[Asterisk-Users] BAD/GOOD Echo Cancel

[Ken D'Ambrosio]

For the record, I've done a couple of Asterisk installs, and HATED echo
-- or feebly attempting to get Asterisk's flakey software algorithms to
do anything about it.  Finally got sick 'n tired, and threw money at it
-- got the Sangoma quad-span T1 card.

And echo freaking VANISHED.  (Note that, with EC disabled, I do get echo
about 1/6 of the places I call.  So it's really, truly working, and not
just luck.)

They use the G.168-2002 algorithm; I, personally, had never heard of it
before, but I bounced it off a friend of mine (he's a hardware architect
for a major VoIP switch manufacturer -- they sell to places like Time
Warner), and he was of the opinion that G.168 is the _ONLY_ algorithm.

So, from now on, I'm doing DSP-based EC.  And Sangoma just came out with
some analog cards with EC -- haven't tried 'em out yet, but I'm looking
forward to doing so.

-Ken


Krystian Filiks wrote:

> Did you test the echo delay?
> will 64ms be suffitient?
>
> You can easily test the delay by recording the transmit and receive
> path to a sound file and using some sound editing software see how big
> the delay is.
> That is how I did it when I worked for a Telco in Switzerland on theis
> TDM switch they had a big Echo problem on their SS7 links and PRI's
>
> Krystian
>
> Doug Lytle wrote:
>
>> asterisk at anime.net wrote:
>>
>>> On Mon, 6 Feb 2006, trixter aka Bret McDanel wrote:
>>>
>>>> Again, I know Sangoma is a sore subject with some on this list, but
>>>> the
>>>> echo cancelation stuff I heard while presented by a Sangoma
>>>> employee was
>>>> not Sangoma specific, although it did include some research into
>>>> different hardware/software based cancelers.
>>>
>>>
>>
>> I put a Tellabs 64ms echo canceller into my facility this weekend and
>> am praying that it removes are echo problem.  If it does, I plan on
>> making it a standard on my Asterisk installs that have a channel bank
>> or T1.
>>
>> Doug
>>
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