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 ?
LSI said that its ECAN software provides a robust set of real-world VoIP communications features including a maximum tail length of 128ms, the ability to detect and compensate for up to three windows with the tail, rapid convergence, and 24ms of active echo cancellation.
I can program the IDNX to accept only data traffic on channels 20 through 24, with the echo cancellation turned off on the echo canceler on those same channels.
Echo Cancellation is essential for T1/E1 circuit emulation that involves voice connections to the PSTN and delay in excess of 20 milliseconds.
Digium's hardware echo cancellation solution provides 128ms of echo cancellation for each of the eight channels.
Echo problems in Asterisk are well-known and many IP PBX makers up-sell echo cancellation solutions," said Fabio Gambacorta, vice president of sales and marketing at OctWare.
The SoundClear brand of patented full-duplex communication, echo cancellation, and noise reduction solutions is enabling significant advancements in telecommunications voice quality and is proven in millions of products around the globe.
1VOICE[R] noise cancellation technology, based on SoftMax's patented signal processing techniques, is a revolutionary new approach to the problem of acoustic noise elimination and acoustic echo cancellation on mobile audio platforms like Bluetooth[R] headsets and cell phones.
The SoundClear solution enables a natural bi-directional conversation through acoustic and network echo cancellation and full-duplex control.
The SoundClear(R) brand of patented full-duplex communication and echo cancellation solutions is enabling significant advancements in telecommunications voice quality.
The FXO or FXS cards are a new addition to our recently launched A104d that uses a common printed circuit board as a host to several daughterboard solutions including hardware-based echo cancellation, 1, 2, 4 or 8 port T1/E1, T3/E3, as well as the FXO/FXS technologies.
POCATELLO, Idaho -- AMI Semiconductor (Nasdaq:AMIS), a designer and manufacturer of state-of-the-art integrated mixed-signal and structured digital products for the automotive, medical and industrial markets, today announced the availability of its Echo Cancellation algorithm optimized for the ultra-low power BelaSigna 200 and recently launched BelaSigna 250 DSP-based audio processing systems.