By Clifford B. Schrock, CableBus Systems Corporation
As more two-way services are turned on and proliferate on CATV systems, the return path continues to be a limiting factor in the economic viability and reliability of the services.
A practical discussion of the sources and characteristics of noise and ingress in a two-way CATV plant is presented. A number of current practices including bridger switching, filtering, and frequency agility are compared and evaluated.
A technique of using narrowband width transmissions in the return path and other enhancement circuitry at the headend as an alternative to the bridger switching, filtering, and other current methods is described. Test results and comparative data is presented along with a summary of 2 years practical experience using the narrowband techniques.