measerl(1) Measure the echo-return loss on Voicetronix telephony hardware


measerl [options]


The measerl utility tests the echo-return loss on the phone line. For hardware that supports it, it can scan through bybrid balance register settings to help establish a lower ERL. Having a lower ERL improves DTMF cutthrough and audio quality. The software echo cancellation needs at least -6dB before it can make a difference.

FXS (station) ports should perform this test using the --nohook option with the handset already off hook and the microphone muted.

FXO (trunk) ports will answer to an incoming call.

A series of tones will be played down the line to determine the ERL in several parts of the audio spectrum. You should avoid creating any other noise on the line while this test is running, or the results may be skewed.


The following options are available:
--help, -?
Show summary of options.
--card number
Explicitly select the card to test. Default is card 0.
--port number
Explicitly select the port to test. Default is port 0 of the card being tested.
Use this option for testing station (FXS) ports.
Take an FXO port off hook immediately. Don't wait for an incoming ring.
--bal1 value
--bal2 value
--bal3 value
Set codec hybrid balance registers. Only for hardware which explicitly supports that.
Enable the echo canceller.
--pg gain
Set codec play gain. Values may range from -12.0 to 12.0.
--rg gain
Set codec record gain. Values may range from -12.0 to 12.0.
--dial port
Dial out another port on the same card.
--dial port number
Dial number from port on the same card.
--scan file start end step
Scan the hybrid balance register settings from start to end in increments of step, recording the results to file. Only for hardware that explicitly permits setting these registers. Valid values for the start and end are in the range 0 - 255.
Automatically scan the codec balance values.
Proto handset mode.
Enable software loopback.
Enable the host based echo canceller.


Ron Lee, Peter Wintulich, David Rowe, Voicetronix <[email protected]>

This manual page was written by Ron <[email protected]>, for the Debian project (but may be used by others).