By Richard Citta And Dennis Mutzabaugh, Zenith Radio Corp
Two-way cable plant characteristics, specifically of the return plant, are needed to aid cable operators and cable engineers in understanding the problems encountered in a return plant. This is extremely important with the advent of two-way interactive services being included in franchise contracts.
Data from twelve operating two-way plants was gathered and correlated, resulting in a "composite" or typical return plant. From this "composite", five major characteristics were constructed and analyzed. These five characteristics are: white noise floor, the tunneling effect; ingress, unwanted external signals; common mode distortion, the difference products resulting from forward plant rectification; impulse noise, specifically 60 Hz power line contributions; and amplifier nonlinearities.