Andrew,I doubt there is ANYHING in the boxes that run close to 130V (I am not
sure about the sealed secluded DSL red box). Techs on daily basis cut and
displace the cables all over the box. You'd be surprised the sort of really
really messy boxes I have seen. Heck they probably knock off a cable or two as
they do a bad job at least 10-20% of the time. 130V probably would shock 10-20%
of Bell's stuff on daily basis :-) **I really wish the tech who knocked the
pair thought of it as 130V line and not go anywhere close to it.
But yeah the red label just says "Do Not Disconnect" like Stephan mentioned and
it's also done for Dry Loop DSL.
Stephan, I would be interested to know what Bell uses for more than 1 or 2 T1
if not copper wire? And wondering if that sort of service ends up in the
pedestal boxes on the streets at all because again I don't see much of good
service level to that. And thanks for your input.
Dave,I just got off the phone with the testing center lady tech and she checked
all the channels found nothing abnormal. She had to wait long time until she
got access to system ; Apparently they share a monitoring system and they have
to take turns. It's nice to know how they work :-). But she had no clue what
sort of tester they use and only thing should could tell me was along the lines
of that the test is placed at DSX Panel before the Pair Gain before the PRI
card....something like that. So, yeah it is at CO side. However, she doesn't
know what the tester looks and what kind of a noise it emits. The reason she
can see the problem is maybe because when she turns on her listening tool the
monitoring tool switches off like exactly when a channel connects.....
**To clarify, I am recording idle channel. "ztmonitor" tool when using Zaptel
or "dahdi_monitor" when using dahdi allows for this. The tool is very neat. I
am not sure if it's from Asterisk or Sangoma but allows for visual and for
recording of idle and non-idle channel. And yes, once the channel is up the
test is gone because now I don't hear the ear screeching noise but when channel
is down then the recording shows the Rx. I always use this tool to tune
analogue lines to milliwatt testers. Very easy and handy to almost perfect the
echo setting using this.
Problem is that this noise level should not exists on an idle channel. Indeed
PRI is to be 0/0 for Rx/Tx and analogue line is to NOT be at any time due to
known reasons.
Sample of readings:
Channel 4: root@pbx $ ztmonitor 4 -vvRx:
12 ( 12) Tx: 0 ( 0)Channel 6:
root@pbx $ ztmonitor 6 -vvRx: 0 ( 0) Tx: 0 ( 0)Channel 5:
root@pbx $ ztmonitor 5 -vv( # = Audio Level * = Max
Audio Hit )<----------------(RX <----------------(TX #*
Rx: 228 ( 228) Tx: 0
( 0)
So, I just recorded the Rx (pre-echo) and (post echo) on Channel 5 and sent
you. That has the highest level of noise right now and it indeed shows the #
sign which is volume VS like channel 4 that show (12 Rx) but really audio is
too low to qualify for even 1 # sign. Though it is still noise. This wasn't
there previously. All other channels are CLEAR CLEAR like they should always be
when there is no call.
Oh, and yeah of course they deny fault noting when our tech arrived everything
was fine but he reconnected as good measure :-)
Regards,Bruce
> Date: Fri, 18 Feb 2011 14:39:57 -0500
> From: [email protected]
> To: [email protected]
> Subject: Re: [on-asterisk] Noise on PRI link that is hearable - Really?! What
> does that mean technically? (Thought it's not possible)
>
> On Fri, Feb 18, 2011 at 2:04 PM, Bruce N <[email protected]> wrote:
>
> > I have sent you the file I recorded from the Tx stream and converted it to
> > a format that can play on VLC Media Player.
> >
> >
> Interesting. It's a sawtooth wave, not a sine wave. Not that it matters I
> guess but I would have bet on a square wave.
>
> The pitch variation only shows up when you play it in VLC. If you play it
> in Audacity, there's no pitch change. That solves one of the mysteries of
> "why would a Milliwatt have frequency drift".
>
> I can still see the reason for Milliwatt tests. Even though you've got a
> digital circuit, you could be putting that into a channel bank and
> terminating on analog circuits. I agree thought, I can't think of much use
> for it in testing a PRI. It's TDM, if your timing is ok, your frames are
> arriving intact and your signalling is setup right, you should have good
> voice quality. At least that's how I see it.
>
> I'd be interested to know how it works out. If I had to make a prediction,
> it would be that you tell Bell about the problem, the problem goes away and
> they deny changing anything on your circuit.
>
> One thing I'm not clear on is this: You say the problem goes away when the
> call is connected. Does the user hear this sound at all or are you
> recording idle channels? (I wouldn't have thought to try that or even though
> it was possible)
>
> Dave
