Who'd I upset

[D-Dan]

After my power outage last month - which stopped me getting to a full month of solid, uninterrupted service, I was on the brink last week (actually into the last day) of a complete - solid month)

I went to work in the morning, and got home at night - checked my router stats as normal - and to my dismay I'd had a re-sync that same day. It must have been quick because my internet connection hadn't realised. I rebooted my router to get everything back to normal - and synced no problem.

So what's wrong? My sync is down to 6188 from 6880 (and has been for the best part of a week), and throughput is at best 77% of sync - until 3 - 4 weeks ago it was generally 82%. So I'm getting a lower ratio throughput on a slower sync - which is generally bad news all round.

There have been no changes to the wiring, I'm not aware of any exchange "upgrades" and SNR is consistently above 6 (usually 6.5 - 7.5). Line attenuation is at 45 (which it has been for months).

I'd like to test my IP profile (was 6000 but I'm guessing that's down to 5500 or lower now) but I can't get into the BT speedtester ATM.

Any ideas what may have caused this?

Steve

[Simon]

Christmas lights?  No, seriously, apparently they can generate 'noise'.  Rik will explain, but of course, it might not be that. 

[Sebby]

As far as the reasons for sync'ing lower go, the most likely explanation (as Simon says) is Christmas lights. The noise on my line has increased for no apparent reason recently, and I'm putting it down to this. They create extra noise, and therefore your router has to sync lower to achieve the same target SNRM (Signal-to-Noise Ratio Margin). Alternatively, it could simply be that you've sync'd at night when there is generally more noise around; if you re-sync in the morning, you may find you achieve your "normal" sync.

Concerning your throughput, you should never calculate it as a percent of the sync rate because of bRAS profiles. BT assign a profile depending on your sync. With a sync of 6,880kb you'll have a profile of 6,000kb; with a sync of 6,188kb you'll have a profile of 5,000kb (the sync must be 6,240kb for a 5,500kb profile). This would explain why the throughput as percent of sync rate has declined.

I hope this helps. 

[Rik]

Great answer, Sebby.

Just to give you an idea of noise sources, Dan, I have a street light at the front of the house. I can see on the Routerstats graph when it turns on and off, the noise margin drops 1db when it comes on, then returns to normal the following morning when it goes off.

[Ann]

Here's the sync list

SYNC rate     Data rate

288 – 575     250 Kbps
576 – 1151    500 Kbps
1152 – 1727   1.0 Mbps
1728 – 2271   1.5 Mbps
2272 – 2847   2.0 Mbps
2848 – 3423   2.5 Mbps
3424 – 3999   3.0 Mbps
4000 – 4543   3.5 Mbps
4544 – 5119   4.0 Mbps
5120 – 5695   4.5 Mbps
5696 – 6239   5.0 Mbps
6240 – 6815   5.5 Mbps
6816 – 7391   6.0 Mbps
7392 – 7967   6.5 Mbps
7968 – 8127   7.0 Mbps
8128             7.15 Mbps

[Rik]

There are rumoured to be some more 250k steps coming in at the lower end, Ann, though I haven't heard anything definite.

[Glenn]

I was on a 1750k profile pre 2700HGV

[Rik]

Ah, the coming of spring.

Any idea what the speed range was for the 1750 profile, Glenn?

[Sebby]

I've never seen 1,750 before. That's certainly a new one!

I wish they'd add some more around the 4-4.5Mb sync mark. You need 4,544 sync to get a 4,000 profile, and I can only just about get this; usually I sync at 4.3-4.4Mb, so I end up getting a 3,500 profile. The profiling system is a nuisance!

[Rik]

It's not a nuisance, Sebby, it's a BIG nuisance. 

[ReDGryphoN]

The changes to the IP profiles was quite some time ago.

See this link for the full current list..............

http://www.kitz.co.uk/adsl/IPprofile.htm

ReD

MAABOF

[Rik]

Useful link, thanks Red.

[D-Dan]

Obviously - unlike a lot of you - my boss still makes me work this close to Christmas - so I've only just caught up with replies.

Anyway - we can rule out Christmas lights. I don't do Christmas after my third relationship in a row broke down during the "festive" season - so no lights, no tinsel, no cards and no Santa to blame. In fact - absolutely nothing has changed except my sync speed

Oh - and I get the irony complaining about working so close to Christmas when I don't really bother with it - but I still want my holiday

Any other ideas?

BTW - happy end of the year, time for an argument holidays to everyone. 

[Sebby]

It doesn't have to be your Christmas lights, it can be neighbours'.

[Rik]

Obviously - unlike a lot of you - my boss still makes me work this close to Christmas

Some of us have given up work for good, Steve.

We can only speculate without figures. As Sebby says, the noise doesn't have to be in your house, it can be across the road or down the road, even just on the same mains phase.

If you can't get into the BT tester, your best bet would be to talk to IDNet, who can look at your line data from their end.

[Sebby]

The biggest issue is that BT aren't going to be interested in looking into this one, which I think is fair (it's not often I side with BT!). Whilst frustrating (I know how it feels when sync degrades for no apparent reason) you've only lost 700k (albeit at the cost of 1,000k in terms of the bRAS profile), so there is certainly no fault in the usual sense of the term. There is definitely just a bit of increased noise somewhere, and the likelihood is that it'll disappear anyway. 

[Rik]

(it's not often I side with BT!)

I've just made a note in the diary and checked for a star in the east, Sebby. 

[Sebby]