[cisco-voip] Where's the echo?

[Erick Bergquist]

This THL Sweep test method to get best-match in newer
IOS versions rocks. Way better then the older versions
where you had to guess and play with numbers and trial
and error. Still may need to adjust input/output gains
afterwards but overall quicker results.

Just have to hope the lines are good and you're not
out in boonies where the line characteristics change
or carriers change things out, etc upstream. Had a
client out in boonies whose analog lines were good for
weeks after the settings were adjusted, etc then one
day after a weekend they could barely use the lines
until we redid the THL sweep which resulted in
different best match, and had to adjust gain levels
again to. 

Erick


--- Wes Sisk <wsisk at cisco.com> wrote:

> most likely at the remote site... and most likely in
> those analog lines.
> 
>
http://www.cisco.com/en/US/customer/tech/tk652/tk701/technologies_white_pape
> r09186a00800d6b68.shtml
> 
> look for impedance mismatch.  can try tuning voice
> port echo settings, if
> it's impedance mismatch, echo is created at
> electrical interface and nothing
> the DSP's can do about that.  most platforms allow
> impedance tuning
> 
>
http://www.cisco.com/en/US/customer/tech/tk652/tk701/technologies_tech_note0
> 9186a0080477a06.shtml
> 
> 
> /Wes
> 
> -----Original Message-----
> From: cisco-voip-bounces at puck.nether.net
> [mailto:cisco-voip-bounces at puck.nether.net]On Behalf
> Of Voll, Scott
> Sent: Wednesday, August 17, 2005 1:23 PM
> To: cisco-voip at puck.nether.net
> Subject: [cisco-voip] Where's the echo?
> 
> 
> I have this setup
> 
> PSTN - (VGW ---central site- CM) ----- T1 ---(remote
> location) - VGW ---
> PSTN
> 
> If I call out the PSTN from the central site to the
> remote location via the
> PSTN, I at the central location here echo.  Where's
> the echo problem?
> Central site?
> 
> This is a new remote location.
> 
> Thanks
> 
> Scott
> 
> PS.  Central site has PRI's w/ 128ms echo
> cancellation and the remote site
> has FXO ports with 64ms echo cancellation.  All is
> running MGCP and CM
> 4.1.3sr1
> 
> 
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> cisco-voip at puck.nether.net
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> 



		
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