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Author Topic: Cable Pairs - A Question  (Read 35391 times)

snadge

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Re: Cable Pairs - A Question
« Reply #15 on: April 22, 2012, 06:53:00 PM »

thanks for the clarification BS :) really appreciate it

it was a user on Sky-Forums (Mr-Slant) who said he has changed the e-side & d-side pairs from my description? this guy knows a lot about it ..I learn a lot from the guy and I think Kitz speaks to him too - he said the fault initially sounded like a split pair, anyway, its pretty obvious that only that short run has been switched over, I'am  99.99% certain of it - perhaps he mis-read my posts..

anyway, i have had a few dropouts in las 24 hours and again the Line Attenuation has fluctuated between 8db and 16db - I have screenshots, it only changes between re-sync's, it doesnt change whilst connected - there has also been a 98db upstream noise margin once, needless to say the router dropped within 15 seconds or so...

ASBOKID - find the zip file attached to the post, I put your commands into DMT tool 1 by 1 and copied & paste into a text file, I put about 10 lines of space between each result

still no replies to my emails from SKY and no call back from Tier 2 as promised... Iam losing my faith in sky support again...just when I thought they got better, does CST Tier 2 not work weekends?
thanks a lot guys.. :)
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Black Sheep

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Re: Cable Pairs - A Question
« Reply #16 on: April 22, 2012, 07:32:33 PM »

thanks for the clarification BS :) really appreciate it

it was a user on Sky-Forums (Mr-Slant) who said he has changed the e-side & d-side pairs from my description? this guy knows a lot about it ..I learn a lot from the guy and I think Kitz speaks to him too - he said the fault initially sounded like a split pair, anyway, its pretty obvious that only that short run has been switched over, I'am  99.99% certain of it - perhaps he mis-read my posts..

anyway, i have had a few dropouts in las 24 hours and again the Line Attenuation has fluctuated between 8db and 16db - I have screenshots, it only changes between re-sync's, it doesnt change whilst connected - there has also been a 98db upstream noise margin once, needless to say the router dropped within 15 seconds or so...

ASBOKID - find the zip file attached to the post, I put your commands into DMT tool 1 by 1 and copied & paste into a text file, I put about 10 lines of space between each result

still no replies to my emails from SKY and no call back from Tier 2 as promised... Iam losing my faith in sky support again...just when I thought they got better, does CST Tier 2 not work weekends?
thanks a lot guys.. :)

I can tell you, that from the wording of your post that I answered to, there is no way you can deduce the engineer has performed an E-side change !!

Is Mr Slant looking at other historical data, from other engineers visits to your line ??? As you say yourself, the engineers never left site, so how can they perform an E-side change, unless you're a citizen of Hogwarts ?? ;D
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snadge

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Re: Cable Pairs - A Question
« Reply #17 on: April 22, 2012, 07:58:46 PM »

haha - no he has no historical data, maybe I didnt word it properly or confused him using the word "tie-pairs" lol

the thread is here, never mind!!
« Last Edit: April 23, 2012, 01:20:55 AM by snadge »
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burakkucat

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Re: Cable Pairs - A Question
« Reply #18 on: April 23, 2012, 01:18:26 AM »

the thread is here, never mind!!

Oh no it isn't!  :no:  Taking that link just gives a --

Quote
Forum > Page Not Found

 ::)
« Last Edit: April 23, 2012, 06:58:48 PM by burakkucat »
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snadge

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Re: Cable Pairs - A Question
« Reply #19 on: April 23, 2012, 01:21:21 AM »

thanks for pointing that out B'kat :)  I have amended it... :)
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asbokid

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Re: Cable Pairs - A Question
« Reply #20 on: April 23, 2012, 01:30:08 AM »

Hi snadge!

just plotted the graphs..


Bit late to look now, but will try to study them properly 'tomorrow'   :)

cheers, a
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snadge

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Re: Cable Pairs - A Question
« Reply #21 on: April 23, 2012, 01:40:34 AM »

wow!! - brilliant, thanks for that - similar to DMT's graphs but in much finer detail :) :)

I had a call from SKY tonight, she was wanting to close the ticket cos my phone was working and tier2 were dealing with me ??? - i said "noooo" - so she kept it open and will call me when she is back in on Wed.
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asbokid

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Re: Cable Pairs - A Question
« Reply #22 on: April 23, 2012, 01:45:05 AM »

Just for reference, here are my stats..  LLU talktalk..

Code: [Select]

# xdslcmd info --stats
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 8000
Max: Upstream rate = 1104 Kbps, Downstream rate = 17348 Kbps
Path: 0, Upstream rate = 1020 Kbps, Downstream rate = 15736 Kbps

Link Power State: L0
Mode: ADSL2+
TPS-TC: ATM Mode
Trellis: U:ON /D:ON
Line Status: No Defect
Training Status: Showtime
Down Up
SNR (dB): 8.8 12.4
Attn(dB): 19.0 9.7
Pwr(dBm): 20.8 12.0


cheers, a
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Black Sheep

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Re: Cable Pairs - A Question
« Reply #23 on: April 23, 2012, 09:41:53 AM »

Completely OT, but as I was reading these informative posts, I've only just noticed Asbo's 'signature' (?) at the end of his posts, the one about skydiving.  :lol: :lol:

As you were ......... :)
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kitz

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Re: Cable Pairs - A Question
« Reply #24 on: April 23, 2012, 11:02:20 AM »

Going back a bit in the thread but just wanted to confirm a couple of points.

>>> It's quite possible that DMT was wrongly reporting Annex M

That O2 DMT graph is weird. Its showing fully loaded upstream bins in the region of tones 31-56 which means that the line was on Annex_M. 
But the odd thing that strikes me is the shape of the bit loading indicating a PSD mask more in line with Annex_A than Annex_M.
From the graph its almost like only 'half a job' was done at putting that line on Annex_M.  ???   Could well be DMT being stupid but it is all rather odd.

>>> it was a user on Sky-Forums (Mr-Slant) /snip/ and I think Kitz speaks to him too

Just to confirm an earlier post which I said I would... although I speak to him under his real name, I did ask him last week..  and yes it is the same person. 
No... He's not a BT/telecom engineer but knows a lot about adsl & the adsl equipment in the exchange (eg DSLAMS/MSANS/routing), through his work and a previous occupation.
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asbokid

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Re: Cable Pairs - A Question
« Reply #25 on: April 23, 2012, 09:50:41 PM »

Snadge.. i just read your thread on the official sky forum, and the excellent advice from Mr Slant.  The frequency-dependent noise is a cursory issue to your other line problems, since the noise pre-existed your migration to sky, and the subsequent fault at the exchange.   If I'm reading it correctly, Mr Slant is recommending that now the problem in the exchange is rectified, you try to get back your original good pair (i.e., all of the sections of your line which were changed or swapped in vain attempts to resolve the problem.)  Mr Slant didn't hold much hope of success there tho', but if Sky has promised to return your line to its previous performance...

As for that noise, basic arithmetic would probably reveal the theoretical loss of bandwidth due to the noise.  A 'line-of-best-fit' could be added to the Bit Loading graph. Where the loading for a carrier is zero or much reduced because of noise, calculate from the l-o-b-f what the loading should have been without that noise. Sum the bit loading for the whole bandplan. Then subtract the difference based on what you get compared to what you should theoretically get without noise.  Since you were getting very good performance with O2/Be,  maybe that noise doesn't cause as many problems as the graph suggests.

cheers, a
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snadge

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Re: Cable Pairs - A Question
« Reply #26 on: April 23, 2012, 11:11:17 PM »

@ Asbokid - Mr-Slant is saying that , but he also thinks my entire run of cable has been switched, when it hasn't - I am on the same cable and same pairs to the exchange apart from the last 70-90m up here.

consider this:


1) only a 70-90m run has been changed into different pair / same cable
2) I was getting the same 11-12Mb speed for 36 hours after the switch before any engineers came out.
3) those noise spikes were present on my old line
4) Line Attenuation (upstream) fluctuates 8-16db

what happened was as soon as they switched the phone line over to MSAN (my broadband was already there for 6 weeks) the speed dropped and would be anywhere from 7Mb-13Mb and we had problems on the line, I contacted sky and the next day they sent an engineer out too exchange too fix what they said was a "crossed wire" - when he done this my broadband speed dropped to the 3Mb and no phone...for 4 days...until the next lot of engineers eventually changed that 70m run onto a different pair but in same cable, then its back up to 11-12Mb again (but stable).

I am pretty certain considering the above AND the fact my upstream line attenuation fluctuates between 8-16db that there is still a fault at the exchange somewhere - if it was the change in pairs then the speed loss would not have happened before?? - that speed fluctuated because them switching me over kicked over a fault at this end which wasn't previously affecting my signal..but now it did...dunno how? change in voltages or build up of resistance due to the fault at the exchange , the phone rang a few times and other people were on the line - i think there was too much voltage on the line because of this new fault and caused my degrading cable (which previously wasnt affecting my broadband) to "fall-over" and become a massive nuisance...I dunno if that's possible but thats what I think happened. this is when the phone become really bad, the next day the engineer done something at the exchange and the phone went dead and the broadband dropped to 3Mb...like I say it stayed like that for 4 days - then these 3 engineers manage to find the bad bit in cable that was "kicked over" by the fault at the exchange...change the pair in that run which repaired that...then my broadband is back up to 12Mb (roundabout the same figure after the switch and before phone went dead)

taking into account all that and the fluctuating Upstream Line Attenuation; I think there is still a problem in the exchange...

what do you think?

Iam so pee'd off with it you wont believe it - two weeks and still not sorted, major stress chasing sky all the time cos they do NOTHING once ther reply to you, full of false promises - the tier 2 rep didnt even call me back and teir 1 called me last night and wanted to close the case!!! i told her no... she had a look on Tier 2 case it says "CLOSING PENDING"...?? she says she is back in on Wednesday and will call me at 3.30pm to see if he has called me up yet...

annoying thing is I said to sky weeks before the switch that I wanted to opt out as I was worried that the switch would screw it all up for me and give me less speed!!!! - I PREDICTED THIS WOULD HAPPEN - they said "no you cant opt out, but if your speed drops we will sort it out for you"...

iam really upset about it all actually.... feel like Iam being conned and messed about...WHY DID I BOTHER...its like being with Tiscali again! :( I certainly wont ever recommend them

and they now go and advertise 6 months free on TV - I reckon they will introduce FUP/TS to manage the network congestion from further surges of new customers because of such offers - they already have loads of exchanges congested and go and do that?
« Last Edit: April 23, 2012, 11:17:14 PM by snadge »
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asbokid

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Re: Cable Pairs - A Question
« Reply #27 on: April 24, 2012, 02:49:43 AM »

EDIT: sorry, I didn't appreciate that your upstream attenuation value is fluctuating across re-syncs. So the above, now deleted, was garbage.

Quote
- that speed fluctuated because them switching me over kicked over a fault at this end which wasn't previously affecting my signal..but now it did...dunno how? change in voltages or build up of resistance due to the fault at the exchange , the phone rang a few times and other people were on the line - i think there was too much voltage on the line because of this new fault and caused my degrading cable (which previously wasnt affecting my broadband) to "fall-over" and become a massive nuisance...I dunno if that's possible but thats what I think happened. this is when the phone become really bad, the next day the engineer dID something at the exchange and the phone went dead and the broadband dropped to 3Mb...like I say it stayed like that for 4 days - then these 3 engineers manage to find the bad bit in cable that was "kicked over" by the fault at the exchange...change the pair in that run which repaired that...then my broadband is back up to 12Mb (round about the same figure after the switch and before phone went dead)

taking into account all that and the fluctuating Upstream Line Attenuation; I think there is still a problem in the exchange...

what do you think?

Hmm...

it's very difficult to say - i'm also no telephone engineer so have no practical experience..

it's not clear exactly what sections of the line have been swapped, nor the exact nature of the work that was undertaken in the exchange.  maybe there was other undocumented work?

wish i could say something useful! good luck with the tier 2 staff at sky, though. There are no doubt some very competent engineers at sky, as with openreach and all other telcos.  Once you've found someone experienced in trouble-shooting, the problem will hopefully soon be solved.

cheers, a
« Last Edit: April 24, 2012, 10:58:56 AM by asbokid »
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asbokid

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Re: Cable Pairs - A Question
« Reply #28 on: April 24, 2012, 04:47:54 AM »

Fortunately, Snadge has made no secret of his geographical location - Newcastle upon Tyne, hometown of the heavenly Cheryl Cole.

However, with or without Snadge's disclosure, the QLN data from his modem could be used to pin-down his whereabouts..

The very specific narrowband spikes in Snadge's QLN tonemap correspond to noise from RF interference that can be mapped to broadcast frequencies of MW radio stations.


The two largest spikes of noise in the QLN tonemap are at xDSL subcarriers DMT#161 and DMT#267. 

We know that ADSL2+ has channel spacing 4.3125kHz.

So DMT#161 is transmitted between 694.3125kHz and 698.6250kHz
And DMT#267 is transmitted between 1151.4375kHz and 1155.7500kHz



We can poke those two frequency ranges into Mark Hattam's excellent web resource, mediumwaveradio.com [1].

From this we can pinpoint that Snadge probably lives in or near one of the following towns: Newcastle, Droitwich or Plymouth.

How so?

From the map below, we can see that those two frequencies (~694kHz and ~1151kHz) are used for medium wave radio broadcasts from transmitters serving those three towns.

It turns out that lucky old Snadge has BBC Radio 5 Live on his doorstep belching out their RF pollution at a whopping 50kW on 693kHz from the Stagshaw MW transmitter.

Snadge also has the pleasure of tiddler AM station, Magic 1152, gracing his QLN graph with the output of their 1800 Watt transmitter at Greenside..


Fun project there for someone?!  Using QLN data for geo-location?!

cheers, a

[1] http://www.mediumwaveradio.com

« Last Edit: April 24, 2012, 05:24:43 AM by asbokid »
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Black Sheep

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Re: Cable Pairs - A Question
« Reply #29 on: April 24, 2012, 07:14:03 AM »

Asbo, sir ......... you are not of this planet. :lol: ;D You belong in another century mate, and I don't mean back in time.

Only jesting of course, I love your posts, I don't understand most of them, but I love them. ;D
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