A method for intermodulation noise calculations in a cable television network with HD-MAC, PAL and FM radio signals

A statistical method for calculating intermodulation noise in CATV systems whose traffic can be characterized as a sum of a large number of independent signals is presented. The method is demonstrated by calculating the signal-to-intermodulation-noise ratio in the various channels of a prototype cable network supporting HD-MAC, PAL, and FM radio signals. The spectra of these individual signals are simplified in order to perform part of the calculation analytically. It is shown that the signal-to-intermodulation-noise ratio decreases when the total signal power is increased. This method can be used to calculate the necessary back-off of a cable network for a given frequency plan and to determine suitable plans for loading and controlling CATV networks.<
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