Its an automatic system so runs 365 days a year.

And not just in the first ten days of your account, either. This is part of normal operations, not training. If something, however temporary, knocks your speed down, BT's system waits for three days to establish a new rate and raises you to it. This may seem harsh, but if you are subject to frequent disconnections because of poor conditions, you would probably prefer to have a connection all the time rather than one that is sometimes good and usually not there at all.

But the settings established during training, SNR etc., effectively restrict the top sync speed available, although there are occasional automatic adjustments made later, normally to lower the speed, and very occasionally to increase it - thought that normally requires the customer making big waves.

This only happens if your line is so noisy that the target SNR has to be continuously raised in 3db steps until a stable line is arrived at. Then if whatever caused the problem later disappears MAX rarely reduces the target SNR back down on its own, at least not in any decent time frame. However, that is the only possible long term limiting effect on your actual line speed during training. The other main reason for training is to basically set up what is considered your fault level speeds under which BT will respond. Otherwise, if you happen to sync stably at a relatively low speed during training but your target SNR is not raised above the target of 6db and you later get a better noise figure, that better SNR will be traded for more speed when you next sync. Not forgetting the three days to recover form a low sync even of course, but that is active all the time not only during training.

In reply to:

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MAX rarely reduces the target SNR back down on its own, at least not in any decent time frame

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BT stated some time ago that DLM has been improved to detect if a line is more stable over a period of a few days, and then to lower the target SNR margin accordingly. However anybody who leaves their modem on continuously would need to force a resync to take advantage of this.

The '10 day period' has no significance other than that empirically BT have found that in the majority of cases the settings chosen by DLM have stablised by then (usually long before). The system makes a note of the speed at this time, but only as a basis for the service team to evaluate whether a line has significantly deteriorated later on.

Your noise margin down is right on the limit at 6dB, this is causing your IP Profile possibly to be lowered due to noise errors.

Where your phone line comes into the house should be a BT socket with a split front plate. If you have a socket like this undo the two screws of the lower plate and pull the plate gently forward. This front plate is plugged into a hidden socket on the left behind it. Plug your router, with as short a lead as possible into this socket without a filter. If your noise margin is better, say 12dB or more you have faulty internal extension wiring.
(Removing this front plate disconnects all internal extension wiring).

Brian

In reply to:

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The system makes a note of the speed at this time, but only as a basis for the service team to evaluate whether a line has significantly deteriorated later on.

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That is the point I was trying to make. The only thing that is set by the training period is the threshold level above which a speed is deemed to be acceptable. The Maximum Stable Rate (MSR) is the highest sync rate detected in the period. The only real significance of this is that the Fault Threshold Rate (FTR) is 30% less than it. If your system synchronises at anything above this, it is deemed to be performing within acceptable bounds. I may have some of the detail wrong here and I have no idea if there is any possibility of changing this.

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Your noise margin down is right on the limit at 6dB, this is causing your IP Profile possibly to be lowered due to noise errors
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It's supposed to be 6dB. It's a MAX dsl line.

It only goes over 6dB, if the line is in sync at 8meg & has margin to spare or BT has forced a higher margin due to problems.

Sorry, very much disagree with you, 6dB is very marginal.

Extract from: http://www.farina1.com/bookmark/000004/2005/02/27/00020260.HTM

What would be the ideal attenuation and SNR values?
Quote:
Ideally you want low attenuation, and a high SNR, some examples are:

If you have a line of 2km long, and the downstream attenuation is 20dB with a SNR of 30dB that is very good.
A 2km line with the same attenuation of 20dB and SNR of 8dB is not very good. The SNR is now low.
A 6km line with an attenuation of 57dB, and SNR of 18dB is very good also. You do expect the attenuation to rise as the line gets longer.
A similar 6km line with 57dB attenuation, but a SNR of 5dB is really on the edge of working, or not working, and thus very bad.
Normally you would expect a lower attenuation line to have a high SNR. If you do not have a high SNR, and the line is unstable then it is worth looking at the wiring in the property. We would suggest a visit to bbs.adslguide.org.uk to discuss the issue on our forums, where people will ask about the wiring in the house and hopefully suggest some course of action.

Unquote
Brian

I don't pretend to be knowledgable on the subject - but I am about 3 KM away from my exchange and have a max DSL with 6dB. My neighbours either side of me are the same. A friend just a few hundred metres from the exchange is also 6dB on a max connection, whilst my Sister who lives ina different town and is five KM from her exchamge is also on 6dB.

Surely that suggests that max is 6dB doesn't it?.

Incidentally I always get around 6mb with a 37 attenuation.