Telephonic communications – Subscriber line or transmission line interface – Network interface device
Patent
1986-10-01
1989-02-14
Ng, Jin F.
Telephonic communications
Subscriber line or transmission line interface
Network interface device
370 321, H04B 323
Patent
active
048052159
ABSTRACT:
This invention relates to an echo canceller, for a transmission line, including a shift register having an input for receiving an input signal from a signal source and having a plurality of output taps for providing a plurality of equally spaced delayed signals. A tap coefficient storage memory stores a plurality of tap coefficients. A multiplier multiplies certain of the delayed signals by certain tap coefficients to produce multiplier outputs. A tap allocation circuit determines, on a tap by tap basis, how many and which of the taps are to be turned ON so that its corresponding tap coefficients are multiplied by the multiplier. A subtracter cancels echoes by subtracting the multiplier outputs from signals received on the transmission line. Taps which are turned OFF may be assigned a status of STANDBY and these taps may be activated to compensate for changes in the characteristics of the transmission line.
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Miller Jerry A.
Ng Jin F.
Racal Data Communications Inc.
Vaas Randall S.
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