At&t Bell Laboratories

Nancy M Saraf

Dimitrios P Prezas

Disclosed is a digital arrangement utilizing linear predictive coding for equalizing over a desired frequency spectrum the variable attenuation of a voice-frequency message signal transmitted on a communication line. The arrangement comprises a digital signal processor, program memories for storing program instruction sets, and a data memory for storing samples of a spectrally white test signal that has been variably attenuated by the line. Under control of one instruction set that incorporates linear predictive coding, the processor uses the stored test samples to calculate the reflection coefficients of the line that characterize the variable attenuation of a signal on the line. Under the control of the other instruction set, the processor functions as a digital inverse filter employing the calculated reflection coefficients for equalizing over the desired frequency spectrum the variable attenuation of a voice-frequency message signal transmitted on the line.

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Lisle, IL, United States of America

Nancy M Saraf