measerl - Measure the echo-return loss on Voicetronix telephony
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
The following options are available:
Show summary of options.
Explicitly select the card to test. Default is card 0.
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
Set codec hybrid balance registers. Only for hardware which
explicitly supports that.
--ec Enable the echo canceller.
Set codec play gain. Values may range from -12.0 to 12.0.
Set codec record gain. Values may range from -12.0 to 12.0.
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.
--loop Enable software loopback.
Enable the host based echo canceller.
Ron Lee, Peter Wintulich, David Rowe, Voicetronix
This manual page was written by Ron <email@example.com>, for the Debian
project (but may be used by others).