SNR Problems

Hi All,

Please could you have a look at this ?

http://s168.photobucket.com/albums/u165/trolltamer2/?action=view&current=SNRMargin230407.jpg

Has anyone seen SNR fluctuate like this ..... the readings are 2 secs apart and go from 9.4 - 0.1dB

No internal wiring, BT ADSL V1.0 Faceplate

I'm 1.55km from exchange as the crow flies !!!!!! (Aluminium cable in part of the line)

I know i have a RUBBISH line but it never used to do this... BT say the line is OK !!!

Any help would be GREATLY appreciated

I had a fault a bit like that a month or so ago. Downstream SNR target set at 15db. Anytime from midday onwards it started falling. Fell through first 15db (sometimes with a straight drop through around 10db), router resynced at lower rate back to 15db SNR. Usually fell through that 15db as well and another resync. BT tested line and found no faults. Had a second ADSL line which didn't suffer so that eliminated local noise at my end. I produced SNR logs for them and they started to look at the exchange. Ended up a full cease and reprovide was needed to solve it. Now runs like a dream!!

Brian

Have you had the chance to try a different modem / router to see if it behaves the same?

Which modem / router are you using? Some are better than others on long lines.

In reply to:

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Has anyone seen SNR fluctuate like this ..... the readings are 2 secs apart and go from 9.4 - 0.1dB

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Yes I have, when I was using a D-Link G604T. I bought a Speedtouch 546 to replace it and the problem went away, the Speedtouch was much more stable. At the time, I was on fixed 2Mb/s. The Speedtouch is currently hanging onto a sync of 5760 with a margin of 4.5dB

In reply to:

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I know i have a RUBBISH line but it never used to do this... BT say the line is OK !!!

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Have your line stats always been similar to your screenshot or have they changed recently. You have a high attenuation (for a short distance) of at least 63dB, a lot of modems / routers don't report anything higher than 63dB so it could be higher.

Is there anything electrical e.g. streetlights, thermostats etc that could be causing noise on your line ?

I have the down-spikes but they occur occasionally a couple in a minute or so, more commonly 10-15 minutes, best about 90 minutes. I sample at the default 8 seconds. They never affect my sync or connection. I am still hunting for the cause of them, but it doesn't seem to matter what I switch off in the house they still occur.

Obviously like me you don't lose sync when it happens.

Strange thing is I have attenuation 52dB, but can sync over 7 days at 6464 (done it twice) and only stopped because I wanted to mess with settings. Normal sync is 5120-5184, profile 4500. Most ppl would kill for that on 52 attenuation.

How do you know it goes to 0.1dB? Mine never shows the low figure, just variations corresponding to the main horizontal graph-line. I got confused until I realised the left-hand scale is a percentage from the start SNRM, not a value. Mine starts at a scale 0-10, then quickly changes to 0-40, like yours. I wonder if that's the maximum it can show, or whether we are both getting at most a 40% momentary drop?

Don't know if any of that helps. The other two graphs look pretty ropey as well imo, but I'm no expert.

It's that bad i WATCH IT lol <sad GIT> , well mine was like yours i could get 3mbps profile when on 6dB snr and like you say the spikes were less frequent but its like this all the time now.....and every couple of weeks its just syncs/loses sync every 10 seconds......... and no connection ....... but according to BT no line fault !!!!! i wouldn't mind so much but i actually brought this house as it was close to the exchange as i was on 512kbps at last house 6km line and only 60dB attenuation...... just goes to show how USELESS the 21CN upgrade will be to MOST .......... currently talking to CEO @ BT ......they know the problem .... but its a COMMERCIAL decision if they will replace the aluminium cable..... so 2 weeks of no contact has really answered my question.......as they have NO OBLIGATION to provide a BB service .... just a voice line you can hardly hear people on !!!!!!!!!!

I've spent in excess of 300 quid on routers <excluding the bundled voyager ones> currently using a DG834N <seems to be the best on [censored] lines>

yes the Voyager 2500V would show 15.5 when it meant 63.5dB but lost sync everytime the SNR dropped .... @ least the Netgear holds sync ....... i've had the router all over the front room with shielded cat5 cable !!!! i have disconnected the upstairs extension and have a 1 metre adsl cable and a BT phone plugged in and thats it ......i could understand if it was certain times of day....... but its like that 24/7

Thanks for the post........ they tried that last august..... but ALAS the same ........ i'm thinking of ringing Mr. Branson and BEGGING he runs a cable 100 metres from the other side of the green...... OHHHHHHHHHH to have a choice!!!!!