[Asterisk-Users] Woodpeckers Revisited

[Steve Underwood]

Some people have some really wacky ideas about how sampled systems work :-)

Regards,
Steve


Michael Welter wrote:

> Just when I thought I couldn't be wrong, I was wrong.  We have 
> woodpeckers that drill into the arial telephone cables, and water 
> seeps through the holes and partially grounds the tip and/or ring 
> wires causing hum.  I thought the hum/buz on my lines was a telco 
> problem.
>
> The Qwest HQ noise team assures me that my lines are within spec.  
> Sure enough, when I listen on the test set the lines are clear.
>
> The lines terminate at an Adtran 750 channel bank on my * system.  
> When I reconnect the lines to the channel bank and make a call, I get 
> the hum/buz noise. I have replaced every Adtran component (even the 
> chassis), but the hum/buz stays with the lines.
>
> From the CO we have a digital fibre optic system which terminates at a 
> neighborhood cabinet.  From there, analog copper cables distribute 
> service to the houses.  I'm suspecting that the digital-to-analog 
> process doesn't give a smooth analog signal but rather a 
> "stair-stepped" signal, with each step 1/8000 sec in duration (I wish 
> I had a 'scope to confirm this.)  The human ear can't hear this 
> stair-stepped signal, so it's ok for POTS use.
>
> However, when I put this stair-stepped signal to the channel bank, it 
> converts it back into a digital signal.  I'm thinking that, because 
> it's not a smoothed signal, the analog-to-digital process injects hum 
> and buz.  Does _anyone_ have more information on this?
>
> In the meantime I've had an ISDN circuit installed so as to have 
> digital all the way to the * box.  However, I can't get the ASUSCOM 
> ISDNLink card to work with ISDN4Linux :-(
>
> Cheers,
> Mike
>
> P.S.  The woodpeckers are still eating my house.  There is a nest is 
> an exterior wall which is driving my cats nuts!