asterisk users - Aug 2005 - Send 12khz or 16khz billing pulse through fxs

Hi,

I search how to send a 12khz or 16khz to a payphone throught and FXS port.

It seem that asterisk sample is 8khz but in the documentation of si3215
(the slic of FXS module) samples rates is 16khz.
Anyone can help me ?

Thanks


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WEB : http://www.jeremy-salmon.org

Jeremy Salmon wrote:
> Hi,
> 
> I search how to send a 12khz or 16khz to a payphone throught and FXS port.
Not going to happen.
> It seem that asterisk sample is 8khz but in the documentation of si3215
> (the slic of FXS module) samples rates is 16khz.
Except that currently Asterisk deals with every at 8Khz.  There have been
conversations about changing this, but nothing has eventuated.
> Anyone can help me ?
Um...well, not me at least :)

Is ther no way you could pitch it down an octave and then back up at the other
end?

Maybe you could get away with using the harmonics of a lower signal, but I
think that there would be low pass filters somewhere along the line that would
kill it.   Maybe not though...

:)

-- 
Cheers,

Matt Riddell
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On Tuesday 16 August 2005 09:12, Jeremy Salmon wrote:
> I search how to send a 12khz or 16khz to a payphone throught and FXS port.
>
> It seem that asterisk sample is 8khz but in the documentation of si3215
> (the slic of FXS module) samples rates is 16khz.
> Anyone can help me ?
Basic sampling theory -- you sample at 2x your max acceptable rate.  A 16kHz 
sine wave, when sampled at 16kHz, will appear identical to an 8kHz sine wave, 
as will a 24, 32, 40, 48kHz... 

In short: not possible.  You need something external to inject that tone, or 
you need to redesign your FXS part.  :-)

-A.