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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.

 

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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Line Stats Analysis Results

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Jan 24, 2010 12:44:39 PM
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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

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 

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Jan 24, 2010 1:15:40 PM
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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
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.

Re: Line Stats Analysis Results

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Jan 24, 2010 3:41:30 PM
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Thanks for all your time...SOMEBODY should pay you for your findings...  :smileywink:
Thanks for all your time...SOMEBODY should pay you for your findings...  :smileywink:

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Jan 24, 2010 4:01:17 PM
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         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

         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

Re: Line Stats Analysis Results

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Jan 24, 2010 4:39:00 PM
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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.

 


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.

 

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Jan 24, 2010 5:57:36 PM
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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:

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:

Re: Line Stats Analysis Results

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Jan 24, 2010 6:18:57 PM
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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:

 

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:

 

Re: Line Stats Analysis Results

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Jan 24, 2010 7:35:15 PM
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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? 

 

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? 

 

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Jan 24, 2010 8:07:55 PM
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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.

 


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.

 

Re: Line Stats Analysis Results

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Jan 24, 2010 9:13:01 PM
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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.

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.

Re: Line Stats Analysis Results

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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

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

Re: Line Stats Analysis Results

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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.

 


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.

 

Re: Line Stats Analysis Results

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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:


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.

Re: Line Stats Analysis Results

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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


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

Re: Line Stats Analysis Results

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oobleck wrote:
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.


 

You are indeed a choice test case, oobleck. :smileyhappy:  Yes, that is your data point.

 

I would love to see I&R test your line and see if you indeed do have a bridge tap on it.  I'm betting that you do, because your stats certainly don't line up with everyone else's.

 

Can you do me a favor and also run the Dohrenburg analysis test?  Go to http://adslm.dohrenburg.net/tools/3800hg-stats.php and follow the instructions, which I'll also print here:

 

1. Open up a web browser and pull up the DSL diagnostics page from the RG's MDC using http://192.168.1.254/xslt?PAGE=J42&THISPAGE=A02_POST&NEXTPAGE=J42.

2. Right-click on the page and select "View Source".

3. In the HTML source code window that pops up, click your mouse in it, then hit CTRL-A on your keyboard to select all the code.  Then hit CTRL-C on your keyboard to copy all of it to the clipboard.  Close the source code window.

4. On the Dohrenburg analysis page, click your mouse in the first box and hit CTRL-V on your keyboard to paste all the HTML source code.  Then click the Process Form button.

5. The analysis page that appears will have a URL in green at the top of the page.  Copy that URL and paste it in a post here.

 

The shape of the DMT distribution chart in the analysis page can also tell us if there is a bridge tap.

 


oobleck wrote:
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.


 

You are indeed a choice test case, oobleck. :smileyhappy:  Yes, that is your data point.

 

I would love to see I&R test your line and see if you indeed do have a bridge tap on it.  I'm betting that you do, because your stats certainly don't line up with everyone else's.

 

Can you do me a favor and also run the Dohrenburg analysis test?  Go to http://adslm.dohrenburg.net/tools/3800hg-stats.php and follow the instructions, which I'll also print here:

 

1. Open up a web browser and pull up the DSL diagnostics page from the RG's MDC using http://192.168.1.254/xslt?PAGE=J42&THISPAGE=A02_POST&NEXTPAGE=J42.

2. Right-click on the page and select "View Source".

3. In the HTML source code window that pops up, click your mouse in it, then hit CTRL-A on your keyboard to select all the code.  Then hit CTRL-C on your keyboard to copy all of it to the clipboard.  Close the source code window.

4. On the Dohrenburg analysis page, click your mouse in the first box and hit CTRL-V on your keyboard to paste all the HTML source code.  Then click the Process Form button.

5. The analysis page that appears will have a URL in green at the top of the page.  Copy that URL and paste it in a post here.

 

The shape of the DMT distribution chart in the analysis page can also tell us if there is a bridge tap.

 

Re: Line Stats Analysis Results

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SomeJoe7777, 

 

Thanks for analyzing the data and explaining your methods and results. I took a look at the plot you created, and I didn't come to the came conclussion of the five possible lines with bridge taps. I’m on the 3SD/1HD setup, so it was in my vested interest to look at the data only for the 19/2 profile.  Plus I didn’t have time to extract all the data for the other profiles.  

 

These are the assumptions that I’m making:

1)       When the attenuation is calculated an estimate of the resistance on the loop is performed.  This measurement does not take into account any bridge taps or noise on the line.

2)       The noise margin specified by the RG is only valid for the downstream rate that the loop is synched at.  For instance, if the noise margin for the 25/2 profile is 15dB this figure is only valid for the 25/2 profile.  The noise margin would be greater if the loop were configured for the 19/2 profile (because the signaling scheme is probably less complex at a lower rate) and would be lower if the loop were configured for the 32/5 profile (because the signaling scheme is probably more complex at a higher rate).

 

These are the four data points for the users on the 19/2 profile that I found in the thread.

 Attenuation        Noise Margin     Max Sync Rate

27                     15                     25.8

24                     18.5                  29.0

27                     16                     26.3

27                     10                     19.1 

 

All these users in this group have high line attenuation.  I’m guessing that it’s long loop length which puts us on the 19/2 profile.  The fourth data point may also have a fairly noisy line.

 

I’m curious what the plot would look like for Attenuation vs. Profile.   I’m guessing that there will be a distinct cut-off between the 19/2 & 25/2 profiles, and another distinct cut-off between the 25/2 and 32/5 profiles.

 

Also Noise Margin vs. Attenuation for a given profile.  I’m guessing that there will be a correlation between higher noise margins at lower attenuations and vice versa for each profile.

 

And finally Noise Margin vs. Max Sync Rate for a given profile.  I’m guessing this will show higher noise margins correlating with higher maximum sync rates and vice versa for each profile. 

 

Would you mind sharing your raw data so I can attempt to run these plots? 

 

Thanks,

Steve

SomeJoe7777, 

 

Thanks for analyzing the data and explaining your methods and results. I took a look at the plot you created, and I didn't come to the came conclussion of the five possible lines with bridge taps. I’m on the 3SD/1HD setup, so it was in my vested interest to look at the data only for the 19/2 profile.  Plus I didn’t have time to extract all the data for the other profiles.  

 

These are the assumptions that I’m making:

1)       When the attenuation is calculated an estimate of the resistance on the loop is performed.  This measurement does not take into account any bridge taps or noise on the line.

2)       The noise margin specified by the RG is only valid for the downstream rate that the loop is synched at.  For instance, if the noise margin for the 25/2 profile is 15dB this figure is only valid for the 25/2 profile.  The noise margin would be greater if the loop were configured for the 19/2 profile (because the signaling scheme is probably less complex at a lower rate) and would be lower if the loop were configured for the 32/5 profile (because the signaling scheme is probably more complex at a higher rate).

 

These are the four data points for the users on the 19/2 profile that I found in the thread.

 Attenuation        Noise Margin     Max Sync Rate

27                     15                     25.8

24                     18.5                  29.0

27                     16                     26.3

27                     10                     19.1 

 

All these users in this group have high line attenuation.  I’m guessing that it’s long loop length which puts us on the 19/2 profile.  The fourth data point may also have a fairly noisy line.

 

I’m curious what the plot would look like for Attenuation vs. Profile.   I’m guessing that there will be a distinct cut-off between the 19/2 & 25/2 profiles, and another distinct cut-off between the 25/2 and 32/5 profiles.

 

Also Noise Margin vs. Attenuation for a given profile.  I’m guessing that there will be a correlation between higher noise margins at lower attenuations and vice versa for each profile.

 

And finally Noise Margin vs. Max Sync Rate for a given profile.  I’m guessing this will show higher noise margins correlating with higher maximum sync rates and vice versa for each profile. 

 

Would you mind sharing your raw data so I can attempt to run these plots? 

 

Thanks,

Steve

Re: Line Stats Analysis Results

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SteveC,

 

I think you might not be looking at a few things the right way.

 

1) I believe the attenuation is calculated by the RG, not measured.  I don't know the exact scheme used to calculate the attenuation, but since the power levels at the VRAD and at the RG are available, it's likely calculated as Attenuation (dB) = 10 * log (Power level at VRAD / Power Level at RG).

 

I suspect the power levels are read from the VDSL chipset in the RG, but I don't know if they represent a single frequency, an average power level per DMT over the spectrum, or a total power level over the spectrum.  I would think they are probably referenced to a single frequency or tone (DMT) on the line, and if so, won't vary with whether the high frequencies are present or not.  If that's the case, then a bridge tap wouldn't affect the reported power levels, or the attenuation.

 

2) The noise margin doesn't vary with the profile.  Keep in mind that the profile level is a software thing -- basically the assigned profile just means that the DSLAM limits the total bitrate transmitted on the line through software limits.  It has nothing to do with the physical line conditions.

 

You can have a line rate of 64 Mbps capped, with a 32 dB noise margin and still tell the software to put you on the 19/2 profile.  The physical line parameters wouldn't change, you'd just have a lot of capacity on the line that wouldn't be used.

 

There is no difference in the signaling scheme when different profiles are assigned.  The signaling scheme is always OFDM, using the VDSL2 protocol.

 

The conclusion that you should draw from this is that you cannot compare a physical line parameter (such as attenuation, noise margin, or max line rate) to a software-imposed parameter (the profile rate).  They don't have anything to do with each other.

 

The main point of the graph I made above is that there are different people who have different max line rates with the same noise margin.  Since the noise margin directly relates to the bitloading in each DMT frequency, the only explanation of different max line rates is that a different number of DMT slots are available.  This corresponds with the available frequencies that can be used for each installation.  24 gauge wire removes some high frequencies, and a bridge tap removes even more.

 

If oobleck posts a link to his Dohrenburg analysis, you'll see what I'm talking about when you look at his DMT plot.  If he has a bridge tap, there will be a notable absence of usable bits in the high frequencies, and we may even see the tell-tale Sine wave shape to the bitloading in the low frequencies.

 

I will be posting some other graphs soon for the entire data set, including Attenuation vs. Max Line Rate, and Output Power Level vs. Max Line Rate.  These two graphs show a decent correlation as well, although not nearly as dramatic as the Noise Margin vs. Max Line Rate graph that's already posted.  Attenuation graphs are further complicated by the fact that the RG quantizes the attenuation number to the nearest 3 dB measurement, thus the data is really coarse compared to the noise margin.  This is also further proof that the RG computes the attenuation, it doesn't measure it.

 

If your parameters for your own line are down on the line I've labeled as "Bridge Tap", I'd be interested in seeing your Dohrenburg analysis as well.  I posted the instructions above in my response to oobleck.

 

SteveC,

 

I think you might not be looking at a few things the right way.

 

1) I believe the attenuation is calculated by the RG, not measured.  I don't know the exact scheme used to calculate the attenuation, but since the power levels at the VRAD and at the RG are available, it's likely calculated as Attenuation (dB) = 10 * log (Power level at VRAD / Power Level at RG).

 

I suspect the power levels are read from the VDSL chipset in the RG, but I don't know if they represent a single frequency, an average power level per DMT over the spectrum, or a total power level over the spectrum.  I would think they are probably referenced to a single frequency or tone (DMT) on the line, and if so, won't vary with whether the high frequencies are present or not.  If that's the case, then a bridge tap wouldn't affect the reported power levels, or the attenuation.

 

2) The noise margin doesn't vary with the profile.  Keep in mind that the profile level is a software thing -- basically the assigned profile just means that the DSLAM limits the total bitrate transmitted on the line through software limits.  It has nothing to do with the physical line conditions.

 

You can have a line rate of 64 Mbps capped, with a 32 dB noise margin and still tell the software to put you on the 19/2 profile.  The physical line parameters wouldn't change, you'd just have a lot of capacity on the line that wouldn't be used.

 

There is no difference in the signaling scheme when different profiles are assigned.  The signaling scheme is always OFDM, using the VDSL2 protocol.

 

The conclusion that you should draw from this is that you cannot compare a physical line parameter (such as attenuation, noise margin, or max line rate) to a software-imposed parameter (the profile rate).  They don't have anything to do with each other.

 

The main point of the graph I made above is that there are different people who have different max line rates with the same noise margin.  Since the noise margin directly relates to the bitloading in each DMT frequency, the only explanation of different max line rates is that a different number of DMT slots are available.  This corresponds with the available frequencies that can be used for each installation.  24 gauge wire removes some high frequencies, and a bridge tap removes even more.

 

If oobleck posts a link to his Dohrenburg analysis, you'll see what I'm talking about when you look at his DMT plot.  If he has a bridge tap, there will be a notable absence of usable bits in the high frequencies, and we may even see the tell-tale Sine wave shape to the bitloading in the low frequencies.

 

I will be posting some other graphs soon for the entire data set, including Attenuation vs. Max Line Rate, and Output Power Level vs. Max Line Rate.  These two graphs show a decent correlation as well, although not nearly as dramatic as the Noise Margin vs. Max Line Rate graph that's already posted.  Attenuation graphs are further complicated by the fact that the RG quantizes the attenuation number to the nearest 3 dB measurement, thus the data is really coarse compared to the noise margin.  This is also further proof that the RG computes the attenuation, it doesn't measure it.

 

If your parameters for your own line are down on the line I've labeled as "Bridge Tap", I'd be interested in seeing your Dohrenburg analysis as well.  I posted the instructions above in my response to oobleck.

 

Re: Line Stats Analysis Results

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I'm the one with the 10dBM noise margin and 19/2 profile.

 

Here is the link to my Dohrenburg analysis:

 

http://adslm.dohrenburg.net/tools/db-link.php?link=1341

 

A premise tech was supposed to come out today to check my line, but no one showed.  I can tell they were running some diagnostics because my DSL diagnostics showed all kinds of issues around 4pm this afternoon.

 

My noise margin moved up to 12dBm, and my max sync rate went up to 22533.  I don't know if they physically did anything, but I will follow up tomorrow and find out why they didn't show.

 

I am also going to try to find out my distance from the VRAD, and if there is a Bridge tap on the line. 

I'm the one with the 10dBM noise margin and 19/2 profile.

 

Here is the link to my Dohrenburg analysis:

 

http://adslm.dohrenburg.net/tools/db-link.php?link=1341

 

A premise tech was supposed to come out today to check my line, but no one showed.  I can tell they were running some diagnostics because my DSL diagnostics showed all kinds of issues around 4pm this afternoon.

 

My noise margin moved up to 12dBm, and my max sync rate went up to 22533.  I don't know if they physically did anything, but I will follow up tomorrow and find out why they didn't show.

 

I am also going to try to find out my distance from the VRAD, and if there is a Bridge tap on the line. 

Re: Line Stats Analysis Results

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SomeJoe, thanks for all the time and effort spent on this project. It may (will!) take me a few readings to fully comprehend it all. Nonetheless, as a novice in the studies of UV, I find this fascinating. Thanks.:smileywink:

 

Any idea regarding gauge of wire as to when installed? 22 gauge more recent? Just curious. With a 59.9K max & 24 db noise margin in a sub division 20/25 years old, most likely 22 gauge? 

 

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.

 

I find this most interesting as we were all hung up on the distance thing.

 

 

SomeJoe, thanks for all the time and effort spent on this project. It may (will!) take me a few readings to fully comprehend it all. Nonetheless, as a novice in the studies of UV, I find this fascinating. Thanks.:smileywink:

 

Any idea regarding gauge of wire as to when installed? 22 gauge more recent? Just curious. With a 59.9K max & 24 db noise margin in a sub division 20/25 years old, most likely 22 gauge? 

 

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.

 

I find this most interesting as we were all hung up on the distance thing.

 

 

Re: Line Stats Analysis Results

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aross99 wrote:

 

My noise margin moved up to 12dBm, and my max sync rate went up to 22533.  I don't know if they physically did anything, but I will follow up tomorrow and find out why they didn't show.


 

That's good, improving the noise margin raised your max rate, but you've still got a bridge tap on the line.  Your line capacity is no longer at 100% either, which will improve your errors as well.

 

Your Dohrenburg analysis is a classic bridge tap pattern.  A bridge tap is a "T" connection in your line between the VRAD and you, where the end of the "T" wire isn't connected to anything.  What this does is reflect the signal back to your line, which causes interference.  The interference emphasizes some frequencies and attenuates others.  What this does is give a sine wave pattern of noise on the line in the frequency domain.  By looking at the DMT graph from the Dohrenburg analysis, you can see the sine wave noise show up in the bitloading of the different tones.

 

Here is your DMT graph from the Dohrenburg analysis page:

 

 

 

You can see the sine wave pattern that the bridge tap causes:

 

 

 

Continue to work with AT&T and the I&R group and see if then can remove the bridge tap.  Between the removal of the bridge tap and the increase in the noise margin to 12.0 dB, I predict that you may be able to get a sync rate near 30-31 Mbps, which may be just barely enough to move you to the 25/2 profile, and therefore 2HD/2SD.

 


aross99 wrote:

 

My noise margin moved up to 12dBm, and my max sync rate went up to 22533.  I don't know if they physically did anything, but I will follow up tomorrow and find out why they didn't show.


 

That's good, improving the noise margin raised your max rate, but you've still got a bridge tap on the line.  Your line capacity is no longer at 100% either, which will improve your errors as well.

 

Your Dohrenburg analysis is a classic bridge tap pattern.  A bridge tap is a "T" connection in your line between the VRAD and you, where the end of the "T" wire isn't connected to anything.  What this does is reflect the signal back to your line, which causes interference.  The interference emphasizes some frequencies and attenuates others.  What this does is give a sine wave pattern of noise on the line in the frequency domain.  By looking at the DMT graph from the Dohrenburg analysis, you can see the sine wave noise show up in the bitloading of the different tones.

 

Here is your DMT graph from the Dohrenburg analysis page:

 

 

 

You can see the sine wave pattern that the bridge tap causes:

 

 

 

Continue to work with AT&T and the I&R group and see if then can remove the bridge tap.  Between the removal of the bridge tap and the increase in the noise margin to 12.0 dB, I predict that you may be able to get a sync rate near 30-31 Mbps, which may be just barely enough to move you to the 25/2 profile, and therefore 2HD/2SD.

 

Re: Line Stats Analysis Results

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SomeJoe777,

 

Thanks for the additional information.  I've read it over five or six times, and each time it makes a bit more sense.

 

I also ran the test you suggested, and here is the attached link:

http://adslm.dohrenburg.net/tools/db-link.php?link=1344

 

My browser didn't correctly show the pull-down menu for VRAD distance, so I had to guess where 3500 was.  That's why it's listed as 3590 feet on the link.  To my untrained eyes, I don't see the bridge-tap sine wave which showed up on the other user's plot.  Is that how you interpret it?

 

Thanks,

Steve

SomeJoe777,

 

Thanks for the additional information.  I've read it over five or six times, and each time it makes a bit more sense.

 

I also ran the test you suggested, and here is the attached link:

http://adslm.dohrenburg.net/tools/db-link.php?link=1344

 

My browser didn't correctly show the pull-down menu for VRAD distance, so I had to guess where 3500 was.  That's why it's listed as 3590 feet on the link.  To my untrained eyes, I don't see the bridge-tap sine wave which showed up on the other user's plot.  Is that how you interpret it?

 

Thanks,

Steve

Re: Line Stats Analysis Results

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Jan 25, 2010 9:44:53 PM
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Does this look like a bridge tap? I lose sync once or twice every day now.

 

http://adslm.dohrenburg.net/tools/db-link.php?link=1345

Does this look like a bridge tap? I lose sync once or twice every day now.

 

http://adslm.dohrenburg.net/tools/db-link.php?link=1345

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Jan 25, 2010 9:53:32 PM
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SomeJoe777 - This is incredible work.   I can see my service neatly jumps under your "22 gauge" line.   This explains why 32/5 is holding so far away from the VRAD.  This gives me great peace of mind .  Thanks!   For reference, my home was built in 98. 

 

 

 

 

Message Edited by djrobx on 01-25-2010 10:11 PM

SomeJoe777 - This is incredible work.   I can see my service neatly jumps under your "22 gauge" line.   This explains why 32/5 is holding so far away from the VRAD.  This gives me great peace of mind .  Thanks!   For reference, my home was built in 98. 

 

 

 

 

Message Edited by djrobx on 01-25-2010 10:11 PM

Re: Line Stats Analysis Results

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Jan 25, 2010 10:03:12 PM
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milkman,

 

Yes, with 24 dB/59 Kbps, that's 22 gauge wire.  I don't know what makes the difference ... I've read online that 22 gauge used to be the standard, but more neighborhoods are using 24 gauge these days because it's less expensive.  So you would think that older neighborhoods would tend towards 22 and newer ones would tend towards 24.  But, my neighborhood is brand new (construction began 2005, ended 2007), and I have 22 gauge wire, so there's obviously exceptions.

 

SteveC,

 

No, I don't see the sine wave pattern on your DMT plot, but I do see a lot of attenuation in your high frequencies.  That's probably due to the extreme distance.  However, you may still have a bridge tap, but it might be so close to your house or so close to the VRAD that the sine wave doesn't appear.  Do you have a home run from your NID directly to your RG?  If not, you may want to have one installed.

 

ChrisPC,

 

Same advice as to SteveC.

 

 

djrobx,

 

Yours was a very important data point.  I was a bit concerned that all the data points I had where the noise margin was below 15 dB (which was 10 data points) were all on 24 gauge wire or look like they have a bridge tap.  Your data point is the first one below 15 dB on 22 gauge wire, and it still lines up on the rate line perfectly.  A 13 dB noise margin indicates you're probably at least 3000' from the VRAD or further, and are still easily getting 32/5.

 

Message Edited by SomeJoe7777 on 01-26-2010 12:12 AM

milkman,

 

Yes, with 24 dB/59 Kbps, that's 22 gauge wire.  I don't know what makes the difference ... I've read online that 22 gauge used to be the standard, but more neighborhoods are using 24 gauge these days because it's less expensive.  So you would think that older neighborhoods would tend towards 22 and newer ones would tend towards 24.  But, my neighborhood is brand new (construction began 2005, ended 2007), and I have 22 gauge wire, so there's obviously exceptions.

 

SteveC,

 

No, I don't see the sine wave pattern on your DMT plot, but I do see a lot of attenuation in your high frequencies.  That's probably due to the extreme distance.  However, you may still have a bridge tap, but it might be so close to your house or so close to the VRAD that the sine wave doesn't appear.  Do you have a home run from your NID directly to your RG?  If not, you may want to have one installed.

 

ChrisPC,

 

Same advice as to SteveC.

 

 

djrobx,

 

Yours was a very important data point.  I was a bit concerned that all the data points I had where the noise margin was below 15 dB (which was 10 data points) were all on 24 gauge wire or look like they have a bridge tap.  Your data point is the first one below 15 dB on 22 gauge wire, and it still lines up on the rate line perfectly.  A 13 dB noise margin indicates you're probably at least 3000' from the VRAD or further, and are still easily getting 32/5.

 

Message Edited by SomeJoe7777 on 01-26-2010 12:12 AM

Re: Line Stats Analysis Results

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Well AT&T send out a tech, but he didn't call first, so I don't know what he did.  The note on the door just says "A problem was repaired in the outside lines".  The people at uversecare said there is no bridge tap, and that I am just too far away - at 3870 feet (!).

 

They said they would send out the tech again today - should I keep pushing the bridge tap issue? 

Well AT&T send out a tech, but he didn't call first, so I don't know what he did.  The note on the door just says "A problem was repaired in the outside lines".  The people at uversecare said there is no bridge tap, and that I am just too far away - at 3870 feet (!).

 

They said they would send out the tech again today - should I keep pushing the bridge tap issue? 

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Jan 26, 2010 9:41:38 AM
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No, I don't see the sine wave pattern on your DMT plot, but I do see a lot of attenuation in your high frequencies.  That's probably due to the extreme distance.  However, you may still have a bridge tap, but it might be so close to your house or so close to the VRAD that the sine wave doesn't appear.  Do you have a home run from your NID directly to your RG?  If not, you may want to have one installed.


 

I had a homerun installed, and Cat5 all over the house. A tech came yesterday, and checked the line from the VRAD. He said there aren't any bridge taps. There were some bad connections that he fixed. He said there are some unbonded pairs he couldn't fix, though. My error rate has gone down, but I still got a picture freeze last night. My margin and max sync haven't changed.

Message Edited by ChrisPC on 01-26-2010 11:45 AM

No, I don't see the sine wave pattern on your DMT plot, but I do see a lot of attenuation in your high frequencies.  That's probably due to the extreme distance.  However, you may still have a bridge tap, but it might be so close to your house or so close to the VRAD that the sine wave doesn't appear.  Do you have a home run from your NID directly to your RG?  If not, you may want to have one installed.


 

I had a homerun installed, and Cat5 all over the house. A tech came yesterday, and checked the line from the VRAD. He said there aren't any bridge taps. There were some bad connections that he fixed. He said there are some unbonded pairs he couldn't fix, though. My error rate has gone down, but I still got a picture freeze last night. My margin and max sync haven't changed.

Message Edited by ChrisPC on 01-26-2010 11:45 AM

Re: Line Stats Analysis Results

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Jan 26, 2010 9:57:44 AM
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More progress this morning...

 

Another tech came out and when I mentioned my concern for the Bridge Tap, he said he would run a test.  Sure enough, he said his test showed one about 140' down the line.  He called another department to remove the bridge tap, and I am waiting for confirmation.

 

Interesting that the people on the phone insisted there was no Bridge tap, but the tech found it right away... 

 

He also told me my distance from the VRAD showed up at 3168 feet - not the 3875 that the person on the phone told me.

 

I am hoping for a call back after the Bridge Tap is removed, but if not, I should be able to tell from the DSL diagnostics if they were working on the line. 

 

I will report back later once I have more info. 

More progress this morning...

 

Another tech came out and when I mentioned my concern for the Bridge Tap, he said he would run a test.  Sure enough, he said his test showed one about 140' down the line.  He called another department to remove the bridge tap, and I am waiting for confirmation.

 

Interesting that the people on the phone insisted there was no Bridge tap, but the tech found it right away... 

 

He also told me my distance from the VRAD showed up at 3168 feet - not the 3875 that the person on the phone told me.

 

I am hoping for a call back after the Bridge Tap is removed, but if not, I should be able to tell from the DSL diagnostics if they were working on the line. 

 

I will report back later once I have more info. 

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SomeJoe7777,

 

Thanks for taking a look at the plot.  I do have a homerun from the NID to RG.  It's an external CAT-3 run, and the last time the tech was out he swapped pairs to see if that would resolve the DSL link instability issues.  The next time someone comes out I'll suggest they replace it with CAT5e as you recommended.

 

Thanks,

Steve

SomeJoe7777,

 

Thanks for taking a look at the plot.  I do have a homerun from the NID to RG.  It's an external CAT-3 run, and the last time the tech was out he swapped pairs to see if that would resolve the DSL link instability issues.  The next time someone comes out I'll suggest they replace it with CAT5e as you recommended.

 

Thanks,

Steve

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SomeJoe7777 wrote:

You are indeed a choice test case, oobleck. :smileyhappy:  Yes, that is your data point.

 

I would love to see I&R test your line and see if you indeed do have a bridge tap on it.  I'm betting that you do, because your stats certainly don't line up with everyone else's.

 

Can you do me a favor and also run the Dohrenburg analysis test?  Go to http://adslm.dohrenburg.net/tools/3800hg-stats.php and follow the instructions, which I'll also print here:

 


Here's the link:

http://adslm.dohrenburg.net/tools/db-link.php?link=1364

 

I'll be interested to see what you find.  When they changed my pair it didn't seem to make much difference one way or the other; I was still getting lots of uncorrected blocks.  If they had changed me from a pair without a bridge tap to one with a tap I'd think it would have increased the error rate.  But the error rate was pretty variable back then, so the effect might not be discernible.

-- 

oobleck


SomeJoe7777 wrote:

You are indeed a choice test case, oobleck. :smileyhappy:  Yes, that is your data point.

 

I would love to see I&R test your line and see if you indeed do have a bridge tap on it.  I'm betting that you do, because your stats certainly don't line up with everyone else's.

 

Can you do me a favor and also run the Dohrenburg analysis test?  Go to http://adslm.dohrenburg.net/tools/3800hg-stats.php and follow the instructions, which I'll also print here:

 


Here's the link:

http://adslm.dohrenburg.net/tools/db-link.php?link=1364

 

I'll be interested to see what you find.  When they changed my pair it didn't seem to make much difference one way or the other; I was still getting lots of uncorrected blocks.  If they had changed me from a pair without a bridge tap to one with a tap I'd think it would have increased the error rate.  But the error rate was pretty variable back then, so the effect might not be discernible.

-- 

oobleck

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