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Author Topic: Discussion of QLN and HLog graph scaling  (Read 5367 times)

Bald_Eagle1

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Discussion of QLN and HLog graph scaling
« on: July 19, 2014, 05:24:35 PM »

Finally, a comment about the size of the y-axis scale for the QLN and HLog plots. I have never seen a QLN plot where the curve is below -150 dBm/Hz. So perhaps using the range -80 to -160 dBm/Hz would make better use of the space? Similarly I have never seen a HLog plot where the curve is below -100 dB. So, again, using a range of 0 to -120 dB would make better use of the space? Perhaps Bald_Eagle1, having viewed many QLN and HLog plots from different circuits over the last few years, has an opinion upon the y-axis scales?



Here's a snippet of recently obtained QLN data from a G.DMT connection:-

Tone number      QLN
   0            -88.0000
   1            -146.0000
   2            -147.0000
   3            -148.0000
   4            -150.0000
   5            -149.0000
   6            -150.0000
   7            -150.5000
   8            -150.5000
   9            -150.0000
   10           -150.0000
   11           -150.5000
   12           -149.0000
   13           -150.0000
   14           -150.0000
   15           -148.0000
   16           -147.0000
   17           -146.0000
   18           -144.0000


So, with a little spare, perhaps -160dBm/Hz should be the value for bottom of the Y axis.

I have attached 3 versions of the same data.
One uses 0 to -160 one uses -80 to -160 & the other uses -110 to -160

My preference is 0 to -160 as some users might panic on seeing larger spikes as shown in the -80 to -160 & -110 to -160 graphs & it might prompt them into asking many (possibly) unnecessary questions?  ???  ;)

Whichever values are used, if wishing to compare stats from different connections, in my opinion it is wise to have fixed rather than auto-scaled axes.

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burakkucat

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Re: Discussion of QLN and HLog graph scaling
« Reply #1 on: July 19, 2014, 05:32:14 PM »

Making use of DSLstats, this is what I see for QLN and HLog plots --
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Bald_Eagle1

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Re: Discussion of QLN and HLog graph scaling
« Reply #2 on: July 19, 2014, 05:37:04 PM »

Similarly I have never seen a HLog plot where the curve is below -100 dB. So, again, using a range of 0 to -120 dB would make better use of the space? Perhaps Bald_Eagle1, having viewed many QLN and HLog plots from different circuits over the last few years, has an opinion upon the y-axis scales?



Neither had I until I recently obtained the stats from the G.DMT connection mentioned above.

It prompted me to adjust the Hlog axis values for ADSL connections.

I have attached an example I replotted from some ADSL2+ testing data you sent me from your own connection.

« Last Edit: July 19, 2014, 05:59:27 PM by Bald_Eagle1 »
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burakkucat

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Re: Discussion of QLN and HLog graph scaling
« Reply #3 on: July 19, 2014, 05:57:07 PM »

Ah, I vaguely remember!

The violent swings present in the "mush" from tone 330 upwards should really be discounted. I put it down to the CPE transceiver attempting to "find something that isn't there".

Perhaps we should make a study of Kitizens' QLN and HLog plots in the region of tones 0 to 10. That might indicate what could be regarded as a sensible "lower limit"?  :-\
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roseway

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Re: Discussion of QLN and HLog graph scaling
« Reply #4 on: July 19, 2014, 07:03:08 PM »

I'm certainly interested in optimising the scales of the QLN and HLog graphs. It seems to me that the best thing for all concerned would be that HG612-stats and DSLstats use the same scales, and for the same reason I agree that a fixed scale is better than autoscaling.

I think my preference for the QLN graph would be a range of -60 to -160, because it would seem to cover all the likely values and doesn't leave a lot of empty space (which starting at zero would).

For HLog, 0 to -100 would cover most cases, but there would be the few that go below -100. Perhaps in this case a degree of autoscaling might be appropriate, rather than leaving a lot of empty space on most connections.

For HLog, 0 to -120 would seem to cover all likely cases, without too much empty space.
« Last Edit: July 20, 2014, 08:15:53 AM by roseway »
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roseway

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Re: Discussion of QLN and HLog graph scaling
« Reply #5 on: July 19, 2014, 11:19:09 PM »

I've split this into a separate topic, as it's relevant to any monitoring program.
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burakkucat

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Re: Discussion of QLN and HLog graph scaling
« Reply #6 on: July 19, 2014, 11:40:45 PM »

I've split this into a separate topic, as it's relevant to any monitoring program.

A good move!  :thumbs:
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roseway

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Re: Discussion of QLN and HLog graph scaling
« Reply #7 on: July 20, 2014, 10:51:52 AM »

For reference, here are my QLN and HLog graphs using the scaling I suggested above.
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kitz

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Re: Discussion of QLN and HLog graph scaling
« Reply #8 on: July 20, 2014, 12:09:24 PM »

Quote
I have never seen a QLN plot where the curve is below -150 dBm/Hz. So perhaps using the range -80 to -160 dBm/Hz would make better use of the space? Similarly I have never seen a HLog plot where the curve is below -100 dB.

My line does.


My QLN already goes as low as -160 dBm/Hz in several regions so perhaps just a bit more is needed to say -170 please to make the graph look like its not falling off the bottom of the page, and also allow for the fact that there are many lines shorter than mine.

Code: [Select]
858          -124.8750
   859          -127.3750
   860          -160.0000
   861          -160.0000
   862          -160.0000
   863          -160.0000
   864          -160.0000
   865          -160.0000
   866          -160.0000
   867          -160.0000
   868          -160.0000
   869          -160.0000
   870          -160.0000
   871          -160.0000
   872          -160.0000
   873          -160.0000
   874          -160.0000
   875          -160.0000
   876          -160.0000
   877          -160.0000
   878          -160.0000
   879          -160.0000
   880          -160.0000
   881          -160.0000
   882          -160.0000
   883          -160.0000
   884          -160.0000
   885          -160.0000
   886          -160.0000
   887          -160.0000
   888          -131.5000
   889          -131.5000
   890          -131.5000
   891          -131.5000


1191         -132.0000
   1192         -160.0000
   1193         -160.0000
   1194         -160.0000
   1195         -160.0000
   1196         -160.0000
   1197         -160.0000
   1198         -160.0000
   1199         -160.0000
   1200         -160.0000
   1201         -160.0000
   1202         -160.0000
   1203         -160.0000
   1204         -160.0000
   1205         -160.0000
   1206         -160.0000
   1207         -160.0000
   1208         -160.0000
   1209         -160.0000
   1210         -160.0000
   1211         -160.0000
   1212         -160.0000
   1213         -160.0000
   1214         -160.0000
   1215         -160.0000
   1216         -128.9375




My Hlog in the corresponding frequencies reaches -96

Code: [Select]
850          -17.1875
   851          -17.1875
   852          -17.1875
   853          -17.1875
   854          -17.1875
   855          -17.1875
   856          -17.1875
   857          -17.1875
   858          -96.0000
   859          -96.0000
   860          -96.0000
   861          -96.0000
   862          -96.0000
   863          -96.0000
   864          -96.0000
   865          -96.0000
   866          -96.0000
   867          -96.0000
   868          -96.0000
   869          -96.0000
   870          -96.0000
   871          -96.0000
   872          -96.0000
   873          -96.0000
   874          -96.0000
   875          -96.0000
   876          -96.0000
   877          -96.0000
   878          -96.0000
   879          -96.0000
   880          -96.0000
   881          -96.0000
   882          -96.2500
   883          -96.2500
   884          -96.2500
   885          -96.2500

1192         -19.5625
   1193         -19.5625
   1194         -96.0000
   1195         -96.0000
   1196         -96.0000
   1197         -96.0000
   1198         -96.0000
   1199         -96.0000
   1200         -96.0000
   1201         -96.0000
   1202         -96.0000
   1203         -96.0000
   1204         -96.0000
   1205         -96.0000
   1206         -96.0000
   1207         -96.0000
   1208         -96.0000
   1209         -96.0000
   1210         -96.0000
   1211         -96.0000
   1212         -96.0000
   1213         -96.0000
   1214         -96.0000
   1215         -96.0000
   1216         -96.0000
   1217         -96.0000
   1218         -96.2500
   1219         -96.2500
   1220         -96.2500
   1221         -96.2500
   1222         -96.2500
   1223         -96.2500
   1224         -21.6875
   1225         -21.6875
   1226         -21.6875
   1227         -21.6875
   1228         -21.6875
   1229         -21.6875
   1230         -21.6875
   1231         -21.6875
« Last Edit: July 20, 2014, 12:15:45 PM by kitz »
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burakkucat

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Re: Discussion of QLN and HLog graph scaling
« Reply #9 on: July 20, 2014, 01:04:46 PM »

Quote
I have never seen a QLN plot where the curve is below -150 dBm/Hz. So perhaps using the range -80 to -160 dBm/Hz would make better use of the space? Similarly I have never seen a HLog plot where the curve is below -100 dB.

My line does.


My QLN already goes as low as -160 dBm/Hz in several regions so perhaps just a bit more is needed to say -170 please to make the graph look like its not falling off the bottom of the page, and also allow for the fact that there are many lines shorter than mine.

I would be interested to know, for tones 0 - 10, if you see a horizontal line and the level it indicates. (If not at -160 dBm/Hz, then my postulation will be false.)
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roseway

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Re: Discussion of QLN and HLog graph scaling
« Reply #10 on: July 20, 2014, 01:36:38 PM »

Taking note of Kitz' comments, I propose the following:

QLN: -60 to -170 dBm/Hz
HLog: 0 to -120 dB (as before)
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les-70

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Re: Discussion of QLN and HLog graph scaling
« Reply #11 on: July 20, 2014, 02:53:54 PM »

  I suspect that kitz is reporting values in unused bands on vdsl.  They do go to the values she notes but it probably would not matter is the graphs did not get that far. See examples below.
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Bald_Eagle1

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Re: Discussion of QLN and HLog graph scaling
« Reply #12 on: July 20, 2014, 07:25:49 PM »

I prefer to show the data from usable & unusable tones.
If nothing else, it partly provides an explanation as to why those tones can't be used (Attenuation too high etc.)

For VDSL2 connections, my Hlog graphs currently display everything between 0 & -95.999 (I assumed -96.000 meant 'invalid' or N/A data).

For G.DMT & ADSL2, the parameters currently used are 0 & -140.999

For ADSL2+, 0 & -120.000


For QLN, the parameters are currently 0 & -159.999 for all modes.



As per the attached Hlog graph, attenuation in the D3 band was too poor for my connection to use any of it, but at least I can see how poor it is.


It has deteriorated since then & I have nothing at all better than -96.000 in the U2 & D3 bands (see the other graph).


I intentionally chose not to show a flat line for 'invalid' or N/A data, thinking it 'could' be misleading.


EDIT:

Just for 'fun', I replotted the 2nd Hlog graph (attached) with parameters 0 to -100.

It has alerted me to the fact that since the October firmware update, -96.250 now seems to be the limit rather than -96.000 for VDSL2 connections.




Does anyone have a preference for what is actually plotted & if so, please explain why?


« Last Edit: July 20, 2014, 07:42:18 PM by Bald_Eagle1 »
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burakkucat

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Re: Discussion of QLN and HLog graph scaling
« Reply #13 on: July 20, 2014, 11:45:28 PM »

b*cat, having been the one to instigate this round of discussions prefers to stand back and let others express opinions.

It would be nice to have both DSLstats and modem_stats using the same y-axis range for QLN and HLog plots.

My experience is solely with DSLstats and an ADSL2 mode service -- and there is a lot of wasted vertical space in the HLog plot.
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kitz

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Re: Discussion of QLN and HLog graph scaling
« Reply #14 on: July 21, 2014, 01:19:29 AM »

Thank you, yes I'd be happy with -170. 

Yes bcat you are correct -160 is my base line for the starting tones and also any unused tones such as stop bands.  I'm not at the pc atm to check but iirc it was tones 1-7 that were at -160 too.

Like bald eagle, if possible I would like to be able to see data both from usable and unusable tones, otherwise if the graph stopped at -160' it would just look like the bottom of the graph had been chopped off, aside from the fact I'd never know if it did get any lower.

Finally it would be confirmation of my base noise floor measurement, which when it comes to QLN can be a very important figure in its own right.


@BE I'm not using the hg612, and I can't double check right now, but I'm 99% certain that I also see -96.250
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