Diagnosing drop outs on a long line.

So, I've decided to take it upon myself to try and sort my brother in laws ailing long line.

I was first made aware of this over a year ago and at the time logged in to the router (A thomson 585v6) to check sync and it was 3meg so didn't think anything of it.

Recently I had a closer look and discovered it was synced at 500Kbps with a large 16db noise margin!

As the house was old and a lot of very old extensions I set about disconnecting it as most of it was unused.

So now we are left with the drop wire that comes in to the house, a junction box and then a short run to an NTE5 which was put in a few years ago. Bell wire also removed.

Sync then went up to ~2800kbps

Went back next day - back down to 500k, quick check of the logs shows the router re-syced down in steps from around 1am onwards over night.


One other thing I noticed looking at a quick router stats graph is that the snr margine is contantly changing - compared to my short line which is almost always solid on 8.6db. Is this normal for a long line?

30 mins router stat graph:

http://img546.imageshack.us/img546/4057/92557886.jpg

Current router stats:


System Up Time 02:34:26

Port Status TxPkts RxPkts Collisions Tx B/s Rx B/s Up Time
WAN PPPoA 176434 132849 0 2328 10436 02:33:47
LAN 10M/100M 1772 0 0 36 0 02:34:23
WLAN 54M 142474 199791 0 11059 2705 02:34:18

ADSL Link Downstream Upstream
Connection Speed 2528 kbps 448 kbps
Line Attenuation 63.5 db 31.5 db
Noise Margin 7.7 db 14.0 db


I've currently got a laptop hanging off the router collecting stats 24/7 to see where the noise events are.

Any thoughts or suggestions as to what to do would be welcome!

edit: forgot to mention that I also changed the router for a DG834GT as I thought the thomson might be unstable.

Edited by huwwatkins (Wed 23-Nov-11 22:55:30)

For a line of 63.5dB (it will be higher as that is the maximum most routers display) the 2.5Meg is very good.

On the linked graph the SNR variation is perfectly ok, you would only worry if it was plunging below a level at which the modem carries out a resync

Hi
Yes - Im guessing his line is long, about 3 miles from the exchange by road so add a bit for extras.

I did manage to get some router stats info the other day (Which is cleverly didnt save!) it showed a solid connection from around 6pm when I started logging up till 23:57 when the snr dropped to 0 and it re-synced, same happened 5 minutes later. Sync back to 500k.

Im expecting the same to happen to night.

Dropped out again:

http://img845.imageshack.us/img845/6154/70980208.jpg

If the troughs are regularly spaced and only start at the same time each day consider

1. Heating that comes on at night e.g. water pump every five minutes
2. Security light
3. Economy 7 devices
4. Anything electrical in property only on at those times

If flat or got near neighbours it could be in their house