asterisk users - Oct 2005 - Terrible echo with Te110P and Adit 600

8 POTS lines - Adit 600 - TE110P - Dell Precision 530 Dual Xeon running
1.0.9 and 1.2 (tried both)


The echo is insurmountable.  I have tried everything, and the pots lines
are clean.  If I go from an FXO on the Adit 600 straight to an FXS, I
get no echo from an analog phone.  

I put an 128ms T1 echo canceller in between the adit and the TE110P, and
the echo was still horrible.  

I finally disabled the Zapata echo canceller....and WHAMMO!  It's
perfect now.  

The TE110P is on it's own IRQ...... and the machine has PLENTY of
horsepower.

Any ideas so I don't have to spend $1000 on an echo canceller?

-Darren

> -----Original Message-----
> From: asterisk-users-bounces@lists.digium.com
> [mailto:asterisk-users-bounces@lists.digium.com]On Behalf Of Darren Wright
> Sent: Tuesday, October 18, 2005 7:42 PM
> To: Asterisk Users Mailing List - Non-Commercial Discussion
> Subject: [Asterisk-Users] Terrible echo with Te110P and Adit 600
> 
> 8 POTS lines - Adit 600 - TE110P - Dell Precision 530 Dual 
> Xeon running 1.0.9 and 1.2 (tried both)
> 
> The echo is insurmountable.  I have tried everything, and the 
> pots lines are clean.  If I go from an FXO on the Adit 600 straight to an
FXS, I
> get no echo from an analog phone.  
No echo that you can hear - remeber that echo relies on two things, a reflected
signal and a delay between the transmission and the reception of the signal long
enough for the brain to perceive it. Looping the channel bank will not introduce
any delays. Passing through Asterisk will, by design.
> I put an 128ms T1 echo canceller in between the adit and the 
> TE110P, and the echo was still horrible.  
> 
> I finally disabled the Zapata echo canceller....and WHAMMO!  It's
> perfect now.  
> 
It sounds like something is confusing the zaptel canceller causing it to distort
the signal. It seems to be very sensitive to signals that are too 'hot'
(ie. too loud). Try lowering the gain on the signal going out of the channel
bank into the T1. If it's too quiet try increasing the RX gain on the Zaptel
side to compensate.

{clip}
> Any ideas so I don't have to spend $1000 on an echo canceller?
> 
I provided the patches to 1.2 that formed the basis for the kb1 echo canceller,
which is a derivative of the mark2 used in v1.0, and I still use a 64ms Tellabs
hardware echo can as well as the zaptel echo canceller. Note that, in my case at
least, the zaptel tends to handle those echos that leak through the Tellabs gear
- such as acoustic room echos from speaker phones or cheap cordless handsets.

If you need the echo issue resolved, stick with hardware cancellation. If you
don't want to spend $1k, take a look at
http://www.voip-info.org/wiki/view/Tellabs+Hardware+Echo+Cancellers. It's
not everyones cup of tea, but it works fine for me which is why I shared it.

The Zaptel echo can will be fixed so it performs predictably for everyone
eventually, but until then go with 3rd party T1 gear if you want it reliably
avoided.

Hope that helps.

Kris Boutilier
Information Services Coordinator
Sunshine Coast Regional District

-----Original Message-----
From: asterisk-users-bounces@lists.digium.com
[mailto:asterisk-users-bounces@lists.digium.com] On Behalf Of Kris
Boutilier
Sent: Wednesday, October 19, 2005 12:13 AM
To: Asterisk Users Mailing List - Non-Commercial Discussion
Subject: RE: [Asterisk-Users] Terrible echo with Te110P and Adit 600
> -----Original Message-----
> From: asterisk-users-bounces@lists.digium.com
> [mailto:asterisk-users-bounces@lists.digium.com]On Behalf Of Darren
Wright
> Sent: Tuesday, October 18, 2005 7:42 PM
> To: Asterisk Users Mailing List - Non-Commercial Discussion
> Subject: [Asterisk-Users] Terrible echo with Te110P and Adit 600
> 
> 8 POTS lines - Adit 600 - TE110P - Dell Precision 530 Dual 
> Xeon running 1.0.9 and 1.2 (tried both)
> 
> The echo is insurmountable.  I have tried everything, and the 
> pots lines are clean.  If I go from an FXO on the Adit 600 straight to
an FXS, I
> get no echo from an analog phone.  
No echo that you can hear - remeber that echo relies on two things, a
reflected signal and a delay between the transmission and the reception
of the signal long enough for the brain to perceive it. Looping the
channel bank will not introduce any delays. Passing through Asterisk
will, by design.

-----------------------
I meant that if I take an incoming POTS line to the FXO port, map that
to the FXS, and then make a call from the analog phone to the same
person that I tried calling on the Cisco 7960, the echo on the 7960 is
terrible, and the FXS port is just fine.  
----------------------- 
> I put an 128ms T1 echo canceller in between the adit and the 
> TE110P, and the echo was still horrible.  
> 
> I finally disabled the Zapata echo canceller....and WHAMMO!  It's
> perfect now.  
> 
It sounds like something is confusing the zaptel canceller causing it to
distort the signal. It seems to be very sensitive to signals that are
too 'hot' (ie. too loud). Try lowering the gain on the signal going out
of the channel bank into the T1. If it's too quiet try increasing the RX
gain on the Zaptel side to compensate.

------------------------
Agreed.  I've tried them lowered to the point that DTMF becomes an
issue, and they have the volume pegged on the 7960's to even hear the
callers.  I cannot adjust the TX/RX on the T1 coming out of the Adit
600.  I can adjust the FXO ports, as well as the TE110P.  

-------------------------



{clip}
> Any ideas so I don't have to spend $1000 on an echo canceller?
> 
I provided the patches to 1.2 that formed the basis for the kb1 echo
canceller, which is a derivative of the mark2 used in v1.0, and I still
use a 64ms Tellabs hardware echo can as well as the zaptel echo
canceller. Note that, in my case at least, the zaptel tends to handle
those echos that leak through the Tellabs gear - such as acoustic room
echos from speaker phones or cheap cordless handsets. 

If you need the echo issue resolved, stick with hardware cancellation.
If you don't want to spend $1k, take a look at
http://www.voip-info.org/wiki/view/Tellabs+Hardware+Echo+Cancellers.
It's not everyones cup of tea, but it works fine for me which is why I
shared it.

The Zaptel echo can will be fixed so it performs predictably for
everyone eventually, but until then go with 3rd party T1 gear if you
want it reliably avoided.
------------------------

Yup....got one running at home thanks to your WIKI.  But for clients
moving forward, I need something a bit more mainstream.  I'm
disappointed that the TE110P + adit 600 has been an issue on multiple
systems now, and that the software echo canceller has been a major
failure.  

It makes that solution WAY to expensive with the echo
canceller....that's well into the 2k range, and a good FXO - SIP gateway
with echo canceling is significantly less than that.  

Thanks for your help

-Darren

On Wed, 2005-10-19 at 13:32 +0200, steve@daviesfam.org
wrote:
> 
> On Tue, 18 Oct 2005, Matt wrote:
> 
> > try sangoma card which has a very good echo cancel solution.
> 
> 
> Huh?  I believe that the Sangoma uses the same zaptel echo cancellers that 
> are used with the Digium cards.
Unless you have the Sangoma card with the hardware echo can on board.

Regards,
Patrick

Darren Thanks for your reply to my problem with the same setup, I have
found the problem to be Telco related and had it fixed since. But not
before I tried a Mediatrix 1204 on that setup. It was then that I
ralized that the problem is with the telco.
The Mediatrix came in at around $600 + (for 4 ports) while the Adit
with the Digium card came in at $1100 + (for 8 ports). What make the
Adit attractive is that you can let the customers hook up fax machine
and credit card machines if they want, using FXS cards with the Adit.
This all came in as a very good expereince for me, it allowed me to
try out both setups. In general I think, that if its a small setup for
just a few POTS, and the Fax/CC machine can be connected directly to a
POTS and not Asterisk then solutions like the Adit should be avoided,
it makes the whole system much cheaper. If all the transcoding gets
done outside Asterisk (as is the case with using something like the
Mediatrix) then you should be able to hook up around 70-80 Sip phones
or ATAs with Asterisk using just a single P4, and 512 MB RAM. While
some have seen the same results with the TE110 that is only true to
the maximum of 23 channels, but not if you plan on using 70, 80
simultaneus channels.

When you have to deal with lots of POTS lines (12 to 16 range), it
still might be cheaper to use the Mediatrix than the Adit 600, since
with something like the Adit you will need a more powerfull machine,
while with external gateways you can get by with just a P4 (or
something as small as the mini ITX systems).

When comparing sound quality I got the same with both devices (actualy
as long as I had the Adit with the TE110 and the problem form the
Telco I had better quality with the Adit since Asterisk was doing a
great job with the Echo can).

In overall I would recommend using an external Sip gateway instead of
the Adit when trying to compete (like for small offices with just a
few extensions). But where more then just the FXO is needed (like
faxing/CC) then the Adit is the way to go.

On 10/18/05, Darren Wright <dwright@d2-tech.com>
wrote:
>
> 8 POTS lines - Adit 600 - TE110P - Dell Precision 530 Dual Xeon running
> 1.0.9 and 1.2 (tried both)
>
>
> The echo is insurmountable.  I have tried everything, and the pots lines
> are clean.  If I go from an FXO on the Adit 600 straight to an FXS, I
> get no echo from an analog phone.
>
> I put an 128ms T1 echo canceller in between the adit and the TE110P, and
> the echo was still horrible.
>
> I finally disabled the Zapata echo canceller....and WHAMMO!  It's
> perfect now.
>
> The TE110P is on it's own IRQ...... and the machine has PLENTY of
> horsepower.
>
> Any ideas so I don't have to spend $1000 on an echo canceller?
>
> -Darren
>
>
>
>
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>

> Darren Thanks for your reply to my problem with the same setup, I have
> found the problem to be Telco related and had it fixed since. But not
> before I tried a Mediatrix 1204 on that setup. It was then that I
> ralized that the problem is with the telco.
Do you know what the specific problem was with the telco?

I have a similar setup... I set the canceller on the incoming PSTN
lines, but turn it off on the FXS.  

I have no local internal echo over the t1, but moderate over the PSTN.
I managed to tweak it a little and most of my  outbound (local side)
echo is minimized, but still there a little. I have no incoming echo.

You mind elaborating on where you are getting the echo? 

-----Original Message-----
From: asterisk-users-bounces@lists.digium.com
[mailto:asterisk-users-bounces@lists.digium.com] On Behalf Of Darren
Wright
Sent: Tuesday, October 18, 2005 10:42 PM
To: Asterisk Users Mailing List - Non-Commercial Discussion
Subject: [Asterisk-Users] Terrible echo with Te110P and Adit 600


8 POTS lines - Adit 600 - TE110P - Dell Precision 530 Dual Xeon running
1.0.9 and 1.2 (tried both)


The echo is insurmountable.  I have tried everything, and the pots lines
are clean.  If I go from an FXO on the Adit 600 straight to an FXS, I
get no echo from an analog phone.  

I put an 128ms T1 echo canceller in between the adit and the TE110P, and
the echo was still horrible.  

I finally disabled the Zapata echo canceller....and WHAMMO!  It's
perfect now.  

The TE110P is on it's own IRQ...... and the machine has PLENTY of
horsepower.

Any ideas so I don't have to spend $1000 on an echo canceller?

-Darren




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Followup, I set a -2.0 gain from my asterisk t1 > pbx, and echo seems
mostly gone.

A note, I also turned on the aggressive suppressor in zconfig.h

Greg

-----Original Message-----
From: asterisk-users-bounces@lists.digium.com
[mailto:asterisk-users-bounces@lists.digium.com] On Behalf Of Gregory
Wiktor - ADCom Corp.
Sent: Saturday, October 22, 2005 11:07 AM
To: asterisk-users@lists.digium.com
Subject: RE: [Asterisk-Users] Terrible echo with Te110P and Adit 600

I have a similar setup... I set the canceller on the incoming PSTN
lines, but turn it off on the FXS.  

I have no local internal echo over the t1, but moderate over the PSTN.
I managed to tweak it a little and most of my  outbound (local side)
echo is minimized, but still there a little. I have no incoming echo.

You mind elaborating on where you are getting the echo? 

-----Original Message-----
From: asterisk-users-bounces@lists.digium.com
[mailto:asterisk-users-bounces@lists.digium.com] On Behalf Of Darren
Wright
Sent: Tuesday, October 18, 2005 10:42 PM
To: Asterisk Users Mailing List - Non-Commercial Discussion
Subject: [Asterisk-Users] Terrible echo with Te110P and Adit 600


8 POTS lines - Adit 600 - TE110P - Dell Precision 530 Dual Xeon running
1.0.9 and 1.2 (tried both)


The echo is insurmountable.  I have tried everything, and the pots lines
are clean.  If I go from an FXO on the Adit 600 straight to an FXS, I
get no echo from an analog phone.  

I put an 128ms T1 echo canceller in between the adit and the TE110P, and
the echo was still horrible.  

I finally disabled the Zapata echo canceller....and WHAMMO!  It's
perfect now.  

The TE110P is on it's own IRQ...... and the machine has PLENTY of
horsepower.

Any ideas so I don't have to spend $1000 on an echo canceller?

-Darren




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Why?

On 10/23/05, Andrew Kohlsmith <akohlsmith-asterisk@benshaw.com>
wrote:
> On Sunday 23 October 2005 18:02, C F wrote:
> > Sorry guys I forgot to mention that in my setup I always enable
> > agressive in zconfig
>
> Yuck.  I find the agressive echo canceller totally unacceptable.
>
> -A.
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On Sunday 23 October 2005 18:30, C F wrote:
> Why?
Because it sounds like ass.  I (and my customers) are used to the full-duplex 
nature of the telephone system.  Half duplex sounds very unnatural.

-A.

Yes I did notice it immediately.  I intend to tweak more, but for the
moment it seems like echo is minimized to zero.

This is a big step up from where I was.  Now I just need to see if it
bothers people at the office.

Also been looking for a way to restore CNG (comfort noise) to avoid the
'are you there' issues.  No luck on researching it with t1 yet though.

Greg 

-----Original Message-----
From: asterisk-users-bounces@lists.digium.com
[mailto:asterisk-users-bounces@lists.digium.com] On Behalf Of
steve@daviesfam.org
Sent: Monday, October 24, 2005 3:07 AM
To: Asterisk Users Mailing List - Non-Commercial Discussion
Subject: Re: [Asterisk-Users] Terrible echo with Te110P and Adit 600



On Sun, 23 Oct 2005, C F wrote:
> Why?
> 
> On 10/23/05, Andrew Kohlsmith <akohlsmith-asterisk@benshaw.com>
wrote:
> > On Sunday 23 October 2005 18:02, C F wrote:
> > > Sorry guys I forgot to mention that in my setup I always enable 
> > > agressive in zconfig
> >
> > Yuck.  I find the agressive echo canceller totally unacceptable.

Did you listen to the aggressive suppressor working?  Every time you
speak, the other end of the line gets muted "dead".  

I guess if you have to use it then you have to use it.  But I wouldn't
make it my default.

Steve

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> -----Original Message-----
> From: asterisk-users-bounces@lists.digium.com [mailto:asterisk-users-
> bounces@lists.digium.com] On Behalf Of steve@daviesfam.org
> Sent: Monday, October 24, 2005 12:07 AM
> To: Asterisk Users Mailing List - Non-Commercial Discussion
> Subject: Re: [Asterisk-Users] Terrible echo with Te110P and Adit 600
> 
> On Sun, 23 Oct 2005, C F wrote:
> 
> > Why?
> >
> > On 10/23/05, Andrew Kohlsmith <akohlsmith-asterisk@benshaw.com>
wrote:
> > > On Sunday 23 October 2005 18:02, C F wrote:
> > > > Sorry guys I forgot to mention that in my setup I always
enable
> > > > agressive in zconfig
> > >
> > > Yuck.  I find the agressive echo canceller totally unacceptable.
> 
> 
> Did you listen to the aggressive suppressor working?  Every time you
> speak, the other end of the line gets muted "dead".
> 
>From the source code for the echo canceller (slightly reformatted):
#ifdef AGGRESSIVE_SUPPRESSOR
if ((ec->HCNTR_d < AGGRESSIVE_HCNTR) && (ec->Ly_i >
(ec->Lu_i << 1))) {
	 for (k=0; k < RESIDUAL_SUPRESSION_PASSES; k++) {
           u = u * (ec->Lu_i >> DEFAULT_SIGMA_LU_I) 
 		   / ((ec->Ly_i >> (DEFAULT_SIGMA_LY_I)) + 1);
       }
}

#else
if (ec->HCNTR_d == 0) {
   if ((ec->Ly_i/(ec->Lu_i + 1)) > DEFAULT_SUPPR_I) {
       for (k=0; k < RESIDUAL_SUPRESSION_PASSES; k++) {
           u = u * (ec->Lu_i >> DEFAULT_SIGMA_LU_I) 
		   / ((ec->Ly_i >> (DEFAULT_SIGMA_LY_I + 2)) + 1);
       }
   }
}

Put another way, when the aggressive canceller is swapped in, a two
interesting things happen:

 - The echo canceller begins to be able to subtract again
AGGRESSIVE_HCNTR samples _before_ the doubletalk detection timer has
completely expired, ie. when (ec->HCNTR_d < AGGRESSIVE_HCNTR), and it is
only subtracted from each sample so long as the average signal level
exceeds the energy level of this particular sample, ie. (ec->Ly_i >
(ec->Lu_i << 1)). Put another way, this seems to say to me, 'there
might
be the tail end of some far end speech going on, so lets start canceling
again, at the risk of some limited distortion of the far end talkers
voice. Also, if the frame is quieter than most then it needs to be
canceled.' 

 - The magnitude of the theoretical echo component is artificially
increased before being subtracted from the returning signal. ie.
(DEFAULT_SIGMA_LY_I + 2)

Likely the latter causes the acoustical 'deadness'. It would be an
interesting academic exercise to replace (DEFAULT_SIGMA_LY_I + 2) with
the original (DEFAULT_SIGMA_LY_I), recompile and see if you still get
superior echo cancellation performance but with a more acceptable
acoustical response. 

However, if anyone has better/more correct interpretations of aggressive
suppression please do enlighten me. :-)

Also, if you're not already, try using the kb1 echo canceller from
CVS-HEAD without aggressive cancellation before taking time to do any of
the above. It can be dropped into stable if needed by just copying it
(and the contents of the header file) over the top of the mec2 files.

Hope that helps.

Kris Boutilier
Information Services Coordinator
Sunshine Coast Regional District

I've done some very interesting testing recently:

The 64ms cards are working wonderful.  $19.00 a pop is a steal.   They
work great with your KB1 canceller, but any others cause HORRIBLE echo.
I am facing the tail end AWAY from the asterisk box....so the echo is
definitely coming from somewhere between the TE110P and the Adit 600.  

Interesting hunh?

I have not gotten my hands on a VX2 card yet, but the 64's are working
so well I'm not sure there is a reason too.  


The Orion canceller is very nice as well, but $1000.

-Darren


-----Original Message-----
From: asterisk-users-bounces@lists.digium.com
[mailto:asterisk-users-bounces@lists.digium.com] On Behalf Of Kris
Boutilier
Sent: Wednesday, October 19, 2005 12:13 AM
To: Asterisk Users Mailing List - Non-Commercial Discussion
Subject: RE: [Asterisk-Users] Terrible echo with Te110P and Adit 600
> -----Original Message-----
> From: asterisk-users-bounces@lists.digium.com
> [mailto:asterisk-users-bounces@lists.digium.com]On Behalf Of Darren
Wright
> Sent: Tuesday, October 18, 2005 7:42 PM
> To: Asterisk Users Mailing List - Non-Commercial Discussion
> Subject: [Asterisk-Users] Terrible echo with Te110P and Adit 600
> 
> 8 POTS lines - Adit 600 - TE110P - Dell Precision 530 Dual 
> Xeon running 1.0.9 and 1.2 (tried both)
> 
> The echo is insurmountable.  I have tried everything, and the 
> pots lines are clean.  If I go from an FXO on the Adit 600 straight to
an FXS, I
> get no echo from an analog phone.  
No echo that you can hear - remeber that echo relies on two things, a
reflected signal and a delay between the transmission and the reception
of the signal long enough for the brain to perceive it. Looping the
channel bank will not introduce any delays. Passing through Asterisk
will, by design.
> I put an 128ms T1 echo canceller in between the adit and the 
> TE110P, and the echo was still horrible.  
> 
> I finally disabled the Zapata echo canceller....and WHAMMO!  It's
> perfect now.  
> 
It sounds like something is confusing the zaptel canceller causing it to
distort the signal. It seems to be very sensitive to signals that are
too 'hot' (ie. too loud). Try lowering the gain on the signal going out
of the channel bank into the T1. If it's too quiet try increasing the RX
gain on the Zaptel side to compensate.

{clip}
> Any ideas so I don't have to spend $1000 on an echo canceller?
> 
I provided the patches to 1.2 that formed the basis for the kb1 echo
canceller, which is a derivative of the mark2 used in v1.0, and I still
use a 64ms Tellabs hardware echo can as well as the zaptel echo
canceller. Note that, in my case at least, the zaptel tends to handle
those echos that leak through the Tellabs gear - such as acoustic room
echos from speaker phones or cheap cordless handsets. 

If you need the echo issue resolved, stick with hardware cancellation.
If you don't want to spend $1k, take a look at
http://www.voip-info.org/wiki/view/Tellabs+Hardware+Echo+Cancellers.
It's not everyones cup of tea, but it works fine for me which is why I
shared it.

The Zaptel echo can will be fixed so it performs predictably for
everyone eventually, but until then go with 3rd party T1 gear if you
want it reliably avoided.

Hope that helps.

Kris Boutilier
Information Services Coordinator
Sunshine Coast Regional District
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