Tellabs, Inc.

Charles E Rohrs

John Belden Kenney

Peter J Melsa

Richard C Younce

Wayne E Walters

A neural network solution for routing calls through a three stage interconnection network selects an open path through the interconnection network if one exists. The neural network solution uses a neural network with a binary threshold. The weights of the neural network are fixed for all time and therefore are independent of the current state of the interconnection network. Preferential call placement strategies are implemented by selecting appropriate external inputs to the neural network. An interconnection network controller stores information reflecting the current usage of the interconnection network and interfaces between the interconnection network and the neural network.

Neural network solution for interconnection apparatus

An adaptive transversal filter is characterized by a first adaptive filter for generating a plurality of estimated impulse response coefficients representing an impulse response of a transmission path. An averaging circuit is coupled with the first adaptive filter, and generates a plurality of average estimated impulse response coefficients having values in accordance with the average values over a most recent time interval of associated ones of the estimated impulse response coefficients, and a second adaptive filter receives the average estimated coefficients. The average estimated impulse response coefficients more closely represent and have less variance with respect to the actual impulse response of the transmission path than do the estimated coefficients, and the second filter generates an estimate of an echo signal through a process including convolution of the average estimated coefficients and an input signal. The adaptive transversal filter is particularly suited for use in an adaptive hybrid circuit.

Adaptive filter with coefficient averaging and method

A double talk detector for echo cancellers monitors the ratio of four wire transmit in energy to transmit out energy (ERLE), along with the change and direction of change of an estimated impulse response, to control updating of the estimated inpulse response. When the ERLE is low and the directional change of the impulse response is high, indicating an end path switch, the double talk detector enables the estimated impulse response to be updated. If the directional change of the impulse response and the ERLE are both low, indicating the occurrence of double talk, the detector inhibits updating of the impulse response until either the ERLE becomes sufficiently high, indicating single talk, or the directional change of the impulse response becomes sufficiently large, indicating an inconverged state of the canceller. The arrangement allows convergence of the echo canceller to be properly controlled both in response to double talk and to changes in the impulse response of the end path.

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South Bend, IN, United States of America

Charles E Rohrs