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a_e
Contributor
744 Views
Message 1 of 56

SNR fluctuation and banded after line upgrade

Hi,

 

I have recently been upgraded to ADSL2+. I only found out after checking dslchecker coincidentally on the exact day that the order was due to be completed (09-Jan-2018). I didn’t request the upgrade but it was a welcome surprise! 

 

DSLCHECK_09012018.jpg

 

A day after the upgrade I saw a nice increase on download/upload speeds - 4.14 Down/ 0.70 Up with a higher attainable rate! 

 

At the time, there was no mention of what modulation I had been upgraded to and I couldn’t see it anywhere in my router stats ( Billion 7800DXL) or on the BT email notification. So I stupidly unplugged the Billion and plugged in a HomeHub 4 to find I had been upgraded from ADSL1 (G.992.1) to ADSL2+ (G.992.5). I disconnected the Homehub and reconnected the Billion which was working before.

 

I instantly got a reduced line rate at 3070/828 and the SNR was fluctuating a lot more than normal. On the Billion 7800DXL router I've always had a SNR reduction in place to lower by 2dB so all figures are inclusive of this tweak. During the day, the downstream SNR would be fairly stable at around 6-8dB, at around 6pm it would decrease to 3-4dB and then at 9pm it would then hit -0.2dB which would force the router to disconnect for a good 5-10 mins. The router would then reconnect and sync at a higher SNR. 

 

After a couple of days of this SNR fluctuation and disconnects, I think I have now been banded at 2Mbps downstream

 

I’ve been monitoring my line since and my SNR fluctuates from 0.5-8dB but I haven’t seen it hit negative figures again. Here are some SNR graphs to illustrate the fluctuations:

 

2018-01-22-17.08.29-SNRMargin.png

 

2018-01-22-19.08.29-SNRMargin.png

 

2018-01-22-21.08.29-SNRMargin.png

 

2018-01-22-23.08.28-SNRMargin.png

 

I have performed a quiet line test which is sounding nice and clear.

 

The router isn’t connected to the test socket but is connected to the master socket.

 

Through research, I discovered REIN, but if the router disconnects because of low SNR and then reconnects at a higher SNR with no major degradation after that, would that suggest electrical interference isn’t the issue?

 

I’m not sure what’s physically involved in upgrading lines but could it be a wire/connection issue from the switch over at the cabinet?

 

I have left the router alone with the hope of achieving 10-14 days uptime but so far it’s only reached 4 days and then reset with no change.

 

Here are my current stats with an uptime of 1 day 5:10

 

xDSL

Mode

ADSL_2

Traffic Type

ATM

Status

Up

Link Power State

L0

 

 

Downstream

Upstream

Line Coding (Trellis)

On

On

SNR Margin (dB)

7.8

7.3

Attenuation (dB)

36.5

22.1

Output Power (dBm)

19.1

12.2

Attainable Rate (Kbps)

6176

1324

 

Rate (Kbps)

2270

828

 

K (number of bytes in DMT frame)

0

0

R (number of check bytes in RS code word)

0

0

S (RS code word size in DMT frame)

0

0

D (interleaver depth)

160

8

Delay (msec)

7

5

INP (DMT symbol)

7.50

1.50

 

Super Frames

42936319

24367401

Super Frame Errors

5891

1768

RS Words

2187224103

1365619

RS Correctable Errors

9967305

47325

RS Uncorrectable Errors

10237

0

 

HEC Errors

11327

2853

OCD Errors

34

0

LCD Errors

34

0

Total Cells

526168566

191888649

Data Cells

349622122

23385919

Bit Errors

0

40288

 

Total ES

609

349

Total SES

61

30

Total UAS

132

102

  

I hope someone can advise.

 

Thanks in advance.

 

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55 REPLIES 55
Distinguished Sage
Distinguished Sage
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Message 2 of 56

Re: SNR fluctuation and banded after line upgrade

I would try moving to the test socket with a filter and see if that helps as you have a lot of errors in the stats  adsl2 can be less stable than adslmax on longer lines so what was ok on adslmax may not be on adsl2

 

the banded profile normally releases automatically in 3/5 days stable connection but any drops in that perios and the timescale starts again



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a_e
Contributor
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Message 3 of 56

Re: SNR fluctuation and banded after line upgrade

Thanks @imjolly

 

I connected the router to the test socket yesterday and will leave it connected there.

 

The SNR didn’t drop below 2dB yesterday evening but I’ll keep monitoring.

 

Is it normal for the SNR to fluctuate as much as it has (-0.2db-8dB)? Do you think this will improve when the router has a longer uptime and the line is seen as more stable?

 

 

Also, regarding the automatic banding release, I had an uptime of approx 4 days 5 hours before the line dropped. Do you think I could have been close to being released from this profile?

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Distinguished Sage
Distinguished Sage
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Message 4 of 56

Re: SNR fluctuation and banded after line upgrade

that is a a huge noise margin fluctuartion and not normal   hopefully it will be better in test socket

 

if now in test socket with filter can you post stats from your router for comparison to previous stats.

 

if you have extension sockets in other rooms have you checked that there are 'dead' with no dial tone



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a_e
Contributor
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Message 5 of 56

Re: SNR fluctuation and banded after line upgrade

@imjolly

 

That’s what I thought and I can’t say I’ve noticed it to this extreme before. So far today the downstream margin has been around 8-9dB and the upstream around 2-3dB. But I usually see a decline in the downstream from around 4pm. The upstream has just this minute increased to around 8dB.

 

I’ve just double checked the extensions and they are completely silent with no dial tone.

 

Here are my current stats:

 

Line Rate - Upstream (Kbps)

828

Line Rate - Downstream (Kbps)

2270

Connection Time

21:18:18

xDSL

Mode

ADSL_2

Traffic Type

ATM

Status

Up

Link Power State

L0

 

 

Downstream

Upstream

Line Coding (Trellis)

On

On

SNR Margin (dB)

8.9

7.9

Attenuation (dB)

36.5

21.9

Output Power (dBm)

19.2

12.2

Attainable Rate (Kbps)

6004

1332

 

Rate (Kbps)

2270

828

 

K (number of bytes in DMT frame)

0

0

R (number of check bytes in RS code word)

0

0

S (RS code word size in DMT frame)

0

0

D (interleaver depth)

160

8

Delay (msec)

7

5

INP (DMT symbol)

7.00

1.50

 

Super Frames

50689209

28707442

Super Frame Errors

7754

1921

RS Words

1708396006

3454384

RS Correctable Errors

1850913

21274

RS Uncorrectable Errors

35814

0

 

HEC Errors

15371

3097

OCD Errors

101

0

LCD Errors

101

0

Total Cells

410971509

149877779

Data Cells

119208392

10287755

Bit Errors

0

14949

 

Total ES

1117

426

Total SES

71

30

Total UAS

180

140

 

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Distinguished Sage
Distinguished Sage
644 Views
Message 6 of 56

Re: SNR fluctuation and banded after line upgrade

now nee to stay in test socket if possible andsee if line stays stble and the noise margin fluctuation are not as extreme as before.  you are in a banded profile which hopefully will relent if sable and you can get the 6mb speed

 

can you try the quiet line test make sure there is no line noise



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a_e
Contributor
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Message 7 of 56

Re: SNR fluctuation and banded after line upgrade

Thanks @imjolly

 

I'll make sure to stay connected to the test socket and keep monitoring the line for noise fluctuations. The downstream is now 6dB and the upstream is 8dB

 

Fingers crossed it stays stable and the banded profile gets lifted because it would be nice to hit that 6Mbps mark! That's double what I'm used to on ADSLmax!

 

I've been trying the quiet line test at all different times of the day since the fluctuations began but it's showing the line to be crystal clear. Just double checked again now and it's all clear.

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Distinguished Sage
Distinguished Sage
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Message 8 of 56

Re: SNR fluctuation and banded after line upgrade

that's good hopefully it stays clear and just keeep checking the noise margin



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a_e
Contributor
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Message 9 of 56

Re: SNR fluctuation and banded after line upgrade

Hi,

 

I’ve now been connected for 5 days 16 hours, however, the banded profile doesn’t seem to be shifting.

 

My SNR seems to be higher in comparison to before, which I assume is part of training. The downstream seems to fluctuate between 6.5dB - 13dB. Does this still seem a little extreme? The upstream seems more stable at 9.2dB with a few dips here and there. Here are some graphs to illustrate the SNR range:

 

28/01

 

2018-01-28-20.51.43-SNRMargin.png

 

29/01

 

2018-01-29-23.03.55-SNRMargin.png

 

30/01

 

2018-01-30-10.14.41-SNRMargin.png

 

Here are my router stats too:

 

Line Rate - Upstream (Kbps)

732

Line Rate - Downstream (Kbps)

2270

Connection Time

5 Day(s) 16:13:07

 

xDSL

Mode

ADSL_2

Traffic Type

ATM

Status

Up

Link Power State

L0

 

 

Downstream

Upstream

Line Coding (Trellis)

On

On

SNR Margin (dB)

11.9

9.1

Attenuation (dB)

36.0

21.7

Output Power (dBm)

19.0

12.2

Attainable Rate (Kbps)

6088

1164

 

Rate (Kbps)

2270

732

 

K (number of bytes in DMT frame)

0

0

R (number of check bytes in RS code word)

0

0

S (RS code word size in DMT frame)

0

0

D (interleaver depth)

160

8

Delay (msec)

7

5

INP (DMT symbol)

6.00

2.00

 

Super Frames

43321586

24252653

Super Frame Errors

593

498

RS Words

2327104796

1180125

RS Correctable Errors

1920016

15684

RS Uncorrectable Errors

15172

0

 

HEC Errors

2753

619

OCD Errors

41

0

LCD Errors

41

0

Total Cells

2626264183

846655495

Data Cells

598752830

62276853

Bit Errors

0

73931

 

Total ES

269

230

Total SES

0

2

Total UAS

23

23

 

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Distinguished Sage
Distinguished Sage
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Message 10 of 56

Re: SNR fluctuation and banded after line upgrade

still big fluctuations in noise margin  is quiet line test quiet when connected to the filter in test socket?



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