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Author Topic: FTTC - Distance from the Cabinet - Realistic speed estimate  (Read 254011 times)

burakkucat

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #405 on: February 06, 2012, 01:18:08 PM »

Indeed, Walter. My comment was based on pure logic rather than that of the fantasy world in which the Evil Empire of Newgate Street likes to reside.

Perhaps Mr Eagle could rent a JDSU HST-3000c for one weekend and obtain his own TDR data for the line?  :-\
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Bald_Eagle1

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #406 on: February 06, 2012, 05:20:38 PM »

Indeed, Walter. My comment was based on pure logic rather than that of the fantasy world in which the Evil Empire of Newgate Street likes to reside.

Perhaps Mr Eagle could rent a JDSU HST-3000c for one weekend and obtain his own TDR data for the line?  :-\

Indeed, that is one option.

Another would be to purchase a used 301c 'Mole', or a Hawk tester (at a reasonable price).
They may be uncalibrated, but would surely indicate any potential "issues".

If any such tests proved inconclusive or completely clear, the question would remain - how on earth did I ever achieve a reasonably sustained throughput of up to 33Mb, with a probable sync speed of around 35Mb or higher, for the first month (on the "slower" 8c profile) & why can I not achieve or improve on it now that I am on the "faster" 17a profile, after so many engineer visits that have supposedly "fixed" everything at each visit?

EDIT:
Examining my Hlog graph (plotted as lines as apparently plotted via a JDSU, rather than the usual boxes) does not indicate any particular HR or capacitance issues for the tones my connection is actually able to use (see attached) other than generally highish attenuation over frequency.

Could it be simply a matter of crosstalk due to increased takeup of FTTC services from my cabinet or that output power from my cabinet has been reduced to avoid crosstalk onto ADSL frequencies?


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« Last Edit: February 06, 2012, 05:34:06 PM by Bald_Eagle1 »
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burakkucat

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #407 on: February 06, 2012, 10:44:00 PM »

EDIT:
Examining my Hlog graph (plotted as lines as apparently plotted via a JDSU, rather than the usual boxes) does not indicate any particular HR or capacitance issues for the tones my connection is actually able to use (see attached) other than generally highish attenuation over frequency.

Could it be simply a matter of crosstalk due to increased takeup of FTTC services from my cabinet or that output power from my cabinet has been reduced to avoid crosstalk onto ADSL frequencies?


If everything else proves to be satisfactory, then either of your postulations could be the answer. However I am highly suspicious of what you have recently reported -- that when a "proper man" goes up the pole, your service throws a "funny fit".  :-\

Also, you are no closer to finding the length of your D-side cable.  :-X
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Bald_Eagle1

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #408 on: February 06, 2012, 11:19:39 PM »

If everything else proves to be satisfactory, then either of your postulations could be the answer.

I doubt it really. I was just trying to remain "positive"

Quote
However I am highly suspicious of what you have recently reported -- that when a "proper man" goes up the pole, your service throws a "funny fit".  :-\

Me too. It threw another funny fit just after 9:00 tonight. Sync speed back down to 23753 K & SNRM levels/attainable rates all over the place.
No massive error counts though.

Quote
Also, you are no closer to finding the length of your D-side cable.  :-X

True. I wonder if we should start a sweep for the real distance.

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Bald_Eagle1

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #409 on: February 07, 2012, 10:17:28 PM »


Me too. It threw another funny fit just after 9:00 tonight. Sync speed back down to 23753 K & SNRM levels/attainable rates all over the place.
No massive error counts though.


I rebooted the modem at 14:49 today, following advice from Plusnet:-

"I would recommend to force a re-sync to obtain a higher sync speed and then attempt to maintain this connection for as long as possible."



Not bad - Sync speed 30160 k & SNRM at 6.4dB (actually the highest sync speed since last July).



It was a bit short-lived though.
A grand total of 2 hours & 12 minutes later, at 17:01, the connection re-synced itself.

I didn't spot any engineers up the pole this time though.
Maybe they don't need to come back & mess up my connection any further as they seem to have done a prettty good job of it already  :o >:(


Sync speed ended up back down to 23367 k, with SNRM back up to 10dB:-


Of course, I immediately reported this to Plusnet, reminding them that my line was quite stable & gradually building speed until 2 engineer's messed it up for me late last week.

Hopefully they will confirm what they will be doing about it some time during tomorrow.

I'm sure I posted a similar message earlier on.
I wonder if it was removed because I may just have let a naughty word slip in.
It did display as "{censored}" though.

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waltergmw

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #410 on: February 08, 2012, 12:04:50 AM »

@ paul,

I suspect you have long since passed the record for the longest thread on Kitz's famous site - and VERY well done for being so persistent !

(In a different context perhaps you have noticed my tenacity elsewhere !)

I did just have a nasty fear that the engineers' up the pole might have been using a tone generator but I'm relieved  to read your recent reports of ongoing difficulties.

I'm trying to summarise the likely causes of the recent disturbances after quite a long time of reasonably steady, but degraded, performance.

1. It is much colder now that when you started this marathon, but there were perturbations in warmer times too, so this is unlikely to be a major factor.

2. Upon the assumption that the engineers are actually climbing on the pole, physical movement and vibration on the pole generally might be a contributory factor.
I.e. a)  it is possible that a joint or the local feed cable has poor crimps and / or corrosion
      b)  the drop wire itself or the cable towards the static house components is damaged; however I seem to recall that the drop wire has been replaced ?
      c)  EITHER the idc connections, if they are provided, that your service uses have been stretched or corroded OR similarly the crimp joints, if they are provided, are faulty ?
      d)  assuming that the drop wire was replaced, then the supply cable pair within the DP has been damaged - either the wires themselves or the insulation to other metallic parts is damaged
      f)  an unusual connection method has been employed where there are other components in circuit such as another cable join, perhaps in a BT 66 box or similar ?

3.  Given the current minimal maintenance regime employed by BT Openreach (at least around here), the chances of having the entire DP replaced are probably minimal. You just might, if you are very lucky, persuade the next engineer called out to investigate to swap the pair from the through joint up on to a different pair of connectors and also perhaps to replace the drop-wire with a new length of drop-wire 12 preferably as a single length direct into your NTE.

Kind regards,
Walter

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burakkucat

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #411 on: February 08, 2012, 12:57:41 AM »

Walter,

My recollection is that the NTE5/A (in the office at "The Aerie") and entire length of drop-cable from it to the DP pole-top was replaced, with new, a couple of months ago. The reason why that has remained in my mind is because the drop-cable is affixed to Doris' house, Mr Eagle's neighbour to the west, and then travels down the side & along the back of the buildings to it's destination in the office.

My suspicion is thus directed to the pole-top and the junctions "up there" or to the supply cable (20-pair ?) that "climbs" the pole from underground. Perhaps Mr Eagle could take a series of photographs for us to examine? Looking at images from Google maps, dated November 2009, offers no great help.  :no:

Edit: Re-visiting those images, It now looks as if both Doris' and Mr Eagle's drop-cables have a pole of their own, which is fed, in turn, by an aerial feed from a pole on the north side of the road. It is the second pole (on the north side of the road) which has a "climbing" 20-pair and that can be traced back to its "three-cover" joint-chamber, in the east, by the "scar" in the pavement surface. However, it all looks a bit "odd", for I think I can see a "two-cover" joint-chamber in the pavement at the front of Doris' house.  :-\
« Last Edit: February 08, 2012, 01:21:13 AM by burakkucat »
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waltergmw

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #412 on: February 08, 2012, 08:29:42 AM »

@ BKK,

I am pleased that you too recall the drop wire replacement.

Following our recent postulation that the latest interventions by BT Openreach engineers to provide a new service somewhere from the existing DP pole, I think we both agree with your para 2 statements upon the likely area of the problem which, if I recall, is across the main road. (It might help if Mr Eagle can confirm whether or not the adjacent houses share a single drop cable as that would imply a break in the drop cable where the two house separate their services. However as that is reasonably remote from DP pole mechanical vibration it seems unlikely that is the culprit.)

We must also not completely rule out other causes of the difficulties at least up to and including the PCP and FTTC.

Kind regards,
Walter
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Bald_Eagle1

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #413 on: February 08, 2012, 08:39:56 AM »

Hi Walter,

I suspect you have long since passed the record for the longest thread on Kitz's famous site - and VERY well done for being so persistent !

(In a different context perhaps you have noticed my tenacity elsewhere !)

I have indeed noticed & I wish you all the best of luck in what appears to be an increasingly uphill struggle.

Quote
I did just have a nasty fear that the engineers' up the pole might have been using a tone generator but I'm relieved  to read your recent reports of ongoing difficulties.

I'm not quite sure what you mean by that. Could you please clarify it for me?

Quote
I'm trying to summarise the likely causes of the recent disturbances after quite a long time of reasonably steady, but degraded, performance.

1. It is much colder now that when you started this marathon, but there were perturbations in warmer times too, so this is unlikely to be a major factor.

A few slight improvements do appear to have occured as the weather has become colder. Some slight improvement did coincide with with being switched to the 17a profile in October (a few more DS bit-loading tones available at the lower frequencies - although the slight speed increase did appear to be the start of me seeing massive error counts).

I have wondered if any contraction of cables could cause a "tightening" effect & make some dry joints better?
Also, I'm sure I have read of a seasonal phenomenon where broadband speeds & stability can increase due to reduced radio propagation/skip in winter, thus reducing any effect of interference/noise levels.

The worst period of instability was from reinstatement of my services at the end of July to around the middle of September.
The double jumpering issue was “fixed” near the end of August.

Quote
2. Upon the assumption that the engineers are actually climbing on the pole, physical movement and vibration on the pole generally might be a contributory factor.

The 2 engineers from last week did indeed climb the pole.
AFAIK, any previous engineers have used a cherry picker.

Quote
I.e. a)  it is possible that a joint or the local feed cable has poor crimps and / or corrosion
      b)  the drop wire itself or the cable towards the static house components is damaged; however I seem to recall that the drop wire has been replaced ?

The drop wire was indeed replaced, along with the complete master socket and faceplate.

Quote
 
      c)  EITHER the idc connections, if they are provided, that your service uses have been stretched or corroded OR similarly the crimp joints, if they are provided, are faulty ?
      d)  assuming that the drop wire was replaced, then the supply cable pair within the DP has been damaged - either the wires themselves or the insulation to other metallic parts is damaged
      f)  an unusual connection method has been employed where there are other components in circuit such as another cable join, perhaps in a BT 66 box or similar ?

The pole is an old timber telegraph pole.
The new drop wire does appear to be quite tight in comparison with the previous sagging drop wire.
My immediate neighbour & I do not have BT 66 boxes.

Quote
3.  Given the current minimal maintenance regime employed by BT Openreach (at least around here), the chances of having the entire DP replaced are probably minimal. You just might, if you are very lucky, persuade the next engineer called out to investigate to swap the pair from the through joint up on to a different pair of connectors and also perhaps to replace the drop-wire with a new length of drop-wire 12 preferably as a single length direct into your NTE.

I think the chances of any of that are remarkably slim.


The whole point of all this is that my connection was perfectly fine until it was accidentally disconnected at the end of July & that nobody has yet discovered why it has been rather unstable with low speeds ever since.

For all I know, the double jumpering could well have been in place right from the start, the drop wire could have needed replacing right from the start, the internal shielded cable that has raised a few eyebrows was in place right from the start.

All of these various “fixes” have brought some slight improvement, but the underlying cause of the issue, in my opinion, is still to be located & “fixed”.

If all the other incidental “fixes” have improved matters, maybe I should by now be expecting the full 40Mb sync speed, very low error counts & very infrequent re-syncs.

Maybe I should also be looking forward to a slight possibility of being able to achieve something from BT’s soon to be rolled out 80/20 speed doubling.

My maximum attainable rates are still only around 35Mb maximum & that is only immediately following a re-sync (on the occasions that I do actually sync at just below 30Mb).

My connection MUST have actually synced at around 35Mb or so when I was able to achieve throughput of 33Mb (as reported via speedtest.net & mybroadbandspeed.co.uk et al.

Even then, I was aware that BT’s own speed/performance test produced DS throughput speeds of 1Mb to 2Mb lower than the other online testers.

Here is just one example of the result from a BT speed test, from around 23:00 on 30th June, some 6 days after installation.
Download speed achieved during the test was - 32359 Kbps.

According to BT’s SIN 498 document, the “training period” for FTTC services is not 10 days (it would be quite helpful if all ISP agents were aware of that).
The document states that if any severe instability is seen within the first 24 hours of installation, DLM will take immediate action.
Otherwise, it will take action within the next 24 hour period.

As we know, my connection was able to maintain higher speeds & apparent stability right through the irrelevant 10 day period starting 24th June to 21st July when it all suddenly fell apart.


Paul.
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Bald_Eagle1

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #414 on: February 08, 2012, 09:29:38 AM »

Hi b*cat,

Walter,

My recollection is that the NTE5/A (in the office at "The Aerie") and entire length of drop-cable from it to the DP pole-top was replaced, with new, a couple of months ago. The reason why that has remained in my mind is because the drop-cable is affixed to Doris' house, Mr Eagle's neighbour to the west, and then travels down the side & along the back of the buildings to it's destination in the office.

My suspicion is thus directed to the pole-top and the junctions "up there" or to the supply cable (20-pair ?) that "climbs" the pole from underground. Perhaps Mr Eagle could take a series of photographs for us to examine? Looking at images from Google maps, dated November 2009, offers no great help.  :no:

I will take some photographs & post them here.

Quote
Edit: Re-visiting those images, It now looks as if both Doris' and Mr Eagle's drop-cables have a pole of their own, which is fed, in turn, by an aerial feed from a pole on the north side of the road. It is the second pole (on the north side of the road) which has a "climbing" 20-pair and that can be traced back to its "three-cover" joint-chamber, in the east, by the "scar" in the pavement surface. However, it all looks a bit "odd", for I think I can see a "two-cover" joint-chamber in the pavement at the front of Doris' house.  :-\

The "two cover" joint chamber is a red herring.
It has NTL on it, but I have no idea what it is as it has been confirmed there is absolutely no possibility of me having NTL/Virgin cable TV or broadband.

Please see the attached roughly drawn sketch of the poles & cables.

From the PCP, the supply could take one of two routes Route A, up the main road or Route B up a smaller road.
Quite thick looking cables all meet at the pole at the road junction.
One engineer thought it came via the shorter route & another thought it came via the longer route.

The dotted cable line may be an underground supply from the pole in front of the petrol station to the pole across the road from my house.
Alternatively, again thick cables can be seen going up the lane behind the petrol station & down the footpath to the pole facing my house.
None of the engineers have confirmed which route is used.

Regardless of which routes are actually used. The line length still appears to be less than the 1000m as displayed on an engineer's JDSU.

For all I know, my connection might have been originally supplied via the more direct underground route (shown dotted - if it actually exists).
How could I tell whether it exists or not?

When my services suddenly ceased for 4 days back in July, it might have been an expensive to repair issue in the underground section.
So my connection might have been rerouted around the back of the petrol station & down the footpath, adding quite a few metres to the overall D-side length.

I have asked the question a few times, but unfortunately nobody can (or they just won't) confirm the exact route for me.


Paul.

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waltergmw

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #415 on: February 08, 2012, 07:31:56 PM »

Hi Paul,

Quote
I'm not quite sure what you mean by that. Could you please clarify it for me?

BT Engineers regularly use tone generators and tone tracers to identify the required pairs to be connected or changed etc.
I had wondered if their tone generators had produced cross talk on to your rather delicate CCT.
The fact that the problems continued after the BT engineers had gone away suggests tone generators are unlikely to be the cause of all your anguish.

Kind regards,
Walter
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Bald_Eagle1

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #416 on: February 26, 2012, 08:53:13 PM »

Just for "fun" I thought I would plot my IP Profiles since FTTC was installed 24th June 2011.

The graph is attached.

I had to calculate my IP Profile from my Sync speed & speed tests for a few of the days, as I wasn't logging my IP Profie all the time (FTTC's IP Profile works out at 96.8% of sync speed (approx) & speed tests approximate 97% of IP Profile (at quiet times).



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burakkucat

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #417 on: February 27, 2012, 12:58:12 AM »

Hmm.  :hmm:  Not a pretty sight.  :no:

What you really need is for B*Sheep to be seconded from his normal Lancashire & Cumbria area to the Devil Worshippers' catchment area and then to be assigned to resolve all of your long standing line issues . . .  :-X
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waltergmw

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #418 on: February 27, 2012, 08:22:36 AM »

@ Paul,

You could perhaps illustrate the serious problems of the FTTC implementation by drawing a horizontal line at 15,000 Kbps to show that, as from about 10 November 2011, your line has stayed within the BT Openreach declared acceptable performance levels thus absolving them from all fault-finding responsibilities whatever, whilst you continue to pay for your monthly "sack of potatoes" with varying sized holes in it.

Kind regards,
Walter
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Bald_Eagle1

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #419 on: February 27, 2012, 12:11:57 PM »

Haha,

Nicely worded Walter.

You have to laugh though, otherwise......................

Let's see what happens when BT engineers connect up an extra bit of black underground cabling that has recently been coiled up, ready for connection at the DP at the top of the pole where my drop wire starts.

I have no idea what the cable is for, but it is around 12mm in diameter & it appears to come from a joint chamber a little further away from the cabinet than the pole (maybe 30m or so).


Paul.
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