Echo Cancellation on the Wildcard X100P

If you are experiencing echo on the Digium Wildcard X100P, you can configure the Zap Channel Module to do echo cancellation training. Use the echotraining option in the Zap Channel Module's configuration file. Note that this had a few issues before Dec 2, 2003 when Mark nailed down the bug that caused the DTMF to be unreliable.

Configuration

From the zapata.conf.sample:


If you set this to yes, use ztmonitor to adjust the rxgain and txgain. Ztmonitor isn't installed by default; but it is included with the Zaptel source code, so look in /usr/src/zaptel. Use ztmonitor like this:

 ./ztmonitor 1 -v
 Rx #################################* Tx

When there is echo on one side, both sides will have hashes even when one side is completely silent, like this:
 Rx ################################ * Tx ##### *
The objective of using visual cues from ztmonitor to tune rxgain and txgain is so when you talk and remote mute, Tx side has visual bars but Rx side has nil; and vice versa.

Place a call, mute yourself and let the remote party talk. Adjust rxgain and txgain until the remote side no longer hears echo. Then mute the remote party and you talk. Adjust again. You can do this by your own. It appears to me that txgain is more effective to control remote side echo, and rxgain is more effective to control Asterisk side echo.

For example, try this setting in zapata.conf:

 rxgain=10.5
 txgain=-4.5

Note: If you set the txgain value too low, your outbound calls may not go thorugh since the DTMF tones are too quiet to be picked up.

Hope this helps with Wildcard X100P echo issues. I no longer have that 5-10 seconds of echo when making a call. HUGE IMPROVEMENT!

bkw dec 2, 2003

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If echocancel=256 instead of 128(yes) then that could also be causing a echo + some terrible feedback. Cause i tried those same settings and was still getting echos. So try echocancel=yes, rxgain=4.5, txgain=4.5.

g powell Dec 30,2004


If you are unable to get rid of echo it is worth trying this: In the zconfig.h file a new zaptel echo canceller called ECHO_CAN_MG2 (MG2), Edit this file (found in /usr/src/zaptel on AAH) compile the driver and compile Asterisk - no echo at either end!!!

See Also

• Asterisk zapata gain adjustment This page describes how to properly adjust rx/txgain instead of using the eyeball approach.
• David Rowe's blog post on Open Echo Cancellation which explains X100P echo problems and how the OSLEC echo canceller fixes them.
• Zap Channel Module Configuration: Audio Quality Tuning Options
• Hunting the Echo: What to do if you have echo problems in Asterisk
• Asterisk Echo Cancellation: FXO and FXS lines
• Asterisk Echo Avoidance
• Echo Analysis for Voice over IP
• Digium
• Digium's High Performance Echo Cancellation

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