Adtran Gmbh

Ayman Ghobrial

Michael D Turner

Steven R Blackwell

Richard Lee Goodson

Daniel M Joffe

Fred Chu

Bruce Edward Mitchell

Cynthia Lin

Kevin W Schneider

Jason N Morgan

Paul Graves McElroy

Jerry Lynn Greer

A communication system adaptively cancels noise and/or interference from signals communicated through a communication channel, such as signals communicated by a telecommunication network. The system, based on a common mode signal of a received signal, generates an estimate of noise or interference within a differential mode signal of the received signal. The system then subtracts the estimate from the differential mode signal in an effort to remove noise from the differential mode signal thereby providing a differential mode signal that is substantially free of the estimated noise or interference.

Adaptive interference canceling system and method

A system for canceling impulse noise comprises an adaptive impulse canceler and a combiner. The adaptive impulse canceler is configured to receive a common mode component of a received signal and to detect a noise impulse in the common mode component. The impulse canceler is further configured to provide, based on the noise impulse in the common mode component, an impulse noise estimation for a differential mode component of the received signal. The combiner is configured to receive the differential mode component and the impulse noise estimation and to subtract the impulse noise estimation from the differential mode component.

System and method for canceling impulse noise

A system for adaptively updating precoder taps comprises a first signal path, a second signal path, a delay mechanism, and logic. The first signal path is configured to receive encoded signals. The first signal path has a decoder that is configured to decode the encoded signals thereby recovering data originally transmitted from a remote transmitter. The delay mechanism is configured to receive and delay the encoded signals. The second signal path is connected in parallel with the first signal path and is configured to receive the encoded signals delayed by the delay mechanism. The second signal path has an adaptive filter configured to filter the encoded signals received by the second signal path based on a set of coefficients of the adaptive filter. The adaptive filter is configured to adaptively update the coefficients based on the data recovered by the first signal path. The logic is configured to adaptively generate new precoder taps based on the coefficients and to transmit the new precoder taps to a precoder.

System and method for adaptively updating precoder taps

A cascaded signal processing arrangement processes digitally encoded voice samples transported over a time division multiplex (TDM) communication path for application to a processor-controlled digital communication device, in particular an integrated access device. Processed voice samples are packetized in accordance with an encapsulating protocol and transmitted as a packetized voice output stream to a destination receiver device. The arrangement includes an echo canceller coupled to the TDM communication path and performing echo cancellation processing on the digitally encoded voice samples. The echo cancellation-processed voice sample signals are compressed by a data compression operator and applied to a packet encapsulating host processor via the TDM communication path. This obviates the necessity of the host processor having to use data bus cycles to download processed digitized voice samples.

Echo canceller and compression operators cascaded in time division multiplex voice communication path of integrated access device for decreasing latency and processor overhead

An echo canceler for a fractionally spaced telecommunication receiver employs a signal estimator, which generates a fractionally spaced representation of a received information signal that has been subjected to Tomlinson preceding. The output of the signal estimator is differentially combined with fractionally spaced outputs of the echo canceller, so as to effectively remove the contribution of the received information signal from the echo cancellation update operation. As a result, the echo update signal will consist primarily of the residual echo and the noise from the wireline/loop. The error signal can be used at the fractional spacing rate to update all of the echo canceler coefficients, largely without interference from the much larger received information signal. This allows a higher echo canceler gain than that currently incorporated into HDSL2 echo canceler updates.

Echo-canceler for precoded fractionally spaced receiver using signal estimator

Adaptive clock recovery for the receiving entity of a communication system transporting constant bit-rate (CBR) services over an asynchronous transfer mode (ATM) or ATM-like network is performed by a digital phase locked loop (DPLL). The recovered clock is based on the DPLL's phase detector's count of high frequency service clock cycles between transitions in an input signal representative of instances of receipt of ATM cells subject to cell delay variations through the network, and a reference clock signal whose frequency is a prescribed fraction of that of the output clock. The DPLL's VCO function is an increment/decrement of the service clock frequency, which avoids constraining the operation of a high performance modem (such as a V.90 modem).

Method and apparatus for providing reliable voice and voice-band data transmission over asynchronous transfer mode (ATM) network

A timing loop is used in a data communications receiver to time lock the receiver to a transmitter sending data across a communications loop, where the receiver includes a linear equalizer for correcting signal distortion associated with the communications loop. The timing loop includes a timing equalizer filter functionally positioned to provide an equalized signal to the phase detector portion of the timing loop. After the linear equalizer trains, the equalizer coefficients are copied to the timing equalizer.

Timing loop and method filter for a digital communications system

A method of training and operating a dual-duplex, four-wire communications system to provide for time alignment in the receivers of data that is time aligned in the transmitters, even in the presence of a differential transmission delay in the wire pairs. In a training mode, a known sequence of training data is concurrently sent across each wire pair such that equalizers in the receivers are forced to train together. After the equalizers have been trained to eliminate the differential delay, the system is switched to a data mode.

Timing device and method using a timing equalizer filter for a digital communications systems

A system and method for transmitting data over a twisted pair with or without load coils using a transmitter and receiver is disclosed. The system detects load coils by generating and transmitting a test signal having signal power concentrated in two different frequency bands across the twisted pair and comparing the signal power of the received signal to determine whether the twisted pair is loaded or unloaded. If load coils are detected, an adjustment circuit is used to configure the receiver for reception of data over a twisted pair having load coils. Otherwise, the adjustment circuit configures the receiver for reception of data over a twisted pair without load coils.

System and method for transmitting data over loaded and unloaded twisted pairs

A distortion compensation filtering mechanism for a direct spread-spectrum radio receiver comprises an iteratively adaptive FIR filter installed in the received signal processing path of the radio just upstream of the despreading function. The filter may be implemented as a relatively small numbered tap filter, having its precursor tap fixed at a maximum value. The remaining filter tap values are individually adaptively adjusted by the radio's control processor, which executes a tap adjustment routine to iteratively increment or decrement each variable tap value of the FIR filter to an 'optimized' value, that effectively minimizes the total (I and Q) power in the error in the data decisions performed by data signal analyzer.

Growing community of inventors

Huntsville, AL, United States of America

Ayman Ghobrial