Coding to alleviate intermodulation distortion in coherent optical FSK single-octave SCM systems

For a coherent optical single-octave SCM system, the number of channels that can be located within a given optical band is a major concern. A theoretical analysis of the FSK single-octave SCM system employing Reed-Solomon codes to increase the number of channels is presented. The example shows that by using a (256, 192) rate 3/4 Reed-Solomon code, the number of channels can be increased threefold and the influence of intermodulation distortion can also be greatly reduced.