Talk:Echo cancellation

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Contents 1 Incorrect statement regarding echo suppression 2 Merge echo suppression with echo cancellation 3 Basic Article Layout 4 Dont merge echo suppression with echo cancellation

[edit] Incorrect statement regarding echo suppression

The following paragraph, modified by Darmstro at 02:04, 10 June 2006 has an incorrect statement:

Echo suppression may have the unwanted side-effect of removing valid voice signals from the transmission. This can cause audible signal loss that is called "clipping." For that reason, echo suppression has been obsoleted by echo cancellation.it is done with due respect

In modern software applications echo cancellation and suppression work in conjunction to remove echo. The variability of computer hardware creates all kinds of difficulties that generally make it impossible for echo cancellation alone to perform sufficiently well. I have changed the paragraph to:

Echo suppression may have the unwanted side-effect of removing valid signals from the transmission. This can cause audible signal loss that is called "clipping." In an ideal situation then, echo cancellation alone will be used. However this is insufficient in many applications, notably software phones. Here, echo cancellation and suppression can work in conjunction to achieve acceptable performance.

--Andrew J. MacDonald 03:13, 18 August 2006 (UTC)

[edit] Merge echo suppression with echo cancellation

I agree with the merging of the two entries. I understand "echo suppression" to be synonymous with "echo cancellation"... the only difference is the term used. BOTH attempt to achieve complete removal of echo in telecommunication circuits. Does anyone have a clearer definition of the difference between suppression and cancellation than I'm assuming? --220.233.25.235

Neither is ever complete. Suppression comes closer, but is less often used than it once was. Echo suppression was developed in the 1950s and 60s for intercontinental telephony. It turns off the receive leg when the talk leg is talking, thus sacrificing full duplex in order to suppress echo. Echo cancellation was developed in the 1970s. It figures out the time/amplitude characteristic of the echo, listens to the talk leg, produces an equal and opposite echo signal, and feeds that down the listen leg, thus cancelling the echo. It was greatly expanded in the 1980s for use in modems, and nowadays the principal users of echo cancellation are DSL modems. Jim.henderson 01:40, 29 March 2007 (UTC)

[edit] Basic Article Layout

I think the problem with this article is the lack of any description of how talker A signal gets mixed in with talker B signal and heard. In Telephony this is the two wire to four wire converters in the network. In acoustical, the end "room" is the two wire converter. So we have 3 cases. A) Telephones (far echo), the signal from person A goes to person B but some is reflected back at the far 2/4 wire converter. B) Acoustic, the reflection is the room and C) the reflection is in the local handset. Hmmm. Any suggestions on how to first introduct how signals may be reflected to cause an echo?. That would be a good introductory piece --User: jlpayton —The preceding signed but undated comment was added at 03:18:32, August 19, 2007 (UTC).

[edit] Dont merge echo suppression with echo cancellation

The distinction between the two concepts is important. It is important to understand the difference and to know which one you are talking about. Having two separate articles means that when you search on one, that is what you get. It is good, to explain the difference between them in each article, of course and to refer to the other with SEE ALSO. —Preceding unsigned comment added by Braithwa (talk • contribs) 06:03, 18 March 2008 (UTC)