[Asterisk-Users] tuning an x100p in Australia for echocancellation

[Trevor G. Hammonds]

James Harper wrote on Saturday, 14 January 2006 3:17 PM:

>> Are the AU telephone standards the same as US standards (eg, 600 ohm
>> impedence)?
> 
> This is a question I've been trying to answer too. I had a look at
> the standard phone that Telstra would provide to customers about 5
> years ago, and it has an impedence switch on the bottom to toggle
> between 'NORM' and '600', which suggests that 600 ohms isn't the
> normal impedence.    
> 
> On an au configuration example for the pap2 I have seen on the web,
> the impedence is set to '220+820||120nF', which suggests that our
> standard here isn't 600.  

Indeed, the AU standard is just what you quoted.  It is complex impedance.
A 220-ohm resistive load connected in series to an 820-ohm resistive load
which is connected in parallel with a 120nF cap.  

>>> Does anyone know of an addon device which can do impedence matching
>>> on the line, or of a modification to the
> card

I don't know if this will help you, but you may do a Google search for the
ETAL P3324 and P3356.  I believe they may handle the impedance matching you
need.

Here is a link to a PDF spec sheets:
http://www.ibselectronics.com/pdf/pa/etal/line_P3324.pdf
http://www.ibselectronics.com/pdf/pa/etal/line_P3356.pdf


		-- Trevor Hammonds