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uk.telecom.broadband (UK broadband) (uk.telecom.broadband) Discussion of broadband services, technology and equipment as provided in the UK. Discussions of specific services based on ADSL, cable modems or other broadband technology are also on-topic. Advertising is not allowed.

very slow connection yet high SNR



 
 
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  #1  
Old May 22nd 12, 07:43 AM posted to uk.telecom.broadband
Gordon Freeman
external usenet poster
 
Posts: 39
Default very slow connection yet high SNR

Over the last few days my ADSL router has been connecting slower and slower
each day, basically halving each day - I used to get 2-3 Mbit, then at the
weekend I got 1152kbit on Saturday, 512K on Sunday and now 288Kbit on
Monday. But the SNR has gone up and up! Since there doesn't seem to be a
problem with line quality, I wonder could it be that my router is failing?

was:

d/s SNR: 9.3dB, u/s SNR: 11.0dB
d/s Attenuation: 57.6dB, u/s Attenuation: 31.5dB
d/s Data Rate: 3072kbps, u/s Data Rate: 448kbps

then

d/s SNR: 25.9dB, u/s SNR: 12.0dB
d/s Attenuation: 59.1dB, u/s Attenuation: 31.5dB
d/s Data Rate: 576kbps, u/s Data Rate: 448kbps

now

d/s SNR: 29.2dB, u/s SNR: 11.0dB
d/s Attenuation: 58.1dB, u/s Attenuation: 31.5dB
d/s Data Rate: 288kbps, u/s Data Rate: 448kbps


  #2  
Old May 22nd 12, 08:56 AM posted to uk.telecom.broadband
Mark
external usenet poster
 
Posts: 165
Default very slow connection yet high SNR

On Tue, 22 May 2012 06:43:20 +0000 (UTC), Gordon Freeman
wrote:

Over the last few days my ADSL router has been connecting slower and slower
each day, basically halving each day - I used to get 2-3 Mbit, then at the
weekend I got 1152kbit on Saturday, 512K on Sunday and now 288Kbit on
Monday. But the SNR has gone up and up! Since there doesn't seem to be a
problem with line quality, I wonder could it be that my router is failing?

was:

d/s SNR: 9.3dB, u/s SNR: 11.0dB
d/s Attenuation: 57.6dB, u/s Attenuation: 31.5dB
d/s Data Rate: 3072kbps, u/s Data Rate: 448kbps

then

d/s SNR: 25.9dB, u/s SNR: 12.0dB
d/s Attenuation: 59.1dB, u/s Attenuation: 31.5dB
d/s Data Rate: 576kbps, u/s Data Rate: 448kbps

now

d/s SNR: 29.2dB, u/s SNR: 11.0dB
d/s Attenuation: 58.1dB, u/s Attenuation: 31.5dB
d/s Data Rate: 288kbps, u/s Data Rate: 448kbps


Have you rebooted your router? Your problem could be just be bursts
of noise that caused your router to sync at a lower speed. When the
noise goes away you see a higher SNRM.

If this doesn't fix it then follow the usual procedure for
troublehooting speed problems.

  #3  
Old May 22nd 12, 09:05 AM posted to uk.telecom.broadband
Graham J
external usenet poster
 
Posts: 620
Default very slow connection yet high SNR

Gordon Freeman wrote:
Over the last few days my ADSL router has been connecting slower and slower
each day, basically halving each day - I used to get 2-3 Mbit, then at the
weekend I got 1152kbit on Saturday, 512K on Sunday and now 288Kbit on
Monday. But the SNR has gone up and up! Since there doesn't seem to be a
problem with line quality, I wonder could it be that my router is failing?

was:

d/s SNR: 9.3dB, u/s SNR: 11.0dB
d/s Attenuation: 57.6dB, u/s Attenuation: 31.5dB
d/s Data Rate: 3072kbps, u/s Data Rate: 448kbps

then

d/s SNR: 25.9dB, u/s SNR: 12.0dB
d/s Attenuation: 59.1dB, u/s Attenuation: 31.5dB
d/s Data Rate: 576kbps, u/s Data Rate: 448kbps

now

d/s SNR: 29.2dB, u/s SNR: 11.0dB
d/s Attenuation: 58.1dB, u/s Attenuation: 31.5dB
d/s Data Rate: 288kbps, u/s Data Rate: 448kbps


I have only ever known one router fail, and that was after a lightning
stike. But your ISP will insist that you try another - so you might as
well admit defeat and borrow one ...

You should monitor the connection to see when it drops. Get
"Routerstats" so you can automate the monitoring.

The increase in SNR margin you show suggests that the phone line is
becoming very noisy, but perhaps only on an intermittent basis. Try a
"quiet line test" - also remove any phone extensions and connect the
router via a microfilter direct to the test point in the master socket.

If you can see when the connection drops, try the "quiet line test" at
that moment - you might hear the noise that has caused the drop. If so,
report it to your telephone service provider as a voice fault - don't
mention broadband, it will only confuse them!

Again, I have only ever known one microfilter to fail (and it went dead
short across the voice connection) but your ISP will insist that you try
another ....

--
Graham J




  #4  
Old May 22nd 12, 09:15 AM posted to uk.telecom.broadband
Peter Able
external usenet poster
 
Posts: 114
Default very slow connection yet high SNR


"Mark" wrote in message
...
On Tue, 22 May 2012 06:43:20 +0000 (UTC), Gordon Freeman
wrote:

Over the last few days my ADSL router has been connecting slower and
slower
each day, basically halving each day - I used to get 2-3 Mbit, then at the
weekend I got 1152kbit on Saturday, 512K on Sunday and now 288Kbit on
Monday. But the SNR has gone up and up! Since there doesn't seem to be a
problem with line quality, I wonder could it be that my router is failing?

was:

d/s SNR: 9.3dB, u/s SNR: 11.0dB
d/s Attenuation: 57.6dB, u/s Attenuation: 31.5dB
d/s Data Rate: 3072kbps, u/s Data Rate: 448kbps

then

d/s SNR: 25.9dB, u/s SNR: 12.0dB
d/s Attenuation: 59.1dB, u/s Attenuation: 31.5dB
d/s Data Rate: 576kbps, u/s Data Rate: 448kbps

now

d/s SNR: 29.2dB, u/s SNR: 11.0dB
d/s Attenuation: 58.1dB, u/s Attenuation: 31.5dB
d/s Data Rate: 288kbps, u/s Data Rate: 448kbps


Have you rebooted your router? Your problem could be just be bursts
of noise that caused your router to sync at a lower speed. When the
noise goes away you see a higher SNRM.

If this doesn't fix it then follow the usual procedure for
troublehooting speed problems.


You say "very slow connection yet high SNR" as though this is a
contradiction in terms. It isn't. If the exchange equipment doesn't like
what it is hearing then the required SNR is raised, resulting in a lower
data rate.

Has your d/s Attenuation always been 58dB attenuation? Can you hear any
problems when using the telephone line (crackling/humming/quiet speech)?
Have you an alternate modem you could try? Is there any pattern in the
drop-outs (time-of-day)? Do you switch the modem off at night?

PA


  #5  
Old May 22nd 12, 09:56 AM posted to uk.telecom.broadband
The Natural Philosopher
external usenet poster
 
Posts: 2,728
Default very slow connection yet high SNR

Gordon Freeman wrote:
Over the last few days my ADSL router has been connecting slower and slower
each day, basically halving each day - I used to get 2-3 Mbit, then at the
weekend I got 1152kbit on Saturday, 512K on Sunday and now 288Kbit on
Monday. But the SNR has gone up and up! Since there doesn't seem to be a
problem with line quality, I wonder could it be that my router is failing?


Look again. The signal is almost non existent and varying at 57.6-59
-58dB att...I would say you have a wiring problem or a line fault.




was:

d/s SNR: 9.3dB, u/s SNR: 11.0dB
d/s Attenuation: 57.6dB, u/s Attenuation: 31.5dB
d/s Data Rate: 3072kbps, u/s Data Rate: 448kbps

then

d/s SNR: 25.9dB, u/s SNR: 12.0dB
d/s Attenuation: 59.1dB, u/s Attenuation: 31.5dB
d/s Data Rate: 576kbps, u/s Data Rate: 448kbps

now

d/s SNR: 29.2dB, u/s SNR: 11.0dB
d/s Attenuation: 58.1dB, u/s Attenuation: 31.5dB
d/s Data Rate: 288kbps, u/s Data Rate: 448kbps




--
To people who know nothing, anything is possible.
To people who know too much, it is a sad fact
that they know how little is really possible -
and how hard it is to achieve it.
  #6  
Old May 22nd 12, 07:56 PM posted to uk.telecom.broadband
Andy Champ
external usenet poster
 
Posts: 187
Default very slow connection yet high SNR

On 22/05/2012 09:56, The Natural Philosopher wrote:
Gordon Freeman wrote:
Over the last few days my ADSL router has been connecting slower and
slower each day, basically halving each day - I used to get 2-3 Mbit,
then at the weekend I got 1152kbit on Saturday, 512K on Sunday and now
288Kbit on Monday. But the SNR has gone up and up! Since there doesn't
seem to be a problem with line quality, I wonder could it be that my
router is failing?


Look again. The signal is almost non existent and varying at 57.6-59
-58dB att...I would say you have a wiring problem or a line fault.




was:

d/s SNR: 9.3dB, u/s SNR: 11.0dB
d/s Attenuation: 57.6dB, u/s Attenuation: 31.5dB
d/s Data Rate: 3072kbps, u/s Data Rate: 448kbps
then
d/s SNR: 25.9dB, u/s SNR: 12.0dB
d/s Attenuation: 59.1dB, u/s Attenuation: 31.5dB
d/s Data Rate: 576kbps, u/s Data Rate: 448kbps

now
d/s SNR: 29.2dB, u/s SNR: 11.0dB
d/s Attenuation: 58.1dB, u/s Attenuation: 31.5dB
d/s Data Rate: 288kbps, u/s Data Rate: 448kbps





FFS. I prefer bottom post. Top post I can live with. But middle post?

Anyway... I have this:

ADSL Link Downstream Upstream
Connection Speed 3648 kbps 640 kbps
Line Attenuation 57.0 db 31.5 db
Noise Margin 6.2 db 11.0 db

My attenuation figures aren't a lot better than his, yet it goes, albeit
slowly. Maybe he has head crabs on the line?

Incidentally, Graham, this is my new router. The old one died, and
AFAIK it wasn't lightning.

Andy
  #7  
Old May 22nd 12, 08:34 PM posted to uk.telecom.broadband
Graham J
external usenet poster
 
Posts: 620
Default very slow connection yet high SNR

Andy Champ wrote:
On 22/05/2012 09:56, The Natural Philosopher wrote:
Gordon Freeman wrote:
Over the last few days my ADSL router has been connecting slower and
slower each day, basically halving each day - I used to get 2-3 Mbit,
then at the weekend I got 1152kbit on Saturday, 512K on Sunday and now
288Kbit on Monday. But the SNR has gone up and up! Since there doesn't
seem to be a problem with line quality, I wonder could it be that my
router is failing?


Look again. The signal is almost non existent and varying at 57.6-59
-58dB att...I would say you have a wiring problem or a line fault.




was:

d/s SNR: 9.3dB, u/s SNR: 11.0dB
d/s Attenuation: 57.6dB, u/s Attenuation: 31.5dB
d/s Data Rate: 3072kbps, u/s Data Rate: 448kbps
then
d/s SNR: 25.9dB, u/s SNR: 12.0dB
d/s Attenuation: 59.1dB, u/s Attenuation: 31.5dB
d/s Data Rate: 576kbps, u/s Data Rate: 448kbps

now
d/s SNR: 29.2dB, u/s SNR: 11.0dB
d/s Attenuation: 58.1dB, u/s Attenuation: 31.5dB
d/s Data Rate: 288kbps, u/s Data Rate: 448kbps





FFS. I prefer bottom post. Top post I can live with. But middle post?

Anyway... I have this:

ADSL Link Downstream Upstream
Connection Speed 3648 kbps 640 kbps
Line Attenuation 57.0 db 31.5 db
Noise Margin 6.2 db 11.0 db

My attenuation figures aren't a lot better than his, yet it goes, albeit
slowly. Maybe he has head crabs on the line?

Incidentally, Graham, this is my new router. The old one died, and AFAIK
it wasn't lightning.


Bound to be one, I suppose, that dies a natural death.

Your figures are about as good as one can expect.

The OP started with d/s attenuation 57.6dB and this did indeed get a
little worse, to 59.1 dB. Normally I don't see more than +/- 0.5dB
change in attenuation from day to day. So the 1.5dB change is a little
worrying, but probably not the direct cause of the problem.

However the change in SNR margin from 9.3dB to 29.2dB shows that the
line is very noisy and the data rate has been reduced to allow for this.
Of course it might mean that the router is faulty - so it's worth
borrowing one to test.

So the OP should follow all the diagnostic steps suggested, or ask for
help from somebody who can do it for him.

--
Graham J


  #8  
Old May 22nd 12, 09:35 PM posted to uk.telecom.broadband
The Natural Philosopher
external usenet poster
 
Posts: 2,728
Default very slow connection yet high SNR

Andy Champ wrote:
On 22/05/2012 09:56, The Natural Philosopher wrote:
Gordon Freeman wrote:
Over the last few days my ADSL router has been connecting slower and
slower each day, basically halving each day - I used to get 2-3 Mbit,
then at the weekend I got 1152kbit on Saturday, 512K on Sunday and now
288Kbit on Monday. But the SNR has gone up and up! Since there doesn't
seem to be a problem with line quality, I wonder could it be that my
router is failing?


Look again. The signal is almost non existent and varying at 57.6-59
-58dB att...I would say you have a wiring problem or a line fault.




was:

d/s SNR: 9.3dB, u/s SNR: 11.0dB
d/s Attenuation: 57.6dB, u/s Attenuation: 31.5dB
d/s Data Rate: 3072kbps, u/s Data Rate: 448kbps
then
d/s SNR: 25.9dB, u/s SNR: 12.0dB
d/s Attenuation: 59.1dB, u/s Attenuation: 31.5dB
d/s Data Rate: 576kbps, u/s Data Rate: 448kbps

now
d/s SNR: 29.2dB, u/s SNR: 11.0dB
d/s Attenuation: 58.1dB, u/s Attenuation: 31.5dB
d/s Data Rate: 288kbps, u/s Data Rate: 448kbps





FFS. I prefer bottom post. Top post I can live with. But middle post?

Anyway... I have this:

ADSL Link Downstream Upstream
Connection Speed 3648 kbps 640 kbps
Line Attenuation 57.0 db 31.5 db
Noise Margin 6.2 db 11.0 db

My attenuation figures aren't a lot better than his, yet it goes, albeit
slowly. Maybe he has head crabs on the line?


you have a better noise margin=cleaner line.

Incidentally, Graham, this is my new router. The old one died, and
AFAIK it wasn't lightning.

Andy



--
To people who know nothing, anything is possible.
To people who know too much, it is a sad fact
that they know how little is really possible -
and how hard it is to achieve it.
  #10  
Old May 23rd 12, 01:23 AM posted to uk.telecom.broadband
The Natural Philosopher
external usenet poster
 
Posts: 2,728
Default very slow connection yet high SNR

Alan LeHun wrote:
In article , lid says...
ADSL Link Downstream Upstream
Connection Speed 3648 kbps 640 kbps
Line Attenuation 57.0 db 31.5 db
Noise Margin 6.2 db 11.0 db

My attenuation figures aren't a lot better than his, yet it goes, albeit
slowly. Maybe he has head crabs on the line?

you have a better noise margin=cleaner line.


The noise margin is variable depending on the channels used. 6db is the
target noise margin that the router (or rather the exchange dslam) tries
to train to. As a result, most adsl connections in the UK will have a DS
NM of about 6db.

IOW, you can't determine the cleanliness of a line by it's NM.

you can.

long lines always show degraded target margin

I had severe problems with my line when I switched to adsl2+. The noise
margin would suddenly drop by 6-8db and the connection would become
mostly unusable. As a result, bt set the dslam to train my line to 15db
and everything is hunky dory now with the connection still stable even
when the NM drops. Of course, my speed has dropped from about 14kbps to
9.5kbps but that's fast enough for me atm.


there you are. You proved my point



--
To people who know nothing, anything is possible.
To people who know too much, it is a sad fact
that they know how little is really possible -
and how hard it is to achieve it.
 




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