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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.

Varying Noise Margin



 
 
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  #1  
Old December 6th 05, 04:31 PM posted to uk.telecom.broadband
Chris
external usenet poster
 
Posts: 151
Default Varying Noise Margin

I have been getting occasional ADSL loss of synchronisation and varying
noise margin figures. I have tried everything I can think of, including
rewiring my extension with ethernet cable - and I'm wondering if anyone
can suggest anything else?

Situation:
* 5 km from exchange
* Pipex
* Netgear DG834 version 2 latest firmware
* Line loss 49

Noise margin is all over the place.
It doesn't seem to relate to anything in my house
(although there may be things I'm not yet aware of).
Sometimes connecting another computer to the router causes the SNR to
drop - but not always.

It is usually between about 6 and 17.
(But why should it vary?)

Sometimes the router loses synch continuously, dropping out and
re-connecting about once a minute. When this happens, rebooting the
router usually helps.

BT have been very helpful and have given me the best available on the
E-side and on the D-side and my Line Loss has gone from 59 to 49.

Any ideas will be gratefully received and valued.
--
Chris
  #2  
Old December 6th 05, 04:47 PM posted to uk.telecom.broadband
Tiscali Tim
external usenet poster
 
Posts: 755
Default Varying Noise Margin

In an earlier contribution to this discussion,
Chris ] wrote:

I have been getting occasional ADSL loss of synchronisation and
varying noise margin figures. I have tried everything I can think
of, including rewiring my extension with ethernet cable - and I'm
wondering if anyone can suggest anything else?

Situation:
* 5 km from exchange
* Pipex
* Netgear DG834 version 2 latest firmware
* Line loss 49

Noise margin is all over the place.
It doesn't seem to relate to anything in my house
(although there may be things I'm not yet aware of).
Sometimes connecting another computer to the router causes the SNR to
drop - but not always.

It is usually between about 6 and 17.
(But why should it vary?)

Sometimes the router loses synch continuously, dropping out and
re-connecting about once a minute. When this happens, rebooting the
router usually helps.

BT have been very helpful and have given me the best available on the
E-side and on the D-side and my Line Loss has gone from 59 to 49.

Any ideas will be gratefully received and valued.


Have you tried a different router and/or power supply for the router?

I don't know whether the problem I had affects Netgear kit, but my 3Com
router won't work reliably with the switch-mode power supply provided by
3Com - but is fine with a generic 3rd-party power supply.

Have you got any other kit (e.g. laptop computer) using a switch-mode power
supply, which could be injecting noise into the system?
--
Cheers,
Tim
______
Please reply to newsgroup. Reply address is invalid.


  #3  
Old December 6th 05, 05:21 PM posted to uk.telecom.broadband
Kraftee
external usenet poster
 
Posts: 422
Default Varying Noise Margin

Tiscali Tim wrote:
In an earlier contribution to this discussion,
Chris ] wrote:

I have been getting occasional ADSL loss of synchronisation and
varying noise margin figures. I have tried everything I can think
of, including rewiring my extension with ethernet cable - and I'm
wondering if anyone can suggest anything else?

Situation:
* 5 km from exchange
* Pipex
* Netgear DG834 version 2 latest firmware
* Line loss 49

Noise margin is all over the place.
It doesn't seem to relate to anything in my house
(although there may be things I'm not yet aware of).
Sometimes connecting another computer to the router causes the SNR to
drop - but not always.

It is usually between about 6 and 17.
(But why should it vary?)

Sometimes the router loses synch continuously, dropping out and
re-connecting about once a minute. When this happens, rebooting the
router usually helps.

BT have been very helpful and have given me the best available on the
E-side and on the D-side and my Line Loss has gone from 59 to 49.

Any ideas will be gratefully received and valued.


Have you tried a different router and/or power supply for the router?

I don't know whether the problem I had affects Netgear kit, but my
3Com router won't work reliably with the switch-mode power supply
provided by 3Com - but is fine with a generic 3rd-party power supply.

Have you got any other kit (e.g. laptop computer) using a switch-mode
power supply, which could be injecting noise into the system?


Have found that Netgear isn't to accurate for SNR readings (latest
firmware 3.01.5) so the OP maybe chasing ghosts there. Have you (the
OP) tried removing the bell wire on the master/frontplate to see what
happens, generally your Loop attenuation will increase by a couple of
points but your SNR should be affected to a greater extent to the
positive, it should also be more stable as well. Even though you may
have wired it all in cat5 cable, it still doesn't make any difference to
the bell wire being unbalanced & effectively it can become a long wire
aeriel. You don't require the bell wire as each filter will decouple the
ringing, if it is required by the phone at all


  #4  
Old December 6th 05, 06:03 PM posted to uk.telecom.broadband
Chris
external usenet poster
 
Posts: 151
Default Varying Noise Margin

In article , Tiscali Tim
writes
In an earlier contribution to this discussion,
Chris ] wrote:

I have been getting occasional ADSL loss of synchronisation and
varying noise margin figures. I have tried everything I can think
of, including rewiring my extension with ethernet cable - and I'm
wondering if anyone can suggest anything else?

Situation:
* 5 km from exchange
* Pipex
* Netgear DG834 version 2 latest firmware
* Line loss 49

Noise margin is all over the place.
It doesn't seem to relate to anything in my house
(although there may be things I'm not yet aware of).
Sometimes connecting another computer to the router causes the SNR to
drop - but not always.

It is usually between about 6 and 17.
(But why should it vary?)

Sometimes the router loses synch continuously, dropping out and
re-connecting about once a minute. When this happens, rebooting the
router usually helps.

BT have been very helpful and have given me the best available on the
E-side and on the D-side and my Line Loss has gone from 59 to 49.

Any ideas will be gratefully received and valued.


Have you tried a different router and/or power supply for the router?


In the past - yes.
Both of those have had an effect.
My old Netgear 814 gave problems, which were cured by a different power
supply.
A very old borrowed D-Link router never disconnected - but I didn't want
to continue using it - because of its lower security than a modern
Netgear router. Netgear replaced my 814 with the latest 834 - and that
has been a lot better.

Have you got any other kit (e.g. laptop computer) using a switch-mode power
supply, which could be injecting noise into the system?


What do you mean?
Sometimes I connect a laptop, which is powered from the mains - but that
doesn't seem to affect anything.
What is a switch-mode power supply?
--
Chris
  #5  
Old December 6th 05, 06:22 PM posted to uk.telecom.broadband
Chris
external usenet poster
 
Posts: 151
Default Varying Noise Margin

In article ,
Kraftee writes
Tiscali Tim wrote:
In an earlier contribution to this discussion,
Chris ] wrote:

I have been getting occasional ADSL loss of synchronisation and
varying noise margin figures. I have tried everything I can think
of, including rewiring my extension with ethernet cable - and I'm
wondering if anyone can suggest anything else?

Situation:
* 5 km from exchange
* Pipex
* Netgear DG834 version 2 latest firmware
* Line loss 49

Noise margin is all over the place.
It doesn't seem to relate to anything in my house
(although there may be things I'm not yet aware of).
Sometimes connecting another computer to the router causes the SNR to
drop - but not always.

It is usually between about 6 and 17.
(But why should it vary?)

Sometimes the router loses synch continuously, dropping out and
re-connecting about once a minute. When this happens, rebooting the
router usually helps.

BT have been very helpful and have given me the best available on the
E-side and on the D-side and my Line Loss has gone from 59 to 49.

Any ideas will be gratefully received and valued.


Have you tried a different router and/or power supply for the router?

I don't know whether the problem I had affects Netgear kit, but my
3Com router won't work reliably with the switch-mode power supply
provided by 3Com - but is fine with a generic 3rd-party power supply.

Have you got any other kit (e.g. laptop computer) using a switch-mode
power supply, which could be injecting noise into the system?


Have found that Netgear isn't to accurate for SNR readings (latest
firmware 3.01.5) so the OP maybe chasing ghosts there.


My firmware is 3.01.25 ... just checked.

Have you (the
OP) tried removing the bell wire on the master/frontplate to see what
happens, generally your Loop attenuation will increase by a couple of
points but your SNR should be affected to a greater extent to the
positive, it should also be more stable as well. Even though you may
have wired it all in cat5 cable, it still doesn't make any difference to
the bell wire being unbalanced & effectively it can become a long wire
aeriel. You don't require the bell wire as each filter will decouple the
ringing, if it is required by the phone at all


I am getting results which confuse me.
At first I connected to the MEP and got a really good SNR of 27.
That was with mains powered laptop plugged into MEP.

I left it on overnight and next morning it was 24 ... still good.

Then, before I did my extension re-wiring, I checked again ... and got
15.

That is an enormous difference!

Then I re-did my extension wiring - about 90 feet - with cat5 cable -
with 4 wires connected:

PIN 2 - CAT5 cable White (blue)
PIN 3 - CAT5 cable Orange (white)
PIN 4 - CAT5 cable White (orange)
PIN 5 - CAT5 cable Blue (white)

Then I got - on the end of the extension - 22 - then 17 - 16 - 16 ...

Why should it be changing?
This is not making sense!
And why should it be better at the extension than at the MEP?

Later I got 11.

After a reboot of the router I got 17-16-16-16-17-17.

Later I got 6-6-6-6-6-9-9-9-9.

Later I got 12-12-12-12-12-12.

This afternoon it was 14-14-14-14-14-14.

Now it is 12-12-12-12-12.

I am at a loss for hypotheses.
Can you suggest what might be going on?
--
Chris
  #6  
Old December 6th 05, 06:55 PM posted to uk.telecom.broadband
Tiscali Tim
external usenet poster
 
Posts: 755
Default Varying Noise Margin

In an earlier contribution to this discussion,
Chris ] wrote:

What is a switch-mode power supply?


AIUI, it is one which produces a low voltage from a high voltage by
switching itself on and off rapidly - with a capacitor to smoothe the
output - rather than a conventional one which uses a transformer. The rapid
switching can generate a lot of high frequency noise - which can interfere
with the ADSL signal, making it appear to have a lower noise margin than it
really has.

Whereas router supplies probably have the greatest effect, others have
claimed that noise from supplies powering other equipment can affect their
signal.
--
Cheers,
Tim
______
Please reply to newsgroup. Reply address is invalid.


  #7  
Old December 6th 05, 07:56 PM posted to uk.telecom.broadband
Reg Edwards
external usenet poster
 
Posts: 168
Default Varying Noise Margin

What is a switch-mode power supply?
--
Chris

========================================
It is a cheap and nasty collection of electronic components which
radiates noise and interference for yards and yards, causing all sorts
of misbehaviour in all sorts of electrical and digital equipment in
both the near vicinity and at considerable distances.

Its effects are propagated via radio waves at all frequencies and
along equipment interconnecting cables and transmission lines,
screened or otherwise.

Switch-mode power supplies are best completely housed in metal boxes,
the metal being a partially-effective screen. Very common plastic
enclosures are useless - they may as well not be there.

Switch-mode power supplies can appear in all types of mains-driven
electronic equipment, from TV receivers to computers and their
peripherals. Reasons - cheapness of manufacture!

The results - electronic noise, interference and polution of the
whole environment.

Incidentally, transmission of Broadband signals along overhead wires
and along domestic power wiring is also a source of noise and
interference to other equipment, including radio, TV and even other
broadband circuits.

Results and effects are unpredictable. If your broadband line keeps
dropping out then blame your, your service provider's and everybody
else's installation.

If you should experience a useable service then consider yourself to
be lucky.
----
Reg.


  #8  
Old December 6th 05, 08:16 PM posted to uk.telecom.broadband
Kraftee
external usenet poster
 
Posts: 422
Default Varying Noise Margin

Tiscali Tim wrote:
In an earlier contribution to this discussion,
Chris ] wrote:

What is a switch-mode power supply?


AIUI, it is one which produces a low voltage from a high voltage by
switching itself on and off rapidly - with a capacitor to smoothe the
output - rather than a conventional one which uses a transformer. The
rapid switching can generate a lot of high frequency noise - which
can interfere with the ADSL signal, making it appear to have a lower
noise margin than it really has.

Whereas router supplies probably have the greatest effect, others have
claimed that noise from supplies powering other equipment can affect
their signal.


As well as things like flashing Christmas tree lights, rope lights,
heating thermostats & mercury switched central heating systems
themselves, fridges, TV's, freezsers, lighting relays etc etc etc...In
fact anything powered of the mains can cause a problem


  #9  
Old December 6th 05, 08:24 PM posted to uk.telecom.broadband
Phil Thompson
external usenet poster
 
Posts: 2,720
Default Varying Noise Margin

On Tue, 6 Dec 2005 15:31:54 +0000, Chris ] wrote:

It is usually between about 6 and 17.
(But why should it vary?)


more or less interference.

What speed is this line at ?

Phil
--
Tiscali - dialup speeds at Broadband prices, see
http://bbs.adslguide.org.uk/postlist...&Board=tiscali

AOL - the unlimited ISP of choice for heavy downloaders.
  #10  
Old December 6th 05, 08:26 PM posted to uk.telecom.broadband
Kraftee
external usenet poster
 
Posts: 422
Default Varying Noise Margin

Chris wrote:
In article ,
Kraftee writes
Tiscali Tim wrote:
In an earlier contribution to this discussion,
Chris ] wrote:

I have been getting occasional ADSL loss of synchronisation and
varying noise margin figures. I have tried everything I can think
of, including rewiring my extension with ethernet cable - and I'm
wondering if anyone can suggest anything else?

Situation:
* 5 km from exchange
* Pipex
* Netgear DG834 version 2 latest firmware
* Line loss 49

Noise margin is all over the place.
It doesn't seem to relate to anything in my house
(although there may be things I'm not yet aware of).
Sometimes connecting another computer to the router causes the SNR
to drop - but not always.

It is usually between about 6 and 17.
(But why should it vary?)

Sometimes the router loses synch continuously, dropping out and
re-connecting about once a minute. When this happens, rebooting
the router usually helps.

BT have been very helpful and have given me the best available on
the E-side and on the D-side and my Line Loss has gone from 59 to
49. Any ideas will be gratefully received and valued.

Have you tried a different router and/or power supply for the
router? I don't know whether the problem I had affects Netgear kit,
but my
3Com router won't work reliably with the switch-mode power supply
provided by 3Com - but is fine with a generic 3rd-party power
supply. Have you got any other kit (e.g. laptop computer) using a
switch-mode power supply, which could be injecting noise into the
system?


Have found that Netgear isn't to accurate for SNR readings (latest
firmware 3.01.5) so the OP maybe chasing ghosts there.


My firmware is 3.01.25 ... just checked.

Have you (the
OP) tried removing the bell wire on the master/frontplate to see what
happens, generally your Loop attenuation will increase by a couple of
points but your SNR should be affected to a greater extent to the
positive, it should also be more stable as well. Even though you may
have wired it all in cat5 cable, it still doesn't make any
difference to the bell wire being unbalanced & effectively it can
become a long wire aeriel. You don't require the bell wire as each
filter will decouple the ringing, if it is required by the phone at
all


I am getting results which confuse me.
At first I connected to the MEP and got a really good SNR of 27.
That was with mains powered laptop plugged into MEP.

I left it on overnight and next morning it was 24 ... still good.

Then, before I did my extension re-wiring, I checked again ... and got
15.

That is an enormous difference!

Then I re-did my extension wiring - about 90 feet - with cat5 cable -
with 4 wires connected:

PIN 2 - CAT5 cable White (blue)
PIN 3 - CAT5 cable Orange (white)
PIN 4 - CAT5 cable White (orange)
PIN 5 - CAT5 cable Blue (white)

Then I got - on the end of the extension - 22 - then 17 - 16 - 16 ...

Why should it be changing?
This is not making sense!
And why should it be better at the extension than at the MEP?

Later I got 11.

After a reboot of the router I got 17-16-16-16-17-17.

Later I got 6-6-6-6-6-9-9-9-9.

Later I got 12-12-12-12-12-12.

This afternoon it was 14-14-14-14-14-14.

Now it is 12-12-12-12-12.

I am at a loss for hypotheses.
Can you suggest what might be going on?


Some of the Netgear routers (& 3Com for that matter) do display such
tendencies. With the 3Com it appears to have been pinned down to fault
prone power supplies & I wouldn't be suprised that it could be that with
the Netgear ones as well the only problem would be actualy proving it as
even with the latest firmware I still am apparently rebooting around
every 36-40 hours...

Think I'll stick with my Draytek ;-)


 




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