echo

> My other question (and a more important one) is: will
moving to  
> ISDN or a different FXO card help? Does ISDN have echo
problems at  
> all, or because it is all digital, is this problem
completely gone?  
> We are thinking of installing Asterisk for our
customers, but they  
> will not be as tolerant of a little echo as we are. So
should we  
> mandate ISDN as the best approach?

ISDN should make a sufficient difference in regards to echo.
What  
echo canceller are you currently using for Zaptel?

> Otherwise, are other FXO cards better at echo
cancellation or is  
> this a software feature built into the driver?

The Sangoma A200 cards with hardware echo cancellation are
fantastic,  
and they work great under BSD.

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[ jeremyvoicebox.net.au ]


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On Wednesday 11 October 2006 03:12, Jeremy Bogan wrote:
> > My other question (and a more important one) is:
will moving to
> > ISDN or a different FXO card help? Does ISDN have
echo problems at
> > all, or because it is all digital, is this problem
completely gone?
> > We are thinking of installing Asterisk for our
customers, but they
> > will not be as tolerant of a little echo as we
are. So should we
> > mandate ISDN as the best approach?
>
> ISDN should make a sufficient difference in regards to
echo. What
> echo canceller are you currently using for Zaptel?

The amount of echo one is able to cancel on ISDN, very much
depends on the 
phone one is using. ISDN phones are just like analogue
phones, and do not 
contain any echo canceller themselves.

> > Otherwise, are other FXO cards better at echo
cancellation or is
> > this a software feature built into the driver?
>
> The Sangoma A200 cards with hardware echo cancellation
are fantastic,
> and they work great under BSD.

I have good experience with my own ISDN4BSD, the SVN
version:

http://www
.turbocat.net/~hselasky/isdn4bsd

http://www.turbocat.net/~
hselasky/isdn4bsd/sources/src/sys/i4b/layer1/i4b_echo_cancel
.c

The echo canceller in I4B is a little bit more advanced than
the echo 
canceller in Zaptel. It is a work in progress, but at the
moment it performs 
very well. It needs around 5% CPU usage on a 1.2 GHz
machine, per channel.

--HPS
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On 11/10/2006, at 11:12 AM, Jeremy Bogan wrote:

> ISDN should make a sufficient difference in regards to
echo. What  
> echo canceller are you currently using for Zaptel?

I didn't even know there were choices. It looks like the
default from  
zconfig.h would be used which appears to be ECHO_CAN_MARK3.
I guess  
it would be nice if these were config options in the Zaptel
port. Who  
are Mark and Steve and what do they know about echo
cancellation?

Mostly it is OK, often the first 2 seconds of a call are
awful and  
then it settles down. But sometimes the echo comes back from
time to  
time during a call.

The other problem we've had is one of the TDM FXO ports
getting  
wedged somehow and not answering any calls until a restart
of the  
zaptel driver and/or whole machine. That happened about 2 or
3 times  
now over 6 months.

We are thinking of rolling this out to customers, who would
not be  
happy with this level of reliability.


Ari Maniatis



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> I didn't even know there were choices. It looks like
the default  
> from zconfig.h would be used which appears to be
ECHO_CAN_MARK3. I  
> guess it would be nice if these were config options in
the Zaptel  
> port. Who are Mark and Steve and what do they know
about echo  
> cancellation?

Try ECHO_CAN_MG2 this works the best for us on Telstra/Optus
lines.

> The other problem we've had is one of the TDM FXO ports
getting  
> wedged somehow and not answering any calls until a
restart of the  
> zaptel driver and/or whole machine. That happened about
2 or 3  
> times now over 6 months.

What size power supply is in the machine?

--
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VoiceBox Communications
[ jeremyvoicebox.net.au ]



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On 12/10/2006, at 10:11 PM, Jeremy Bogan wrote:

>> I didn't even know there were choices. It looks
like the default  
>> from zconfig.h would be used which appears to be
ECHO_CAN_MARK3. I  
>> guess it would be nice if these were config options
in the Zaptel  
>> port. Who are Mark and Steve and what do they know
about echo  
>> cancellation?
>
> Try ECHO_CAN_MG2 this works the best for us on
Telstra/Optus lines.

Great, thanks. I'll give that a go. I've also noticed from
http:// 
www.voip-info.org/wiki/view/Asterisk+echo+cancellation that
zaptel  
1.2 introduced kb1 as the default. Is there a reason why the
FreeBSD  
version is still defaulting to Mark3?

Anyhow, I've followed your advice thank you. I guess, it
would be  
nice if I could figure out how to make the FreeBSD port
switch echo  
cancellers based on a config toggle.


>
>> The other problem we've had is one of the TDM FXO
ports getting  
>> wedged somehow and not answering any calls until a
restart of the  
>> zaptel driver and/or whole machine. That happened
about 2 or 3  
>> times now over 6 months.
>
> What size power supply is in the machine?

Quite sizable since this is a Supermicro server class
machine and not  
a little desktop machine used for the purpose. I guess next
time I'd  
buy a Sangoma card which many people seem to rate highly and
they  
appear to have hardware based echo cancellation.


Thanks for you help

Cheers
Ari Maniatis



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On 12/10/2006, at 10:50 PM, Aristedes Maniatis wrote:

> On 12/10/2006, at 10:11 PM, Jeremy Bogan wrote:
>>
>> Try ECHO_CAN_MG2 this works the best for us on
Telstra/Optus lines.
>
> Great, thanks. I'll give that a go.


Just to report back to the list, this was much worse for us.
I am  
going to give kb1 a try next.

Are there any comparisons somewhere about the differences
between the  
different algorithms? How about the hardware cancellation on
the  
Sanoma cards? Is that better or worse?


Ari Maniatis


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> Just to report back to the list, this was much worse
for us. I am  
> going to give kb1 a try next.

You need to use in combination with adjusting the gain
levels on your  
line. You should also use fxotune to test your lines and run
this  
before you start up Zaptel drivers.

--
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[ jeremyvoicebox.net.au ]


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On 10/12/06 20:50 Aristedes Maniatis said the following:
> Great, thanks. I'll give that a go. I've also noticed
from http:// 
> www.voip-info.org/wiki/view/Asterisk+echo+cancellation
that zaptel  1.2 

the zaptel-bsd drivers haven't been fully synced with the
latest Linux 
zaptel drivers. the last time it was synced was with
zaptel-1.2.3 as 
released by digium.

> introduced kb1 as the default. Is there a reason why
the FreeBSD  
> version is still defaulting to Mark3?

i've just committed a change to zaptel-bsd subversion which
changes the 
default to MG2 as that has been tested to work well for most
people. KB1 
can be made a default when we've got more people testing it
and submitting 
reports.

> Anyhow, I've followed your advice thank you. I guess,
it would be  nice 
> if I could figure out how to make the FreeBSD port
switch echo  
> cancellers based on a config toggle.

using the ports options mechanism, i'm sure this can be
achieved by the 
port maintainers.

> Quite sizable since this is a Supermicro server class
machine and not  a 
> little desktop machine used for the purpose. I guess
next time I'd  buy 

older Digium TDM analog cards used to have this problem on
some 
motherboards. however, it has been a while since i've
touched one of these 
babies and the wcfxs.ko driver has remained stagnant since
then, other than 
the sync with zaptel-1.2.3 as mentioned above.

-- 
Regards,                           /_/   "All dogs go
to heaven."
dineshalphaque.com                (0 0)   http://www.openmalay
siablog.com/
+==========================----oOO--(_)--OOo----============
==============+
| for a in past present future; do                          
             |
|   for b in clients employers associates relatives
neighbours pets; do   |
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On 10/12/06 20:04 Aristedes Maniatis said the following:
> 
> Who  are 
> Mark and Steve and what do they know about echo
cancellation?

Mark Spencer and Steve Underwood, and i think they do know
quite a bit 
about echo cancellation in the zaptel/asterisk context. why
don't you 
google their names up ? 

-- 
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to heaven."
dineshalphaque.com                (0 0)   http://www.openmalay
siablog.com/
+==========================----oOO--(_)--OOo----============
==============+
| for a in past present future; do                          
             |
|   for b in clients employers associates relatives
neighbours pets; do   |
|   echo "The opinions here in no way reflect the
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| done; done                                                
             |
+===========================================================
==============+
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On 14/10/2006, at 2:52 PM, Jeremy Bogan wrote:

> You should also use fxotune to test your lines and run
this before  
> you start up Zaptel drivers.

Thanks for this pointer. But is it available on FreeBSD? I
can't see  
it anywhere as part of the Zaptel port source. All I can
find are the  
usual zttool, zttest, etc.

Ari Maniatis



-------------------------->
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phone +61 2 9550 5001   fax +61 2 9550 4001
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