echo cancellation


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echo cancellation

A process which removes unwanted echoes from the signal on a telephone line. Echoes are usually caused by impedance mismatches along an analogue line.

echo cancellation

The elimination of an echo in a two-way voice transmission. Echo is created in the telephone company's central office switch when two-wire lines from the customer are converted to four-wire lines for backbone trunks. The echo is exacerbated over longer distances and by certain kinds of network equipment. A delay of 30ms or more is noticeable, and 50ms is annoying. To eliminate it, the carriers put echo cancellers on their switch ports and in their long-distance trunks at 500 mile intervals.

Using sophisticated DSP circuits that isolate the echo and transmit a reverse frequency to cancel it, echo cancellation is also built into analog modems, speakerphones and quality sound cards. See echo suppression and noise cancellation.
References in periodicals archive ?
15, 400020 Cluj-Napoca, Romania,2011 .Behavior of Variable Step Size NLMS Algorithms for Acoustic Echo Cancellation, IEEE 10th International Symposium on Signals, Circuits and Systems (ISSCS 2011): 1-4.
Vetterli, "Adaptive filtering in subbands with critical sampling: analysis, experiments, and application to acoustic echo cancellation," IEEE Transactions on Signal Processing, vol.
Also included are papers on echo cancellation, pseudonoise sequences, optimum receivers, forward error-correction coding, spread spectrum communications, diversity techniques, digital communications system performance and standards-setting bodies.
The output of the modem is an ISDN U interface circuit that employs adaptive echo cancellation and data scrambler.
(NYSE:MXL), a provider of radio frequency (RF), analog and mixed-signal integrated circuits, has introduced its Full Duplex DOCSIS[R] (FDX) technology with proprietary echo cancellation technology, the company said.
It also features a six-microphone array with advanced echo cancellation that allows Siri to understand people even from distance.
ClearOne (Nasdaq:CLRO), a global provider of audio and visual communication solutions, announced on Wednesday the award of a new US patent for acoustic echo cancellation methods.
With over 100 patents and superior performance in beam-forming noise suppression, echo cancellation and wind noise suppression, Fortemedia's solutions have been adopted by industry leaders across a wide variety of markets.
Highlights include all-new streaming capability, the new 64X64 DigitalMedia Switcher with 4K Ultra HD support, and the DMPS-300-C-AEC with acoustic echo cancellation. Crestron DigitalMedia is the world's only complete, engineered digital AV distribution solution and the most powerful audio/video networking platform ever developed.
Capable of hosting a conference call over a company's intranet, or online, special boundary microphones, echo cancellation, and direction recognition allow for full duplex, natural and smooth conversation.
The audio processors unleash the capabilities of digital MEMS microphones in multi-microphone arrays, enabling features like acoustic echo cancellation, noise suppression, or beam-forming, which are desirable with the increasing use of cell phones and other consumer devices in noisy and uncontrollable environments.
The integrated speakerphone works with Bluetooth-enabled phones via a built-in microphone while the sound is enhanced through Digital Sound Processing (DSP) and echo cancellation. Aside from its docking capabilities, the 'OnBeat Xtreme' also works compatibly with Bluetooth wireless audio, thereby allowing the unit to play any music file from any Bluetooth supported device, including smartphones, tablets or PCs and non-Apple portables.