An optically repeated SCM system with subcarrier frequency conversion

We propose use of an optically repeated SCM system with subcarrier frequency conversion for video monitoring, with the aim of realizing benefits in two areas: first, cost-effectiveness and simple design by using standardized transmission equipment and reducing preparation for lasing wavelength selection of light sources; and second, to increase the transmission length and number of terminals. In order to characterize transmission performance, we simulated CNR affected by optical beat interference derived from the simultaneous detection of multiple optical signals, and by noise accumulation in electric amplifiers. We also simulated composite distortions generated at a light source and a receiver in an optical repeater where, for the first time, we used a simulation of composite distortions depending on subcarrier frequencies in semiconductor lasers, which we previously proposed. To practically evaluate those simulations, an SCM system having two optical repeaters with subcarrier frequency conversion was set up. We confirmed that the simulated CNR and composite distortions are in good agreement with measured results. As we confirmed the validity of those simulations, we derived limits of transmission length, number of terminals, and number of optical repeats by evaluating CNR and composite distortions. We also demonstrate those results.