DLM + Manually setting target SNR?

[norm360]

I've been manually adjusting my target SNR using the Sagem 2504 router.

@ 100%



@ 1%

http://i.imgur.com/rKkkB.png



Obviously my profile is capped. If I ask for DLM to be restarted, what do I keep target SNR at?

[Isitme]

If DLM training is going to be rerun you should leave it at default. If DLM finds your line is good enough it will reduce the noise margin. If you want to reduce the margin yourself, you should ask them to remove the cap from your line completely.

I find it a bit puzzling that you are able to reduce the noise margin without a corresponding increase in speed. Normally if you are capped the noise margin will remain the same, whether you reduce it artificially or not, it will not actually show a reduction in the stats. There is something iffy going on.

[timc]

I find it a bit puzzling that you are able to reduce the noise margin without a corresponding increase in speed. Normally if you are capped the noise margin will remain the same, whether you reduce it artificially or not, it will not actually show a reduction in the stats. There is something iffy going on.

Not sure I agree totally with that.

However low I reduce my SNRM I can't get above the sync figure I get at 4dB, even by going down to 2dB (still fairly stable at that btw).

[Isitme]

I am no great expert at this but if your line is capped at a figure, say 10Mb, it does not matter how low you put the noise margin it will still sync at 10Mb. Let's say you put the noise margin at zero, it will still sync at 10Mb and leave the noise margin it does not require to sync at that figure. It should not show a noise margin of zero in your stats.

In my own case, DLM capped me at 11.264Mb with a noise margin of 6db. If I reduce the noise margin to 3 db, I will still sync at 11.264(or near as dammit) but my stats still show I have a noise margin of 6db. The 3db does not come into play until the noise on my line increases to such an extent that at the original 6db it would drop out. The fact that it is 3db gives me a bigger cushion. If my cap was removed I could probably sync a good bit higher, probably 12.5-13Mb, then my stats would show a noise margin of 3db. I'm sorry if you don't get what I am trying to put over, but in the case of the first post, where has the noise margin gone? The speed has not increased, so the noise margin should not have decreased. I suspect the router is reporting incorrectly.

[timc]

I guess it could well be down to how the router reports the stats. Mine's the Billion 7800n & clearly reports it's end of things , maybe others do it differently.

[norm360]

If you take my stats above, when the noise margin dropped to 2.4dB shouldn't DLM management kick in at the exchange because it thinks the line quality has deteriorated and it wants to keep it at 6dB (or whatever Sky have it set to)?

Also when you talk about removing the cap, does that mean DLM gets switched off from the line (I didn't think this was possible)?

[Isitme]

Also when you talk about removing the cap, does that mean DLM gets switched off from the line (I didn't think this was possible)?

The knowledgeable Sky agents can remove the cap and suspend DLM. Many are unwilling to do it as they believe it may destabilise the line and lead to more calls for help.

If you take my stats above, when the noise margin dropped to 2.4dB

That is my point, your noise margin cannot drop like that. It is only what the router is reporting, I would bet from Sky's end they are still seeing your original noise margin.

[norm360]

Wonderfully generic/useless response by Sky after requesting DLM be rerun. Who do you contact that can actually configure the line?

Thank you for your email.


I certainly understand your concern regarding the Broadband speed.


I have checked your account and see that you are currently receiving a download speed of 10234 kbps which is the optimum speed available on your Broadband line. Also, the line stable.


The DLM will be automatically started only if there are any errors on the line due to which the speed gets affected. As there are no errors on your line the DLM can't be started.


However,to ensure that you receive the optimum speed available on your line, it would be advisable to perform the following setup checks

[Isitme]

You would be better phoning, emails are always liable to get the response you had.

[norm360]

Ok so I rang Sky and requested DLM be turned off, and they said it had after a few mins on hold to Higher Technical Support.

But my sync rate is still holding at 10mbits. But the CRC error rate is going up when I set a lower target SNR so it must be doing something. I've also note seen 'Max Rate' of higher than 12mbits before.

@ 1%



@ 25%


PS Ignore the higher CRC error rate at 25% that was after using 1% so it skewed it.