Kitz Forum
Broadband Related => FTTC and FTTP Issues => Topic started by: pooclah on September 15, 2016, 09:41:06 PM
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Hi all
Posting this here because I think it shows the effect of crosstalk on a connection.
This evening in we had a large electrical storm that knocked out our power supply so I took the opportunity to connect the modem to a power pack that I’d bought a few years ago to jump start cars.
I collected stats from during the power outage and when I reconnected a few minutes after the power came back on.
Below shows that I have lost 11 dB of SRNM and 46 Mbps of downstream attainable due to crosstalk.
During power outage
VDSL Training Status: Showtime
Mode: VDSL2 Annex B
VDSL Profile: Profile 17a
G.Vector: Disable
Traffic Type: PTM Mode
Link Uptime: 0 day: 0 hour: 0 minute
====================================================================================
VDSL Port Details Upstream Downstream
Line Rate: 20.063 Mbps 79.998 Mbps
Actual Net Data Rate: 19.999 Mbps 79.999 Mbps
Trellis Coding: ON ON
SNR Margin: 23.2 dB 17.4 dB
Actual Delay: 0 ms 0 ms
Transmit Power: - 0.7 dBm 12.7 dBm
Receive Power: -15.9 dBm 1.0 dBm
Actual INP: 0.0 symbols 48.0 symbols
Total Attenuation: 0.0 dB 11.7 dB
Attainable Net Data Rate: 38.874 Mbps 121.985 Mbps
====================================================================================
VDSL Band Status U0 U1 U2 U3 U4 D1 D2 D3
Line Attenuation(dB): 3.3 12.9 19.8 N/A N/A 7.1 15.9 25.3
Signal Attenuation(dB): 3.3 12.1 19.0 N/A N/A 8.4 15.8 25.3
SNR Margin(dB): 24.8 23.0 23.2 N/A N/A 17.5 17.4 17.4
TX Power(dBm): -14.9 -30.0 -0.8 N/A N/A 8.8 7.7 7.1
====================================================================================
VDSL Counters
Downstream Upstream
Since Link time = 51 sec
FEC: 1303 71
CRC: 0 10
ES: 0 1
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Latest 15 minutes time = 1 min 27 sec
FEC: 1303 71
CRC: 0 10
ES: 0 1
SES: 0 0
UAS: 35 35
LOS: 0 0
LOF: 0 0
LOM: 0 0
Previous 15 minutes time = 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 = 1 min 27 sec
FEC: 1303 71
CRC: 0 10
ES: 0 1
SES: 0 0
UAS: 35 35
LOS: 0 0
LOF: 0 0
LOM: 0 0
Previous 1 day time = 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
Total time = 1 min 27 sec
FEC: 1303 71
CRC: 0 10
ES: 0 1
SES: 0 0
UAS: 35 35
LOS: 0 0
LOF: 0 0
LOM: 0 0
====================================================================================
And after
VDSL Training Status: Showtime
Mode: VDSL2 Annex B
VDSL Profile: Profile 17a
G.Vector: Disable
Traffic Type: PTM Mode
Link Uptime: 0 day: 0 hour: 3 minutes
====================================================================================
VDSL Port Details Upstream Downstream
Line Rate: 20.063 Mbps 75.680 Mbps
Actual Net Data Rate: 19.999 Mbps 75.681 Mbps
Trellis Coding: ON ON
SNR Margin: 15.0 dB 6.0 dB
Actual Delay: 0 ms 0 ms
Transmit Power: - 0.6 dBm 12.6 dBm
Receive Power: -15.9 dBm 0.9 dBm
Actual INP: 0.0 symbols 48.0 symbols
Total Attenuation: 0.0 dB 11.8 dB
Attainable Net Data Rate: 25.210 Mbps 75.199 Mbps
====================================================================================
VDSL Band Status U0 U1 U2 U3 U4 D1 D2 D3
Line Attenuation(dB): 3.3 12.9 19.7 N/A N/A 7.1 15.9 25.1
Signal Attenuation(dB): 3.3 12.0 18.9 N/A N/A 8.4 15.7 25.1
SNR Margin(dB): 14.9 15.3 14.9 N/A N/A 5.1 6.4 6.4
TX Power(dBm): -15.1 -30.2 -0.8 N/A N/A 8.7 7.7 7.1
====================================================================================
VDSL Counters
Downstream Upstream
Since Link time = 3 min 7 sec
FEC: 26523 1925
CRC: 55 225
ES: 12 23
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Latest 15 minutes time = 3 min 34 sec
FEC: 26523 1925
CRC: 55 225
ES: 12 23
SES: 0 0
UAS: 27 27
LOS: 0 0
LOF: 0 0
LOM: 0 0
Previous 15 minutes time = 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 = 3 min 34 sec
FEC: 26523 1925
CRC: 55 225
ES: 12 23
SES: 0 0
UAS: 27 27
LOS: 0 0
LOF: 0 0
LOM: 0 0
Previous 1 day time = 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
Total time = 3 min 34 sec
FEC: 26523 1925
CRC: 55 225
ES: 12 23
SES: 0 0
UAS: 27 27
LOS: 0 0
LOF: 0 0
LOM: 0 0
Edited to correct my sums.
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Interesting.
I've taken your two data sets and displayed the difference between them, ignoring the "VDSL Counters" sections. The "before" data is indicated by "<" at the start of a line. The "after" data is indicated by ">" at the start of a line.
I wonder if the values shown can be manipulated in some way to . . . hmm . . . :-\
< Line Rate: 20.063 Mbps 79.998 Mbps
< Actual Net Data Rate: 19.999 Mbps 79.999 Mbps
---
> Line Rate: 20.063 Mbps 75.680 Mbps
> Actual Net Data Rate: 19.999 Mbps 75.681 Mbps
< SNR Margin: 23.2 dB 17.4 dB
---
> SNR Margin: 15.0 dB 6.0 dB
< Transmit Power: - 0.7 dBm 12.7 dBm
< Receive Power: -15.9 dBm 1.0 dBm
---
> Transmit Power: - 0.6 dBm 12.6 dBm
> Receive Power: -15.9 dBm 0.9 dBm
< Total Attenuation: 0.0 dB 11.7 dB
< Attainable Net Data Rate: 38.874 Mbps 121.985 Mbps
---
> Total Attenuation: 0.0 dB 11.8 dB
> Attainable Net Data Rate: 25.210 Mbps 75.199 Mbps
< Line Attenuation(dB): 3.3 12.9 19.8 N/A N/A 7.1 15.9 25.3
< Signal Attenuation(dB): 3.3 12.1 19.0 N/A N/A 8.4 15.8 25.3
< SNR Margin(dB): 24.8 23.0 23.2 N/A N/A 17.5 17.4 17.4
< TX Power(dBm): -14.9 -30.0 -0.8 N/A N/A 8.8 7.7 7.1
---
> Line Attenuation(dB): 3.3 12.9 19.7 N/A N/A 7.1 15.9 25.1
> Signal Attenuation(dB): 3.3 12.0 18.9 N/A N/A 8.4 15.7 25.1
> SNR Margin(dB): 14.9 15.3 14.9 N/A N/A 5.1 6.4 6.4
> TX Power(dBm): -15.1 -30.2 -0.8 N/A N/A 8.7 7.7 7.1
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I make the drop in SNRM to be 11.4dB, plus the drop in actual speed of 4Mbps.
IIRC, my rule-of-thumb is that 3dB is worth around 10-11Mbps for lines short enough to use the full spectrum. That would fit roughly with the overall drop in attainable.
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I make the drop in SNRM to be 11.4dB, plus the drop in actual speed of 4Mbps.
IIRC, my rule-of-thumb is that 3dB is worth around 10-11Mbps for lines short enough to use the full spectrum. That would fit roughly with the overall drop in attainable.
Ah, I see. That is what I could not quite rationalise and so tailed off with a . . . hmm . . .
There are two other lines, one item, in the difference that intrigue me and they are the Attainable Net Data Rate lines.
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I make the drop in SNRM to be 11.4dB
Sorry about that, I made the post in a bit of a rush as I had a grandchild tugging my sleeve to go and watch the storm with them and must have read the wrong line.
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And it's great another user making use of a car jump starter pack it works well on modems but don't know how long the power would last on those packs I used it for 4-5 five hours and it was still showing 12.3 volts.
The Attainable DS & US show a heck of a difference have enjoyed seeing your before & after stats thanks.
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Huawei cabinet? BDUK? You might get vectoring, perhaps.
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@NS
The pack has been sat in a cupboard for months so I was surprised when it still worked, but it was good to see ‘clean’ vs ‘dirty’ stats.
@GigabitEthernet
Yes
I'm not 100% sure but I don't think so
Possibly - who knows