Conceptual Design of a Switched Television-Distribution System Using Optical-Fiber Waveguides

Abstract

A conceptual design of a switched television-distribution system based on analogue intensty-modulated (IM) transmission through optical-fiber waveguides is discussed. Transmission of two TV channels and provision of telephone or data service over two optical-fiber waveguides to each subscriber by frequency-division multiplexing is considered first and then other design options such as spatial-division multiplexing, inclusion of copperwire pairsfor the supply of electrical power and telephone or data service is reviewed. Thepresent state ofdevelopment of system components is also discussed and areas requiring further development are pointed out. Theoretical Calculation of the possible transmission distances for analogue IM transmission of baseband and frequency-division multiplexed video signals is described. The results show that if-3 dBm (0.5 mW) of optical power modulated by a baseband video signal to a peak modulationfactor of 80% is launched into an optical-fiber waveguide, a distance of approximately 15 km can be spanned without a repeater. It is concluded that in view ofthe distances that can be covered by low-loss optical-fiber transmission systems, a centrally switched optical television distribution system may well be attractive for applications not only to urban areas, but also to rural areas. It is further suggested that an economic analysis is needed to ascertain the practicality of such a system.