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Author Topic: FTTC - Distance from the Cabinet - Realistic speed estimate  (Read 253972 times)

Bald_Eagle1

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #105 on: August 17, 2011, 11:34:20 AM »


I'll check in with you on Monday to discuss the outcome of the telephone engineer visit.  ;)


Thanks Alex.

FYI, This really is the best forum I've seen.
The members on here only really deal with facts & well informed real-life "hands on" experience, unlike some other forums that I won't name that really are full of BS & falsehoods (not Plusnet's by the way).

EDIT:-

Also thanks for not just agreeing to, but actually suggesting we keep the feedback going via this public forum.
Plusnet cant really be any more open & transparent than that.

Now, where is it that I apply for my completely free broadband & phone services? (hint)  ;)

Paul.
« Last Edit: August 17, 2011, 01:17:00 PM by Bald_Eagle1 »
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razpag

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #106 on: August 17, 2011, 06:16:26 PM »

Now then .......... just to add to the 'feelgood factor' the latest additions to this thread have given, I have a wee bit of info I personally found out today.

This morning out of the blue, I received a call from my 'Control' asking if I'd help another patch out with a FTTC Managed Install task. As previously mooted, these tasks now go to the ex-servicemen and apprentices that BTOR have drafted in. Obviously, workstacks must have been to high for them to cope, so off I went.

With burning issues from this thread on my mind, I couldn't wait to get to the damned Fibre Cab !! Anyhows, as again mooted previously, the first test we do is to see if we can gain synch direct from the Fibre Cab (approx 10mtrs away) which I did at 40 Meg DS and 10 Meg US, with an attenuation of 1.5dB. Went through the other usual stuff and then off to the premises, which is approx 500/600 mtrs away (I will get the exact distance later when I get time to add up the cable lengths). When testing at the NTE5 with my JDSU, I had an attenuation of 13.5dB and an US of the full 10 Meg and a DS of 39.9 Meg.

Therefore, my conclusion from this one and only hands-on test that I've done since this thread started, is that the attenuated figure taken from the NTE5 VDSL frontplate, with a JDSU/EXXFO tester, only reports the line length from the Cab to premises, NOT the line length from the Exchange. I thought this may be the case, but wasn't 100% sure until today.

So, Baldy  ;D, we have three issues. 1) Are your attenuated stats mentioned on here, taken from the NTE5 VDSL frontplate, or from the Hub V3 ???  2) Are you positively sure you are only 0.5Miles from the Fibre Cab ?? 3) If you are, then your attenuated reading is way too high unless you are fed over wet string.

Going from what you said above only today, I suspect you still have that HR fault lurking, especially as you could still hear a 'crackling' noise ?? This is what is hopefully pushing your attenuation through the roof. I say hopefully, as it means if it is a HR, it can be faulted and fixed.

Please, please, please ask the engineer to use his TDR function (affectionately called a 'mole'). If the HR is miniscule, it still won't show. If that's the case, ask them to explain how your line is so highly attenuated over such a (reported) short distance ?? If they look at you blankly, don't be surprised (as the training we get is very, very basic), just ask them if they can ring a colleague who will know about attenuation and get them to what we call 'Assist' on the task.

Sounds like you may have turned a corner at last here Paul. Best of luck bud. ;) ;D
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burakkucat

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #107 on: August 17, 2011, 07:47:14 PM »

What a co-incidence, Mr Pag. Although it is not the same as having personal experience (and how, one may ask, can a black felis domesticus have the experience of a OR employee?), it is very useful to read your first hand experience.

Did you, perchance, think of taking a set of photographs at each stage so that they could be added to a new FTTC section on Kitz' website? If not, would it be possible to do so at a later install that you attend?

Deviating slightly, b*cat is still keeping his critical eyes open for a means to get hold of a Huawei HG612, as modified for supply by OR.

Deviating a little more, with regards to obtaining the usual statistics from the OR modem, asbokid has managed to do so. I attach to this post a series of screen-shots he has obtained (cropped by me, so that they may be attached). :)

[attachment deleted by admin]
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razpag

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #108 on: August 17, 2011, 07:57:46 PM »

Hi B*Cat

Unfortunately, no I didn't take any snap-shots. TBH, time is precious when working for OR these days. Photo's and the like, just don't occupy ones thoughts when you know there's up to 4 individuals monitoring your progress. >:(

Regarding the Modem mate, E-bay's yer best bet I would guess. Apart from the fact that, all stores allocated to an individual are itemised and billed to that individuals OUC (Manager in other words), It would be foolish of me to risk my livelihood (sp) over a Modem. Jobs are precious these days, and apart from the micro-managing and i-POP, I like mine. ;D ;D   
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burakkucat

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #109 on: August 17, 2011, 08:22:54 PM »

Quote
Unfortunately, no I didn't take any snap-shots. TBH, time is precious when working for OR these days. Photo's and the like, just don't occupy ones thoughts when you know there's up to 4 individuals monitoring your progress. >:(

That's unfortunate, as they would prove to be a very useful addition to this web-site. Obviously, though, the requirements of your job comes first.

Quote
Regarding the Modem mate, E-bay's yer best bet I would guess. Apart from the fact that, all stores allocated to an individual are itemised and billed to that individuals OUC (Manager in other words), It would be foolish of me to risk my livelihood (sp) over a Modem. Jobs are precious these days, and apart from the micro-managing and i-POP, I like mine. ;D ;D

For the record -- i.e. for any "outsider" who may read this thread -- b*cat recognises that it would be absolutely incorrect for Mr Pag (or for any other OR employee in the "front line") to pass his employer's stock on to a third party (and wishes it to be noted that no such request has been made). :no:
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Bald_Eagle1

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #110 on: August 17, 2011, 10:37:46 PM »


Therefore, my conclusion from this one and only hands-on test that I've done since this thread started, is that the attenuated figure taken from the NTE5 VDSL frontplate, with a JDSU/EXXFO tester, only reports the line length from the Cab to premises, NOT the line length from the Exchange. I thought this may be the case, but wasn't 100% sure until today.

So, Baldy  ;D, we have three issues. 1) Are your attenuated stats mentioned on here, taken from the NTE5 VDSL frontplate, or from the Hub V3 ???  2) Are you positively sure you are only 0.5Miles from the Fibre Cab ?? 3) If you are, then your attenuated reading is way too high unless you are fed over wet string.

Going from what you said above only today, I suspect you still have that HR fault lurking, especially as you could still hear a 'crackling' noise ?? This is what is hopefully pushing your attenuation through the roof. I say hopefully, as it means if it is a HR, it can be faulted and fixed.

Please, please, please ask the engineer to use his TDR function (affectionately called a 'mole'). If the HR is miniscule, it still won't show. If that's the case, ask them to explain how your line is so highly attenuated over such a (reported) short distance ?? If they look at you blankly, don't be surprised (as the training we get is very, very basic), just ask them if they can ring a colleague who will know about attenuation and get them to what we call 'Assist' on the task.

Sounds like you may have turned a corner at last here Paul. Best of luck bud. ;) ;D

@ razpag

Thanks for the info - distances, attenuation etc.

1) The stats that I have listed are indeed taken directly from the faceplate. I am not aware they can be taken from anywhere else in the EU's premises.
What is a Hub v 3? Is it the BT Home Hub? I don't have one of these. I have a Netgear router plugged into the Echolife HG612 v 2B modem.

2) By road I am near as damn it 0.4 miles from the PCP. I have driven the "probable" route. Due to the lack of other roads &  DPs in my area there is only 1 other "possible" route. That route is unlikely though as it would take me back toward the Oldham exchange for a few hundred yards or so before doubling back toward my house.
The overhead cable goes from my house on a slight detour before heading toward the PCP, so 0.5 miles is probably about right.

3) The wet string is quite possible when considering my attenuation, dropped connections etc. It was warm & sunny when I first lost connection today. Maybe the string dried out & we just have a simple "dry joint" to track down?

I had a further 3 disconnections around noon today, resulting in my profile dropping back down from 23 Mb to 15 Mb again.
In a strange way, that is good news as it clearly points to a "fault".
I do hope the "fault" is still present on Monday. As we all know it appears to be of an "intermittent" nature.

THis is what Alex added to my Plusnet ticket:-
"PSTN engineer booked to check for HR fault on D-side which may be affecting broadband
speed",
But don't worry. I have already been rehearsing what to say when the engineer turns up.
Alex mentioned the Hawk for TDR testing, but didn't you say these have been regretfully replaced by the JDSU now.

On a "good" line, what sort of line length would you expect for my reported attenuation of 30.2 dB downstream & 52.9 dB upstream & is there usually such a difference between downstream & upstream attenuations?

If you haven't specifically noted JDSU attenuation readings to date, I have a funny feeling you may well look at them a little more closely from now on.

If you were able to pass on such actual values & line length comparisons to us (me in particular at the moment) A pretty useful record of statistics could be built up that may assist us all to gain a much better understanding of FTTC matters.

Fingers (& everything else) crossed for Monday then.

Paul.
« Last Edit: August 18, 2011, 08:47:07 AM by Bald_Eagle1 »
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Bald_Eagle1

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #111 on: August 18, 2011, 12:54:35 AM »


Deviating a little more, with regards to obtaining the usual statistics from the OR modem, asbokid has managed to do so. I attach to this post a series of screen-shots he has obtained (cropped by me, so that they may be attached). :)


@ b*cat

I have seen those screenshots before. It's just a shame it is so difficult to obtain them.

Just imagine, if I could have obtained that basic level of info from my BT modem, I could have saved us all an awful lot of time.

I appeciate that SNR values fluctuate for many reasons, but I take it that attenuation on a "good" line should remain reasonably static.

If I had been able to monitor the attenuation readings for my own connection, I would have been immediately alerted to a problem.

e.g. if my actual line length is roughly the same as the example that razpag quoted today, I should expect an attenuation of around 13.5 dB, or maybe a little higher as I do know that my line takes a slight detour.
How I wish I could get my hands on the attenuation value from the day that FTTC was first installed & compare it against the last checked value.

As my attenuation, when last checked by the BT engineer, was 30.2 dB, a "problem" is immediately suspected.
As attenuation is a logarithmic value, a reading of 30.2 dB would suggest quite a big problem for my likely actual line length.

Had I been able to monitor the attenuation for myself I would surely have detected large fluctuations, the value being possibly a lot lower on the good days when I didn't drop connection, & possibly sky-high today when I had 4 disconnections & a crackly phone line.

With this basic information I could have passed a log of readings to Plusnet, who in turn could have passed them to BT as evidence of a "fault", possibly of an intermittent nature.

It may just be that my issue(s) could have been resolved back in July.

When I think back, I will have had FTTC for 8 weeks by this Friday.
The first 2 weeks were absolutely brilliant & the other 6 weeks not so brilliant at all.

As I have been unable to monitor line conditions myself, as & when connections and/or speeds have dropped, I have needed to rely on others, who appear to have not carried out the relevant tests to date, resulting each time in a Line Tests O.K. response.

Hopefully, & I believe partly due to our persistence & well informed discussions on this forum with regard to this matter, everything will be permanently fixed on Monday.

I do accept that a little knowledge can be very dangerous in the wrong hands, but the decision to deny everyone the facility of at least monitoring their own connection does seem to be a little strange.

Having no data whatsoever as to what may be causing dramatic & sometimes quite sudden speed reductions & disconnections makes it incredibly difficult for users to prove they have a problem in the first place, & incredibly easy for BT to "fob off" the less persistent user.

I do hope that you can somehow get your hands on a modem to experiment with, ideally resulting in an "approved" firmware update that we can all easily install, thus allowing us to see the basic stuff that we all feel we should be able to see.

Paul.
« Last Edit: August 18, 2011, 05:28:42 PM by Bald_Eagle1 »
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burakkucat

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #112 on: August 18, 2011, 02:13:30 AM »

Mr Eagle,

I fully understand and appreciate what you have written.

With regards to your line attenuation -- copied photographically, as we appreciate, from the engineer's JDSU -- I still think there is something wrong with the upstream & downstream values. Currently, as I have no experience of VDSL (perhaps I should go and visit my neighbour, who has BT Infinity installed, clutching my laptop, dodahs & whatsits and ask if I could have a "fiddle"), I think it should be possible to obtain a general "feeling" by extrapolating from ADSL --> ADSL2 --> ADSL2+ --> VDSL2 (which is used "copper-side", cabinet <--> EU, for FTTC). So at ADSL frequencies, it has been observed that the upstream attenuation is somewhere between 50 - 60% of the downstream attenuation. What were the values reported by the JDSU? Upstream 52.9 dB and downstream 30.2 dB. Eh??

(1) Let's assume the values have been swapped over due to a JDSU software bug. So we consider 52.9 dB downstream and 30.2 dB upstream. A quick calculation gives U/S to be ~57% of D/S. It fits. But the overall values are too high for your D-side copper length.

(2) Let's assume the JDSU has reported them correctly. With D/S at 30.2 dB, I would expect an U/S of ~16.6 dB. What could cause such an asymmetric distortion of attenuation v frequency? A corroded joint, acting as a diode, perhaps?

Hmm :hmm: Interesting but, as Mr Pag will say, web-based fault-finding is no substitute for the real thing.

b*cat looks at the time -- gone 0212 hours BST -- so he waves a paw in acknowledgement and pads of to find a warm, sleepy spot (his bed).
« Last Edit: August 18, 2011, 05:00:38 PM by burakkucat »
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razpag

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #113 on: August 18, 2011, 07:19:17 AM »

Will have to reply to all later as off to work but a copy of the PM sent to BE for others to mull over. More-so Plusnet.

Very quick reply as off to work in a minute. I'm not sure (as I haven't seen one for a while), but if there was a case of attenuation increasing by 6dB from baseline (ie- the figure reported when you will have first had ADSL activated), then there was such a thing as a RADE1 task built by the ISP's. This meant an engineer who knows about attenuation etc would be despatched, in order to bring the attenuation back to  (or better than) the original baseline.
Not sure if this can be done on a FTTC job, but tbh, the fault does sound like a RADE1 on the D-side rather than on the Fibre side.
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Bald_Eagle1

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #114 on: August 18, 2011, 05:33:07 PM »

Quote
Regarding the Modem mate, E-bay's yer best bet I would guess. Apart from the fact that, all stores allocated to an individual are itemised and billed to that individuals OUC (Manager in other words), It would be foolish of me to risk my livelihood (sp) over a Modem. Jobs are precious these days, and apart from the micro-managing and i-POP, I like mine. ;D ;D


@ b*cat,

Have you noticed the PM that I sent to you?

Paul.
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burakkucat

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #115 on: August 18, 2011, 06:15:53 PM »

@ b*cat,

Have you noticed the PM that I sent to you?

Indeed I have, Mr Eagle. There should be a significant stream of electrons flowing from Suffolk to Lancashire. ;)
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razpag

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #116 on: August 18, 2011, 08:34:31 PM »

Addendum to my post further up this thread re: the attenaution from the PCP to the EU's. It was as said, 13.5dB on a 488mtr length of wire ......... and 95% of this was made up of Aliminium. The EU still received 39.9Meg on the DS.

 ;D
« Last Edit: August 18, 2011, 08:37:22 PM by razpag »
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Bald_Eagle1

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #117 on: August 18, 2011, 09:43:32 PM »

Addendum to my post further up this thread re: the attenaution from the PCP to the EU's. It was as said, 13.5dB on a 488mtr length of wire ......... and 95% of this was made up of Aliminium. The EU still received 39.9Meg on the DS.

 ;D

Just curious razpag, did you obtain the 488m length from the JDSU, or by some other means?

488m = 0.3 miles (approx)

0.5 miles = 805m (approx)

Roughly, what do you reckon the attenuation should be for 0.5 miles (805m)?

Paul.
« Last Edit: August 18, 2011, 09:50:06 PM by Bald_Eagle1 »
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burakkucat

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #118 on: August 18, 2011, 11:31:16 PM »

By the only means of divination available to me (catch a passing young rat, slaughter it, disembowel it, scatter and study the entrails :tongue: ) I have come up with the range of approximately 15 - 18 dB attenuation, for a distance of 0.5 mile, of an average copper pair, at VDSL2 frequencies.
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Bald_Eagle1

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #119 on: August 18, 2011, 11:43:02 PM »


 I have come up with the range of approximately 15 - 18 dB attenuation, for a distance of 0.5 mile, of an average copper pair, at VDSL2 frequencies.


Go on then, what's the formula?

Paul.
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