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Author Topic: Bizarre low upstream SNRM - line #3 again  (Read 883 times)

Weaver

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Bizarre low upstream SNRM - line #3 again
« on: November 22, 2018, 11:24:28 AM »

Just now I am seeing an amazingly low SNRM upstream on my line #3 of only 0.4 dB. It should be 6dB. None of the others are showing this. For quite a while, until today, the upstream sync rate had been far lower, at 358 kbps, now 509 kbps. It has a history of jumping up and down between these two levels, jumps of around 100k or more, often 150k, but always between these two levels of ~350k and ~450-500k.

Quote
xdslctl: ADSL driver and PHY status
Status: Showtime
Last Retrain Reason:   8000
Last initialization procedure status:   0
Max:   Upstream rate = 336 Kbps, Downstream rate = 3448 Kbps
Bearer:   0, Upstream rate = 509 Kbps, Downstream rate = 3136 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       0.4
Attn(dB):    64.5       40.4
Pwr(dBm):    18.5       12.4

The following SNRM graph shows the bizarre 24 hour history of the upstream SNRM in green. Huge jumps down to this very low level, no gradual changes over time. Would anyone care to comment?
    https://www.dropbox.com/s/ogjfm5lv1gld4rr/IMG_0029.jpg?dl=0

It seems that therein lies the explanation for the sync rate jumps: it all depended on when one resynched: if done at the right time then the current noise level was would be very different, on the other side of one of the strange upward/downward transitions.
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hacktrix2006

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Re: Bizarre low upstream SNRM - line #3 again
« Reply #1 on: November 22, 2018, 11:37:22 AM »

I have been having same issue on my upstream as well however mine goes in either low SNRM or high SNRM.

Bet the line test shows no faults up either.
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re0

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Re: Bizarre low upstream SNRM - line #3 again
« Reply #2 on: November 22, 2018, 08:52:54 PM »

I am curious to see the bitloading with SNR also plotted. Ideally both graphs when normal SNR (~6 dB) and extremely low SNR (but the latter is most important).

Since the upstream tones, on ADSLx, occupy the very low frequencies it should not be subject to issues relating to high loop loss as much. Even still, this jump in SNR is huge and perhaps I would consider something at fault somewhere at the near end. Presumptuous, I know.
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Weaver

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Re: Bizarre low upstream SNRM - line #3 again
« Reply #3 on: November 22, 2018, 11:44:24 PM »

Bitloading:

Code: [Select]
xdslctl: ADSL driver and PHY status
Status: Showtime
Last Retrain Reason: 8000
Last initialization procedure status: 0
Max: Upstream rate = 436 Kbps, Downstream rate = 3356 Kbps
Bearer: 0, Upstream rate = 509 Kbps, Downstream rate = 3136 Kbps

Tone number      Bit Allocation
   0 0
   1 0
   2 0
   3 0
   4 0
   5 0
   6 0
   7 9
   8 10
   9 10
   10 10
   11 10
   12 10
   13 9
   14 9
   15 8
   16 8
   17 8
   18 8
   19 7
   20 7
   21 7
   22 6
   23 6
   24 6
   25 6
   26 6
   27 6
   28 6
   29 5
   30 5
   31 5
   32 0
   33 8
   34 9
   35 10
   36 10
   37 10
   38 10
   39 11
   40 11
   41 11
   42 11
   43 11
   44 11
   45 11
   46 8
   47 12
   48 12
   49 12
   50 12
   51 12
   52 12
   53 12
   54 12
   55 2
   56 12
   57 12
   58 10
   59 10
   60 11
   61 12
   62 12
   63 12
   64 12
   65 11
   66 11
   67 10
   68 11
   69 11
   70 11
   71 11
   72 11
   73 11
   74 11
   75 11
   76 10
   77 10
   78 10
   79 10
   80 10
   81 10
   82 10
   83 10
   84 10
   85 10
   86 9
   87 9
   88 9
   89 9
   90 9
   91 9
   92 9
   93 9
   94 9
   95 8
   96 8
   97 8
   98 8
   99 8
   100 8
   101 8
   102 8
   103 7
   104 7
   105 7
   106 7
   107 7
   108 7
   109 7
   110 7
   111 7
   112 6
   113 6
   114 6
   115 6
   116 6
   117 6
   118 6
   119 6
   120 5
   121 5
   122 5
   123 4
   124 3
   125 2
   126 0
   127 3
   128 3
   129 3
   130 3
   131 3
   132 4
   133 4
   134 4
   135 3
   136 3
   137 3
   138 3
   139 3
   140 3
   141 3
   142 3
   143 3
   144 0
   145 3
   146 1
   147 3
   148 0
   149 2
   150 2
   151 1
   152 0
   153 1
   154 1
   155 1
   156 1
   157 0
   158 0
   159 0

[Moderator note: It is best to wrap such blocks of data with [code] . . . [/code] tags. It preserves the format, allows the code block to be scrollable and allows the data to be easily selected by left-clicking on [select].]
« Last Edit: November 22, 2018, 11:55:09 PM by burakkucat »
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re0

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Re: Bizarre low upstream SNRM - line #3 again
« Reply #4 on: November 23, 2018, 12:10:15 AM »

I am curious to see the bitloading with SNR also plotted. Ideally both graphs when normal SNR (~6 dB) and extremely low SNR (but the latter is most important).
I meant in graph form. Sorry if that was not clear. You can use DSLstats or HG612 stats for it.

Alternatively, if you are unable to use those programs to provide a graph, you could provide the individual stats for me to look at using the following commands:
Code: [Select]
adsl info --Bits
adsl info --SNR
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Weaver

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Re: Bizarre low upstream SNRM - line #3 again
« Reply #5 on: November 23, 2018, 12:36:02 AM »

Charts, data and spreadsheets of bitloading available :
« Last Edit: November 23, 2018, 12:38:23 AM by Weaver »
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Weaver

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Re: Bizarre low upstream SNRM - line #3 again
« Reply #6 on: November 23, 2018, 01:00:59 AM »

And spreadsheets and charts of the SNR-vs-frequencies dataset, again ‘hi SNRM’ unfortunately. Unfortunately the modem gave me all zeros for the low tones, the upstream. No idea why. ?
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re0

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Re: Bizarre low upstream SNRM - line #3 again
« Reply #7 on: November 23, 2018, 11:53:58 PM »

I can't see the SNR plot? Perhaps just provide raw output using commands I supplied previously if possible.
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burakkucat

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Re: Bizarre low upstream SNRM - line #3 again
« Reply #8 on: November 24, 2018, 04:14:33 PM »

I can't see the SNR plot? Perhaps just provide raw output using commands I supplied previously if possible.

You have a PM. b*cat has acted as an intermediary and the raw data (bit loading and SNR per sub-carrier) should now be available to you.  ;)
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Weaver

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Re: Bizarre low upstream SNRM - line #3 again
« Reply #9 on: November 24, 2018, 05:56:49 PM »

This is the SNR history pic for the 24 hours leading up to last night. Generated by our very own Johnson’s superb B10A-embedded stats and SNR graphing http server thanks to his custom B10A firmware. See
    https://www.dropbox.com/s/p3ae1jyuf1q8na4/IMG_0031.PNG?dl=0
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re0

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Re: Bizarre low upstream SNRM - line #3 again
« Reply #10 on: November 24, 2018, 06:01:55 PM »

@b*cat:
I have responded. Thanks for the PM.

@Weaver:
I apologise that I misunderstood what you meant with the all zeros at lower tones (I thought you were referring to the gaps for some reason, but I didn't have access to SNR stats at the time). I can see you meant it in reference to SNR on the upstream tones.
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Weaver

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Re: Bizarre low upstream SNRM - line #3 again
« Reply #11 on: November 24, 2018, 06:10:16 PM »

In a later SNR-history graph captured right now, Sat 17:59, it shows nicely the droop in downstream SNRM from its daylight high of say 3.1 dB - its downstream target is 3dB, so that is as it should be - down slowly to a current 2.5 dB, the downward slope starting at sunset. Based on history it will only get slightly lower still eventually. The previous day’s minimum was at around 21:30, followed by a sligh rise and then a lesser, broad dip whose minimum was at around 04:10. So I am assuming that temperature is controlling the d/s SNR. The upstream doesn’t show any such thing much as the jumps up and down are so overwhelming. And the odd thing is that the high upstream rung value is still way too low, at 4.1 dB roughly, instead of the 6 dB u/s target.
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burakkucat

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Re: Bizarre low upstream SNRM - line #3 again
« Reply #12 on: November 24, 2018, 08:54:03 PM »

re0 and the black cat have discussed the oddity that is occasionally observed with the circuit using line number three. (Extremely low SNR margin.) It might be interesting to see the snapshot data following a circuit retrain during an "odd" period. If the output produced by the following command sequence could be captured it might shed some light on the puzzle --

xdslctl connection --up
(Wait while the circuit retrains.)
xdslctl info --Hlog
xdslctl info --QLN
xdslctl info --Bits
xdslctl info --SNR


There is the possibility that the retrain may clear the oddity but whatever the end result, it would be a worthwhile experiment. 
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Weaver

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Re: Bizarre low upstream SNRM - line #3 again
« Reply #13 on: November 25, 2018, 03:29:34 AM »

Will certainly do so and will post raw data here as post-attachments. Unfortunately it has just transitioned to the ‘high’ upstream SNRM state, so will have to wait for a few hours.
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Weaver

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Re: Bizarre low upstream SNRM - line #3 again
« Reply #14 on: November 25, 2018, 04:04:47 AM »

I realise that I should have waited until it was a ‘low’ SNRM time, but just out of curiosity, I did an xdslctl connection —up. After retraining, the upstream sync rate dropped from 509 kbps to 445 kbps because the sync rate went back to normal at 6 dB from 4.1 dB. At 04:00 Sunday:

Code: [Select]
> xdslctl info --stats
xdslctl: ADSL driver and PHY status
Status: Showtime
Last Retrain Reason:    8000
Last initialization procedure status:   0
Max:    Upstream rate = 420 Kbps, Downstream rate = 3392 Kbps
Bearer: 0, Upstream rate = 445 Kbps, Downstream rate = 3012 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):        3.3             6.0
Attn(dB):        64.0            40.2
Pwr(dBm):        18.0            12.4

                        ADSL2 framing
                        Bearer 0
MSGc:           52              14
B:              34              46
M:              4               1
T:              3               1
R:              12              12
S:              1.4633          3.3007
L:              831             143
D:              2               8

                        Counters
                        Bearer 0
SF:             54476           52923
SFErr:          0               0
RS:             2369716         1057486
RSCorr:         12              25
RSUnCorr:       0               0

ReXmt:          14              0
ReXmtCorr:      13              0
ReXmtUnCorr:    0               0

                        Bearer 0
HEC:            0               0
OCD:            0               0
LCD:            0               0
Total Cells:    6199996         914755
Data Cells:     252564          24440
Drop Cells:     0
Bit Errors:     0               0

ES:             303             114
SES:            26              0
UAS:            216             195
AS:             873

                        Bearer 0
INP:            26.00           2.50
INPRein:        0.00            0.00
delay:          8               7
PER:            15.91           16.50
OR:             29.15           9.69
AgR:            3027.88 453.88

Bitswap:        232/237         8/8

Total time = 12 days 13 hours 58 min 1 sec
FEC:            115337          36582948
CRC:            1997            146
ES:             303             114
SES:            26              0
UAS:            216             195
LOS:            3               0
LOF:            18              0
LOM:            0               0
Latest 15 minutes time = 13 min 1 sec
FEC:            11              23
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:            42              62
CRC:            0               0
ES:             0               0
SES:            0               0
UAS:            52              52
LOS:            0               0
LOF:            0               0
LOM:            0               0
Latest 1 day time = 13 hours 58 min 1 sec
FEC:            4602            3614813
CRC:            13              2
ES:             10              2
SES:            0               0
UAS:            52              52
LOS:            0               0
LOF:            0               0
LOM:            0               0
Previous 1 day time = 24 hours 0 sec
FEC:            5740            4968487
CRC:            3               13
ES:             2               10
SES:            0               0
UAS:            0               0
LOS:            0               0
LOF:            0               0
LOM:            0               0
Since Link time = 14 min 33 sec
FEC:            12              25
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
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