asterisk users - Aug 2005 - Is this echo problem down to IP Phone hardware?

On Fri, 5 Aug 2005, Angus Comber wrote:
> Hello
>
> I have a Grandstream GXP2000 with latest firmware.  When I use it holding
the handpiece I don't hear any echo - neither does other end.  However, if I
use it handsfree, the other end notices echo when they speak - ie their voice is
echoy.  I hear their voice being a bit echoy.
>
> Is this purely down to the IP Phone?  Is there anything I can do about it? 
I considered buying a more expensive phone - eg a Snom to see what they were
like for echo.  Is there something I can do with the Asterisk?  codec to use? 
Anything?
This has nothing to do with the IP.   This is a badly designed phone.  The 
mic is picking up the speaker.  So when the end party talks, they hear 
themselves.  Pick up a 7940/60. You will not have this issue.

Michael

> Angus
>

Hello

I have a Grandstream GXP2000 with latest firmware.  When I use it holding the
handpiece I don't hear any echo - neither does other end.  However, if I use
it handsfree, the other end notices echo when they speak - ie their voice is
echoy.  I hear their voice being a bit echoy.

Is this purely down to the IP Phone?  Is there anything I can do about it?  I
considered buying a more expensive phone - eg a Snom to see what they were like
for echo.  Is there something I can do with the Asterisk?  codec to use? 
Anything?

Angus
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This known as is 'acoustic echo' or 'room reverb' and involves
mathematics that is quite a bit different from that used when cancelling regular
'reflected electrical signal' echos, as the signal is being acousically
distorted as it echos around the room. On many handsfree handsets it doesn't
manifest itself until you move into a physically large room, which increases the
reflection delay and overwhelms the internal mechanisms.
 
It would need to be handled internally by the handset or you would need to
insert a hardware echo canceller capable of dealing with this type of echo,
assuming your signal is exposed on a T1 somewhere. If it's IP all the way
for you then you're really just down to the handset vendors as far as I know
- Asterisk doesn't currently offer any form of echo cancellation on the VoIP
side.
 
Hope that helps.
 
Kris Boutilier
Information Systems Coordinator
Sunshine Coast Regional District

-----Original Message-----
From: asterisk-users-bounces@lists.digium.com
[mailto:asterisk-users-bounces@lists.digium.com]On Behalf Of Angus Comber
Sent: Friday, August 05, 2005 10:46 AM
To: asterisk-users@lists.digium.com
Subject: [Asterisk-Users] Is this echo problem down to IP Phone hardware?


Hello
 
I have a Grandstream GXP2000 with latest firmware.  When I use it holding the
handpiece I don't hear any echo - neither does other end.  However, if I use
it handsfree, the other end notices echo when they speak - ie their voice is
echoy.  I hear their voice being a bit echoy.
 
Is this purely down to the IP Phone?  Is there anything I can do about it?  I
considered buying a more expensive phone - eg a Snom to see what they were like
for echo.  Is there something I can do with the Asterisk?  codec to use? 
Anything?
 
Angus

> -----Original Message-----
> From: asterisk-users-bounces@lists.digium.com
> [mailto:asterisk-users-bounces@lists.digium.com]On Behalf Of Steve
Underwood
> Sent: Friday, August 05, 2005 11:40 AM
> To: Asterisk Users Mailing List - Non-Commercial Discussion
> Subject: Re: [Asterisk-Users] Is this echo problem down to IP Phone
hardware?
> 
> 
> Kris Boutilier wrote:
> 
> >This known as is 'acoustic echo' or 'room reverb' and 
> involves mathematics that is quite a bit different from that 
> used when cancelling regular 'reflected electrical signal' 
> echos, as the signal is being acousically distorted as it 
> echos around the room.   
> >
> The maths is exactly the same. 
{clip}

I had understood that the distortion of the spectral makeup of the acoustically
reflected signal messed with the simpler forms of echo cancellers, hence the
availability of 'AEC' daughterboards and so on for hardware echo
cancellers, even those with tails already as long as 128ms. However, I'm
frequently known to be wrong.

:-)