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AT&T Broadband ?



 
 
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  #1  
Old August 25th 18, 11:59 AM posted to alt.comp.hardware
philo
external usenet poster
 
Posts: 1,309
Default AT&T Broadband ?

My service went out and AT&T ran a diagnostic and said my router went
out and they would send a new one. While waiting I decided to try my
router at a neighbor's house who also has AT&T broadband and it worked
OK there so I called them back and they will eventually send a tech out
to repair the line.

At the wires coming into my house I only got a reading of 2mv ac

I know back in the days of landline and DSL the voltage should have been
48vdc as best as I recall...however I don't know what a normal voltage
would be for broadband. Anyone here have that knowledge?

Thanks


Fortunately I can tether my machine to my smartphone to post this.
  #2  
Old August 25th 18, 01:10 PM posted to alt.comp.hardware
Mike S
external usenet poster
 
Posts: 78
Default AT&T Broadband ?

On 8/25/2018 3:59 AM, philo wrote:
My service went out and AT&T ran a diagnostic and said my router went
out and they would send a new one. While waiting I decided to try my
router at a neighbor's house who also has AT&T broadband and it worked
OK there so I called them back and they will eventually send a tech out
to repair the line.

At the wires coming into my house I only got a reading of 2mv ac

I know back in the days of landline and DSL the voltage should have been
48vdc as best as I recall...however I don't know what a normal voltage
would be for broadband. Anyone here have that knowledge?

Thanks


Fortunately I can tether my machine to my smartphone to post this.


Do you have phone service on that phone line? If not it may be a 'dry
loop', in which case I'd expect you'd see a lot less DC, if any.

"A dry loop is an unconditioned leased pair of telephone line from a
telephone company. The pair does not provide dial tone or battery
(continuous electric potential), as opposed to a wet pair, a line
usually without dial tone but with battery."

https://en.wikipedia.org/wiki/Dry_loop
  #3  
Old August 25th 18, 02:06 PM posted to alt.comp.hardware
Paul[_28_]
external usenet poster
 
Posts: 1,467
Default AT&T Broadband ?

philo wrote:
My service went out and AT&T ran a diagnostic and said my router went
out and they would send a new one. While waiting I decided to try my
router at a neighbor's house who also has AT&T broadband and it worked
OK there so I called them back and they will eventually send a tech out
to repair the line.

At the wires coming into my house I only got a reading of 2mv ac

I know back in the days of landline and DSL the voltage should have been
48vdc as best as I recall...however I don't know what a normal voltage
would be for broadband. Anyone here have that knowledge?

Thanks


Fortunately I can tether my machine to my smartphone to post this.


http://www.dslreports.com/forum/r412...for-DSL-to-run

"Since ADSL can be deployed on a dry pair with no DC bias whatsoever,
it's not too surprising that it shows so low."

If POTS service has specifically been removed, there's
no reason for -48V to be on the line. Neither would
you expect the occasional 180VAC at 25Hz for ringing
voltage.

If you had combo service, the "phone filter" passes DC to 8KHz
to the phone. The ADSL needs the 25KHz or higher part. The phone
filter is necessary, so the higher frequency signals don't
alias down into the voice band.

ADSL starts at 25KHz and extends upwards (1.5MHz or higher).
It depends on the standard involved, as to how high the
highest frequency is.

You expect the launch amplitude to be significant,
because the line loss could be 50dB or more by the time
it gets to the other end. When you have a pedestal at the
corner serving ADSL, then not as much signal might be
needed (the box may not be designed to drive 18000 feet
of wire, but designed for a shorter max distance).

https://www.eetimes.com/document.asp?doc_id=1224781

"Assuming a line impedance of 100 ohms, the resulting
RMS voltage is 3.31 volts and the RMS current is 33 mA."

And notice they're using transformers and differential
circuits for it too. Wouldn't be good for DC to be
shoved through the transformer (saturation issue).

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.

Paul
  #4  
Old August 25th 18, 02:39 PM posted to alt.comp.hardware
philo
external usenet poster
 
Posts: 1,309
Default AT&T Broadband ?

On 8/25/2018 7:10 AM, Mike S wrote:

Fortunately I can tether my machine to my smartphone to post this.


Do you have phone service on that phone line? If not it may be a 'dry
loop', in which case I'd expect you'd see a lot less DC, if any.

"A dry loop is an unconditioned leased pair of telephone line from a
telephone company. The pair does not provide dial tone or battery
(continuous electric potential), as opposed to a wet pair, a line
usually without dial tone but with battery."

https://en.wikipedia.org/wiki/Dry_loop


I do not have a land line so suspect this is not a dry loop, thank you
  #5  
Old August 25th 18, 02:47 PM posted to alt.comp.hardware
philo
external usenet poster
 
Posts: 1,309
Default AT&T Broadband ?

On 8/25/2018 8:06 AM, Paul wrote:
philo wrote:
My service went out and AT&T ran a diagnostic and said my router went
out and they would send a new one. While waiting I decided to try my
router at a neighbor's house who also has AT&T broadband and it worked
OK there so I called them back and they will eventually send a tech
out to repair the line.

At the wires coming into my house I only got a reading of 2mv ac

I know back in the days of landline and DSL the voltage should have
been 48vdc as best as I recall...however I don't know what a normal
voltage would be for broadband. Anyone here have that knowledge?

Thanks


Fortunately I can tether my machine to my smartphone to post this.


http://www.dslreports.com/forum/r412...for-DSL-to-run


Â*Â* "Since ADSL can be deployed on a dry pair with no DC bias whatsoever,
Â*Â*Â* it's not too surprising that it shows so low."

If POTS service has specifically been removed, there's
no reason for -48V to be on the line. Neither would
you expect the occasional 180VAC at 25Hz for ringing
voltage.

If you had combo service, the "phone filter" passes DC to 8KHz
to the phone. The ADSL needs the 25KHz or higher part. The phone
filter is necessary, so the higher frequency signals don't
alias down into the voice band.

ADSL starts at 25KHz and extends upwards (1.5MHz or higher).
It depends on the standard involved, as to how high the
highest frequency is.

You expect the launch amplitude to be significant,
because the line loss could be 50dB or more by the time
it gets to the other end. When you have a pedestal at the
corner serving ADSL, then not as much signal might be
needed (the box may not be designed to drive 18000 feet
of wire, but designed for a shorter max distance).

https://www.eetimes.com/document.asp?doc_id=1224781

Â*Â* "Assuming a line impedance of 100 ohms, the resulting
Â*Â*Â* RMS voltage is 3.31 volts and the RMS current is 33 mA."

And notice they're using transformers and differential
circuits for it too. Wouldn't be good for DC to be
shoved through the transformer (saturation issue).

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* 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.




  #6  
Old August 25th 18, 04:50 PM posted to alt.comp.hardware
Paul[_28_]
external usenet poster
 
Posts: 1,467
Default AT&T Broadband ?

philo wrote:
On 8/25/2018 8:06 AM, Paul wrote:
philo wrote:
My service went out and AT&T ran a diagnostic and said my router went
out and they would send a new one. While waiting I decided to try my
router at a neighbor's house who also has AT&T broadband and it
worked OK there so I called them back and they will eventually send a
tech out to repair the line.

At the wires coming into my house I only got a reading of 2mv ac

I know back in the days of landline and DSL the voltage should have
been 48vdc as best as I recall...however I don't know what a normal
voltage would be for broadband. Anyone here have that knowledge?

Thanks


Fortunately I can tether my machine to my smartphone to post this.


http://www.dslreports.com/forum/r412...for-DSL-to-run


"Since ADSL can be deployed on a dry pair with no DC bias whatsoever,
it's not too surprising that it shows so low."

If POTS service has specifically been removed, there's
no reason for -48V to be on the line. Neither would
you expect the occasional 180VAC at 25Hz for ringing
voltage.

If you had combo service, the "phone filter" passes DC to 8KHz
to the phone. The ADSL needs the 25KHz or higher part. The phone
filter is necessary, so the higher frequency signals don't
alias down into the voice band.

ADSL starts at 25KHz and extends upwards (1.5MHz or higher).
It depends on the standard involved, as to how high the
highest frequency is.

You expect the launch amplitude to be significant,
because the line loss could be 50dB or more by the time
it gets to the other end. When you have a pedestal at the
corner serving ADSL, then not as much signal might be
needed (the box may not be designed to drive 18000 feet
of wire, but designed for a shorter max distance).

https://www.eetimes.com/document.asp?doc_id=1224781

"Assuming a line impedance of 100 ohms, the resulting
RMS voltage is 3.31 volts and the RMS current is 33 mA."

And notice they're using transformers and differential
circuits for it too. Wouldn't be good for DC to be
shoved through the transformer (saturation issue).

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.

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".

Paul
  #7  
Old August 26th 18, 04:41 PM posted to alt.comp.hardware
philo
external usenet poster
 
Posts: 1,309
Default AT&T Broadband ?

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
  #8  
Old August 26th 18, 10:17 PM posted to alt.comp.hardware
John McGaw
external usenet poster
 
Posts: 732
Default AT&T Broadband ?

On 8/26/2018 11:41 AM, philo wrote:
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*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


FWIW, I have AT&T uVerse broadband. Each time I've had an isolated outage
(meaning one affecting only my service, not like when head-end equipment
failed) the problem has been the cables and each time the 'service' people
at AT&T determined that the problem was _absolutely_ with my modem.

The first time they insisted that I swap modems. After that phone call I
took a walk up the street and located the point where the cable had broken.
The next time I took the walk _first_ and located the break. The third time
I located the point where it had been cut deliberately because the wire
tech from the second call had done a sloppy job of installing new cable and
put the splice in a more convenient location at head height on the pole
which somebody decided would be entertaining to rip out.
  #9  
Old August 26th 18, 11:47 PM posted to alt.comp.hardware
Mike S
external usenet poster
 
Posts: 78
Default AT&T Broadband ?

On 8/26/2018 2:17 PM, John McGaw wrote:
On 8/26/2018 11:41 AM, philo wrote:
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*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


FWIW, I have AT&T uVerse broadband. Each time I've had an isolated
outage (meaning one affecting only my service, not like when head-end
equipment failed) the problem has been the cables and each time the
'service' people at AT&T determined that the problem was _absolutely_
with my modem.

The first time they insisted that I swap modems. After that phone call I
took a walk up the street and located the point where the cable had
broken. The next time I took the walk _first_ and located the break. The
third time I located the point where it had been cut deliberately
because the wire tech from the second call had done a sloppy job of
installing new cable and put the splice in a more convenient location at
head height on the pole which somebody decided would be entertaining to
rip out.


Makes me wonder what different sectors of their repair department think
of one another.
  #10  
Old August 31st 18, 01:44 AM posted to alt.comp.hardware
philo
external usenet poster
 
Posts: 1,309
Default AT&T Broadband ? Resolved

On 08/25/2018 05:59 AM, philo wrote:
My service went out and AT&T ran a diagnostic and said my router went
out and they would send a new one. While waiting I decided to try my
router at a neighbor's house who also has AT&T broadband and it worked
OK there so I called them back and they will eventually send a tech out
to repair the line.

At the wires coming into my house I only got a reading of 2mv ac

I know back in the days of landline and DSL the voltage should have been
48vdc as best as I recall...however I don't know what a normal voltage
would be for broadband. Anyone here have that knowledge?

Thanks


Fortunately I can tether my machine to my smartphone to post this.




AT&T got here and checked my line all good.

The previous tech who was here 18 months ago replaced the router only
and the guy who was here said the power supply (with has a built in UPS)
is not compatible with it even though it had been working previously.


At any rate he replaced the router and it's DC supply and all is good
 




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