Patent ID: 7757262
Filing Date: 2010-07-13
Classification: H04H,H04N

Abstract:
1. A CATV circuit with an automatic noise controller, for automatically reducing an upstream noise occurred at a CATV circuit for bidirectional communications between a headend control center and a home terminal, characterized in that a variable attenuation method is applied serially to an upstream circuit of said CATV circuit; and a downstream location uses said variable attenuation method to measure an upstream noise level; and said CATV circuit with an automatic noise controller controls the attenuation rate of said variable attenuation method according to a level measured by said noise level measurement method which uses a conversion method for converting a specific frequency component of an unused upstream circuit frequency band in an upstream circuit into a DC level according to a level, and a computing method for outputting an output level X memorized by a memory method from a signal with three different input levels Y in said specific frequency band used for setting factors a and b in an approximation formula Y=a log e X+b, and said conversion method sets a DC level for conversion to X, and substitutes X into said memory approximation formula according to said memory method to obtain said upstream noise level Y.