On 8/25/2018 10:50 AM, Paul wrote:
philo wrote:ice b
That article was written in the year 2000.

I no longer have a "convenient" access point, to take
a reading off the line hot. The demarc used to use those
nice brass screw terminals, and I could take a reading
off that easily. When the installer came in, he defeated
my easy access point. Now, I'd need to get into the
RJ11 junction box to take a reading.

Â*Â*Â* Paul


I have all the tools I need to get to the AT&T input and there is no
voltage there either dc or ac (other than a tiny stray voltage one
could expect being picked up on a long wire run)

Thank you for confirming my suspicion that there should be at least a
few volts there.

My frequency meter died years ago and I have no justification for
replacing it.

BTW: It is very sad that AT&T now has terrible service, they won't get
here until Thursday. When I had a problem two years ago from the time
I called until the time they came out and had it all fixed was 90
minutes.

I spent more time than that just on the phone.

Here's an example of the ADSL startup sequence.

https://s22.postimg.cc/56dmtrxlt/DSL...r_Page_148.gif

The customer premise end sends "phase reversals every 16ms".

Which, roughly translated, is a 60Hz square wave ?

Only then does the AT&T end enable its line driver,
and send C-TONES.

Initially I tried Google searches on "pilot tone" or similar,
thinking there was always a signal on the line. It turns out,
that the frequency bins in the upstream and downstream have
one bin which operates at constant amplitude and is not
modulated. And that's a pilot tone that the DSP can use in
the frequency domain. But all that stuff only exists when everything
is up and operational.

Whereas the initiation sequence is much more crude.
And starts with silence. it's quite possible your
modem "goes first".

Â*Â* Paul

What made me distrust the AT&T diagnostic was their presumption that
their router was bad if they could not communicate with it.
Though it could of course be bad, their line could just as well have
been open.

The second person I talked to understood the logic and I did not have to
waste too much time on the phone before she agreed that a tech needed to
be sent out.

The first person I talked to had me on the phone for an hour running
various tests.

Oh well, someone will hopefully be here on Thursday. I will probably not
check back in here until my service is restored