Kitz Forum

Broadband Related => Router Monitoring Software => Topic started by: kezzaman on November 29, 2011, 11:13:23 PM

Title: SNR db per tone... (DMT tool)
Post by: kezzaman on November 29, 2011, 11:13:23 PM
Hey people,
So i was just playing around with the dmt tool and on this middle graph where it shows SNR db per tone i noticed that the snr drops out at certain levels of tone as you can see from those grey lines cutting through the yellow. I just wondered is that in anyway a problem, whats causing it and can it be fixed?

thx

(https://forum.kitz.co.uk/proxy.php?request=http%3A%2F%2Foi44.tinypic.com%2Fmlhj.jpg&hash=d1103708398f6aff5ae56d676a73ab204dbc5972)

Regards Kezzaman
Title: Re: SNR db per tone... (DMT tool)
Post by: GunJack on November 30, 2011, 10:28:01 PM
Jeez, wish my trace looked like that - you must be up around 20-24Meg ;)

Those few lines you're on about just means there's no bitloading on those tones, look at the panel bottom-right on DMT, it will list the gaps. No major issue with that, it's just the way it is :)
Title: Re: SNR db per tone... (DMT tool)
Post by: kezzaman on December 02, 2011, 12:51:58 AM
Thanks gunjack  ;)
Title: Re: SNR db per tone... (DMT tool)
Post by: GunJack on December 02, 2011, 11:06:59 AM
So what is your download sync ??
Title: Re: SNR db per tone... (DMT tool)
Post by: kezzaman on December 02, 2011, 07:33:11 PM
16 meg
Title: Re: SNR db per tone... (DMT tool)
Post by: GunJack on December 03, 2011, 08:32:10 PM
Quote from: kezzaman on December 02, 2011, 07:33:11 PM
16 meg


lucky s0d !!! ;)
Title: Re: SNR db per tone... (DMT tool)
Post by: asbokid on December 16, 2011, 01:41:07 AM
Quote from: kezzaman on November 29, 2011, 11:13:23 PM
Hey people,
So i was just playing around with the dmt tool and on this middle graph where it shows SNR db per tone i noticed that the snr drops out at certain levels of tone as you can see from those grey lines cutting through the yellow. I just wondered is that in anyway a problem, whats causing it and can it be fixed?

thx

(https://forum.kitz.co.uk/proxy.php?request=http%3A%2F%2Foi44.tinypic.com%2Fmlhj.jpg&hash=d1103708398f6aff5ae56d676a73ab204dbc5972)

Regards Kezzaman

"Pilot tones" maybe.  Although there seem to be a lot of them. 

That bug in DMT which causes the graphs to spew out beyond the right frame border is still there!

I patched that in my half-baked kludge to get DMT working with VDSL2.  It took some while to track down that stinker.  Shame no one is developing DMT any more to patch the official release.  The graphs are quite limited these days due to their fixed size.  It's much worse with VDSL2 because the tone map has ~4000 bins, and the graphs all have to rescaled so they can be squashed into that fixed ~600 pixel wide graph. Doing that makes it very hard to glean much information from the plots.  The graphing scripts developed by burakkucat and bald_eagle are much more useful.

cheers, a