Patent ID: 6785292
Filing Date: 2004-08-31
Classification: H04L,H04N

Abstract:
In a data-over-cable system, a method for determining a source of radio frequency impairment on an upstream path, the upstream path comprising an upstream channel, the upstream channel carrying data transmissions from a plurality of cable modems to a cable modem termination system, the method comprising the steps of:ascertaining a reference signal-to-noise ratio; measuring a plurality of signal-to-noise ratios during a plurality of active periods, wherein only one cable modem transmits during each active period; comparing each measured signal-to-noise ratio to the reference signal-to-noise ratio to obtain a degradation value for the active period; determining whether the degradation value is greater than a threshold, and if so, logging parameters associated with the cable modem that is active during the active period; correlating the logged parameters; and identifying the source of radio frequency impairment; wherein the step of identifying the source of radio frequency impairment comprises the steps of: determining whether the reference signal-to-noise ratio is low, and if so, determining whether parameters for the cable modems have been logged, and if not, concluding that the source of radio frequency impairment is a radio frequency source that is external to the data-over-cable system, wherein the external radio frequency source interferes with the data transmission on the upstream channel.