[Asterisk-Users] TDM Echo issue

[gw at adcomcorp.com]

Hello Sacha,
While it is not the best solution as far as quality is concerned, I
would suggest you at least try the aggressive canceller in zconfig.h.  I
put it into use temporarily while I get an external echo can setup.  It
takes a bit of getting used to (no simultaneous speech/duplex), however
it's really not bad if you are on a long loop from your CO (a cause of
many troubles).
 
Txgain -4.5 seems low to me, but it all depends on your lines.
 
Also, be careful of the locations of the gain settings, they need to be
within the channel definition.  If you are mixing gains on different
lines (like to an ATA or PBX where they are 0), you need to be careful
about the config file.
 
Greg

________________________________

From: asterisk-users-bounces at lists.digium.com
[mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of Sascha
Ferley
Sent: Monday, November 14, 2005 12:09 AM
To: 'Asterisk Users Mailing List - Non-Commercial Discussion'
Subject: [Asterisk-Users] TDM Echo issue



Hi, 

 

I am running into a issue with a TDM04B card. When dialing out I get an
noticeable (extreme to some people) echo, in that I can hear myself. The
person on the other line doesn't hear any echo and the call sounds
perfect to them. 

 

I checked and tested a few things as per suggestions on voip-info.org
with RX/TX gain and using ztmonitor. I adjusted the 

rxgain=10.5 txgain=-4.5 and it doesn't seem  to do to much to eliminate
me hearing myself on the phone. I can't go any lower on txgain then -5.5
before the call doesn't go through any more. If I change the txgain to
above 0 the echo gets even worse.  

 

I am using Cisco 7960 phones and calling IP to IP is perfect; the echo
occurs only when going out the zap channels to the PSTN. Below is the
relevant zapata.conf file.  I also checked the /proc/interrupts file and
the interrupts seem normal (see below). 

 

If anyone has any other suggestion, please let me know,

 

Thanks

 

Sascha

 

 

### /proc/interrupts ############

           CPU0              CPU1

  0:       62224232        62229547        IO-APIC-edge
timer

  1:       0                      3                      IO-APIC-edge
keyboard

  2:       0                      0                      XT-PIC
cascade

  4:       0                      5                      IO-APIC-edge
serial

  8:       0                      1                      IO-APIC-edge
rtc

 14:      0                      2                      IO-APIC-edge
ide0

 18:      556800            715820            IO-APIC-level
libata

 20:      562694111      681819012      IO-APIC-level             wctdm

 53:      24008833        8                      IO-APIC-level
eth0

NMI:    0                      0

LOC:   123628432      123628430

ERR:    0

MIS:   0

 

 

##### /etc/asterisk/zapata.conf #########

;

; Zapata telephony interface

;

; Configuration file

 

[trunkgroups]

 

[channels]

 

language=en

context=from-pstn

signalling=fxs_ks

rxwink=300              ; Atlas seems to use long (250ms) winks

;

; Whether or not to do distinctive ring detection on FXO lines

;

;usedistinctiveringdetection=yes

 

usecallerid=yes

hidecallerid=no

callwaiting=yes

usecallingpres=yes

callwaitingcallerid=yes

threewaycalling=yes

transfer=yes

cancallforward=yes

callreturn=yes

echocancel=yes

echocancelwhenbridged=yes

;echotraining=800

echotraining=yes

rxgain=0.0

txgain=0.0

group=0

callgroup=1

pickupgroup=1

immediate=no

 

;faxdetect=both

faxdetect=incoming

;faxdetect=outgoing

;faxdetect=no

 

;Include genzaptelconf configs

#include zapata-auto.conf

 

;Include AMP configs

#include zapata_additional.conf

 

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