB/km were used. Linear video distortion and nonlinear video distortion measurements were made and compared with commercial-network single-hop relay standards. All of the distortion figures were within the standards except for a slightly low chrominance/luminance gain ratio. This distortion could be corrected by modifying the optical receiver electronics. Differential gain and phase distortions were found to increase linearly with the modulation factor of the optical transmitter´s light-emitting diode, but were within network standards when the factor was 0.5 or less.