Line Stats Analysis Results

Expert

Line Stats Analysis Results

This thread will contain the results of the analysis of everyone's line stats that have been posted in the Data/Stats Collection Thread.

 

My initial analysis is not focused so much on distance from the VRAD.  The reason for this is that not too many people have distances that have been told to them by a tech using their specialized meters.  Furthermore, different line conditions can cause inaccuracy in their measured distances.

 

As it turns out, distance from the VRAD isn't the most important thing regarding the type and quality of service that you get anyway.  Instead, the wiring gauge, presence/absence of bridge taps, and the noise margin (signal-to-noise ratio) of the line are much more important.

 

To this end, the data that has been posted in the Data/Stats Collection Thread led to a rock-solid and extremely useful correlation that can be used to immediately judge the quality of your line and the service you can receive.  That correlation is the Downstream Noise Margin and the Max Line Rate.

 

Using only these two parameters, you can tell if A) Your line is working properly (i.e.. no bridge taps), B) What gauge wire is running from the VRAD to your NID, and C) What line profile you should be able to get.

 

Please note that I arrived at the wire gauge conclusions here because there are two distinct groupings of data points.  I am assuming the difference between them is due to wire gauge, because A) It is known that different neighborhoods around the country use two different wire gauges, 22 gauge, and 24 gauge, B) Thinner wire (24 gauge) would have higher attenuation in the high frequencies, which would reduce the max line rate for a given signal-to-noise ratio, which is exactly what the graph shows.  It is possible that the two groupings of data are due to a different cause, but until I either gather more data or have references to other possible conclusions, I'm going to assume the difference is due to wire gauge even though I cannot currently prove that with certainty.

 

There is a 3rd grouping of data that shows some people with a drastically reduced max line rate.  I'm fairly certain these people have a bridge tap on their line that is reducing the max line rate.  If their line was conditioned by I&R to remove the bridge tap, their max line rate would jump up into one of the other two groupings.  I have witnessed this first-hand, as my initial installation was on a line that had a bridge tap.  When the bridge tap was removed, the max line rate shot up by over 15000 Kbps.  I unfortunately cannot compare the numbers that I had at that point to the numbers I have now because those older numbers were using the VDSL1 protocol and at least 2 revisions earlier of the RG firmware.  Those values cannot be reliably compared to today's values obtained with the VDSL2 protocol and the current RG firmware revision (5.29.135.47).

 

Here's the first fully analyzed chart:

 

 

 

 

 

You can plainly see how well the data groups are formed here.  There are two distinct lines of people with properly working service, and a 3rd line of people with service that is probably not running right.  In addition, you can see the very rare people who are so close to the VRAD that they are currently being capped to a maximum line rate of 64000 Kbps.

 

For those of you who have some background in statistics, the linear correlation coefficients (R^2) for each of the 3 trend lines on the chart was > 0.98.  (This means that the computed lines fit the actual data very nicely).

 

The allowable line profile areas were computed by assuming that a line capacity of 80% is required for properly working service.  Line capacity = downstream profile rate / max line rate.  For example, for a properly working 32/5 profile, the downstream profile rate is 32200 Kbps.  FOr a line capacity of 80%, that means that Max Line Rate = Downstream Profile Rate / 80% = 32200 / .8 =  40250 Kbps, which I rounded to 40000.  The other rates separating the profiles were computed similarly.  The exception is the border for No Service, where I upped the allowed line capacity to 85% to allow just a little less max line rate.

 

The people whom I believe have a bridge tap on their line are very interesting.  The bridge tap reduces the max line rate that the line could theoretically carry by nearly 30%.  In the particular case of the person with an 18.5 dBm noise margin and 29000 Kbps max rate, having the line conditioned could conceivably get him a max line rate of 41000 Kbps, which would boost his allowable profile from 19/2 to 32/5 !  He could conceivable go from 1HD/3SD to 3HD/1SD just by having the bridge tap removed.

 

The person with the 10.0 dBm noise margin and a 19200 Kbps max rate is certainly experiencing poor service.  The line capacity in his case is at 100%, with no margin for errors.

 

 

In short, this chart can tell you at a glance whether your service is operating in agreement with everyone else's service.  It can immediately identify what profile you should be on or be able to get.  It can tell you if your line needs conditioning to have a bridge tap removed.  Based on my assumptions, it can also tell you your wire gauge, although that parameter is questionable.

 

When people post their line stats, this chart can be very useful in quickly determining if they are experiencing line problems or if their service is in agreement with normally working service.

 

Message 1 of 283 (8,792 Views)
Explorer

Re: Line Stats Analysis Results

Just a question, I don't want to sound like an idiot, but how can I tell if I am on VDSL or VDSL2.  I'm sure I missed some simple clue somewhere...

Message 256 of 283 (1,388 Views)
Expert

Re: Line Stats Analysis Results

 


WB9OUF wrote:

Just a question, I don't want to sound like an idiot, but how can I tell if I am on VDSL or VDSL2.  I'm sure I missed some simple clue somewhere...


 

You can look at http://192.168.1.254/xslt?PAGE=C_1_0 on your RG, look under the DSL Details section, and look at the Protocol.  G.993.2 is VDSL2, G.993.1 is VDSL.

 

All U-Verse installations were upgraded to VDSL2 during late 2009 - early 2010.

 

Message 257 of 283 (1,388 Views)
Explorer

Re: Line Stats Analysis Results

I figured it was right in front of me:smileyhappy:

Message 258 of 283 (1,388 Views)
Contributor

Re: Line Stats Analysis Results

2724i61FAD5509657858E2722iDF195FA855643B662720i86D8C602BF2755B8Hello

 

I'm posting my specs to get some feed back.  I have a pair bonding install.  Asked to get moved to the 2 HD stream but was told no.  I think I have a line issue on the first copper line.

2718iE793335418B5C02A

Message 259 of 283 (1,388 Views)
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Expert

Re: Line Stats Analysis Results

Your images are awaiting Mod approval; give it a little time so people here can see them.

Message 260 of 283 (1,388 Views)
Tutor

Re: Line Stats Analysis Results

Hey all, just had my uverse installed.  Tech said I was only about 500 ft from the nearest VRAD and the signal at the NID was very strong so would have no problem installing.  Tech was also on the phone trouble shooting with someone and said the loop length was long so thought he had to switch me down to the 25/2 profile but as of right now, still on the 35/5 profile and the TVs are running fine in HD.

 

Internet on the other hand is an issue.  Getting only about 14mbps downstream and 0.3mbps upstream which really disappointing me because that was what I was getting with cable internet before and one of the reasons why I decided to try uverse was the higher upstream.

 

Called the prem tech and he said he detected a bridge tap on the line and has opened a ticket for someone to come out and fix that within a day or two.  I definitely see a sinusoidal wave in the bitloading graph mentioned before for a bridge tap.

 

 

Message 261 of 283 (1,643 Views)
Expert

Re: Line Stats Analysis Results

dontcallmejeff,

 

I think you could be moved to 25/2.  Contact tech support one more time and request it, if they won't do it, post back here and we'll put you in touch with David & Matt's team.

 

There is the low noise margin reading on line 1, but I've seen some other iNIDs do that and it doesn't appear to cause problems.  The bit allocation analysis seems to indicate that the lines could handle 25/2.

 

Message 262 of 283 (1,643 Views)
Expert

Re: Line Stats Analysis Results

alpha,

 

You have a large bridge tap on the line.  Call tech support, have them send a premises tech, he will call I&R (the linesmen group) to have them remove it.

 

Once it's removed, 32/5 should perform very well for you.

 

Message 263 of 283 (1,643 Views)
Contributor

Re: Line Stats Analysis Results

Thanks for getting back to me.  I've tried twice to get tech support to move me to 25/2 but they refuse.  I would like to try it to see if there any problems.  My only current problem is that the battery backup for the router has gone bad.  Looks like it's hard wired to the router so quess I will need to schedule some one to come out and replace it.

Message 264 of 283 (1,643 Views)
Mentor

Re: Line Stats Analysis Results

I am looking for some help on explaining my Line Stats. I'm pretty close to a VRAD it says 1900 ft, but I'm certain its closer. I have yet to google the actually length from my door to the VRAD. 

 

Thanks in advance for your help. 

 

 

Stats.png

Message 265 of 283 (1,643 Views)
Guru

Re: Line Stats Analysis Results

Alright dontcallmejeff, please send an email to uversecare@att.com with your uVerse Account Number and ask for them to bump you up to the 25M profile.  The uversecare guys are Tier-2 Technicians, they aren't phone script readers.

 

Just send an email to them, they will get it working for you.

Message 266 of 283 (1,643 Views)
Guru

Re: Line Stats Analysis Results

SoxFan894, we'll have to wait for a moderator to approve your images but once they do, we'll take a look at them and see what suggestions we can give you.

Message 267 of 283 (1,643 Views)
Mentor

Re: Line Stats Analysis Results

 


trparky wrote:

SoxFan894, we will have to wait for a moderator to approve your images but once they do, we'll take a look at them and see what suggestions we can give you.


 

trparky,

 

Thanks for the quick response. Do you need me to post the Bitloading graphs?

Message 268 of 283 (1,643 Views)
Expert

Re: Line Stats Analysis Results

SoxFan, please post the bitloading also.  Your line is currently on too high a profile.  Depending on the bitloading, you might be able to raise the max rate instead of lowering the profile.

 

Message 269 of 283 (1,643 Views)
Mentor

Re: Line Stats Analysis Results

Bitloading.png

Here is the bitloader. Thank you joe

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