volt/amp readings using multimeter on ADSL line

appreciate your info!!!

i hear ya - i'll read up a bit...maybe consider getting a 834GT
i'll have to strip that wallbox and play around with the wires.

i've got 2 patterns on my problem...

gonna try illustrate it here:


1)SNR suddenly drops from 29 to 0 - 29,29,29,29,0(LOS),25,25,25,25,0
2)SNR does a series of drops and climbs with los 29,28,27,20,15,20,25,9,6,3,1,0(LOS),29,30,15,10,5

as per:

http://i210.photobucket.com/albums/bb147/jannie40/20aug1014.jpg
http://i210.photobucket.com/albums/bb147/jannie40/31may1800.jpg
http://i210.photobucket.com/albums/bb147/jannie40/15may1046.jpg

gonna try next week to get my line shortened by 90meter + new wall socket
on 3.7km - thats about 1-2% "improvement" but hey...maybe it helps?!

and the thing is - i can hear when my modem drops sync/is training.

or 33% of the time when the phone is just picked up for fun or an actual call - it either spikes my SNR or disconnects the ADSL part - voice=fine..either way.

lots probz
:P

comments welcomed.
 
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@OMN: Those noise margins seem to be fluctuating wildly.

1) What do you think is causing the spikes? Why do you think it only happens sometimes?

2) Are you quite sure that the telephone isn't causing the problem? Some cordless phones have been known to cause big problems with ADSL.

3) When the noise margin drops like that can you hear anything strange on the line if you quickly pickup the phone and dial zero after switching off the router? Nothing like a crossed line etc.? No strange voices or sounds? There must be significant noise on the line to throw off the router. Maybe the frequency is too high to hear anything? One of those DMT frequency plots might be very informative.

4) Could a telephone call to your neighbours' properties be causing this behaviour?

5) Do you still get this kind of behaviour between 12pm and 6am when nobody else is awake?

6) Does it happen at any particular time during the day?

7) Have you tried to get Telkom to switch your telephone onto another set of wires in the cable? This seems to be very simple to do so I guess that you may have tried this already. If there is a crosstalk problem then this might fix it. I think you can do this at the distribution box and also on the cable to your house. Have they checked the insulation resistance of the circuit? Debbie2 wrote up something about this when she was having problems with frequent modem disconnects. Here it is.

http://mybroadband.co.za/vb/showthread.php?t=29692&highlight=disconnect
 
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It seems to me that they (Telkom) can increase the Target SNR on DSLAM to help to compensate for the poor line condition. Quote:

“Increasing stable margin is pretty straight forward. (at least in UK)
Just ask the ISP to submit your fault to BT, requesting an increase of noise margin. (On DSLAM Port)

The SNR depends on the speed of connection. For example, on my line, the SNR is about 10dB now that I'm syncinc at 8Mb. When I was at 2Mb the SNR was around 23dB. When I was at 1Mb it was around 28dB, etc.

So for any given phone line, the SNR is lower as the speed increases.

Therefore you can set (and what is being talked about in this thread) a "Target SNR".
This means that at the time the line syncs, the SNR is not allowed to be lower than the target.

So for my line (10dB at 8128kbps sync), if my target SNR margin was 12dB, it would not let me sync at 8Mb, as the SNR achieved would be lower than 12. Therefore it would readjust and may come in somewhere about 7Mb or thereabouts.

So why people want it increasing? Surely 6dB should be enough

Yes, 6dB is enough, if it stayed that way. Remember target SNR is only of relevance at the exact moment when you sync. Line characteristics (especially of older / poorer quality / longer lines) can change quite dramatically throughout the day, because of interference, or other factors.

SNR can fluctuate by up to 10dB or even more over the course of a day, meaning that you may sync successfully and have an SNR of 6dB, but by the time evening comes, this SNR has dropped to below zero and you're getting dropouts. It may resync again, yet again establishing an SNR of 6dB, and the SNR drops again, once more causing a dropout.

If this occurs every day, it would get VERY frustrating, especially if the user was an avid gamer, or other such customer that needs a steady connection.

By increasing the target SNR, this can hopefully mean that on a particular line, SNR would fluctuate between say 15dB and 5dB, keeping the connection up and solid (albeit at a slower sync speed) rather than 6dB and -6dB, forcing a few reconnects every day”.

Hope that clarifies things a little?
 
@OMN: Maybe you should try Voyt's suggestion about the Target SNR. This may solve the problem. Try to see if Telkom can help you with this. Apparently the DSLAM default is a Target SNR of 6 but it can be increased to 9, 12 or 15dB. See below. This is from the previous posting about setting up DMT in English.

"Each time you connect, your router will try and sync at the highest speed it can whilst still allowing a safe margin of SNR to allow for normal noise fluctuations that occur over the course of the day. The default Target SNR is 6dB, but the DLM at the exchange can also set your Target SNR to 6, 9, 12 or 15dB."
 
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i've got a good friend at Saix NNOC ADSL dept in centurion..

this is his comments:

SA's DSLAMS doesn't train/sync in 32kb increments on the data side..

thats why they have the "up-to" products.

so for what i have figured sofar from exp:

up to 384 should be minimum sync 288/128 but ideal 384/128 -
512 minimum 384/256 but ideal 512/256 -
640/384 - but ideal 1024/384.

the "up to 4meg profile" is the REAL one with 32kb increments.

our town had a 678 ATM backhaul failure yesterday - phoned 375375 - the helpdesk dude - wasn't convinced (altho i do tech support for alot of companies here in town ,quickly figured out it was a total area failure) - anyhow - he disconnected my 1024 profile - and for some odd reason put me back to the up-to-4meg profile.....it synced 100% - 4096/384 on the netgear but with a 6SNR which is TOTAL borderline...having my graphs running 24/7 - i saw it - and the interesting part is - the 6SNR ran flatline for about 10min (very short while to make any conclusion)..but due to the history of my line - i told him to immediately get it back to 1024..did so.

and yeah...this is my graph for last night.

http://i210.photobucket.com/albums/bb147/jannie40/23aug0503.jpg

Big trouble usually starts at around 6:30 in the morning.
 
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Yotch said:
@OMN: Those noise margins seem to be fluctuating wildly.

1) What do you think is causing the spikes? Why do you think it only happens sometimes?

-its not electrical fencing
-sometimes i think the lines have serious crosstalk - almost as if my line is "shared" somehow with another house - and that when that person picks up their telephone it disconnects mine (going from a healthy 29SNR to 0)
-but telkom has checked this - diverted my line - diverted my e side - check all the connection points to the DP ect...
-used their line graph to check for shorts - nothing.
-my 2cents - its humanly induced problem.

2) Are you quite sure that the telephone isn't causing the problem? Some cordless phones have been known to cause big problems with ADSL.

-yip - not the telephone. i am getting the same scenario with even unplugging EVERYTHING...just the adsl connected...have got 2 rj11 jacks in the wallbox...no diffs in behaviour in the two
-no cordless phones.
-have got different filter brands (4sets for spare)

3) When the noise margin drops like that can you hear anything strange on the line if you quickly pickup the phone and dial zero after switching off the router? Nothing like a crossed line etc.? No strange voices or sounds? There must be significant noise on the line to throw off the router. Maybe the frequency is too high to hear anything? One of those DMT frequency plots might be very informative.

-what i can hear SOMETIMES - not always a given - is when i personally use the phone - i can hear the modem loose/gain sync...u can hear its an electronic humm - but only when its sync related.
-when the wind picks up badly - i can hear my line have a BIT of noise - but again - the majority of the time when there is no wind , with no noise on the line - problem occurs.


4) Could a telephone call to your neighbours' properties be causing this behaviour?

-dunno - i've got 5 houses around myself..i'm only 1 with ADSL

5) Do you still get this kind of behaviour between 12pm and 6am when nobody else is awake?

-thats the thing...not NEARLY as much as daytime...i can attribute 90% of the errors/downtime/problem to daytime...but - its not heat/cold / classical copper expanding problem - otherwise a graph would smoothly go down or up.
-we don't have an alarm system connected to the telephone either.
-and all my personal wireless antennas are switched off until 7pm @ night.


6) Does it happen at any particular time during the day?

-from 5am - to 11pm (mostly 6:30am to 6pm )

7) Have you tried to get Telkom to switch your telephone onto another set of wires in the cable? This seems to be very simple to do so I guess that you may have tried this already. If there is a crosstalk problem then this might fix it. I think you can do this at the distribution box and also on the cable to your house. Have they checked the insulation resistance of the circuit? Debbie2 wrote up something about this when she was having problems with frequent modem disconnects. Here it is.

-the only cable at this point that hasn't received "attention" is our 30year old dropdown cable - but aka the tech this cable tests fine...thats why i'm gonna request a new entry point(with new dropdown).

-there are 4 wires in our dropdown cable - and they have switched it - no diff.

http://mybroadband.co.za/vb/showthread.php?t=29692&highlight=disconnect
Click to expand...

thanx again for your contribution
 
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voyt said:
It seems to me that they (Telkom) can increase the Target SNR on DSLAM to help to compensate for the poor line condition. Quote:

“Increasing stable margin is pretty straight forward. (at least in UK)
Just ask the ISP to submit your fault to BT, requesting an increase of noise margin. (On DSLAM Port)

The SNR depends on the speed of connection. For example, on my line, the SNR is about 10dB now that I'm syncinc at 8Mb. When I was at 2Mb the SNR was around 23dB. When I was at 1Mb it was around 28dB, etc.

So for any given phone line, the SNR is lower as the speed increases.

Therefore you can set (and what is being talked about in this thread) a "Target SNR".
This means that at the time the line syncs, the SNR is not allowed to be lower than the target.

So for my line (10dB at 8128kbps sync), if my target SNR margin was 12dB, it would not let me sync at 8Mb, as the SNR achieved would be lower than 12. Therefore it would readjust and may come in somewhere about 7Mb or thereabouts.

So why people want it increasing? Surely 6dB should be enough

Yes, 6dB is enough, if it stayed that way. Remember target SNR is only of relevance at the exact moment when you sync. Line characteristics (especially of older / poorer quality / longer lines) can change quite dramatically throughout the day, because of interference, or other factors.

SNR can fluctuate by up to 10dB or even more over the course of a day, meaning that you may sync successfully and have an SNR of 6dB, but by the time evening comes, this SNR has dropped to below zero and you're getting dropouts. It may resync again, yet again establishing an SNR of 6dB, and the SNR drops again, once more causing a dropout.

If this occurs every day, it would get VERY frustrating, especially if the user was an avid gamer, or other such customer that needs a steady connection.

By increasing the target SNR, this can hopefully mean that on a particular line, SNR would fluctuate between say 15dB and 5dB, keeping the connection up and solid (albeit at a slower sync speed) rather than 6dB and -6dB, forcing a few reconnects every day”.

Hope that clarifies things a little?
Click to expand...

thats the MAIN problem - we are gamers - i myself play Battlefield2 - and brother plays WoW..

and when the poor line drops sync...its just silence in the house *giggle* (past point of swearing) hehe
 
gave my netgear a reset this morning - it went OK for a while then this:

http://i210.photobucket.com/albums/bb147/jannie40/23aug0725.jpg

in that 0 state i couldn't get it to sync - had to switch it off and on ..

i could hear it on the telephone line as it tried to sync....the router side..

i then pulled out the rj11 from the router - and it disconnected my ringtone.

sigh..
aaargg

grrrr aaarg :)
 
OK I'm out of ideas.

Apparently you can improve your upload SNR by changing the settings of the coding gain.
Might be worth a try. Take readings before and after to see if there is any improvement.

http://forums.whirlpool.net.au/forum-replies-archive.cfm/422235.html

Any chance that you could borrow an 834GT and do a frequency plot? I must say that I might be tempted to try to fiddle with the Target SNR if I had a suitable router like a SpeedTouch or an 834GT even if Telkom told me it wouldn't help. Maybe you could try to phone each of your neighbours from a cellphone when your ADSL line is stable to see if the noise doesn't suddenly spike.
 
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i give up aswell - i shall stick up my hand 1st when wimax arrives locally

fed up with this problem.

techs have admitted they can't locate my problem.
 
There is always the anarchists option: If you send enough juice down the line, you might be able to fry the line and hardware on the pole too. Then Telscum have to replace the 40 year old ****. Last time lighting struck the tree next to our Telscum pole, they had to replace everything.
 
Years ago (when the exchanges were still analogue) when I just started out with electronics I designed an answering machine which required lots of fiddling on the phone line.

One day Telkom gave me a visit and told me to stop what I was going as I blew one of the cards at the exchange :) Of course my answer was I don't know what your talking about - it must be the line :D

Conspirator - you sure it was lightning and not your 220V extension cable :D
 
QUESTION - does one HAVE to go thru the 2x connector box - or can you directly hook up to your dropdown wire? - i opened up my wallbox (2x rj11) and there is a small red (looks like a capacitor) thingy.

just scared if i hook it up directly (big copper pair so i'll have to make modifications) that it might pop the router.
 
[OUPA]MrNutz;1193872 said:
QUESTION - does one HAVE to go thru the 2x connector box - or can you directly hook up to your dropdown wire? - i opened up my wallbox (2x rj11) and there is a small red (looks like a capacitor) thingy.
Click to expand...

Never seen that before but could be MOVs to help kill spikes from nearby lightning strikes.
Either way they're irrelevant to what you want to do.

just scared if i hook it up directly (big copper pair so i'll have to make modifications) that it might pop the router.
Click to expand...

You can connect to the line directly without any risk of damage.
 
@bekdik: Please let us know if you find anything - I could really do with something like this for my Billion 7300G. It seems that those SpeedTouch routers have some pretty useful features if you have a lot of noise on your line.

@OMN: I think you are talking about a gas arrestor - it's just a surge device which does nothing until a lightning surge! You can usually just slip it out if necessary.
 
Let us know if there's any improvement in the noise levels.
 
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