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[b4dger]

Thought I would provide an update to my 'ADSL life' in case it adds any value...

As I've mentioned before, I'm on a rural and fairly noisy line and have had a few issues along the way 

The link in my signature contains details of my connection which I have tried to make the most of - filtered faceplate, router changes etc.

I've noticed over the last few weeks my error counts have been much improved.
FECs used to be in the 100,000's or 1millions for a day with HEC/CRCs in the 1000-10,000 range, but lately FECs have been in the 10,000's with some days worse and the HEC/CRCs sometimes staying in the 100's.

In the past as I've improved things at my end I've had to ask for my Target SNR to be manually reduced to improve my sync. This has been done in steps from 15db (set last summer during storms) to 12db and then at the end of March to 9db.

I was reasonably happy with this Target SNR (9db) with an attenuation of 50/51 and a sync of around 4800 - much better than ALL my near neighbours!

But today I've found that my Target SNR seems to have been automatically reduced to the default 6db - increasing my sync to 5504 

Now whether my line is going to be able to support this only time will tell! My SNR used to drop from 9db to around 5.5/6db in the evenings - so I won't be too surprised if I drop my connection with my new Target.

I guess I've got to have some faith in BT's systems ( ) and they know what they are doing. I won't be happy if my stable line suffers with this change...

People often ask questions about the 'rules' of having a Target SNR reduced (which is somewhat 'blackmagic') - so at least this shows a few things:
My router is turned off each night and back on in the morning - showing that you don't have to maintain a continuous sync. My sync's rise and fall by a few 100k.
So in my case it looks like the improvement in my error count has triggered the reduction.

Obviously I'll continue to bore you keep you all updated with the latest news 

[roseway]

Very interesting, thanks.

[Ezzer]

Have your neighbours found a similar improvement ?

[b4dger]

Have your neighbours found a similar improvement ?

Not that I'm aware of. But it's hard to tell as none of them know what speed/connection/attenuation/etc. their lines have!  I only get to see if I'm able to get to their PC and take a look for myself.

I'm assuming that some maintenance or repair has taken place recently which has improved my line.

[Ezzer]

I'm assuming that some maintenance or repair has taken place recently which has improved my line.

Your not near Hickling, Norfolk by any chance

[b4dger]

I'm assuming that some maintenance or repair has taken place recently which has improved my line.

Your not near Hickling, Norfolk by any chance

Nope - I'm in Kent...

[b4dger]

Very interesting, thanks.

It's dark now and the lowest I've seen my SNR margin drop to is 3.5 - no drop of sync - having trouble typing as everything is crossed 

[jid]

Very interesting, thanks.

It's dark now and the lowest I've seen my SNR margin drop to is 3.5 - no drop of sync - having trouble typing as everything is crossed 

Could be that the Low SNR will cause CRC errors as the night progresses on.

But I have everything crossed for you...

[sevenlayermuddle]

Hi B4dger,

Congrats on your DLM reduction.  I had previously believed, and maybe even propagated, some of the rumours that continuous sync was a necessary prerequisite for target reduction, and it's fascinating to hear first-hand evidence that it's not the case.

I can't help wondering whether your habit of powering off your router at night, however, is necessarily helping?  If the router were to lose sync under any givem profile, it would likely do so at night, and then it would resync at a lower speed to maintain the same margin.   Then all other things being equal, the next night, it would still be sync'd at a lower speed and so wouldn't drop out again (and neither would it get as many errors).   By resyncing every morning, you may may well be syncing at a more agressive speed than would be the case if you left everything to its own devices, and hence things may be a little bit more precarious.

Anyway, I for one am deeply jealous of your reduction.  Don't change a thing.  Well done!

[MollyCoddle]

>>>"I had previously believed, and maybe even propagated, some of the rumours" by sevenlayermuddle

I mean only to use your comment to introduce my question, it is not meant critically, yet an interesting comment in light of my experiences, particularly concerning my post :- http://forum.kitz.co.uk/index.php?topic=3689.msg89145#msg89145.

To recap, my SNR drifted in a staedy manner over 6 hours, from 12dB to 7dB. Feedback here was that this was my line and independant of my ISP. Taking you good peoples advice, I have moved ISP. I now get a range of 16dB to 13dB throughout the day. A huge change in level and range.

I cannot accept that the previous SNR action was due to my line.

Please let me have your feedback to my my next step.

I believe I may ask my new ISP (of 5 days), to reduce my target SNR.

Thanks again, MC.

[sevenlayermuddle]

Hi there,

IN my case, my target SNR was increased because of my own stupidity, resetting the modem a lot of times in a short period of time (ten times in an hour).  DLM mistakes that for an unstable line, and raises the target accordingly.  I then have to play a waiting game for months and months, waiting for  DLM to reallise that my line's actually fine, and reduce my SNR again.  The rumours I referred to are those surrounding the rules DLM follows for reducing target SNR under those conditions.

If your SNR is widely fluctuating then DLM may have detected real instability and increased your target for quite valid reasons, as it will make your line more stable.  In that case, and if your line's still unstable, I'd think that you're probably better off with a raised target SNR.

[roseway]

To recap, my SNR drifted in a staedy manner over 6 hours, from 12dB to 7dB. Feedback here was that this was my line and independant of my ISP. Taking you good peoples advice, I have moved ISP. I now get a range of 16dB to 13dB throughout the day. A huge change in level and range.

I cannot accept that the previous SNR action was due to my line.

Sorry MC, but you do have a misunderstanding. If your connection is via a BT line (i.e. not LLU) then the ISP has absolutely no control over your noise margin. The drift with time is a quite normal effect of varying line and interference conditions. If your noise margin is now consistently higher than it was before, then that's almost certain to be the result of DLM increasing the target noise margin to improve the stability of the connection at the expense of some speed. It wasn't the result of a change of ISP.

[MollyCoddle]

>>>>Sorry MC, but you do have a misunderstanding.

I am sure that you do not ignore your own observations roseway. Kindly, I do not misunderstand my own observations.

The only point I am prepared to concede is that by coincidence, to the hour of the cut-over, that there was a nexus in my line conditions, that before the cut-over for the duration I have been posting here (about two weeks) that the line had a daily move of 5-6dB down from 12dB which took 6 hours, it stayed there for 6 hours, it then took 6 hours to drift back up.
Then some event occured to my line at the exact moment of cut-over, by coincidence!!
Since, my line gently moves between 13-16dB, with no time dependance as was exhibted before. What I did not detail before is that due to my new ISP giving incorrect authentication settings, I have had to re-boot my router many times in the last few days, which may have caused the raise in SNR. However for the first few days after cur-over, my SNR varied between 12.5-10.5 (12.5 being the approximate start level before cut-over) again with no time dependance as before. This logically means that the raising of the SNR to 16ish is not the fix for the 6hour 6 db drift, as the SNR action was the same before and after me solving the authentication problem and consequent re-booting during my finding the problem.

Logically and statistically it unlikely to be purely my line. In addition, I do not believe in coincidences.

Hoping to maintain a debate on my understanding, MC

[jeffbb]

as a matter of interest with your new snr margin has your connection speed gone down?

[MollyCoddle]

@jeffbb,

Yes, as you would expect, from about 4meg after cut-over (approx 1meg higher than with old ISP), to 3.5meg after my reboots in discovering the authentication config error from new ISP.

My hope is for the new SNR margin to either adapt and/or my ISP (chosen for their customer care) to lower it OR I buy a tweaky router.

Thanks for your question, Molly Coddle