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Standard User Bald_Eagle1
(committed) Tue 19-Mar-13 18:56:57
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Re: Interpreting line stats


[re: smouty] [link to this post]
 
In reply to a post by smouty:
My understanding is that 6db is the minimum. If you can hit 80mbit with a higher SNR then you will. I looked for other peoples SNR graphs and this appears to be the case.


From my own observations of many other users' connections, I'd agree with/confirm that.

Here's an example from a very, very short D-side length from the cabinet (SNRM at almost 31dB on a capped 40Mb/10Mb service).

I had to increase the y-axis scale of my initial graphing scripts to allow for just such a connection smile:-

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=~=~=~=~=~=~=~=~=~=~=~= PuTTY log 2011.12.29 13:28:59 =~=~=~=~=~=~=~=~=~=~=~=
xdslcmd info --pbParamsxdslcmd: ADSL driver and PHY status
Status: ShowtimeRetrain Reason: 0
Max:    Upstream rate = 40574 Kbps, Downstream rate = 127540 KbpsPath:   0, Upstream rate = 10000 Kbps, Downstream rate = 39998 Kbps
 Discovery Phase (Initial) Band Plan
US: (0,95) (868,1207) (1972,2783) DS: (32,859) (1216,1963) (2792,3939) 
Medley Phase (Final) Band PlanUS: (0,95) (868,1207) (1972,2783) 
DS: (32,859) (1216,1963) (2792,3939)        VDSL Port Details       Upstream        Downstream
Attainable Net Data Rate:      40574 kbps        127540 kbpsActual Aggregate Tx Power:    -   8.6 dBm          13.3 dBm
============================================================================  VDSL Band Status        U0      U1      U2      U3      D1      D2      D3
  Line Attenuation(dB):  2.2     7.8     10.0     N/A    4.4     9.2     13.8   Signal Attenuation(dB):  0.0      N/A    7.6      N/A    4.4     9.2     13.8   
        SNR Margin(dB):  30.6     N/A    30.2     N/A    30.7    30.5    31.1            TX Power(dBm): -25.1   -128.0  -10.2     N/A    10.5    7.7     6.2    
  
 # xdslcmd info --linediag
xdslcmd: ADSL driver and PHY statusStatus: Showtime
Retrain Reason: 0Max:    Upstream rate = 40363 Kbps, Downstream rate = 127540 Kbps
Path:   0, Upstream rate = 10000 Kbps, Downstream rate = 39998 Kbps 
                Down            UpSNRM(dB):        30.8            30.2
LATN(dB):        0.0             0.0SATN(dB):        0.0             0.0
TxPwr(dBm):      13.3           -8.6ATTNDR(Kbps):   127540          40363

Edited by Bald_Eagle1 (Tue 19-Mar-13 18:58:57)

Standard User smouty
(learned) Wed 20-Mar-13 07:52:31
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Re: Interpreting line stats


[re: Bald_Eagle1] [link to this post]
 
So, If my cab is a fairly short distance away and my SNR is <= 6db then I should assume either my atten is high or crosstalk is having an effect.
Is there any way to get around the HG612 bug to measure the attenuation?
Are there other ways to get a loop length without a TDR?
Standard User Bald_Eagle1
(committed) Wed 20-Mar-13 08:05:28
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Re: Interpreting line stats


[re: smouty] [link to this post]
 
In reply to a post by smouty:
So, If my cab is a fairly short distance away and my SNR is <= 6db then I should assume either my atten is high or crosstalk is having an effect.

Yes, that's about the gist of it




Is there any way to get around the HG612 bug to measure the attenuation?


It's already displayed (per US/DS band) via the xdslcmd info --pbParams example as shown above:-

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Line Attenuation(dB):    2.2     7.8     10.0     N/A    4.4     9.2     13.8   
Signal Attenuation(dB):  0.0      N/A    7.6      N/A    4.4     9.2     13.8




Are there other ways to get a loop length without a TDR?

Not that we are aware of.
Attempts have been made to calculate it from attenuation over frequency Hlog data, but results were too inaccurate to be classed as reliable.

Edited by Bald_Eagle1 (Wed 20-Mar-13 08:07:29)


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Standard User smouty
(learned) Wed 20-Mar-13 17:39:02
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Re: Interpreting line stats


[re: Bald_Eagle1] [link to this post]
 
Here are my pbParams

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xdslcmd info --pbParams
xdslcmd: ADSL driver and PHY statusStatus: Showtime
Retrain Reason: 0Max:    Upstream rate = 30793 Kbps, Downstream rate = 70252 Kbps
Path:   0, Upstream rate = 20000 Kbps, Downstream rate = 70711 Kbps 
Discovery Phase (Initial) Band PlanUS: (0,95) (868,1207) (1972,2783) 
DS: (32,859) (1216,1963) (2792,3959) Medley Phase (Final) Band Plan
US: (0,95) (868,1207) (1972,2783) DS: (32,859) (1216,1963) (2792,3959) 
       VDSL Port Details       Upstream        DownstreamAttainable Net Data Rate:      30793 kbps         70252 kbps
Actual Aggregate Tx Power:    -   5.9 dBm          12.4 dBm============================================================================
  VDSL Band Status        U0      U1      U2      U3      D1      D2      D3  Line Attenuation(dB):  2.0     9.5     13.5     N/A    5.6     11.8    17.6   
Signal Attenuation(dB):  2.0     8.6     12.2     N/A    5.6     11.8    17.6           SNR Margin(dB):  15.3    15.2    15.2     N/A    5.8     5.8     5.8    
         TX Power(dBm): -20.3   -34.0   -6.2      N/A    8.0     7.7     7.1
Standard User Bald_Eagle1
(experienced) Wed 20-Mar-13 17:58:14
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Re: Interpreting line stats


[re: smouty] [link to this post]
 
That looks pretty good, but what distance do you estimate you are from the cabinet (allowing for any detours, up & down poles etc.)?
Standard User smouty
(learned) Wed 20-Mar-13 18:39:06
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Re: Interpreting line stats


[re: Bald_Eagle1] [link to this post]
 
I would say no more than 50m.

Edit - I've just measured it on a map and 50m is about right given the probable route.

Edited by smouty (Wed 20-Mar-13 18:51:03)

Standard User RobertoS
(sensei) Wed 20-Mar-13 18:56:28
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Re: Interpreting line stats


[re: smouty] [link to this post]
 
That's close.

The distance required is from the FTTC cabinet to the PCP plus from the PCP to your modem.

My broadband basic info/help site - www.robertos.me.uk | Domains,website and mail hosting - Tsohost.
Connection - Plusnet UnLim Fibre (FTTC). Sync ~ 54.2/15.2Mbps @ 600m. - BQM

"Where talent is a dwarf, self-esteem is a giant." - Jean-Antoine Petit-Senn.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Allergy information: This post was manufactured in an environment where nuts are present. It may include traces of understatement, litotes and humour.
Standard User Bald_Eagle1
(experienced) Wed 20-Mar-13 19:41:24
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Re: Interpreting line stats


[re: smouty] [link to this post]
 
In reply to a post by smouty:
I would say no more than 50m.


Hmm.

I would have expected a higher attainable rate & sync speed for such a short distance (at least the full 80Mb & more), with a higher SNRM level.

Have numerous disconnections caused Interleaving to be applied at quite a high depth?

xdslcmd info --stats would confirm that, along with various error counts etc.

If you are a Windows user, have you tried the new logging/graphing programs downloadable from here yet?:-

HG612 Modem Stats 1.0
Standard User smouty
(learned) Wed 20-Mar-13 19:56:58
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Re: Interpreting line stats


[re: Bald_Eagle1] [link to this post]
 
I'm not sure on interleaving but think it is 1.

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xdslcmd info --stats
xdslcmd: ADSL driver and PHY statusStatus: Showtime
Retrain Reason: 0Max:    Upstream rate = 30769 Kbps, Downstream rate = 70252 Kbps
Path:   0, Upstream rate = 20000 Kbps, Downstream rate = 70711 Kbps 
Link Power State:       L0Mode:                   VDSL2 Annex B
VDSL2 Profile:          Profile 17aTPS-TC:                 PTM Mode
Trellis:                U:ON /D:ONLine Status:            No Defect
Training Status:        Showtime                Down            Up
SNR (dB):        5.8             15.2Attn(dB):        0.0             0.0
Pwr(dBm):        12.4           -5.9                        VDSL2 framing
                        Path 0B:              239             237
M:              1               1T:              21              45
R:              0               16S:              0.1080          0.3782
L:              17775           5373D:              1               1
I:              240             127N:              240             254
                        Counters                        Path 0
OHF:            164223390               2832611OHFErr:         1281            191
RS:             0               2883194RSCorr:         0               1329
RSUnCorr:       0               0 
                        Path 0HEC:            5244            0
OCD:            0               0LCD:            0               0
Total Cells:    3763578860              0Data Cells:     139746331               0
Drop Cells:     0Bit Errors:     0               0
 ES:             549             136
SES:            0               0UAS:            17              17
AS:             280486 
                        Path 0INP:            0.00            0.00
PER:            1.70            4.25delay:          0.00            0.00
OR:             112.85          60.17 
Bitswap:        12530           2987


I'll try that logging tool. Cheers smile

Edited by smouty (Wed 20-Mar-13 19:58:40)

Standard User Bald_Eagle1
(experienced) Wed 20-Mar-13 20:28:08
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Re: Interpreting line stats


[re: smouty] [link to this post]
 
In reply to a post by smouty:
I'm not sure on interleaving but think it is 1.


It is indeed still OFF (fastpath)

You seem to be averaging around 170 errored seconds per day, which is a shade high.
Other error counts seem quite low though.

Do you know if you have aluminium cabling in your D-side connection?

I'm not sure what attenuation levels to expect for such a short distance, but the example I cited is also around 50m or less from the cabinet.

Are you 100% sure you are actually connected to the closest cabinet?
Occasionally users are connected to a cabinet further away, due to actual cable routing.
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