[asterisk-users] fxotune: Unable to set impedance

[Tzafrir Cohen]

Hi

On Thu, Jul 10, 2008 at 01:45:02AM +0200, Udo Schacht-Wiegand wrote:
> Hi,
> 
> we have a strong echo on an Astribank running on
> Asterisk 1.2.29-BRIstuffed-0.3.0-PRE-1y-s
> The echo is on the opposite site of the analogue phones
> connected to the Astribank.

So this is an FXS module.

> 
> I tried to use fxotune. It is a production system, so I cannot
> shutdown Asterisk for long, I did:
> 
> CLI> zap destroy channel 120
> 
> and then:
> 
> # fxotune -vvv -i -b 120 -e 120
> Tuning module /dev/zap/120
> Unable to set impedance on fd 4
> Failure!
> Unable to tune 1 devices, even though those devices are present
> 
> What can I do to use fxotune?

fxotune only works with FXO modules. It helps reducing the generated
echo by tuning some knobs on the analog/digital conversion chip of the
FXO port. Those knobs are rather specific to that chip.

For starters, do you have echo cancellation enabled?

  asterisk -rx 'zap show channel 120' | grep 'Echo'

-- 
               Tzafrir Cohen
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