[Asterisk-Users] Woodpeckers Revisited

[Michael Welter]

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!




-- 
Michael Welter
Introspect Telephony Corp.
Denver, Colorado
+1 303 674 2575
mike at introspect.com
www.introspect.com