[asterisk-users] Noise on FXS ports (Sangoma)

[Jorge Mendoza]

Stephen Bosch wrote:
> Stephen Bosch wrote:
>   
>> Stephen Bosch wrote:
>>     
>>> Hi:
>>>
>>> I have a Sangoma A200 card installed in a server with two FXO modules
>>> and one FXS module.
>>>
>>> Analog sets connected to the FXS module have a "squeaky static" -- it's
>>> like static mixed with the sound of someone vigorously cleaning a window
>>> a few doors down.
>>>
>>> In other words, it's not a classic static noise, but it is noise, and
>>> it's distracting. Remote callers can hear this noise.
>>>
>>> I have, by turns:
>>>
>>> - Tested the line with the same analog sets plugged in at the
>>> demarcation point. No noise. (None of the SIP devices in this
>>> configuration have this noise for outgoing calls, so I'm sure it's got
>>> something to do with the FXS module).
>>>
>>> - Plugged the known good analog sets straight into the server
>>>
>>> - Moved the FXS module off the REMORA daughtercard to the main card
>>>
>>> - Replaced the FXS module with a new one
>>>
>>> - Run the server off of battery power, to see if the noise is garbage
>>> leaking in off the AC
>>>
>>> - Turned off the PoE midspan
>>>
>>> The next thing I'm going to try is turning off the switch it's plugged
>>> into. When that is done, I'll have done everything short of move the
>>> server to a different location.
>>>       
>> Maybe the power supply is generating this crap.
>>
>> Hmn. I'm going to test this hypothesis.
>>     
>
> Okay -- that didn't work. I swapped the power supply out with a better
> one, and even disconnected the extra ventilation fan. The noise is
> different but still there.
>
> To those with experience with FXS modules, I welcome your input.
>
> -Stephen-
>
>   
Never experienced with FXS modules on a PC with  Asterisk. However we 
have experienced that kind of problems on legacy PBX without a good 
ground. If you replace the system with a analogue set and have not 
noise, then a ground current is generated in your system, probably 
originated at FXO side. Have you tested the PC isolated, with not lines 
and not switches? just the FXS calling the voicemail?

Hope this helps

Jorge