Patent ID: 6463041
Filing Date: 2002-10-08
Classification: H04B

Abstract:
A noise reduction system for use in a communications system comprising a communication line having a plurality of twisted wire pairs, a plurality of transmitters, one transmitter at each end of each twisted wire pair, a plurality of receivers, one receiver at each end of each twisted wire pair, each receiver receiving a combination signal including a direct signal from the transmitter at the opposite end of the twisted wire pair with which the receiver is associated and a plurality of noise signals including far-end crosstalk FEXT), near-end crosstalk (NEXT), and echo impairment signals, said noise reduction system comprising:a plurality of NEXT cancellation systems, one associated with each receiver, each NEXT cancellation system for receiving the transmitted signals from the transmitters at the same end of the communications line as the receiver with which the NEXT cancellation system is associated, except for the transmitter at the same end of the twisted wire pair as the receiver with which the NEXT cancellation system is associated, each NEXT cancellation system responsive to the transmitted signals for generating a replica NEXT impairment signal; a plurality of echo cancellers, at least one of said echo cancellers associated with each receiver, each echo canceller for receiving the transmitted signals from the transmitter at the same end of the twisted wire pair as that of the receiver with which the echo canceller is associated, each echo canceller responsive to the transmitted signal for generating a replica echo impairment signal; a plurality of FEXT cancellation systems, one associated with each receiver, each FEXT cancellation system for receiving the transmitted signals from the transmitters at the opposite end of the communications line as the receiver with which the FEXT cancellation system is associated, except for the transmitter at the opposite end of the twisted wire pair as the receiver with which the FEXT cancellation system is associated, each FEXT cancellation system responsive to the transmitted signals for generating a replica FEXT impairment signal; a plurality of first summing devices, one associated with each receiver, said first summing device responsive to the combination signal, the replica NEXT impairment signal and the replica echo impairment signal for providing an initial output signal substantially devoid of NEXT impairment signals and echo impairment signals; a plurality of skew compensators, one associated with each receiver, said skew compensator responsive to the output of the first summing device associated with such receiver, said skew compensator for adjusting the delay of the initial output signal from such summing device so that such delayed initial output signal is in sync with other output signals from the other first summing devices; and a plurality of second summing devices, one associated with each receiver, said second summing device responsive to the delayed initial output signal and the replica FEXT impairment signal for providing a final output signal substantially devoid of FEXT impairment signal.