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Author Topic: Odd shaped SNR-vs-tone graph - line #4 fault again  (Read 21452 times)

Weaver

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Re: Odd shaped SNR-vs-tone graph - line #4 fault again
« Reply #30 on: April 18, 2020, 03:07:03 PM »

Thanks Chrys ! It’s the same general shape on a much wider scale, due to your use of a vastly greater range of tones. When was that snapshot taken btw?

(Btw, I can see just how incredibly good my line is, yours being 15 dB attn better yet having such a low bit rate downstream, yours was only 3.7Mbps d/s sync and my line 3 is 3.05 Mbps currently, so mine is much much cleaner just very weak signal. It’s as I thought, supports the idea that my lines have very thick copper (from Black Sheep) and extremely low noise due to their isolation from human noise sources.)

So the mystery remains, why not before and why now and why only on this line not the others?
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Chrysalis

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Re: Odd shaped SNR-vs-tone graph - line #4 fault again
« Reply #31 on: April 19, 2020, 12:00:16 PM »

Many years ago, its been a long time since I was on ADSL.

The normal sync for the line if on a 6db fast path profile was around 6mbit, but it had huge issues with sudden large bursts of noise, when they occurred it generated those curves eating into the signal, the only way the line could stay online was when I had SRA.  The issue persisted from the day the line was activated until the day it was ceased year's later (moved to cable).

Since the problem is E side, thankfully its gone on VDSl.
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Weaver

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Re: Odd shaped SNR-vs-tone graph - line #4 fault again
« Reply #32 on: April 20, 2020, 10:51:02 PM »

Could anyone comment on the error rates ES and CRCs per unit time ? Good/bad?


xdslctl: ADSL driver and PHY status
Status: Showtime
Last Retrain Reason:   8000
Last initialization procedure status:   0
Max:   Upstream rate = 436 Kbps, Downstream rate = 2680 Kbps
Bearer:   0, Upstream rate = 525 Kbps, Downstream rate = 2667 Kbps

Link Power State:   L0
Mode:         ADSL2 Annex A
TPS-TC:         ATM Mode(0x0)
Trellis:      U:ON /D:ON
Line Status:      No Defect
Training Status:   Showtime
      Down      Up
SNR (dB):     2.4        5.6
Attn(dB):    64.5       41.0
Pwr(dBm):    18.4       12.4

         ADSL2 framing
         Bearer 0
MSGc:      57      11
B:      28      62
M:      8      1
T:      3      1
R:      16      12
S:      2.7403      3.7736
L:      724      159
D:      1      8

         Counters
         Bearer 0
SF:      18161933      720074
SFErr:      6951      46
RS:      429075683      1032124
RSCorr:      1903856      70687
RSUnCorr:   7172      0

ReXmt:      2278836      0
ReXmtCorr:   2278204      0
ReXmtUnCorr:   7855      0

         Bearer 0
HEC:      8894      25
OCD:      0      0
LCD:      0      0
Total Cells:   1856628001      367910954
Data Cells:   112535746      16779885
Drop Cells:   0
Bit Errors:   410203      9838

ES:      108636      117
SES:      75      3
UAS:      4432      4359
AS:      296759

         Bearer 0
INP:      27.00      2.00
INPRein:   0.00      0.00
delay:      8      8
PER:      16.18      16.03
OR:      31.13      8.48
AgR:      2686.98   532.16

Bitswap:   68212/68213      452/452

Total time = 11 days 9 hours 12 min 37 sec
FEC:      10380348      235257
CRC:      218468      208
ES:      108636      117
SES:      75      3
UAS:      4432      4359
LOS:      8      2
LOF:      62      2
LOM:      0      0
Latest 15 minutes time = 12 min 37 sec
FEC:      6968      158
CRC:      25      0
ES:      25      0
SES:      0      0
UAS:      0      0
LOS:      0      0
LOF:      0      0
LOM:      0      0
Previous 15 minutes time = 15 min 0 sec
FEC:      7285      166
CRC:      52      0
ES:      51      0
SES:      0      0
UAS:      0      0
LOS:      0      0
LOF:      0      0
LOM:      0      0
Latest 1 day time = 9 hours 12 min 37 sec
FEC:      240569      10515
CRC:      919      5
ES:      870      4
SES:      0      0
UAS:      0      0
LOS:      0      0
LOF:      0      0
LOM:      0      0
Previous 1 day time = 24 hours 0 sec
FEC:      619848      20663
CRC:      2674      7
ES:      2515      6
SES:      0      0
UAS:      0      0
LOS:      0      0
LOF:      0      0
LOM:      0      0
Since Link time = 3 days 10 hours 25 min 59 sec
FEC:      1903856      70687
CRC:      6951      46
ES:      6556      35
SES:      0      0
UAS:      0      0
LOS:      0      0
LOF:      0      0
LOM:      0      0
NTR: mipsCntAtNtr=0 ncoCntAtNtr=0
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Chrysalis

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Re: Odd shaped SNR-vs-tone graph - line #4 fault again
« Reply #33 on: April 21, 2020, 06:33:56 AM »

the CRC per ES is good, thats almost 1 CRC per ES which is as low as you can get.

the amount of ES is hard to say as these are very lone ADSL lines, longer lines tend to have more errors.

Would need a baseline average of ES/hour figures so could compare to a reasonable expectation.
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Weaver

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Re: Odd shaped SNR-vs-tone graph - line #4 fault again
« Reply #34 on: April 21, 2020, 11:34:18 AM »

I looked at line 3 for comparison, which is 3.066Mbps downstream, so much faster downstream, dreadful upstream, and much cleaner

Live sync rates:
  #1: down 2898 kbps, up 529 kbps
  #2: down 2807 kbps, up 553 kbps
  #3: down 3066 kbps, up 396 kbps
  #4: down 2564 kbps, up 522 kbps

Line 4 is running at a really, really low d/s SNRM at the moment, because I forced resynchs at opportune moments when the SNRM was well above the target. But I don’t like the number of CRCs I’m getting compared with the other lines, so I forced another resynch in the middle of the night to get it back on the target of 3dB d/s as opposed to being so very low at 2.4dB. That has reduced the downstream synch rate somewhat but no errors now.



Line 4 QLN is fairly rubbish too, compared to line 3. Here’s line 4 QLN:





This is line 3 QLN for comparison:



So much quieter.

All this extra noise - I wonder if line 4 is better at detecting it, it’s not that there’s more noise out there, surely? - apart from crosstalk from different neighbours, how can the noise environment be the different? The two conductors are in the same place, (approximately) in the same environment and should be exposed to the same noise, but the QLN says otherwise. Wild speculation: if there is a new non-linear joint in line 4, detecting noise, then that would make sense because whatever the cause of the phenomenon is, it is new: it’s only been around for a week or so; something was done to the line and this noise then appeared, and I lost 300-500k d/s sync which is around 10-15%.

Is that a sensible suggestion?

There’s no way that I can get BT to sort it out as the line is nowhere near faulty; I used to be incredibly lucky with it with extremely low noise and low attenuation for such a long line, and now I’m not quite so lucky any more. If it were to develop a fault then perhaps the repair process might somehow magically kick the current badness out the same way as it was introduced but in reverse. AA is doing their bit, constantly measuring the sync rate, collecting data.
« Last Edit: April 21, 2020, 12:19:48 PM by Weaver »
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Chrysalis

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Re: Odd shaped SNR-vs-tone graph - line #4 fault again
« Reply #35 on: April 21, 2020, 04:39:10 PM »

been able to run those long adsl lines at a 3db margin is very good, my line would vary upwards of 7-8 db on some tones during a typical 24 hour period. 
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burakkucat

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Re: Odd shaped SNR-vs-tone graph - line #4 fault again
« Reply #36 on: April 21, 2020, 05:55:00 PM »

Wild speculation: if there is a new non-linear joint in line 4, detecting noise, then that would make sense because whatever the cause of the phenomenon is, it is new: it’s only been around for a week or so; something was done to the line and this noise then appeared, and I lost 300-500k d/s sync which is around 10-15%.

Is that a sensible suggestion?

Yes, that would fit the observed facts.
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Weaver

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Re: Odd shaped SNR-vs-tone graph - line #4 fault again
« Reply #37 on: June 05, 2020, 11:39:52 PM »

Latest figures - Live sync rates:
  #1: down 2807 kbps, up 519 kbps
  #2: down 2700 kbps, up 544 kbps
  #3: down 2964 kbps, up 389 kbps
  #4: down 2187 kbps, up 532 kbps

All of the lines were faster downstream before, the others by approx 100k very roughly but line 4 downstream is down by 377kbps, if my arithmetic is right, line 4 was 2564 kbps in the earlier post.

Latest line 4 detailed stats:

xdslctl: ADSL driver and PHY status
Status: Showtime
Last Retrain Reason:   8000
Last initialization procedure status:   0
Max:   Upstream rate = 452 Kbps, Downstream rate = 2344 Kbps
Bearer:   0, Upstream rate = 532 Kbps, Downstream rate = 2187 Kbps

Link Power State:   L0
Mode:         ADSL2 Annex A
TPS-TC:         ATM Mode(0x0)
Trellis:      U:ON /D:ON
Line Status:      No Defect
Training Status:   Showtime
      Down      Up
SNR (dB):    3.0       5.7
Attn(dB):    65.5       41.5
Pwr(dBm):    18.2       12.4

         ADSL2 framing
         Bearer 0
MSGc:      54      12
B:      14      62
M:      16      1
T:      5      1
R:      14      12
S:      3.4499      3.7267
L:      589      161
D:      1      8

         Counters
         Bearer 0
SF:      406574      396020
SFErr:      141      0
RS:      7623276      2830906
RSCorr:      20520      2109
RSUnCorr:   145      0

ReXmt:      45128      0
ReXmtCorr:   45119      0
ReXmtUnCorr:   166      0

         Bearer 0
HEC:      155      0
OCD:      0      0
LCD:      0      0
Total Cells:   34060189      8333379
Data Cells:   419321      118148
Drop Cells:   0
Bit Errors:   8245      0

ES:      448610      610
SES:      194      8
UAS:      5415      5234
AS:      6641

         Bearer 0
INP:      27.00      2.00
INPRein:   0.00      0.00
delay:      8      7
PER:      16.17      16.77
OR:      29.68      8.58
AgR:      2208.24   538.85

Bitswap:   1444/1444      35/35

Total time = 57 days 10 hours 19 min 9 sec
FEC:      36764065      1604333
CRC:      658801      903
ES:      448610      610
SES:      194      8
UAS:      5415      5234
LOS:      19      2
LOF:      142      2
LOM:      8      0
Latest 15 minutes time = 4 min 9 sec
FEC:      760      73
CRC:      4      0
ES:      4      0
SES:      0      0
UAS:      0      0
LOS:      0      0
LOF:      0      0
LOM:      0      0
Previous 15 minutes time = 15 min 0 sec
FEC:      3279      307
CRC:      20      0
ES:      21      0
SES:      0      0
UAS:      0      0
LOS:      0      0
LOF:      0      0
LOM:      0      0
Latest 1 day time = 10 hours 19 min 9 sec
FEC:      115341      20594
CRC:      912      13
ES:      873      9
SES:      0      0
UAS:      60      60
LOS:      0      0
LOF:      0      0
LOM:      0      0
Previous 1 day time = 24 hours 0 sec
FEC:      305956      33338
CRC:      3853      24
ES:      3655      13
SES:      0      0
UAS:      0      0
LOS:      0      0
LOF:      0      0
LOM:      0      0
Since Link time = 1 hours 50 min 41 sec
FEC:      20520      2109
CRC:      141      0
ES:      137      0
SES:      0      0
UAS:      0      0
LOS:      0      0
LOF:      0      0
LOM:      0      0
NTR: mipsCntAtNtr=0 ncoCntAtNtr=0
« Last Edit: June 06, 2020, 06:54:11 AM by Weaver »
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Weaver

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Re: Odd shaped SNR-vs-tone graph - line #4 fault again
« Reply #38 on: June 06, 2020, 07:04:35 AM »

In view of the fact that now, at downstream SNRM=3dB, the downstream speed is sufficiently slow that it is a FTB, I have talked to my ISP AA about it, having a minor moan. Since it’s an FTB, does that mean that OR has to do something about it ?

Anyway if so, I’m hoping AA will get it fixed for me.
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Weaver

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Re: Odd shaped SNR-vs-tone graph - line #4 fault again
« Reply #39 on: June 08, 2020, 03:05:28 PM »

AA has booked an SFI engineer, coming out tomorrow morning (Tuesday).
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Weaver

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Re: Odd shaped SNR-vs-tone graph - line #4 fault again
« Reply #40 on: June 09, 2020, 11:46:32 AM »

Openreach engineer has been and gone. Replaced some connectors. Bits per bin and SNR vs frequency curves look fine now, completely normal shape with no depression in the region of tones 40-80. Downstream synch rate is now fine at 2700 which is still a tiny bit low but that’s only because the current SNRM is a bit high still at 3.6 dB and settling it down to 3.0 dB means it will go a little faster yet, so a perfect result. OR SFI man was excellent.

Looks like a normal overall shape. Tiny wiggles at the very top are too small to do anything about. Downstream Line attenuation is a bit high now at 66.5dB, which is 1.5dB.

Current synch rates:
  #1: down 2807 kbps, up 519 kbps
  #2: down 2700 kbps, up 544 kbps
  #3: down 2964 kbps, up 389 kbps
  #4: down 2700 kbps, up 535 kbps

SNR vs frequency curve attached:



Line 4 detailed stats:

xdslctl: ADSL driver and PHY status
Status: Showtime
Last Retrain Reason:   8000
Last initialization procedure status:   0
Max:   Upstream rate = 458 Kbps, Downstream rate = 3020 Kbps
Bearer:   0, Upstream rate = 535 Kbps, Downstream rate = 2700 Kbps

Link Power State:   L0
Mode:         ADSL2 Annex A
TPS-TC:         ATM Mode(0x0)
Trellis:      U:ON /D:ON
Line Status:      No Defect
Training Status:   Showtime
      Down      Up
SNR (dB):    3.5       6.3
Attn(dB):    66.5       41.5
Pwr(dBm):    17.2       12.4

         ADSL2 framing
         Bearer 0
MSGc:      57      12
B:      28      62
M:      8      1
T:      3      1
R:      16      12
S:      2.7067      3.7037
L:      733      162
D:      1      8

         Counters
         Bearer 0
SF:      409669      394691
SFErr:      0      3
RS:      9678446      2808369
RSCorr:      336      3457
RSUnCorr:   0      0

ReXmt:      195      0
ReXmtCorr:   195      0
ReXmtUnCorr:   0      0

         Bearer 0
HEC:      0      11
OCD:      0      0
LCD:      0      0
Total Cells:   41879018      8304776
Data Cells:   311415      132106
Drop Cells:   0
Bit Errors:   0      481

ES:      453166      678
SES:      213      8
UAS:      7869      7678
AS:      6578

         Bearer 0
INP:      27.00      2.00
INPRein:   0.00      0.00
delay:      8      7
PER:      15.98      16.66
OR:      31.52      8.64
AgR:      2720.38   542.20

Bitswap:   92/92      45/45

Total time = 60 days 22 hours 38 min 21 sec
FEC:      37492020      1722719
CRC:      664401      995
ES:      453166      678
SES:      213      8
UAS:      7869      7678
LOS:      21      2
LOF:      159      2
LOM:      8      0
Latest 15 minutes time = 8 min 21 sec
FEC:      17      115
CRC:      0      0
ES:      0      0
SES:      0      0
UAS:      0      0
LOS:      0      0
LOF:      0      0
LOM:      0      0
Previous 15 minutes time = 15 min 0 sec
FEC:      41      249
CRC:      0      0
ES:      0      0
SES:      0      0
UAS:      0      0
LOS:      0      0
LOF:      0      0
LOM:      0      0
Latest 1 day time = 22 hours 38 min 21 sec
FEC:      207099      35728
CRC:      2576      47
ES:      1631      33
SES:      19      0
UAS:      2454      2444
LOS:      2      0
LOF:      17      0
LOM:      0      0
Previous 1 day time = 24 hours 0 sec
FEC:      189009      30725
CRC:      1041      20
ES:      1010      15
SES:      0      0
UAS:      0      0
LOS:      0      0
LOF:      0      0
LOM:      0      0
Since Link time = 1 hours 49 min 37 sec
FEC:      336      3457
CRC:      0      3
ES:      0      2
SES:      0      0
UAS:      0      0
LOS:      0      0
LOF:      0      0
LOM:      0      0
NTR: mipsCntAtNtr=0 ncoCntAtNtr=0


« Last Edit: June 09, 2020, 07:39:33 PM by Weaver »
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Weaver

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Re: Odd shaped SNR-vs-tone graph - line #4 fault again
« Reply #41 on: June 09, 2020, 12:26:19 PM »

Detailed stats after a forced resynch, which gave a very helpful improvement, synch rate downstream up to 2.86Mbps and for some reason the line attn downstream has gone back to normal and the 1.5dB has disappeared. The downstream tx power is up from 17.2 to 18.3dB and that must be contributing to the improvement too.

Lines sync rates now:

  #1: down 2807 kbps, up 519 kbps
  #2: down 2700 kbps, up 544 kbps
  #3: down 2964 kbps, up 389 kbps
  #4: down 2861 kbps, up 528 kbps


Line 4:

xdslctl: ADSL driver and PHY status
Status: Showtime
Last Retrain Reason:   8000
Last initialization procedure status:   0
Max:   Upstream rate = 496 Kbps, Downstream rate = 3148 Kbps
Bearer:   0, Upstream rate = 528 Kbps, Downstream rate = 2861 Kbps

Link Power State:   L0
Mode:         ADSL2 Annex A
TPS-TC:         ATM Mode(0x0)
Trellis:      U:ON /D:ON
Line Status:      No Defect
Training Status:   Showtime
      Down      Up
SNR (dB):    3.1       5.9
Attn(dB):    65.0       41.5
Pwr(dBm):    18.3       12.4

         ADSL2 framing
         Bearer 0
MSGc:      53      12
B:      32      62
M:      4      1
T:      3      1
R:      10      14
S:      1.4508      3.7561
L:      783      164
D:      2      8

         Counters
         Bearer 0
SF:      3599      3376
SFErr:      0      0
RS:      159260      60721
RSCorr:      0      8
RSUnCorr:   0      0

ReXmt:      2      0
ReXmtCorr:   2      0
ReXmtUnCorr:   0      0

         Bearer 0
HEC:      0      0
OCD:      0      0
LCD:      0      0
Total Cells:   392626      67582
Data Cells:   0      0
Drop Cells:   0
Bit Errors:   0      0

ES:      453166      678
SES:      213      8
UAS:      7928      7737
AS:      58

         Bearer 0
INP:      26.00      2.50
INPRein:   0.00      0.00
delay:      8      8
PER:      16.04      16.90
OR:      29.40      8.51
AgR:      2878.13   534.63

Bitswap:   15/15      0/0

Total time = 60 days 22 hours 57 min 27 sec
FEC:      0      8
CRC:      0      0
ES:      453166      678
SES:      213      8
UAS:      7928      7737
LOS:      21      2
LOF:      159      2
LOM:      8      0
Latest 15 minutes time = 12 min 27 sec
FEC:      0      8
CRC:      0      0
ES:      0      0
SES:      0      0
UAS:      59      59
LOS:      0      0
LOF:      0      0
LOM:      0      0
Previous 15 minutes time = 15 min 0 sec
FEC:      0      0
CRC:      0      0
ES:      0      0
SES:      0      0
UAS:      0      0
LOS:      0      0
LOF:      0      0
LOM:      0      0
Latest 1 day time = 22 hours 57 min 27 sec
FEC:      0      8
CRC:      0      0
ES:      1631      33
SES:      19      0
UAS:      2513      2503
LOS:      2      0
LOF:      17      0
LOM:      0      0
Previous 1 day time = 24 hours 0 sec
FEC:      0      0
CRC:      0      0
ES:      1010      15
SES:      0      0
UAS:      0      0
LOS:      0      0
LOF:      0      0
LOM:      0      0
Since Link time = 57 sec
FEC:      0      8
CRC:      0      0
ES:      0      0
SES:      0      0
UAS:      0      0
LOS:      0      0
LOF:      0      0
LOM:      0      0
NTR: mipsCntAtNtr=0 ncoCntAtNtr=0
« Last Edit: June 09, 2020, 07:40:22 PM by Weaver »
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burakkucat

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Re: Odd shaped SNR-vs-tone graph - line #4 fault again
« Reply #42 on: June 09, 2020, 04:47:08 PM »

That looks like a good result. I suspect it is all that the line can support.  :)

(Let's hope that the haggis do not gnaw on the cable sheath and pee in the joint closures.  ::)  )
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Weaver

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Re: Odd shaped SNR-vs-tone graph - line #4 fault again
« Reply #43 on: June 09, 2020, 06:50:37 PM »

It’s a very good result. The bits-per-bins are not as good as line 3, which shows that given a bit more work - which is never going to happen - it could give a bit more speed, another 100k or so, but that is just getting silly.

Latest line 4 bits-per-bins :




One more important thing that I notice is that there are now zero ES d/s - back to what it should be. Before, there were almost always 2-3 ES per hour. That suggests to me support for the increased vulnerability detector of noise theory, where a joint had become a better detector or even demodulator?

Good job by OR and extremely helpful AA. Engineer’s notes are not back yet.
« Last Edit: June 09, 2020, 07:51:05 PM by Weaver »
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burakkucat

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Re: Odd shaped SNR-vs-tone graph - line #4 fault again
« Reply #44 on: June 09, 2020, 08:26:19 PM »

One more important thing that I notice is that there are now zero ES d/s - back to what it should be. Before, there were almost always 2-3 ES per hour. That suggests to me support for the increased vulnerability detector of noise theory, where a joint had become a better detector or even demodulator?

Yes, that is possible. A joint showing semi-conductive tendencies.
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