BIDIRECTIONAL TRUNK AMPLIFIER AND CABLE MODEM FOR HFC NETWORK UTILIZING UPWARD PILOT SIGNAL

摘要

PROBLEM TO BE SOLVED: To attain improvement in the stability of an upward line by constituting a bidirectional amplifier, which is capable of automatic gain control to an upward signal in order to provide the uniform level of the important upward signal. ;SOLUTION: A directional filter(DF) 500 separates downward and upward signals. A PAD 501 is an attenuator having characteristics which are almost equal in the frequency characteristics of a coaxial cable, corrects the attenuation amount of the coaxial cable through buffering operation, such as absorption and makes input levels compatible. An equalizer 502 corrects the deviation of frequencies generated on the lines. An amplifier 503 amplifies the deviation corrected signals to a fixed level. A level control part 504 learns strobe control and AGC&ASC functions 509 with respect to the amplified signal. On a vertically symmetric drawing, the upper part processes signals with downward signals, and the lower part processes signals in with upward signals.;COPYRIGHT: (C)1999,JPO