[Asterisk-Users] X100P noise on ADSL line.

[WipeOut]

Stewart Nelson wrote:

>> I have a single analog line coming into the house.. This line is for 
>> my ADSL and home phone.. My Asterisk box uses an X100P card to 
>> connect to the analog line.. I have a microfilter on the line etc.. 
>> The rest of my phone system works inbound and outbound calls via a 
>> VoIP provider over the ADSL line..
>>
>> The problem I am having is that the X100P seems to introduce a lot of 
>> noise on the line when it its connected to the "phone" socket on the 
>> microfilter and this causes the ADSL quality to drop quite badly.. 
>> When the X100P is not connected I have a signal to noise ratio of 
>> 29dB downstream and 30dB upstream (this stays the same when I connect 
>> an analog phone) when I connect the X100P the SNR drops to 12dB 
>> downstream and 30dB upstream.. At 12dB I get a large number of CRC 
>> errors and errored seconds on the ADSL connection..
>>
>> Anyone got any ideas why the X100P would cause this kind of 
>> deterioration?
>
>
> I suspect that it's not the X100P, but noise from your PC's power
> supply or motherboard.
>
> 1. With the X100P connected, cycle power to the ADSL modem so it
>   renegotiates.  If the noise is relatively narrowband, the
>   noisy bins will be avoided and the SNR should improve.
>
> 2. Try two filters in cascade.  Plug the new filter into the
>   phone socket of the existing filter, and the X100P into the
>   phone socket of the new one.
>
> 3. Try a long (25-foot or 50-foot) cord between the filter
>   and the X100P.  Try winding the cord into a coil about
>   8 inches in diameter.
>
> 4. Try a ferrite clamp-on core, such as those used to suppress
>   noise in car stereo systems, around the cord from the X100P.
>   If the core has a sufficiently large opening, make a two or
>   three turn coil with the phone cord.
>
> 5. Try putting the X100P in a different PCI slot, so it is as
>   far as possible from noisy boards such as video.
>
> Good luck,
>
> Stewart
>
>
Thanks for the suggestions..

I have tried another microfilter, the long cable and the cascaded 
microfilter and all made no difference at all..

I dont think it is the microfilter or the internal house cabling.. Also 
the fact that a standard analog phone doesn't do it also points to the 
X100P..

I can't move the X100P to another PCI slot because I only have two in 
this PC and the other has a TDM400P.. The only thing I could do is setup 
a completely new PC with Asterisk and go from there..

Guess this means that as usual I have bumped into a problem that no one 
else has (of knows they have :) )..

Later..