Patent ID: 7574730
Filing Date: 2009-08-11
Classification: H04L,H04N

Abstract:
1. A system for reducing noise in a signal line, through which upward signals and downward signals are transmitted between a center and terminals, comprising: a noise-reduction device, provided between the center and the terminals, which detects a noise increase regarding the upward signals on the signal line spontaneously without a noise measurement command from the center to generate a control signal indicative of the noise increase, and is directly triggered by said control signal to insert a tone signal into the downward signals and to attenuate the upward signals by an increased amount without transmitting the control signal to the center; and a noise control device, provided at the terminals, which responds to the tone signal sent from the noise-reduction device by boosting a transmission level of the upward signals by an amount compensating for the attenuation of the upward signals by said noise-reduction device.