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: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] 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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