Alot of noises accumulate on the upstream channel in HFC (Hybrid Fiber-Coax)system ,which caused the difficulty in bi directional operations, Therefore,suppressing them is very difficult.

• HFC上行通路汇集了大量的各类噪声 ,严重影响着其双向业务的开通 ,如何对这些噪声进行抑制是个难题。