[Asterisk-Users] Woodpeckers

[Steve Underwood]

Hi Michael,

Michael Welter wrote:

> I live at 8000' in the Rockies.  We have lots of woodpeckers--they 
> especially love to drill 4" holes in the north side of my house.
>
> They also like to drill on the arial telephone cables.  Water then 
> gets into the cable and causes a partial grounding on the circuits.  
> This causes 60Hz hum to be heard on the line as well as a loss of 
> amplitude.  Qwest says tough s--t.
>
> All three of my POTS lines have hum.  They are connected to an Adtran 
> 750 and my asterisk system (a testbench for commercial endeavors.)
>
> The hum has always been bad on my end.  Since I installed *, several 
> of my callers have remarked about the hum.
>
> So here's the question:  Could a notch filter of sorts be installed in 
> the codecs I use?  Filter-out everything between, say, 55 and 65Hz?
>
> Alternatively, is there a feature on the Adtran FXO card that deals 
> with this?


Notching may not be that effective, as it will not deal with the 
harmonics. The analogue to digital converter should already be filtering 
below 300Hz, so you probably have quite a lot of hum if it gets through 
that. There isn't much you can do to eliminate the hum your callers 
hear. For your own hum, additional filtering may be beneficial. This 
could be implemented by analogue or digital filters. Simple RC analogue 
filters probably would not be sharp enough to give much benefit, so you 
would need a more complex active analogue filter. A digital filter would 
require no hardware changes, but you need someone who knows what they 
are doing to implement it for you.

Regards,
Steve