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.

 

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Message 1 of 283

Re: Line Stats Analysis Results

Joe, I would like to thank you very much for all your hard work.  While I have a science background, it is not in electronics/computers/engineering, and I know very little compared to most regulars on this forum.  But your graph has made things much more understandable.  With 43000 kbps/19.0 dBm/24 ga wire, I am within (but near the low end of) the 32/5 allowable range.  I assume that AT&T will upgrade me to 32/5, but that this may mean a decrease in service quality. Perhaps another thread can be started to address what measures, if any, can be taken to improve max rate or noise margin so as to optimize service within one's allowable profile.  Thank you once again for your enormous effort!

 

docbombay 

"Everything should be made as simple as possible--but not simpler."
--Albert Einstein
Message 2 of 283
ACE - Master

Re: Line Stats Analysis Results

Ditto DBB's comments, Joe.  Your information should be very useful in the future.  Sure looks like a lot of work but worth it.  Thank you very much for all your effort.
The problem with socialism is that you eventually run out of other peoples' money. .......Margaret Thatcher
*The views and opinions expressed on this forum are purely my own. Any product claim, statistic, quote, or other representation about a product or service should be verified with the manufacturer, provider, or party.
Message 3 of 283
Expert

Re: Line Stats Analysis Results

Thanks for all your time...SOMEBODY should pay you for your findings...  :smileywink:
Message 4 of 283
Scholar

Re: Line Stats Analysis Results

         Joe

 

            AM i correct in assuming that if i shorten the amount of cat 5e, from my nid outside my house to the RG that it might make a difference in the max rate and noise margin, as i do have that option, approx. 60'.

 

 

 

 

                                                                      Thanks             gofer

Message 5 of 283
Expert

Re: Line Stats Analysis Results


gofer6064 wrote:

 

AM i correct in assuming that if i shorten the amount of cat 5e, from my nid outside my house to the RG that it might make a difference in the max rate and noise margin, as i do have that option, approx. 60'.


 

Doubtful.  60' is not generally enough to make a difference in the line stats, especially if it is Cat5e to begin with.

 

However, if a home run is long and/or possibly picking up interference from somewhere, then shortening it could help.  But Cat5e doesn't pick up hardly any interference to begin with, so in your case it's not likely that you could gain much.

 

Message 6 of 283
Scholar

Re: Line Stats Analysis Results

Hey SomeJoe, many MANY thanks!

 

Now, let me play the part of the forum dummy (a role I'm good at) and ask some dumb questions.  Looking at the chart, I see four red squares in the yellow area.  These four squares represent four Uverse users in the 19/2 profile, correct?  The lowest square is somewhere around 9 -10 dBm and the other 3 are around 12 dBm.  If the two users with the highest squares could clean up their stats somehow (and get an additional 4-5 dBm improvement) they could possibly get into the 25/2 profile (green area), correct again?  Now, if my first two assumptions are correct, and knowing my own stats, I believe I'm one of the two red squares just above the line into the blue 32/5 profile range.  That is probably not good enough to have reliable trouble free 32/5 but I should have excellent 25/2 service (?).

 

The five folks with green diamonds need to call Tech Support.:smileyhappy:

 

You folks with blue diamonds......  may the fleas from your neighbor's dog hop the fence and infest your yard! :smileyvery-happy::smileywink:

Message 7 of 283
Expert

Re: Line Stats Analysis Results

Yes, the four red squares in the yellow area are users with properly working service on the 19/2 profile.  And yes, your square is the 17 dBm/41000 Kbps.  As long as your uncorrected blocks are zero or very low, it should be enough for 32/5 in my opinion.  Whether AT&T believes that or not, I don't know, so I don't know if they will push the 32/5 profile to you.

 

But unfortunately, there is not much that can be done to improve the noise margin if the service is working properly to begin with.  The noise margin is dependent on attenuation (which depends on distance and wire gauge), and the background noise and intererence present on the line.

 

Sometimes for some people, adding a home run from the NID to the RG can improve the stats because the home run picks up less noise than the normal house telephone wiring.  This can improve the noise margin and raise the max line rate.  Other items can also add noise, like improper grounding or a bad VDSL balun.  But most of the differences on the graph in max line rate for a constant noise margin reflect differences in the frequencies that the line can carry.  The bigger wire (22 gauge) can carry more high frequencies, thus the max line rate can be higher.  Bridge taps cause reflections and interference down the line that block the high frequencies, thus lowering the max line rate.

 

Gamers constantly curse the people connected to the gaming server who have the lowest latency, and there's a name for them -- the Low Ping B*stards (LPBs).  I believe you have insinuated that I've now created a new category of people, the Blue Line B*stards (BLBs). :smileyvery-happy:

 

But seriously, the guys in the gray who are capped at 64 Mbps are the true snobs. :smileywink::smileyvery-happy:

 

Message 8 of 283
Explorer

Re: Line Stats Analysis Results

So what should we do if we are one of the people with these "bridge tap's" on their line?

 

I'm the one with the 10dBm noise margin. 

 

Can you call uVerse, and say "I think I have a bridge tap" on my line, and I need to checked out? 

 

Message 9 of 283
Expert

Re: Line Stats Analysis Results


aross99 wrote:

So what should we do if we are one of the people with these "bridge tap's" on their line?

 

I'm the one with the 10dBm noise margin. 

 

Can you call uVerse, and say "I think I have a bridge tap" on my line, and I need to checked out? 


 

Well, a couple things:

 

First, the line on the graph that shows bridge tap is my best estimation of what is going on, but it's not a certainty that your line has a bridge tap on it.  The only way to find that out for sure is to have the line techs test for it.

 

Second, usually tech support won't respond well to tech stuff like this.  The agents aren't trained on this stuff and they won't really know what you're talking about nor what to do if you start talking about bridge taps and line rates.  A better approach is to tell them that you are experiencing picture freezes and pixelation, and that you have looked at your RG stats and see a lot of errors.  They will then look on their end, also see the errors, and will then dispatch a premises tech.

 

Once the premises tech gets to your house, then you can get a bit more technical and show him your RG stats (showing errors), and mention that you believe there might be a bridge tap on the line (the premesis tech will know what that means).  He should call a line tech to come check.

 

Be aware that the line techs are not available at the U-Verse premises tech's request, so you may have to wait for them and/or meet them another day.

 

Also, you should be aware that a 10 dBm noise margin is terrible.  It indicates that you're a long way away from the VRAD and your line is picking up noise and interference.  Even if the line techs find a bridge tap and remove it, and your max line rate comes up some, it still might not be enough to raise your profile to 25/2.  You could still be stuck on 19/2, although at least the errors would go down and the service would be more reliable.

 

Message 10 of 283
Master

Re: Line Stats Analysis Results

Great work and deductive reasoning SomeJoe. I can see where I'm on the graph at a 54778 max line rate and was just upgraded to the 32/5 profile. It should be noted that I worked closely with the prem techs and helped with the install. This is how I found out I'm 1,325 from the VRAD and the tech showed it to me on his meter. They also said it's great that I have the heavy duty 22 gauge wire. One of the tech's also went down and removed a bridge tap for the strongest signal. So in my case you are exactly right about having the 22 gauge wire, no bridge tap, and this is supported by the prem tech's findings.

 

Thanks for all your hard work on this project. :smileywink:

Uniblurb3

If you get to thinking you're a person of influence, try ordering someone else's dog around.

Need help? Contact AT&T at 800-288-2020.
Message 11 of 283

Re: Line Stats Analysis Results

This has actually convinced me that I need to drop Uverse VDSL, get cable for internet and keep Uverse for TV. I am at 43990, 24g which is just  barely in the acceptable range for 32/5. My family and I really like the Uverse TV but we are having problems with TV, Voice and Internet. I will drop Voice and Internet and keep the TV and that should improve the TV quality. I haven't been updated to 32/5, even though I live in an area that has been upgraded, presumably becasuse I'm too far away or my line won't handle the speed. Either way, this is great info and lets me know that I will never be able to expect the full potential of the service that ATT is offering to some customers lucky enough to live close to the VRAD.

 

Thanks for the info

 

Jeff

Message 12 of 283
Expert

Re: Line Stats Analysis Results


kjeffp24 wrote:

This has actually convinced me that I need to drop Uverse VDSL, get cable for internet and keep Uverse for TV. I am at 43990, 24g which is just  barely in the acceptable range for 32/5. My family and I really like the Uverse TV but we are having problems with TV, Voice and Internet. I will drop Voice and Internet and keep the TV and that should improve the TV quality. I haven't been updated to 32/5, even though I live in an area that has been upgraded, presumably becasuse I'm too far away or my line won't handle the speed. Either way, this is great info and lets me know that I will never be able to expect the full potential of the service that ATT is offering to some customers lucky enough to live close to the VRAD.


 

Cancelling voice and internet services will not help your TV service.  If you're having problems, the number of subscribed services is not what is causing them.

 

44 Mbps sync rate is more than adequate for full services including the 32/5 profile.  If you want to get your service repaired, call tech support and discuss the problems with them.  They will do whatever is required to get your problems fixed.  If you continue to run into problems, start a new thread in this forum and we can assist you with your issues.

 

Message 13 of 283
ACE - Expert

Re: Line Stats Analysis Results


SomeJoe7777 wrote:

 

But seriously, the guys in the gray who are capped at 64 Mbps are the true snobs. :smileywink::smileyvery-happy:

 


We're not snobs.  We're just better than all the little people.  :smileytongue: :smileywink:

*The views and opinions expressed on this forum are purely my own. Any product claim, statistic, quote, or other representation about a product or service should be verified with the manufacturer, provider, or party.
Message 14 of 283
Scholar

Re: Line Stats Analysis Results


SomeJoe7777 wrote: 

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.

 


Was that me - 18.5 dB and 28,997 kbps?   My line originally did have a bridge tap, but it was removed a year and a half ago.  However, they switched me to a different pair 10 months ago.  I wonder if the new pair might have a bridge tap on it.  Presumably they would have checked that when making the switch, but who knows?  Something to consider when I go HD.  

 

The I&R's haven't been able to improve things much since then. Downgrading to 19 Mbps reduced the errors a lot, as did the switch to VDSL2.


-- 

oobleck

Message 15 of 283
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