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Posted May 11, 2010
8:52:46 PM
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Need Advice on Line Stats

Background:  This issue has been problematic since March for me and from what the Prem Tech has told me others in my neighborhood coming from the same VRAD.  So far, I have had 3 RG replacements, downgrade to 25 M profile, home network disconnected and outside tests showing the same issues....  The tech is very knowledgeable and has gotten the area manager, network engineer, etc. to try and figure out the problem of the intermittent loss of signal and re-syncs.  I need some advice on what to ask for them to check next since I am only about 800 ft from the VRAD.  Here is a link to analysis and I even will post the screenshots from Joe's 2WireRealtime Tool.  Other useful information is Cat5e running to RG and the RG runs 1 DVR box, Bluray, and 1 CPU by wire and Wii, iPhone, Mobile CPU wirelessly.

http://adslm.dohrenburg.net/tools/db-link.php?link=2519

 

1605iF31182B9F8BCB4B11606i63BA8D83737044A5

Background:  This issue has been problematic since March for me and from what the Prem Tech has told me others in my neighborhood coming from the same VRAD.  So far, I have had 3 RG replacements, downgrade to 25 M profile, home network disconnected and outside tests showing the same issues....  The tech is very knowledgeable and has gotten the area manager, network engineer, etc. to try and figure out the problem of the intermittent loss of signal and re-syncs.  I need some advice on what to ask for them to check next since I am only about 800 ft from the VRAD.  Here is a link to analysis and I even will post the screenshots from Joe's 2WireRealtime Tool.  Other useful information is Cat5e running to RG and the RG runs 1 DVR box, Bluray, and 1 CPU by wire and Wii, iPhone, Mobile CPU wirelessly.

http://adslm.dohrenburg.net/tools/db-link.php?link=2519

 

1605iF31182B9F8BCB4B11606i63BA8D83737044A5

Need Advice on Line Stats

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May 11, 2010 10:31:22 PM
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The moderator has to approve your pictures, once I see them I'll have some answers for you.

 

Just looking at your Dohrenburg plot, I think I know what's wrong, but I'll wait to see the 2WireRealtime screenshots also.

 

The moderator has to approve your pictures, once I see them I'll have some answers for you.

 

Just looking at your Dohrenburg plot, I think I know what's wrong, but I'll wait to see the 2WireRealtime screenshots also.

 

Re: Need Advice on Line Stats

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May 12, 2010 8:21:27 AM
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OK, there's a lot of things wrong here.

 

  • From the attenuation and power levels, the 800 foot distance from the VRAD appears to be correct.
  • Your max rate is not consistent with this distance.  At this distance I would expect a 55 Mbps to 60 Mbps max rate, yours is 43 Mbps.  The noise margin isn't consistent with the distance, either.
  • The attenuation rolloff with increasing frequency is much more than would be expected for your distance.  This is consistent with a line problem.  In some cases that would be a bridge tap indication, but I don't think so in this case.
  • There is something exceedingly strange going on in the 7.6 MHz frequency range.  There are alternate DMT tones there that are alternately 0 bits and then 6 bits.  This indicates a time-delay interference pattern.  Again, this might be consistent with a bridge tap, but I calculated it out and the tap wire would have to be very long for this to occur at this frequency (over 22,000 feet).  Plus, these high frequencies would never survive down a tap that long.  I don't believe this is interference from another device because very few devices operate in this frequency range, and if they did they wouldn't cause this kind of pattern.

 

For your line to be doing these things, there has to be something attached to the line that would cause enough time delay to cause this particular interference pattern in these high frequencies.  I'm thinking some type of filter network, i.e. passive components like capacitors & inductors attached to the line that are either broken/malfunctioning, or hooked up wrong, or something.

 

So, what we need to look for is something that could contain these passive components and remove it.  I can think of a few things that I'd look for:

 

  • ADSL filters.  Did you previously have ADSL service?  Do you have any leftover line filters that plug into the phones/phone jacks?  If so remove them.  Check every phone and every phone jack for these.  Remember that there was a style that was for wall-mounted phones where the DSL filter jack fitted over the wall-mount jack.  Make sure you don't miss one of these.
  • Telephone surge suppressor devices.  Some higer-end power strips have two telephone ports on them that you're supposed to run the telephone line through to prevent lightning strikes from hitting your modem.  If you have one of these connected somewhere, disconnect it.
  • I have seen some telephone jacks that have weird circuitry in them.  Make sure you don't have any of these.  Take apart every jack and ensure it's just a plain telephone jack.
  • Better yet, make sure they've done a home run from the NID to the RG so that it bypasses any problems with your home telephone wiring.
  • Have they replaced the VDSL balun out in the NID?  A bad balun could possibly do this.
  • Have they checked the line for load coils?  A load coil would be rare, and would probably affect your service more than this, but it wouldn't hurt to look.
  • In addition to that, sometimes on short lines if a load coil was present, the load coil may have been bypassed instead of removed.  But this may not work in your case.  If there is a bypassed load coil, both the bypass and the load coil have to be removed.
  • If all else fails, I would have them switch you to another pair.  If the problem remains after the pair switch, then you've eliminated that portion of the line as the source of the problem, and can concentrate on things inside your house.
  • There is an outside chance that there is a bad line card in the VRAD.  AT&T's engineering group will have to come change it out if the I&R technicians can't find anything wrong with the line.

 

There is definitely a problem here.  It's just a matter of finding it.  But you'll know when it's gone ... that comb-looking pattern at 7.6 MHz will go away.

 

OK, there's a lot of things wrong here.

 

  • From the attenuation and power levels, the 800 foot distance from the VRAD appears to be correct.
  • Your max rate is not consistent with this distance.  At this distance I would expect a 55 Mbps to 60 Mbps max rate, yours is 43 Mbps.  The noise margin isn't consistent with the distance, either.
  • The attenuation rolloff with increasing frequency is much more than would be expected for your distance.  This is consistent with a line problem.  In some cases that would be a bridge tap indication, but I don't think so in this case.
  • There is something exceedingly strange going on in the 7.6 MHz frequency range.  There are alternate DMT tones there that are alternately 0 bits and then 6 bits.  This indicates a time-delay interference pattern.  Again, this might be consistent with a bridge tap, but I calculated it out and the tap wire would have to be very long for this to occur at this frequency (over 22,000 feet).  Plus, these high frequencies would never survive down a tap that long.  I don't believe this is interference from another device because very few devices operate in this frequency range, and if they did they wouldn't cause this kind of pattern.

 

For your line to be doing these things, there has to be something attached to the line that would cause enough time delay to cause this particular interference pattern in these high frequencies.  I'm thinking some type of filter network, i.e. passive components like capacitors & inductors attached to the line that are either broken/malfunctioning, or hooked up wrong, or something.

 

So, what we need to look for is something that could contain these passive components and remove it.  I can think of a few things that I'd look for:

 

  • ADSL filters.  Did you previously have ADSL service?  Do you have any leftover line filters that plug into the phones/phone jacks?  If so remove them.  Check every phone and every phone jack for these.  Remember that there was a style that was for wall-mounted phones where the DSL filter jack fitted over the wall-mount jack.  Make sure you don't miss one of these.
  • Telephone surge suppressor devices.  Some higer-end power strips have two telephone ports on them that you're supposed to run the telephone line through to prevent lightning strikes from hitting your modem.  If you have one of these connected somewhere, disconnect it.
  • I have seen some telephone jacks that have weird circuitry in them.  Make sure you don't have any of these.  Take apart every jack and ensure it's just a plain telephone jack.
  • Better yet, make sure they've done a home run from the NID to the RG so that it bypasses any problems with your home telephone wiring.
  • Have they replaced the VDSL balun out in the NID?  A bad balun could possibly do this.
  • Have they checked the line for load coils?  A load coil would be rare, and would probably affect your service more than this, but it wouldn't hurt to look.
  • In addition to that, sometimes on short lines if a load coil was present, the load coil may have been bypassed instead of removed.  But this may not work in your case.  If there is a bypassed load coil, both the bypass and the load coil have to be removed.
  • If all else fails, I would have them switch you to another pair.  If the problem remains after the pair switch, then you've eliminated that portion of the line as the source of the problem, and can concentrate on things inside your house.
  • There is an outside chance that there is a bad line card in the VRAD.  AT&T's engineering group will have to come change it out if the I&R technicians can't find anything wrong with the line.

 

There is definitely a problem here.  It's just a matter of finding it.  But you'll know when it's gone ... that comb-looking pattern at 7.6 MHz will go away.

 

Re: Need Advice on Line Stats

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May 12, 2010 4:42:07 PM
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SomeJoe7777 wrote:
  • ADSL filters.  Did you previously have ADSL service?  Do you have any leftover line filters that plug into the phones/phone jacks?  If so remove them.  Check every phone and every phone jack for these.  Remember that there was a style that was for wall-mounted phones where the DSL filter jack fitted over the wall-mount jack.  Make sure you don't miss one of these.  Homerun of CAT5e from NID to RG, brand new line and jack which the prem tech said was better than what he has on his truck.  Old ADSL Homerun made into Tel Line.
  • Telephone surge suppressor devices.  Some higer-end power strips have two telephone ports on them that you're supposed to run the telephone line through to prevent lightning strikes from hitting your modem.  If you have one of these connected somewhere, disconnect it.  None hooked up.  See above.
  • I have seen some telephone jacks that have weird circuitry in them.  Make sure you don't have any of these.  Take apart every jack and ensure it's just a plain telephone jack.  See above, Homerun.
  • Better yet, make sure they've done a home run from the NID to the RG so that it bypasses any problems with your home telephone wiring.  Homerun.
  • Have they replaced the VDSL balun out in the NID?  A bad balun could possibly do this. Yes, multiple time since this problem began in March.
  • Have they checked the line for load coils?  A load coil would be rare, and would probably affect your service more than this, but it wouldn't hurt to look.  I and the Prem Tech has been trying to get them to check the lines, but they keep thinking its the RG.
  • In addition to that, sometimes on short lines if a load coil was present, the load coil may have been bypassed instead of removed.  But this may not work in your case.  If there is a bypassed load coil, both the bypass and the load coil have to be removed.
  • If all else fails, I would have them switch you to another pair.  If the problem remains after the pair switch, then you've eliminated that portion of the line as the source of the problem, and can concentrate on things inside your house.  I have been trying to get them to change my pair and so has the Prem Tech but this obviously has not happened yet since they keep trying to blame the RG for the problem including lowering my profile which did not fixanything and has not been changed back yet eventhough I have requested it.  Prem Tech pulled my homerun off the line and ran the same tests and they showed the same issues which obviously to me says it is on their lines or VRAD.
  • There is an outside chance that there is a bad line card in the VRAD.  AT&T's engineering group will have to come change it out if the I&R technicians can't find anything wrong with the line.  This could be a possibility, but the engineers want to go through 20 hoops with the RG first for some reason although the line tests show the same issue without my inside line and RG on the network.

 

There is definitely a problem here.  It's just a matter of finding it.  But you'll know when it's gone ... that comb-looking pattern at 7.6 MHz will go away.

 


Joe, see the inline responses.  I have showed my Prem Tech the bit load graph and he has run tests without my home line and equipment attached showing the same issue, but for some reason everyone else wants to stay focused on the RG.  Let me know some suggestions how to get to a Tier 2 support person so that they might actually listen and get the actual lines check or changed.  I already know how to use DSLReports, so I am looking at other suggestions for maybe a phone conversation, etc.


SomeJoe7777 wrote:
  • ADSL filters.  Did you previously have ADSL service?  Do you have any leftover line filters that plug into the phones/phone jacks?  If so remove them.  Check every phone and every phone jack for these.  Remember that there was a style that was for wall-mounted phones where the DSL filter jack fitted over the wall-mount jack.  Make sure you don't miss one of these.  Homerun of CAT5e from NID to RG, brand new line and jack which the prem tech said was better than what he has on his truck.  Old ADSL Homerun made into Tel Line.
  • Telephone surge suppressor devices.  Some higer-end power strips have two telephone ports on them that you're supposed to run the telephone line through to prevent lightning strikes from hitting your modem.  If you have one of these connected somewhere, disconnect it.  None hooked up.  See above.
  • I have seen some telephone jacks that have weird circuitry in them.  Make sure you don't have any of these.  Take apart every jack and ensure it's just a plain telephone jack.  See above, Homerun.
  • Better yet, make sure they've done a home run from the NID to the RG so that it bypasses any problems with your home telephone wiring.  Homerun.
  • Have they replaced the VDSL balun out in the NID?  A bad balun could possibly do this. Yes, multiple time since this problem began in March.
  • Have they checked the line for load coils?  A load coil would be rare, and would probably affect your service more than this, but it wouldn't hurt to look.  I and the Prem Tech has been trying to get them to check the lines, but they keep thinking its the RG.
  • In addition to that, sometimes on short lines if a load coil was present, the load coil may have been bypassed instead of removed.  But this may not work in your case.  If there is a bypassed load coil, both the bypass and the load coil have to be removed.
  • If all else fails, I would have them switch you to another pair.  If the problem remains after the pair switch, then you've eliminated that portion of the line as the source of the problem, and can concentrate on things inside your house.  I have been trying to get them to change my pair and so has the Prem Tech but this obviously has not happened yet since they keep trying to blame the RG for the problem including lowering my profile which did not fixanything and has not been changed back yet eventhough I have requested it.  Prem Tech pulled my homerun off the line and ran the same tests and they showed the same issues which obviously to me says it is on their lines or VRAD.
  • There is an outside chance that there is a bad line card in the VRAD.  AT&T's engineering group will have to come change it out if the I&R technicians can't find anything wrong with the line.  This could be a possibility, but the engineers want to go through 20 hoops with the RG first for some reason although the line tests show the same issue without my inside line and RG on the network.

 

There is definitely a problem here.  It's just a matter of finding it.  But you'll know when it's gone ... that comb-looking pattern at 7.6 MHz will go away.

 


Joe, see the inline responses.  I have showed my Prem Tech the bit load graph and he has run tests without my home line and equipment attached showing the same issue, but for some reason everyone else wants to stay focused on the RG.  Let me know some suggestions how to get to a Tier 2 support person so that they might actually listen and get the actual lines check or changed.  I already know how to use DSLReports, so I am looking at other suggestions for maybe a phone conversation, etc.

Re: Need Advice on Line Stats

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May 12, 2010 4:52:45 PM
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There is definitely a line problem here.  The RG doesn't have anything to do with it, especially since the U-Verse tech's JDSU shows the same problem.  I&R has to get out there and change the pair, and I bet all your problems go away.

 

 

There is an AT&T employee named David that handles special issues regarding U-Verse including persistent problems that have not been solved, as well as address database issues. He is able to sometimes go through different channels to get things done.

Contact him here.

 

 

(This is the same David that is a member of the special tier 2 team who is contactable over on DSL Reports, so if you've already contacted them, follow through with them over there, they will get to the bottom of it).

 

I'm 99% sure that you have a bad pair and it needs to be changed to another pair.

 

There is definitely a line problem here.  The RG doesn't have anything to do with it, especially since the U-Verse tech's JDSU shows the same problem.  I&R has to get out there and change the pair, and I bet all your problems go away.

 

 

There is an AT&T employee named David that handles special issues regarding U-Verse including persistent problems that have not been solved, as well as address database issues. He is able to sometimes go through different channels to get things done.

Contact him here.

 

 

(This is the same David that is a member of the special tier 2 team who is contactable over on DSL Reports, so if you've already contacted them, follow through with them over there, they will get to the bottom of it).

 

I'm 99% sure that you have a bad pair and it needs to be changed to another pair.

 

Re: Need Advice on Line Stats

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May 12, 2010 6:03:02 PM
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Thanks for you suggestions so far, I have sent the email to David and his crew to see what they can do now.  I will post an update if and when it occurs and what the problem and fix is.

Thanks for you suggestions so far, I have sent the email to David and his crew to see what they can do now.  I will post an update if and when it occurs and what the problem and fix is.

Re: Need Advice on Line Stats

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May 19, 2010 4:24:28 PM
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Update:  I have now been assigned to and Esculation Dept person, but no action is being taken to fix the problem yet based on the limited conversation I have had with him.  I was in contact with a Frequent Dispatch Tech for an hour on the phine who run a full battery of tests on the line and believes that the issue may lie with a grounding issue either at the NID, the VRAD, or both, but unfortunately I do not think they are going to check these as the dispatcher requested and has seen before with the stats she got with my line.  I feel the Esculation Agent is useless because I feel like he is giving me the run-around when speaking to him on the phone.  For some reason, I think they are tunnel-visioned on the RGs still instead of checking the NID. line. and VRAD.  I will update this again when they finalling, if ever, fix this problem and tell me what happened.

Update:  I have now been assigned to and Esculation Dept person, but no action is being taken to fix the problem yet based on the limited conversation I have had with him.  I was in contact with a Frequent Dispatch Tech for an hour on the phine who run a full battery of tests on the line and believes that the issue may lie with a grounding issue either at the NID, the VRAD, or both, but unfortunately I do not think they are going to check these as the dispatcher requested and has seen before with the stats she got with my line.  I feel the Esculation Agent is useless because I feel like he is giving me the run-around when speaking to him on the phone.  For some reason, I think they are tunnel-visioned on the RGs still instead of checking the NID. line. and VRAD.  I will update this again when they finalling, if ever, fix this problem and tell me what happened.

Re: Need Advice on Line Stats

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May 31, 2010 2:07:00 PM
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Well I finally got lucky and the timing was right.  I had another PT out this morning due to my service basically being out multiple times yesterday for an hour or more at a time and he put in an IR Tech ticket to swap ports, lines, etc. The IR Tech came out and swapped the ports which made all the stats cleaner and higher to where they should be from my distance and the screenshots show.  He basically said that I and another customer were somehow pulling service from the same port causing alot of crosstalk on my line.  He did say there is a larger issue with that VRAD and that it will have to be fixed soon.

1671iD3F0ECDC8176841A1672i7F76F351F1A1AFD6

Well I finally got lucky and the timing was right.  I had another PT out this morning due to my service basically being out multiple times yesterday for an hour or more at a time and he put in an IR Tech ticket to swap ports, lines, etc. The IR Tech came out and swapped the ports which made all the stats cleaner and higher to where they should be from my distance and the screenshots show.  He basically said that I and another customer were somehow pulling service from the same port causing alot of crosstalk on my line.  He did say there is a larger issue with that VRAD and that it will have to be fixed soon.

1671iD3F0ECDC8176841A1672i7F76F351F1A1AFD6

Update: Need Advice on Line Stats

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May 31, 2010 2:09:27 PM
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Sounds like they have a bad line card in the VRAD.  Engineering will have to come change it out.

 

We can't see the stats pictures yet, when the mod approves them I'll look & see how the stats have improved.

 

Sounds like they have a bad line card in the VRAD.  Engineering will have to come change it out.

 

We can't see the stats pictures yet, when the mod approves them I'll look & see how the stats have improved.

 

Re: Update: Need Advice on Line Stats

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Jun 5, 2010 10:22:48 AM
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I had kinda forgotten about this post because the pictures weren't approved, but they are now.

 

Obviously a night and day difference.  Every line stat has changed to be exactly what it should be, including the max rate and noise margin.

 

The bitloading graph now looks textbook.

 

Engineering always says it's not their equipment, but we see in this case that the bad line card in the VRAD was indeed the cause of the problem.

 

I had kinda forgotten about this post because the pictures weren't approved, but they are now.

 

Obviously a night and day difference.  Every line stat has changed to be exactly what it should be, including the max rate and noise margin.

 

The bitloading graph now looks textbook.

 

Engineering always says it's not their equipment, but we see in this case that the bad line card in the VRAD was indeed the cause of the problem.

 

Re: Update: Need Advice on Line Stats

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Jun 6, 2010 8:02:54 AM
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Thanks for your assistance in confirming what I was thinking.  There still is an issue with the VRAD that was probably thought to be part of my separate issue that has now been fixed.  The line will retrain once every day to every 2 days during the early morning hours, which is what I suspect the engineers are referring to as the problem they are working on.  It will be interesting to see what the esculation agent says this week when he calls me.

Thanks for your assistance in confirming what I was thinking.  There still is an issue with the VRAD that was probably thought to be part of my separate issue that has now been fixed.  The line will retrain once every day to every 2 days during the early morning hours, which is what I suspect the engineers are referring to as the problem they are working on.  It will be interesting to see what the esculation agent says this week when he calls me.

Re: Update: Need Advice on Line Stats

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