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[Bald_Eagle1]

Actually - was able to get in and generate the attached file. Is this any use? I can change my script to get any other figures.

That log was fine for generating the "snapshot" graphs.

I have attached the montage produced by my script to get the plots into the same format as mine for comparison purposes.

It really is a poor connection isn't it?

Has it gradually deteriorated over a few days, or has it always fluctuated?

Your current DS sync speed of only 281 Kbps is unbelievably low, yet your Interleaving depth, Impulse Noise Protection & delay are quite low values:-


D:      5      21
INP:      3.00      4.00
delay:      6.00      8.00


Strangely, pbParams is reporting that all 3 DS bands are useable:-

Medley Phase (Final) Band Plan
US: (0,95)
DS: (32,859) (1216,1963) (2792,3959)

Usually only the useable bands are reported.

Power levels also look rather strange:-

Pwr(dBm):    101.2       10.4

It's hard to say what the issue could be.
Maybe a faulty modem throwing up spurious results?
Possibly a line fault?

Is your best sync speed the 1997 Kbps as shown in a couple of your previous graphs?

Your error seconds aren't the highest values I have seen for the 17 hours or so connection up time, neither are various other errors.

Does your connection regularly resync "on the fly"?
Retrain Reason:   2 suggests a resync rather than a reboot that would be reason 0.

The modem's inbuilt logs (when enabled) should keep tabs on all disconnections/reconnections.

As I haven't previously seen any VDSL2 stats from such a long line, I don't know if the performance (lack of) you are seeing is "typical" or not.

[Bald_Eagle1]

And a 2nd set after doing a remote reboot (using equipcmd 33) as the download speed is truly terrible... 281 kbps. Unbelievable.

TBH, that's not much better (383 Kbps), but some of the stats do now look a little more valid.

The BT Care forum didn't seem too helpful:-
"we  cannot advise  on problems of this nature as  the openreach modem is a locked device  and it is against forum rules  to advise on hacked devices"

[asbokid]

I am getting called back tomorrow by someone who has raised a fault with BT wholesale, and I'd like to be able to direct the discussion somewhat. He has stated that our connection measurements were the worst he has seen...

From your stats (up to DMT#512)..

In terms of RF pollution, it looks like BBC Radio 4 has the slight lead over RTE Radio 1.

It's time that BBC Radio 4 (AM) was told to pipe down with its pips.  My sympathies - we suffer constant online harassment from Edwina Currie (BBC Radio 5 on 693kHz).

On a serious point, it's difficult to see what you could do. Are you on very elevated ground? Does BT ever shield pole-strung cable to solve RF ingress? 

cheers, a

P.S. cold comfort for you, perhaps, but there is a fun project here - the programmatic analysis of QLN data from CPE to recover geolocation data from RF ingress.

There are some algorithm ideas here for "cluster detection", using the opencv function library. [1]

Perhaps the key to success is to geolocate using the QLN noise spikes from the 'tiddler' commercial stations since their transmitter output power (i.e. reception range) will generally be much lower than for the national radio stations.

[1] http://stackoverflow.com/questions/356035/algorithm-for-detecting-clusters-of-dots

[NewtronStar]

The BT Care forum didn't seem too helpful:-
"we  cannot advise  on problems of this nature as  the openreach modem is a locked device  and it is against forum rules  to advise on hacked devices

I read that post on the BT Forum to Bald_Eagle1, God help me if I need help there 

[tristan]

In terms of RF pollution, it looks like BBC Radio 4 has the slight lead over RTE Radio 1.

It's time that BBC Radio 4 (AM) was told to pipe down with its pips.  My sympathies - we suffer constant online harassment from Edwina Currie (BBC Radio 5 on 693kHz).

On a serious point, it's difficult to see what you could do. Are you on very elevated ground? Does BT ever shield pole-strung cable to solve RF ingress? 

Wow - so are you saying there is so much RF 'cross talk' from LW and MW that, potentially, our line is too noisy? Would this stem from not-properly-covered wiring/junction boxes etc? The wiring by us could be _very_ old. We are on a pretty flat piece of rural NI (http://goo.gl/maps/7bsT).

Hard to know the cause for sure but BT are sending someone down to look at the line from cabinet to the house tomorrow. I'll take your input and try to get the engineer to check for the things you mentioned.

Thanks again,

Tristan

[asbokid]

RF ingress from AM broadcast radio certainly adds a lot of noise within those bands, but that only affects the lowest (ADSL1) subcarriers. So what else is going on higher up in the VDSL2 spectrum?   It looks pleasantly quiet between DMTs #470 - #490, but then it gets noisy again around DMT#1400 and DMT#1700.

Hope you get some resolution.

cheers, a

[Bald_Eagle1]

Hi Tristan,

This & the preceding messages may, or may not be of interest to you:-

http://forums.thinkbroadband.com/fibre/f/4141202-fibre-help-pleaseeee.html?page=1&fpart=2#Post4141310

[tristan]

Hmm, so we may be in a fix... Thanks for all the help and I'll report the outcome later. It is frustrating being in London and having to liaise with BT via my mother who is at home!

Tristan

[NewtronStar]

I would go back into the BT forums again this time without the Stats, and ask for a Moderator to look into your very Slow Infinity package, yes you are 2X faster than your old ADSL but someone in BT said your expected download would be 20Mbps which is not right.

[tristan]

Guys,

Thanks once again for all your input. What did we do before the internet?

So the BT came down and checked our socket, and line -> road. Agreed there was a problem after, funnily, the tool gizmo they use couldn't sync at all to the cabinet. Off he went to the cabinet to check, and yep, a problem. He did something at the cabinet end and, overnight, our reported speed has improved. See attached.

I'm guessing this will change (hopefully upwards) over the next few days? The one thing that is strange is that our actual download speed hasn't changed (a quick test by my sister using one of the speed tester sites indicates ~0.25 mbps). I also attach the latest stats.

The engineer is checking back tomorrow I think so it we should be able to get that seen to. It would be interesting to know if the interference is still present so we can get him to check each length of line for problems.

Tristan

[Bald_Eagle1]

That looks a lot better.

The noise spikes are still present at the lower frequencies, but your SNRM of 10.0dB suggests some more can be squeezed out speed-wise.

The connection may require a DLM reset back to a wide open profile & be allowed to retrain to a stable level accordingly, although it doesn't appear to be "stuck" as sync speed has increased to 3929 Kbbs.

Sometimes the ROUTER/HUB (NOT the MODEM) needs disconnecting/reconnecting to force a new PPP session without actually causing a resync.
This usually resets IP Profile to be in relation to sync speed (96.79% of it to be quite precise for FTTC connections).
Your IP Profile may be currently stuck at the level applied when sync speed was much lower.

[tristan]

Guys,

Thought you might like an update. BT (via their Twitter folk) have been very helpful. However, BT Wholesale (or whoever it is that comes out) are not quite there.

We have had countless visits - checking the cabinet (fault found) to checking the house internal cabling and replacing it (no fault found but they thought they'd give it a go anyway). I get the impression the people called out are 'installers' rather than engineers (when will the UK protect that term?). I am having it escalated as high as I can via BT, although the constant back and forth with BT Wholesale is incredibly frustrating.

The new findings are:

1) it is not the internal house cabling/box on the wall
2) it is not the cabinet
3) something is happening between midnight and 5am that causes the speed to drop (according to BT Wholesale)
4) the BT machine fails to sync when they plug it in...

What I am trying to do is gather together the evidence I have with some interpretation suitable for the BT folk to pass on to BT Wholesale and propose some next steps (check the copper might be a good one).

Bald_Eagle1, asbokid, would you be willing to check what I write to ensure it is technically correct and, more importantly, useful for whoever this gets escalated to?

Attached is the latest stats output and plot.

Tristan

[burakkucat]

However, BT Wholesale (or whoever it is that comes out) . . .

They will be employees of Openreach, a division of the BT Group plc.

[Bald_Eagle1]

Hi Tristan,


I have been looking through your latest stats & a few of them look "strange" when compared against any other VDSL2 stats that I have looked at over almost a year now.


Retrain Reason 2 - usual reason for an "on the fly" resync.



Medley Phase (Final) Band Plan
US: (0,95)
DS: (32,859) (1216,1963) (2792,3959)

That suggests that after training up from the reboot, all 3 downstream bands are available for bit-loading.
That is surprising, as connections with such high attenuation as yours simply do not show all 3 bands as being available at Medley Phase.

e.g. My connection is quite poor for VDSL2, but much better than yours.
However, I still can't use all the bands at Medley Phase:-

Medley Phase (Final) Band Plan
US: (0,95) (868,1207)
DS: (32,859) (1216,1963) 


DS Attainable Rate 2368 Kbps - The lowest I have seen on a VDSL2 connection.

Sync speed 410 Kbps - By far the lowest I have seen & less than 1/5 your Attainable Rate.

SNRM 19.5 dB - suggests your connection is able to achieve a higher sync speed, perhaps approaching the 2368 Kbps.

Really high attenuation, also confirmed in the Hlog graph.

Available seconds (AS:) 16949 (around 4.7 hours) matches the reported Since Link time = 4 hours 42 min 27 sec, so O.K.

UnAvailable seconds (UAS:)      10283      10283 - The highest I have seen on ANY connection.

Serious Error Seconds (SES:)      423      0 - Looks quite high.

Error Seconds (ES:)      32922      4787 - Not sure where that is from. Adding DS SES, UAS & AS together only comes to 27655.

Pwr(dBm):   1.5      10.4 - DS at 1.5 looks really low. Mine is 12.4, roughly double my US of 6.3.

Interleaving (D:)      7      1 - Really low, almost OFF, suggesting a really stable connection.



As you appear to be a Linux user, you are unable to monitor & graph your ongoing stats 24/7 using our scripts, so we are unable to see what happens between midnight & 5am.
However, Eric (Roseway) has been developing Windows & Linux versions of a monitoring program that you may be able to leave running overnight, auto-generating snapshot graphs at intervals. This may yield SOME clues?
(see this thread :-   http://forum.kitz.co.uk/index.php/topic,11534.0.html)

Code: [Select]


# xdslcmd info --pbParams
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 2
Max: Upstream rate = 1160 Kbps, Downstream rate = 2368 Kbps
Path: 0, Upstream rate = 1160 Kbps, Downstream rate = 410 Kbps

Discovery Phase (Initial) Band Plan
US: (0,95) (868,1207) (1972,2783)
DS: (32,859) (1216,1963) (2792,3959)
Medley Phase (Final) Band Plan
US: (0,95)
DS: (32,859) (1216,1963) (2792,3959)
       VDSL Port Details       Upstream        Downstream
Attainable Net Data Rate:       1160 kbps          2368 kbps
Actual Aggregate Tx Power:       10.4 dBm           1.5 dBm
============================================================================
  VDSL Band Status        U0      U1      U2      U3      D1      D2      D3
  Line Attenuation(dB): 20.5 84.0   N/A   N/A 35.5 0.1 0.1
Signal Attenuation(dB): 18.9   N/A   N/A   N/A 35.5 0.1 0.1
        SNR Margin(dB): 6.2   N/A   N/A   N/A 19.5 0.0 0.0
         TX Power(dBm): 10.5   N/A   N/A   N/A 1.5 -128.0 -128.0



Code: [Select]


# xdslcmd info --stats
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 2
Max: Upstream rate = 1164 Kbps, Downstream rate = 2384 Kbps
Path: 0, Upstream rate = 1160 Kbps, Downstream rate = 410 Kbps

Link Power State: L0
Mode: VDSL2 Annex B
VDSL2 Profile: Profile 17a
TPS-TC: PTM Mode
Trellis: U:ON /D:ON
Line Status: No Defect
Training Status: Showtime
Down Up
SNR (dB): 19.6 6.3
Attn(dB): 0.0 0.0
Pwr(dBm): 1.5 10.4
VDSL2 framing
Path 0
B: 57 31
M: 1 1
T: 4 51
R: 16 0
S: 4.4755 0.8620
L: 143 297
D: 7 1
I: 80 32
N: 80 32
Counters
Path 0
OHF: 1257032 15452
OHFErr: 0 0
RS: 15087415 1324715
RSCorr: 5889 0
RSUnCorr: 0 0

Path 0
HEC: 0 0
OCD: 0 0
LCD: 0 0
Total Cells: 13076794 0
Data Cells: 338654 0
Drop Cells: 0
Bit Errors: 0 0

ES: 32922 4787
SES: 423 0
UAS: 10283 10283
AS: 16949

Path 0
INP: 3.00 0.00
PER: 13.42 10.98
delay: 7.00 0.00
OR: 46.47 23.29

Bitswap: 16 3




Unfortunately, I don’t know what all that means in terms of faults.

I would be very tempted though to try another unlocked modem (just to eliminate hardware issues & see if the same “strange” data is obtained).

FWIW, I have attached Windows versions of your snapshot graphs, using the data from your most recent log file.


Cheers,


 Paul.


EDIT:

Edited the comment about Retrain Reason.
Retrain Reason 2 is usually from an "on the fly" DLM initiated resync, & possibly a resync caused by a profile change.
Retrain Reason 0 is usually from a reboot.

[Black Sheep]

Tristan quoted ...................

"I get the impression the people called out are 'installers' rather than engineers".

As a qualified Electrical Engineer, I can understand your comments fully. But for pedants sake, the term 'Engineer' has been banded about for eon's when referring to 'us' Openreach guys. God only knows who or how it became so, but I can tell you that it wasn't from BT. As far back as I can remember, we have always been known professionally as 'Technicians'.

Only when I was on the 'Power & BES' group was I referred to as a 'Power engineer'. On this side of the fence, dependant on skill set, we are called Technician 2B (T2B), Technician 2A (T2A), and the following are grades that are still tagged to individuals, but are now obsolete and will be lost as and when the individuals retire. They are Technician 1 (T1), Senior Technician (ST) and Technical Officer (TO).

As you will see, nowhere in our descrip do we refer to ourselves as 'engineers'. So the term is protected as far as BT are concerned.