Communications: electrical – Systems – Selsyn type
Reexamination Certificate
1997-06-09
2001-11-06
Pope, Daryl (Department: 2632)
Communications: electrical
Systems
Selsyn type
C340S315000, C340S315000, C340S315000, C375S297000
Reexamination Certificate
active
06313738
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
This invention relates to eliminating house noise from received power line network signals.
2. Description of Related Art
Power line communication systems transmit and receive information using conventional power lines that supply power to houses. Such systems use blocking circuits to block noise generated within the house by devices such as home appliances. However, the blocking circuits are imperfect due to finite impedances of the inductive elements and limited sizes of the shunt capacitors used in the blocking circuits. Thus, there is a need in power line communication systems to further reduce the effect of house noise from interfering with power line communications.
SUMMARY OF THE INVENTION
A power line adaptive noise cancellation system reduces house noise from interfering with power line communication systems by receiving noise signals from house power lines and adaptively canceling the received noise signals from a power line input signal. The system includes a power line input signal receiver, at least one power line noise signal receiver and an adaptive noise cancellation device. The input signal and the noise signals are bandpass filtered and demodulated by a local oscillator frequency to translate to baseband both the input signal and the noise signals in a selected frequency band of interest. The noise signal is input into an adaptive filter that filters the noise signal based on a set of adaptive weights. The output of the adaptive filter is subtracted from the delayed total baseband input signal plus noise to generate a received filtered input signal. The received filtered input signal is input into a baseband receiver and also fed back as a residual error to the adaptive filter for updating the filter adaptive weights.
REFERENCES:
patent: 4344150 (1982-08-01), McLaughlin
patent: 5278777 (1994-01-01), Cummins
patent: 5870016 (1999-02-01), Shrestha
patent: 6041250 (2000-03-01), DePinto
Jin-Der Wang et al.: “Adaptive Harmonic Noise Cancellation with an Application to Distribution Power Line Communications”, IEEE Transactions on Communications, US, IEEE Inc. New York, vol. 36, No. 7, p. 875-883.
“Adaptive Harmonic Noise Cancellation with an Application to Distribution Power Line Communications”, by J. Wang et al., IEEE Transactions on Communications, vol. 36, No. 7, Jul. 1988, NY, pp. 875-883.
AT&T Corp.
Pope Daryl
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