SNR margins under profile 17a

[joe]

Why are SNR margin figures so much higher under profle 17a than 8c? Many other posts I have since the OR modems have been accessed exhibit similar high SNR margin figures.

I note from griff's postings they went from 6.3dB (8c) to 22.7dB (17a) and my own have risen from 10.9dB (8c) to 22.4dB (17a).

The rise is not accompanied with any drop in synch speed.

[.Griff.]

Our respective SNR margins have increased as 17a has increased the bandwidth available but we're still artificially capped at 40Mbps.

[joe]

thanks griff.  I ask because a contributor on the thinkbroadband forum (XRaySpex 06Dec11 - thread 'Fibre Broadband - SNRM & Error levels') seems to think it represents a noise issue:-

"That's an invalid comparison with another line that has massive noise issues, witnessed by:

DS SNRM = 22.4 dB

Anyway you can't average errors over time, only over quantity of data."

Barry

[.Griff.]

He's assuming, wrongly, that the high SNR is the ISP/CP restricting the sync rate because of an issue, which is done on xDSL lines but that's not the case for our high SNR margins.

Once the 80/20 product goes live and the artificial cap is lifted our line rates will increase and the SNR will decrease accordingly.

[Lance]

Indeed. Essentially if you are not at the sync cap then the lower the better. Once you're at the sync cap it doesn't have to drop any more to try and get a higher sync.

[.Griff.]

Joe if you check some of his subsequent posts on TBB he realises his mistake and backtracks somewhat.

[joe]

griff,

Ah yes I see that now. I certainly didn't notice that retraction yesterday.

At least I now understand the high SNRM figure.  Thanks.

[Steve]

Is 17a been rolled out to every FTTC user or just those entering the trial?

[.Griff.]

Is 17a been rolled out to every FTTC user or just those entering the trial?

Rolled out to all FTTC DSLAM's.

[Steve]