Kitz Forum
Broadband Related => ADSL Issues => Topic started by: kapt69 on January 21, 2010, 04:24:00 PM
-
Hi Folks
Have at last got PC back - have been using laptop via wifi to NetgearDG834GT - connected via NTE5 faceplate BT master socket. (With disconnected ring wire).
I had noticed, having set up routerstats to help with a problem, that when making/receiving a telephone call the SNR margin goes down by approx 1db. No problem as we don't get that many calls.
When I got the PC back (connected via cable to same Netgear router) I firstly noticed small spike when cable was inserted from router to PC(08.50 on attached graph) then a drop of approx. 1db when PC powered up. (09.00 - 10.00 approx. on graph)this recovered when PC switched off.
Since I'm struggling to keep up my SNR margin/speed/IP profile, I could do without this drop.
Any suggestions gratefully received.
[attachment deleted by admin]
-
Do you have another Ethernet cable that you can try?
When you inserted the cable, was the PC powered off at the wall?
-
Hi
Thanks for reply.
First's easy - no, but if you think it may help I can go & buy one.
Second mmmmmm. pretty sure I plugged in cable THEN plugged in power to back of PC.
-
Try replicating what you did before and monitor what happens.
-
Hi
PC currently 'occupied' grinding away though a back-up.
Will try when available, though margin dropped again this pm when PC was turned back on.
I'll keep an eye on things when I switch off after back-up.
Cheers
-
Hi
Have been away for a few days - haven't had time to buy new ethernet cable - BUT - noticed that SNR margin dropped by over 1 db when PC just turned on (NOT CONNECTED TO ROUTER).
I have just done some admin on it then returned to wifi connected laptop to monitor stats whilst PC shut down.
I watched the SNR rise from 10.4 to 11.9 !!!!! Unplugging ethernet cable after this doesn't seem to make any difference. Power to PC,monitor, router etc is through a Stanley (Belkin) surge protection distribution gizmo.
This may be perfectly explainable - but could someone who understands these things please explain?? Obviously a 1.5db difference makes me want to stick to the laptop - but that's my wife's and I would like to stay happily married for a little while longer.
Thanks
-
It sounds as though your PC or its monitor may be radiating some interference. At a guess I would say that it's more likely to be the monitor. If you've got a medium-wave radio you could try tuning it away from any station and then moving it around near the PC and monitor. If this is the problem, then moving the router as far as possible from the PC is about all you can do (apart from replacing the equipment of course).
It could also be mains-borne interference from the PC or monitor, and putting the router on a separate mains socket away from the PC might help.
-
I have had something similar happen to me. It turned out that it was the PSU (power supply unit) in the computer.
If it's a cheap nasty one it can be awful for both ADSL and radio as they leak RF across the spectrum. To show how common it can be I have had it happen twice in two different computers.
I have also had bad experiences with UPSs (Uninterruptible Power Supplies) and my ADSL in the past as these too can sometimes leak RF.
Also some motherboards in their BIOS have a feature called spread spectrum which can also help reduce the RF emitted from a computer.
Hope this helps
Mark
-
Thanks for suggestions folks.
Not sure if we still have MW radio - will have a look.
Will also investigate moving router to different power supply (- though guess it will still be on same ring). Will also need to get a longer ethernet cable as a result, which will be an opportunity to upgrade.
Will let you know what happens.
Really grateful for the advice - much appreciated.
-
Hey ho!
Before going out to buy armfuls of cable I tried moving router as far from PC as possible - given length of cables.
Powered up router via extension lead from another socket and tried shielding router with tinfoil :lol: (don't laugh!!)
Good news: turning off monitor showed no improvement - so - don't need a new one of those presumably.
Bad news: turning off/on PC had same drastic effect, even at maximum distance (admittedly only about 1.5 ish m - without ethernet cable connected.
(Am now wondering if this thread ought to be posted on hardware forum?? - no doubt will be advised - if so apologies to all.)
So. . longer master socket - router cable to be purchased. Not sure about buying ethernet cable yet, as if it turns out I need the router out in the shed to be 'protected', then I may need a 20m one rather than 'just' a 5 or 10!!
Before anyone suggests throwing out the PC - don't think I haven't thought of that!
You would have thought PCs & routers could be mates wouldn't you? :blush:
-
Kapt,
I don't know if anybody's mentioned it yet, but you ought to keep the router cables (both phone lead & ethernet) well away from any mains wiring, not forgetting any wiring that may be inside your walls.
If the interference is being passed via the mains wiring (which sounds possible), then rearranging the cables as above make quite a difference.
- 7LM
-
Hi 7LM
Phew - for a moment there I thought you were going to suggest re- routing the walls. - there is a limit!
Seriously - thanks for advice - I believe some cables have better 'shielding' than others - I'll try & see if the helpful young people in the computer shoppe know of such things - and I'll do my best to keep them as far away from 240v as possible.
Regards
K
-
Anyone want to buy an 'as new' 10m super high speed ADSL RJ11 to RJ11 - only used once. Cost over £20 - offers!!!!!
Note to admin guys - before you axe please read previous threads!
From this you may gather new cable didn't affect things one iota. Tried router other end of house - pretty sure different power ring. Adsl cable strung away from as much 240v as I could (back will soon recover from ducking under - don't worry!)
Oh yes - & added to all this - when I got back from shopping spree, having left laptop + routerstats up I found masses of 2 - 3 db spikes recorded. Also whilst watching saw the lights flickering - we do get this sometimes - not on & off - just for a spell every week or so. Walked up & down lane 200 yds each direction. No circular saws etc that I could hear.
Needless to say I waited for things tosettle before trying new cable - just in case you think I'm completely gaga. (Sorry got to be careful now there's a lady of same!)
I guess you may detect just a slight note of hysteria in all this . . . . . :lol: :baby: :baby: :lol:
-
An obvious neat thing to sort your cabling is to coil them up to keep things tidy. unfortunately this makes the cables loop antennea either transmitting or reciving more electrical noise. the dsl lead from microfilter to router is best laid out and away from other cabling and transformers, mains etc and not running parralel for and distance with another cable. a simple re arangement of the cabling mght help.
Check your monitor to pc cable has a small cylindrical bit part way along the cable, you can get replacements from places like maplins, look up ferrite rings. is the router sitting right by something electrical, that may be a source of backround interference. Although 1-2db difference isn't normaly anything to worry about.
-
Hi Ezzer
Thanks for that.
Cable is routed pretty much as per your suggestion - certainly may need to tidy it more eventually - but until I have solved the 'intereference' I will leave as is.
Yes the monitor cable to PC has ferrite ring fitted.
You say 1 -2 db isn't anything to worry about: well if you are talking percentages - 1.5 / say 11 = 13+% I would have thought that was fairly significant? Especially when I am only just hanging on to an IP profile of 1000kbs ( and that is now currently reduced to 750 - presumably as result of the number of times I've switched off the router to try/move cables.)
Having tried router on different ring main and in another room (approx 5 -6m from PC) - not forgetting these latest 'tests' have been done without any ethernet cable from PC to router, I am left wondering what else it could be. Next on list is to try again to find a MW radio as Roseway suggested.
Would I be right in thinking a 'noisy' PSU should not really affect things in another room? If still likely I guess another visit to the PC repair shop is on the way.
As an aside I have been wondering if updating the firmware on the Netgear would improve router's ability to cope with these reductions?? I have seen this mentioned - but can't find how one goes about it ( and therefore whether my limited tech. ability could manage it.)
Regards
K
-
Hi All
No reply to previous post so I guess there may be no answer??
Have now also obtained 10m of shielded 'best quality' ethernet cable.
Didn't have much hope and - yep - no difference - apart from untidy cables strung around room trying to avoid 240v, coils in cabling & anything else that might affect it.
Still drop on SNR graph by over 1 db whenever PC is switched on.
Now more seriously trying to work out if it would be cheaper/easier to bin PC and buy another laptop, just accept drop & try and improve router's 'flexibility' with upgrade(Still can't find how - tutorial discusses flashing sky router also having difficulty finding error stats.) - or just give up. Just don't like being beaten.
-
You mention several noise spikes even when the PC wasn't running; is your home electrical wiring up to scratch? It could be a power supply quality issue and unfortunately there's not a lot that you can do about that.
The PC may have been installed with a cheaper power supply unit, and that is causing the interference. A solution may be to replace the PSU with a higher quality one.
Another potential solution may be to use a mains power conditioner. I have had experience of a treadmill motor backfeeding distortions through the mains wiring (presumably it wasn't fitted with an electrical choke) which severely affected the SNR margin of an ADSL router. Plugging the treadmill into a Tacima 6-way mains conditioner (around £25) completely stopped the distortions feeding into the main.
There are no guarantees it will work for you, however it may be worth trying.
-
Hi
Thanks for reply.
Spikes appear every so often - fairly infrequently - pretty sure external. House completely rewired 8 years ago. Electricity board coming Monday to install error monitoring equipt. as I eventually contacted them. (Don't mind flickering lights - but if it affects the broadband connection . . .)
This was really just a 'final straw' - main problem happens every time PC switched on (without being connected to router) PSU has been mentioned before and I think I will have to look into getting it changed - I only just got PC back from repair so had wantd to hang on to it for a while . . but . .
PC is fed by Stanley/Belkin Power distribution extension which I think is to prevent surges - not sure if this has same affect as a mains conditioner??
Anyhow thanks for trying . . . will bite the bullet after the weekend - during which time I'll bite the glass :'( :drink:
-
>>>PC is fed by Stanley/Belkin Power distribution extension which I think is to prevent surges - not sure if this has same affect as a mains conditioner??
Surge protectors are generally used to protect against larger voltage spikes and won't provide the same functionality as a mains conditioner (unless it has one built in to it of course).
-
Stanley/Belkin Power distribution extension which I think is to prevent surges
kapt,
It's a long shot, but you could try plugging the PC into the mains directly just in case it improves things (thus implicating the extension socket).
In my experience, extension sockets are often poorly made. I recently found one with a 'dead' socket because all of the internal connection screws were loose, and a while ago I had one that was completely missing an earth terminal on one of its sockets.
That apart, I have to say that at the signal levels Kapt is running at (>=63dB attenuation), it takes only a tiny amount of interference signal to register as 1 or 2 dB on the SNR. At that attenuations, some small 'drift' in SNR, as various bits of stuff are switched on & off, is going to be almost innevitable and perhaps impractical to totally eradicate.
-
SLM
Good to hear from you.
Thank you for the suggestion - will do. I hadn't thought of that!
Also interested in your comment about high attenuation meaning relatively small intereference may equate to 1 or 2 db - I still feel that as this reresents 13% of SNR margin this is considerable - but if you suggest this is almost to be expected - fair enough.
Will now go & change power distribution system (i.e. plug straight into wall socket!!)
Thanks again.
Regards
K
-
Hi again
Pulled printer, monitor,scanner power supplies from any connection. Plugged PC straight into wall socket. Started it up.
NSR dropped from 11.8dbs to 9.1 then 8.9dbs - curently down to 8.5 will have to turn off PC if it continues.
Worth trying - but no go!
k
-
NSR dropped from 11.8dbs to 9.1 then 8.9dbs - curently down to 8.5 will have to turn off PC if it continues.
Oh dear, still -worth a try :(
Edit: Note I've deleted most of this post as I went into an explanation of dB scales, and subsequently realised it was misleading.
Eric has a sticky that explains dB as applied to adsl here:
http://forum.kitz.co.uk/index.php/topic,147.0.html
-
Hi
quote NSR dropped from 11.8dbs to 9.1 then 8.9dbs - curently down to 8.5 will have to turn off PC if it continues.
Looking at the time of your post I am not surprised The SNR margin is dropping . It all depends on how its dropping is it more or less a gradual drop or is it very spiky and noisy . Have you got a Routerstats graph of the time period ?
Regards Jeff
-
Hi Jeff
Have tried to attach log of stats - no graph - sorry. I hope it shows that it's not evening 'drop' - time PC switched on approx 19.39 then off 19.50.
Have selected part of day's stats as whole file too large.
Thanks for your input.
Regards
Kerris
[attachment deleted by admin]
-
Hi
Looking at those results I would say they are 'normal' sort of drift and general noise that can be expected during evening period . you did have a step drop of 1.5db for about 10minutes ,this could just be some small noise source switching on then off again. I have some similar patterns on my line . I have never been able to track them down .
Its quite difficult to get a true picture when looking at rows of figures . As the old saying goes a picture is worth a 1000 words :)
Regards Jeff
-
Hi Jeff
Thanks for looking.
At risk of offending - yes I'm sure you're right - but - that small drop happened exactly when PC was turned on then off. It may just be coincidence, but I rather doubt it. Anyway I need to find MW radio to help identify and am gearing myself up to change PSU. If that doesn't work I will have to change PC. I am determined to do all I can to keep as much of what little speed I have as possible.
As regards pics - again apologies. I need to get my head around setting things up so they are deleted after a specific time once scheduled regularly.
Thanks again
Regards
Kerris
-
SLM
Thanks for link. I saved it for this morning . . . . when I had a clear head. - Note the past tense!! :lol:
K
-
Jeff
Just captured a pic for you - whilst I was sorting through the day's Viagra offerings. From memory 08.42 - 09.33
Kerris
[attachment deleted by admin]
-
A new PSU is really cheap and usually simple to fit if your PC uses a "standard" type.
What make/model of PC and PSU is it?
-
There doesn't seem to be any regular pattern either in the amount of SNR drop or the length of time of the drop or the actual time of day of the drop so you may struggle to identify anything with an MW radio.
If it was the PSU I'd expect some regularity associated with length of time the computer had been on or when the cooling fans start up. Have you opened the case and cleaned out the dust etc ?
Is it the same symptom from the test socket ?
Perhaps you could perform a properly structured check system starting at the test socket rather than thinking of something it could be and checking that.
-
Hi
Not sure if I'm being unclear - the drop in SNR occurs exactly following switching on the PC and recovers exactly as it is switched off. I had it on cehecking emails between 08.42 & 09.33 - hence the attached graph in previous post. Have tried in test socket - no difference.
So I do not have much doubt it is the PC which is causing the drop. (shown on routerstats run on laptop)
HP : thanks for advice re psu. I'm afraid the PC is not a 'brand' name - it was bought from a firm which specialised in building PCs. I will have to look inside to see if I can identify the PSU.
Thanks to all for suggestions.
Kerris
-
the drop in SNR occurs exactly following switching on the PC and recovers exactly as it is switched off.
Apologies, re-reading the whole thread I now realise that I misunderstood.
So you're saying the length of time the computer is on (heat build up) makes absolutely no difference, rather it's the on/off process that triggers the drop.
-
the PC is not a 'brand' name - it was bought from a firm which specialised in building PCs.
That's good. ;D
(it will have a generic, easily-replaced PSU)
-
Hi Oranged
Yep that appears to be so. Length of time on doesn't seem to affect 'drop' - although must admit I have kept it off as much as possible.
It may be that I misunderstand - but - by carefully monitoring routerstats, keeping router on all time, shutting off laptop when/if SNR drops to near 9db I seem to manage to keep sync speed 'up' to (currently) 1408 (probably best so far) and download speed around 940 kbps/IP Profile 1000.
If I mess around with router (on/off etc) it obviously affects profile then speed. That is why I think it is so critical that I don't lose the 1.5 db caused by apparently switching on the PC. At moment (a.m.) SNR is 11.8db and falls in evening - you can see that a 1.5db drop brings it down considerably & close to what I think may be the 'limit' before - is it the dslam??- decides enough is enough & reduces speed to improve SNR.
I stand to be corrected - & no doubt will be!! ::)
Cheers
Kerris
-
shutting off laptop
... I take it you mean 'shutting PC with suspect PSU ?
- you can see that a 1.5db drop brings it down considerably & close to what I think may be the 'limit' before - is it the dslam??- decides enough is enough & reduces speed to improve SNR.
The SNR should be able to drop to 9, and well below it, before anything gets disconnected. Some people even report brief spells where the SNR has gone -ve, and survived.
However, if your SNR was (say) 8dB, and you got a short burst of interference that reduced it by 9dB then you'd probably drop the connection. I'm not sure how long a burst of interference would be required for the connectiuon to drop, maybe some of the Gurus can shed light... a second? more? less?
Be aware that such a burst of interference wouldn't necessarily show up on routerstats, which just takes some atomic samples at regular intervals, and joins up the dots. If a burst of interference occured between samples, routerstats won't show it.
This is making me think, however... didn't you previously report routerstats sometimes showing sharp dips, which we probably attributed to a glitch in the wireless connection, or something? Suppose these dips were real, and happened whenever routerstats got lucky, and took its sample just when the intererence burst was happening?
If you still have the energy to investigate, you could try reducing the routerstats sample time, which would increase the chances of a sample being taken during 'bursty' interference? I've many times confessed to not being a routerstats expert, so somebody who is may correct me.
-
I think 7LM has got it right - the connection shouldn't normally be dropped unless the noise margin drops close to zero, and a short pulse of interference sounds quite a likely explanation.
-
although must admit I have kept it off as much as possible.
;D Perhaps that's the solution....keep it on as much as possible !
-
7LM
Just to clarify - no - actually shutting down laptop. As I suggested, for present I try to leave PC off most of time until I can get PSU sorted.
It may be my wishful thinking, but the little green blinky things on the Netgear seem to be a lot calmer when everything (except router) is shut off - so in order to let it rest when SNR is low I switch off laptop as well and 'get a life'. >:D
I accept that this taken to its logical conclusion would lead to possibly having a faster download speed - but with no actual downloads!! :lol:
Hope I haven't upset any sacred cows . . . will investigate more frequent sampling via routerstats.
Oranged: Perhaps that's the solution....keep it on as much as possible !
I take it you are joking?? - just making sure.
Thanks to all for advice.
Cheers
Kerris
-
Just to say I have found the sample rate setup in config in routerstats and set it to 10s.
OK - here I'm pushing my luck - am I wishing in vain to 'get greedy' & see if I can improve speed by trying to keep SNR up as much as possible by trying to maintain as 'clean' a record as I can? Didn't I read somewhere that you need a sync speed of 1450kbps to get into next category - but then am I thinking of fixed rate lines???(which mine isn't) I'm sure you get used to all this - but it's very confusing. Apologies if you're all going :doh:
-
There's a table of IP profiles versus connection speeds here. (http://www.kitz.co.uk/adsl/IPprofile.htm#IP_and_bRAS_profiles)
-
Just to say I have found the sample rate setup in config in routerstats and set it to 10s.
If we're chasing a noise burst that might last only (say) a quarter of a second, that still leaves odds of 40 to 1 against detecting it. I'd have been inclined to go right down to 1 second sampling or less, if routerstats is cabable of it?
OK - here I'm pushing my luck - am I wishing in vain to 'get greedy' & see if I can improve speed by trying to keep SNR up as much as possible by trying to maintain as 'clean' a record as I can?
One problem with conspiring to get the best speed is that the higher your connection speed, the more vulnerable the connection will be when the SNRM drops (or is hit by a noise burst). Your router will then reconnect, of course, but it will quite likely then be doing so when the background noise levels are already high (that's what caused it to disconnect, just a moment earlier), so when it reconnects it may achieve only a lower-than-ever speed, which affects your IP profile for several days.
To cite my own line as an example... I know that on a good day, with a strong tail wind, and I choose the right moment, it'll connect at 4300 or more, which in theory would give me a profile of 3500. But if I connect at that speed, the SNRM will drop a long way in the evenings, during which it may drop the connection and then it reconnects at around 3000 or so, lumbering me with a 2500 (or sometimes 2000) profile for a few days. However, by watching the SNRM variations, and manually connecting when the SNRM is in the middle - rather than at the peak - of it's wanderings, I get a speed of 3500 which can be sustained for ever and a day, with a reliable profile of 3000.
-
7LM
Oh Joy!
Just had to reply quickly to say thanks.
Only read it once - but sounds like you're doing what I would like to achieve. Always sensible to aim for the middle ground.
By 'manually connecting', I take it you mean powering off router then back on so it re-syncs?
Also - my idea was that if PC & laptop are off - then although router is still connected (hopefully!) during late evening & night there will be 'zero' traffic for exchange to 'sense problems' - thereby making use of higher speed during day which may be maintained by trying to avoid 'vulnerable periods'.
Is this completely daft??
Will re-alter sample rate to one sec - but it does warn something about cpu loading or some such.
Thanks
Kerris
-
If we're chasing a noise burst that might last only (say) a quarter of a second, that still leaves odds of 40 to 1 against detecting it. I'd have been inclined to go right down to 1 second sampling or less, if routerstats is cabable of it?
Unfortunately, as far as I know, Routerstats minimum sample rate is 5 seconds
-
If we're chasing a noise burst that might last only (say) a quarter of a second, that still leaves odds of 40 to 1 against detecting it. I'd have been inclined to go right down to 1 second sampling or less, if routerstats is cabable of it?
Unfortunately, as far as I know, Routerstats minimum sample rate is 5 seconds
Then another option is to use the Netgear administration GUI, which allows 1 second sampling. Unfortunately of course there's no way of recording the figures, and I won't be responsible Kapt's wife's reaction when she discovers he's taken to spending hour upon hour staring unblinkingly at something on the computer screen, which turns out to be... the Netgear status page. :)
-
7LM
Oh Joy!
Just had to reply quickly to say thanks.
Only read it once - but sounds like you're doing what I would like to achieve. Always sensible to aim for the middle ground.
By 'manually connecting', I take it you mean powering off router then back on so it re-syncs?
Also - my idea was that if PC & laptop are off - then although router is still connected (hopefully!) during late evening & night there will be 'zero' traffic for exchange to 'sense problems' - thereby making use of higher speed during day which may be maintained by trying to avoid 'vulnerable periods'.
Is this completely daft??
Will re-alter sample rate to one sec - but it does warn something about cpu loading or some such.
Thanks
Kerris
I replied to HP's without noticing this one was still outstanding.
Yes, the middle-ground gets my vote.
As always I rely on the Gurus may correct me, but I don't actually think powering off the PCs and laptops makes any difference. Even in the absence of traffic, the router is still exchanging data with the exchange (superframes?), and will still drop the connection if that data's getting corrupted.
-
. . . and I guess one power-off of router (i.e. overnight) per 24hr would be a risk??
-
7LM
You're beginning to get my measure . . & . . . . . do you know my wife???[quoteI won't be responsible Kapt's wife's reaction when she discovers he's taken to spending hour upon hour staring unblinkingly at something on the computer screen, which turns out to be... the Netgear status page. ][/quote] :no:
-
. . . and I guess one power-off of router (i.e. overnight) per 24hr would be a risk??
I think the usual advice is to leave the router on 24/7, and that always my own approach.
The big risk is that you currently seem to be on a BT DLM target margin of 12dB. If DLM thinks the line's unstable, it may increase that to 15dB, whereupon subsequent connections, at least for several weeks and maybe forever, will be reduced by several hundred kbps.
That said, if the choice is between voluntarily powering off at night, or an error-rate-induced connection-drop in the small hours, I'd say the former (voluntary power-off) was less likely to be perceived as instability, and so less likely to cause problems.
However, if you ever need to use the DSL unexpectedly in the small hours - say to check a train timetable or whatever - then you'll likely connect at a poor speed which will drag down your IP profile for several days afterwards.
7LM
You're beginning to get my measure . . & . . . . . do you know my wife
No, but I've been there, done that, got the T-shirt. My own partner is also a software engineer, so she ought to understand, but I still manage to surprise(/scare) her once in a while.
-
. . . . I won't ask :o !! Oh & btw it's usually not the DSL that I use in the small hours - don't ask! :lol:
-
Quick note of thanks to all who helped on this: Orainsear, Roseway,Smoke,7LM,Ezzer,Jeff,HpS,Oranged.
Having waited for a few other things to quieten down, I have at last fitted the new Corsair VX550w PSU - and - no interference!!!
Routerstats on laptop monitored as it was switched on and graph didn't move. ;D
Thanks for pointing me in right direction - hope this may help someone with similar problems.
-
:thumbs: :congrats:
-
:thumbs: :congrats:
I second that, now...
:fingers:
-
Excellent news! :)
-
Great :lol: :drink:
Regards Jeff
-
Glad you got it fixed Kapt. ;D
Nearly all problems with PCs interfering with adsl connections that I have seen have been down to nasty cheap PSUs that come supplied with an ATX case.
Corsair is probably the best PSU brand you can buy on the market at the moment and will last you a very long time to come.
Mark