[Asterisk-Users] Fun with Echo

[Colin Anderson]

More taps in the Zaptel echo can = higher CPU usage + longer training times.
In my experience, specifying an overly high number of taps (even 256) will
bog the system when it is under load and lead to subjective delays in the
audio path. But if you are going to be only doing 1 or 2 concurrent calls,
why not experiment? 

-----Original Message-----
From: Brian Swan [mailto:swannie at swannie.net]
Sent: Friday, June 09, 2006 11:29 AM
To: Asterisk Users Mailing List - Non-Commercial Discussion
Subject: Re: [Asterisk-Users] Fun with Echo


My wife is the customer, so she tends to give me funny looks when I  
ask her to sign waivers. ;) In all seriousness, though, I do recall  
reading that the 256 tap limit is "enforced" in software and that you  
can add/remove/whatever a few lines of code, and go up to 1024 (or  
greater I'd assume).  Has anyone tried this?  I'm considering  
attempting it this weekend to see if it does anything.  Does more  
taps always = better echo cancelation?

Thanks!
Brian

On Jun 9, 2006, at 12:15 PM, Mike Fedyk wrote:

> Steve Davies wrote:
>> On 6/9/06, Dr. Michael J. Chudobiak <mjc at avtechpulse.com> wrote:
>>>
>>> Consider getting a Sangoma A200D
>>> (http://www.sangoma.com/datasheets/p_a200-specs) with the optional
>>> hardware echo canceller module. It "just works" for echo  
>>> cancellation;
>>> no tweaks required. It takes a while to figure out how to install  
>>> it,
>>> but once it's working it's great!
>>>
>>
>> Yes, I must agree that hardware echo cancellation from Sangoma (and I
>> am sure Digium and others) is excellent, but it does add to the cost
>> quite significantly sometimes.
> If you haven't had your client sign a waiver that there maybe echo  
> because of the cheap hardware, then don't use the tdm400p.  I've  
> wondered why the software echo can in zaptel doesn't go up to 1024  
> taps and causes major problems at 256 taps.  The tdm400p cards  
> don't have a high port density, you'd run out of slots before  
> hitting CPU barriers so why not use some of those resources for an  
> echo can with a longer tail?
>
> Use either the sangoma cards with echo can, or get a tdm2400p with  
> echo can.  You will have happier customers if you do.
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