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Posted Jan 24, 2010
12:00:55 PM
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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Jan 31, 2010 2:04:40 PM
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OK, here is a revised Noise Margin vs. Max Line Rate graph, now that it is known that the data shows a correlation between profiles rather than wire gauge.

 

 

 

 

 

This graph shows a bit more information than the previous one.

 

For properly working service that won't have a lot of errors, you need two things:

 

1) Sufficient max line rate so that the line capacity doesn't exceed approximately 80% when compared to your profile rate.  Line capacities exceeding approximately 80% causes the line to begin to take some errors.

 

Line Capacity = (Downstream Profile Rate / Max Line Rate) * 100

 

2) Sufficient noise margin such that the line does not take errors.  From people's stats, I am estimating the minimum required noise margin to be around 12.0 dB.

 

These two parameters gives rise to the two red areas on the graph, where the noise margin is too low for reliable service, or the max line rate is too low even for the 19/2 profile.  The minimum required max line rate for the 19/2 profile is given as 21800 kbps.  This is where the 19/2 profile line (derived from customer data) hits the 12 dB noise margin, for a line capacity of 88%.  This line capacity is a little high, but since the alternative is no service, it may turn out to be sufficient.

 

Similarly, the 25/2 profile line intersects the 12 dB noise margin limit at 30400 kbps, establishing that as the minimum required max line rate for the 25/2 profile, at a line capacity of 83%. 

 

Finally, the 32/5 profile line intersects the 12 dB noise margin limit at 39700 kbps, establishing that as the minimum required max line rate for the 32/5 profile, at a line capacity of 81%.

 

 

What is very interesting here is how we now know that the noise margin changes significantly with the selected profile rate.  We also know that the max line rate stays relatively constant when the profile rate is changed (see djrobx's data a few posts above).  Because of this nearly constant max line rate and the consistency of the customer data which has given us the profile lines, we can now predict where you will end up on the graph when your profile rate is changed.

 

For example, let's look at the customer who is currently on the 25/2 profile line (red) at an 18 dB noise margin and 41000 kbps max rate.  When this customer is upgraded to 32/5, the max line rate will stay nearly constant at 41000 kbps (it may go down slightly, no more than a few hundred kbps), but his service point will jump horizontally to the left (constant max line rate) to land on the blue 32/5 profile line at a much lower noise margin.  We can predict from the graph that his noise margin will be around 13.0 dB.

 

Since we know what the new noise margin will be due to the profile lines, we can now also identify by noise margin alone those people who should be able to move to a higher profile.  For example, people on the 19/2 profile who exceed a noise margin of 19.0 dB should be able to move to the 25/2 profile, since their new noise margin will be above 12.0 dB.  Similarly, people on the 25/2 profile whose noise margin exceeds 16.5 dB should be able to move to the 32/5 profile, again because their new noise margin will be above 12.0 dB.

 

And just for fun, we can also estimate that those people on the 32/5 profile with a noise margin exceeding some value would theoretically be able to move to an even higher profile.  Assuming the noise margin drops 6 dB for an increase in the profile rate of 8-10 Mbps, we could theoretically predict the existence of a new 40/5 profile that would be eligible for rollout to people on 32/5 who exceed 18 dB of noise margin and 50000 kbps of max line rate.

 

 

Now, since noise margin and max line rate are locked together on these profile lines, predicting whether a person has a noisy line or a bridge tap becomes more problematic.  The Dohrenburg DMT plot can be instrumental here.  Removing a bridge tap or removing a noise source can raise the max line rate (and noise margin with it), possible allowing someone to upgrade their profile.  However, this has to be done on a case-by-case basis, as there is no guarantee how much additional max line rate/noise margin you can achieve.

 

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Apr 25, 2010 9:08:43 PM
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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

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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.

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Apr 25, 2010 9:36:03 PM
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ACE - Expert

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.

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Apr 28, 2010 4:25:59 PM
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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.

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Apr 28, 2010 5:26:45 PM
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ACE - Expert

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.

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Apr 28, 2010 6:00:56 PM
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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.

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Apr 28, 2010 6:32:01 PM
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ACE - Expert

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.

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May 5, 2010 6:58:34 PM
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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

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May 5, 2010 7:09:04 PM
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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.

 

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May 5, 2010 8:09:13 PM
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Thank you sir. 

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Jun 25, 2010 9:12:33 AM
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Scholar

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

 

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Jun 25, 2010 2:17:59 PM
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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.

 

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Jun 28, 2010 1:16:01 PM
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Jun 28, 2010 1:38:35 PM
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travis77 wrote:

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


 

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

 

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Jun 28, 2010 1:50:02 PM
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ACE - Expert

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

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Jul 20, 2010 10:14:15 AM
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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: ?

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Jul 20, 2010 11:18:37 AM
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ACE - Expert

Think pair bonding will help alot in your case as you are living right on the edge w/no headroom for comfort. :smileywink:


Chris

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Please NO SD stretch-o-vision or 480 SD HD Channels
Your Results May Vary, In My Humble Opinion
I Call It Like I See It, 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.

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Jul 20, 2010 12:44:02 PM
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You have a bridge tap in that line also.  Removing that alone will probably improve your max rate by at least 5 Mbps.

 

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Jul 20, 2010 1:00:04 PM
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ACE - Expert

Joe, I downloaded the latest update of the Uverse Realtime app, and I noticed I could see 3 of my stbs and what channels they were on with the wireless laptop.  However, I didn't see the dvr stb in the list.  I also noticed that the dvr info was not listed.  I am just pointing this out, I figured you already know.  Just making mention of it.  I do see it when I use the computer that is connected wired to the RG.

*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.

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Jul 20, 2010 1:39:15 PM
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I can't guarantee that everything will work properly on UVRT with wireless because different wireless cards handle the multicast traffic very differently.

 

I know that most of the Intel wireless chipsets built into many laptops will work pretty good.  I have reports of other wireless chipsets working OK also.  But I also have seen ones that don't work at all and ones that only work partially.  It completely depends on the manufacturer's drivers and how they handle multicast over wireless.

 

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Jul 20, 2010 11:34:33 PM
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Thanks Chris and thanks Joe!

I appreciate the input.and time.

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Jul 25, 2010 2:42:06 PM
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Teacher

Hey SomeJoe... could you give me your opinion of my bitloading also? Here is a screenshot...

1859i83EB2A6EC4928E0B

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Jul 25, 2010 8:59:59 PM
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Expert

Distance-wise it looks fine, and there appears to be no bridge taps.

 

However, there is some interference at the 1.0 MHz point.  This could be a close AM radio station or some other type of electronic device that's interfering.  Doesn't look like it's really affecting your service, though.

 

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Jul 25, 2010 9:52:23 PM
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ACE - Expert

Zeonis, put your cursor right in the very middle of that point about 1000khz  to find the frequency, then go to radio locator to find the station.


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

I have 760 WJR and 800 CKLW hit my bitloading chart here in metro Detroit, but no problems from them. :smileywink:


Chris

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Please NO SD stretch-o-vision or 480 SD HD Channels
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Your Results May Vary, In My Humble Opinion
I Call It Like I See It, 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.

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Jul 25, 2010 10:42:14 PM
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I checked my bitloading again and found the interference is now less. Based on radio-locator.com it would appear I am getting interference from 1050 AM KTCT which is 3.9 miles away and 1100 AM KFAX which is 4.9 miles away. I would think that I would get interference also from 860 AM KTRB which is 4.8 miles away but I don't see that it is showing up in the bitloading. Here is another screenshot...1861i4E26005C19809AA7

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Jul 25, 2010 11:02:50 PM
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ACE - Expert

W/o seeing the chart yet, might be night time antenna orientation away from you.  KTCT has a smaller night time footprint, KFAX doesn't have a coverage map, but is 50,000 watts 24 hours.  It may hit you w/lower signal strength though at night time. :smileywink:


Edit: Looking at your original bitloading chart I clearly see a spike at 860 kHz for KTRB, it has a night time change too.

 

Chris

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Please NO SD stretch-o-vision or 480 SD HD Channels
1-866-465-1496 for direct TS to avoid Mr. Voice recognition
Your Results May Vary, In My Humble Opinion
I Call It Like I See It, 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.

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Aug 22, 2010 6:11:53 PM
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Professor

Just for shoots and giggles here are my stats.2198i46B336D6706AE3BF2200iDA7694CA20A2FAB02202i15427A15E5F37E25

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Aug 23, 2010 11:44:38 AM
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ACE - Expert

Looks good NorthLine Tony, you're getting hit by WJR (760), just down the street from you, but shouldn't affect any service.  I see it a bit less over here in Grosse Pointe Park, but also see CKLW (800) in mine, but no problems. :smileywink:


Chris

___________________________________________________________________________

Please NO SD stretch-o-vision or 480 SD HD Channels
1-866-465-1496 for direct TS to avoid Mr. Voice recognition
Your Results May Vary, In My Humble Opinion
I Call It Like I See It, 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.

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Aug 24, 2010 1:42:02 PM
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Explorer

I'm wondering if I'm able to get a 3HD profile, based my stats i dont think so.  could someone please take a look at my stats and offer any suggestions for improvement?  thanks in advance.

 

2220i7F5639286B5CBFB1

 

2218iB9F3AC5C18935AA1

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Aug 24, 2010 5:32:24 PM
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No, you will not be able to get the 3HD profile (currently).

 

Technically, you shouldn't really even be on the 2HD profile, but if it's working OK you might want to leave it.

 

There are rumors circulating that everyone will get one additional HD channel added soon, and if you currently have 2HD, you may end up with 3.  But I'm not sure how well your system is going to work if you attempt to eatch 3HD channels simultaneously.  Your line issues may cause problems at that point.

 

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Aug 24, 2010 5:41:14 PM
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Explorer

thats what I thought.  so in terms of improving my stats/performance,  any suggestions?

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