Hi all,
swapped to ADSL2 a few days ago. Was getting about 7500 Kbps, now getting about the same but with a larger upload. Slightly disappointed with this as I was expected to get at least 10 or so - but never mind!
Anyway I'm posting as my connection was terrible this morning, I reset the router and it is moving again but the router is now reporting the following:
Operation Data Upstream Downstream
Noise Margin 5 dB 2147483647 dB
Attenuation 23 dB 21 dB
Now I know that the downstream can not be right. I've never seen it do this before, but restarting the router does not seem to clear it.
Any ideas? Firmware bug maybe or could it be a sign of something?
Thanks
Netgear? That's a sign that the noise margin has dropped into negative territory (theoretically impossible).
Many people are finding that they gain little or nothing in downstream speed I'm afraid.
Quote from: Rik on Aug 17, 2009, 17:37:36
(theoretically impossible).
Nooo... if the signal level drops below the noise level then (in db terms) the margin is negative. Unlikely the router will maintain sync for long under those conditions, but some can manage -1db or -2db. My old Linksys could... pretty rubbish router in many other ways, but boy, could it hold sync ;D
With Netgears, Bill, I often wondered if it was a fault in their reporting as the NM did tend to fade over time, something I don't see with, for example, the 2700.
Netgears (and some others I think) certainly have a firmware bug that causes them not to report negative numbers properly, haven't heard about the NM fading over time.
I've found they can run very hot and integrated circuits don't like that much, so it could be one of the ICs at the "front end" is gradually degrading and introducing its own noise into the circuit... just a guess though.
There was a thread on the subject on TB some 2-3 years ago. It was Andrew, iirc, who indicated the issue. The 2700, otoh, has a fault in the reporting which causes it to report negative power output with some MSANs. ::)
Quote from: Rik on Aug 17, 2009, 17:37:36
Netgear? That's a sign that the noise margin has dropped into negative territory (theoretically impossible).
Many people are finding that they gain little or nothing in downstream speed I'm afraid.
Not a Netgear, but a 3COM unit. It's a few years old now. I'll see what the Sync does tommorow.
Another good guess bites the dust. ;) It's the same problem, though, mis-reporting a negative number. Keep an eye on it. What are your sunc speeds, up and down?
Quote from: Rik on Aug 17, 2009, 19:39:52
Another good guess bites the dust. ;) It's the same problem, though, mis-reporting a negative number. Keep an eye on it. What are your sunc speeds, up and down?
Hi,
Had a check this morning. Still as it was yesterday in respect of the noise.
Stream Type Actual Data Rate
Up Stream 1085 (Kbps.)
Down Stream 7588 (Kbps.)
Cheers
That's low for your attenuation. Do you have an NTE5 master socket, the type where the bottom part of the faceplate can be removed? If so, can you try connecting the router to the test socket which is then revealed?
Quote from: Rik on Aug 18, 2009, 09:05:06
That's low for your attenuation. Do you have an NTE5 master socket, the type where the bottom part of the faceplate can be removed? If so, can you try connecting the router to the test socket which is then revealed?
Hi again,
Yes I managed to connect to the master socket. Pretty much the same, the router did (before i disconnected) lower the profile again:
----------
Stream Type Actual Data Rate
Up Stream 1085 (Kbps.)
Down Stream 6653 (Kbps.)
---------
Operation Data Upstream Downstream
Noise Margin 5 dB 22 dB
Attenuation 23 dB 20 dB
Any suggestions?
I'm wondering whether the router is swapping u/s and d/s stats, the u/s looks much more like a d/s result and vice versa. I'd suggest you call support, they can test the line and see the figures from their end. It looks to me, though, that your line is noisy on the BT side. TBH, the chances of getting BT to do anything about it are slim though.
Quote from: Rik on Aug 18, 2009, 11:07:26
I'm wondering whether the router is swapping u/s and d/s stats, the u/s looks much more like a d/s result and vice versa. I'd suggest you call support, they can test the line and see the figures from their end. It looks to me, though, that your line is noisy on the BT side. TBH, the chances of getting BT to do anything about it are slim though.
I'm temped to change the router as it's a little on the old side anyway - didnt support ADSL2 until a firmware update which was a number of years ago. Any recomendations, no need for WIFI?
I'm also going to invest in a some new microfilters, possibly those ADSL nation ones I've heard mentioned a few times (XF1-E?). See if these changes make any difference?
Thanks
I'd certainly recommend the ADSL Naton filters, I've been using them for a couple of years or more and they're the best I've found (as much as it's possible to compare filters). With routers, Netgear, Speedtouch or the 2-Wire 2700 (eBay, around £15 delivered) would be my choices. Most nowadays have wireless, though you can still find them without.
I agree with Rik about ADSL Nation filters. A Netgear DG834Gv4 seems to be a good router choice at the moment.
Hi all,
Thought I'd post back with an update. Havent changed anything yet, but here is an update on the sync rate:
Data Rate
Stream Type Actual Data Rate
Up Stream 1085 (Kbps.)
Down Stream 15065 (Kbps.)
Operation Data Upstream Downstream
Noise Margin 5 dB 2147483647 dB
Attenuation 23 dB 21 dB
So it looks like the sync will be supported higher, I just need to work out why it isn't very stable!
Thanks
Essentially because the noise margin is low (-2db I think).
Quote from: Sebby on Aug 18, 2009, 12:08:57
I agree with Rik about ADSL Nation filters. A Netgear DG834Gv4 seems to be a good router choice at the moment.
I still have one of those as a spare router Sebby :thumb:
Quote from: Rik on Aug 24, 2009, 10:05:17
Essentially because the noise margin is low (-2db I think).
Agreed. I'll dig out a new router and see if it cures it! :) I shall report back later. :D
Quote from: Gary on Aug 24, 2009, 10:07:48
I still have one of those as a spare router Sebby :thumb:
Want to sell it? ;)
Hi all,
A quick update. I've purchased a new router (as suggested the V4 834G by Netgear).
Here are the new line stats for the initial setup:
| DownStream Connection Speed | 15323 kbps |
| UpStream Connection Speed | 795 kbps |
| ADSL Link | Downstream | Upstream |
| Line Attenuation | 24.5 db | 10.9 db |
| Noise Margin | 4.4 db | 5.4 db |
Any thoughts? Connection is now usable for most sites, but still operating below par.
Thanks
What are your sync speeds now, and why do you feel it's operating below par?
Quote from: Rik on Aug 25, 2009, 12:44:57
What are your sync speeds now, and why do you feel it's operating below par?
Hi,
Sorry I put them in the post above in edit mode.
It's currently downloading at 10.5kb/s. highest I can get it is about 100kb/s. :(
Thanks
It sounds like you have the dreaded BT under-dimensioning, which has afflicted a few of us. Let support know, and let them have some BT speed tests run at various times of day. They can then chase BT down on the issue.
Quote from: Rik on Aug 25, 2009, 12:51:44
It sounds like you have the dreaded BT under-dimensioning, which has afflicted a few of us. Let support know, and let them have some BT speed tests run at various times of day. They can then chase BT down on the issue.
Errr ??? ??? ??? ??? ???
Can you clarify what this means please?
Thanks :D
Sorry. BT have finally acknowledged that some users are afflicted by throughput well below profile speed. They ascribe this to under-dimensioning of their network, a piece of obfuscation designed to conceal the fact that they either set it up wrong, or didn't provide enough fibre to cope with demand. BT are working through this, but the fix date keeps sliding. Some, like me, who were not originally affected have now seen speeds fall, so my own belief is that BT are juggling with the capacity they do have to try and even out supply and demand, a bit like the balancing that IDNet have carried out.
BT speed tests are carried out at http://test.speedtester.bt.com:50301/
It's important that you do them as they are the only evidence which BT accept. Be prepared to be patient, their speed tester is 'under dimensioned' too. You'll need your phone number and also your IDNet login, usually in the form <phone number>@idnet.gwX, or <username>@idnet.gwX.
Just as a note, it's not technically impossible to have a negative dB (http://en.wikipedia.org/wiki/Decibel). At least when audio is involved. No idea when it's electronics. ;)
The unit is not a problem, Ben, but a noise margin which is negative means that the noise is louder than the signal, so ADSL really shouldn't work.
Quote from: Rik on Aug 25, 2009, 13:08:52
Sorry. BT have finally acknowledged that some users are afflicted by throughput well below profile speed. They ascribe this to under-dimensioning of their network, a piece of obfuscation designed to conceal the fact that they either set it up wrong, or didn't provide enough fibre to cope with demand. BT are working through this, but the fix date keeps sliding. Some, like me, who were not originally affected have now seen speeds fall, so my own belief is that BT are juggling with the capacity they do have to try and even out supply and demand, a bit like the balancing that IDNet have carried out.
BT speed tests are carried out at http://test.speedtester.bt.com:50301/
It's important that you do them as they are the only evidence which BT accept. Be prepared to be patient, their speed tester is 'under dimensioned' too. You'll need your phone number and also your IDNet login, usually in the form <phone number>@idnet.gwX, or <username>@idnet.gwX.
Hmm, I've tried 5 times and can't get the tester to work, it just keeps passing back an error. Is it always like this or is something very wrong? - thats 5 times over the two days.
It's often like this, unfortunately, some people seem to have more problems than others - I sense that there are a number of sites (perhaps at nodes) and that some are better resourced than others. Make sure you're running the latest version of Java, and try with a different browser if you're still stuck.
Quote from: Rik on Aug 26, 2009, 09:38:23
It's often like this, unfortunately, some people seem to have more problems than others - I sense that there are a number of sites (perhaps at nodes) and that some are better resourced than others. Make sure you're running the latest version of Java, and try with a different browser if you're still stuck.
Hi,
And the results are in......
Your DSL connection rate: 15008 kbps(DOWN-STREAM), 808 kbps(UP-STREAM)
IP profile for your line is - 12000 kbps
Actual IP throughput achieved during the test was - 10073 kbps
...very strange - since running the test we've managed to download at 900kbps and the general page loading is back to normal. :) Just hope whatever was causing it has gone.
Thanks for your help.
It sounds like BT have got to your line and applied the fix. :thumb: