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 (8,798 Views)
Mentor

Re: Line Stats Analysis Results

 


mibrnsurg wrote:

The chart looks real good and would say the 900' estimate is closest for your distance from the VRAD as the lines almost never go too straight directly there to the crossbox.  You line right up on the blue line w/53m max sync and 20 db noise margin on SomeJoe's chart if you click on the solution on page 1. :smileywink:


Chris

_____________________________________________________________________

Please NO SD stretch-o-vision or 480 SD HD Channels
1-800-983-2811 to avoid Mr. Voice Recognition
I Call It Like I See It, Your Results May Vary, In My Humble Opinion
Simply a U-verse user, nothing more


 

Cool yeah just making sure the FECs and CRCs are normal considering the lightning. The line man has some software on his laptop that can measure the exact distance of the line, including the exact route it takes from the VRAD to my house. It said 750 feet but maybe it's not totally correct.

Message 211 of 283 (855 Views)
ACE - Expert

Re: Line Stats Analysis Results

As long as the CRCs (uncorrected blocks) occured during the lightning and are not a normal situation.  Even though I've had plenty of lightning, including one last summer that was real close and flash/thunder were at exact same time, I've never had an uncorrected block in 21 months on Uverse due to lightning. :smileysurprised:


Chris

______________________________________________________________________

Please NO SD stretch-o-vision or 480 SD HD Channels
1-800-983-2811 to avoid Mr. Voice Recognition
I Call It Like I See It, Your Results May Vary, In My Humble Opinion
Simply a U-verse user, nothing more

*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 212 of 283 (855 Views)
Contributor

Re: Line Stats Analysis Results

Just wondered if the smart people here could give any insight on this graph: http://adslm.dohrenburg.net/tools/db-link.php?link=2436. The service is mostly OK but rarely will it last for more than 36 hours without having to retrain. The reason given is ERR_HI_BER_LIMIT. I'm just trying to figure out if this is what I'm stuck with or if there is something a premisis or line technician could do to improve the situation. Thanks.

Message 213 of 283 (855 Views)
ACE - Expert

Re: Line Stats Analysis Results

You don't have enough headroom max syncing 27.8M on a 25/2M profile.  Actually need about 32-33M for stable 25/2M profiles in most cases.  A product of your distance from the VRAD, have a hunch your max sync has been dropping a bit after Uverse downloads. :smileywink:


Chris

_____________________________________________________________________

Please NO SD stretch-o-vision or 480 SD HD Channels
1-800-983-2811 to avoid Mr. Voice Recognition
I Call It Like I See It, Your Results May Vary, In My Humble Opinion
Simply a U-verse user, nothing more

*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 214 of 283 (855 Views)
Contributor

Re: Line Stats Analysis Results

Up until just today when I reset the system when it desynched it had been getting 31-32M. Even then it was still having to retrain every 24-36 hours.

Message 215 of 283 (855 Views)
ACE - Expert

Re: Line Stats Analysis Results

That's why they had you on the 25/2 profile, I would call TS and they might see something.  It should not be doing all this retraining, use the # in my sig and press 2 for TS, good luck. :smileywink:


Chris

_____________________________________________________________________

Please NO SD stretch-o-vision or 480 SD HD Channels
1-800-983-2811 to avoid Mr. Voice Recognition
I Call It Like I See It, Your Results May Vary, In My Humble Opinion
Simply a U-verse user, nothing more

*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 216 of 283 (855 Views)
Highlighted

Re: Line Stats Analysis Results

http://adslm.dohrenburg.net/tools/db-link.php?link=2486

 

Is my results.  I was told when first went to Uverse that there was a line tap.  Had two different techs stop by to tell me that it was still there and they would request a line tech look into this.  Never heard back from either them or the line tech.  Can anyone decipher the test results and tell me if this fits a pattern for any known issues?

 

Thanks

Message 217 of 283 (855 Views)
Expert

Re: Line Stats Analysis Results

Ya, looks like a bridge tap to me, but looks to be a long one.  This could possibly be bridged fairly far back up the line, away from your house.

 

Message 218 of 283 (855 Views)

Re: Line Stats Analysis Results

Thank you sir. 

Message 219 of 283 (855 Views)
Scholar

Re: Line Stats Analysis Results

Hey Somejoe How does this look with the new 32/5 profile. No issues and going on 2 weeks now.

 

Message 220 of 283 (855 Views)
Expert

Re: Line Stats Analysis Results

Textbook, with the exception of that one drop off at around tone #300.

 

Download U-Verse Realtime (link in my signature), install it, go to the bitloading tab and hover your mouse over that drop to get the actual frequency.

 

That is probably an AM radio station near you.  Go to www.radio-locator.com and put in your zip code and see if there's an AM radio station on that frequency and see how far away the transmitter tower is.  I bet it's less than 5 miles away.

 

Message 221 of 283 (1,229 Views)
Teacher

Re: Line Stats Analysis Results

Message 222 of 283 (1,229 Views)
Expert

Re: Line Stats Analysis Results

 


travis77 wrote:

http://www.radio-locator.com/


 

Yep, sorry, put the wrong link in.  I'll have Wendy fix it.

 

Message 223 of 283 (1,229 Views)
Expert

Re: Line Stats Analysis Results

Oh nice going Joe.  Just send people to the wrong site, why don't you.:smileywink:

Message 224 of 283 (1,229 Views)
Contributor

Re: Line Stats Analysis Results

The first time I tried to get U-verse the tech couldn't get a good enough signal. The reason given was that I am too far from the VRAD ( I forgot what the measurement the line guy told me). Six months later they tried again, after another round of door to door sales, and the tech did some things and got it to work.

 

So here is a livin on the edge of no service link.

http://adslm.dohrenburg.net/tools/db-link.php?link=2801

 

Do I have any options? Pair bonding? Removing a dozen bridges :smileyhappy: ?

Message 225 of 283 (1,229 Views)
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