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Author Topic: FTTC - Distance from the Cabinet - Realistic speed estimate  (Read 254042 times)

burakkucat

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #465 on: March 27, 2012, 07:53:01 PM »

Yes.  :)

Oh, do you want me to continue?  :P  O.k. One or more manky joints.

Do you have the loop attenuation available for the same time periods, when the telephone was used?
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Bald_Eagle1

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #466 on: March 27, 2012, 09:28:24 PM »


Do you have the loop attenuation available for the same time periods, when the telephone was used?



Unfortunately not.

However, I can see that attenuation has generally increased a little, particularly in the U1 & D2 bands.

Code: [Select]
03/02/2012
==========

Path: 0, Upstream rate = 6160 Kbps, Downstream rate = 28721 Kbps

       VDSL Port Details       Upstream        Downstream
Attainable Net Data Rate:       6198 kbps         33104 kbps
Actual Aggregate Tx Power:        6.2 dBm          12.0 dBm
============================================================================
  VDSL Band Status        U0      U1      U2      U3      D1      D2      D3
  Line Attenuation(dB): 8.2 52.3 63.7   N/A 21.4 62.5 0.1
Signal Attenuation(dB): 14.8 51.7   N/A   N/A 21.4 62.5   N/A
        SNR Margin(dB): 6.1 6.2   N/A   N/A 5.8 5.7   N/A
         TX Power(dBm): -4.2 5.8   N/A   N/A 11.0 5.5   N/A







27/03/2012
==========

Path: 0, Upstream rate = 5472 Kbps, Downstream rate = 28346 Kbps

       VDSL Port Details       Upstream        Downstream
Attainable Net Data Rate:       5502 kbps         33280 kbps
Actual Aggregate Tx Power:        6.3 dBm          12.1 dBm
============================================================================
  VDSL Band Status        U0      U1      U2      U3      D1      D2      D3
  Line Attenuation(dB): 8.2 53.7 64.0   N/A 21.9 63.9 0.1
Signal Attenuation(dB): 14.4 53.0   N/A   N/A 21.9 63.9   N/A
        SNR Margin(dB): 6.0 6.2   N/A   N/A 6.1 6.3   N/A
         TX Power(dBm): -4.2 5.8   N/A   N/A 11.1 5.8   N/A
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Bald_Eagle1

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #467 on: March 27, 2012, 10:18:02 PM »

Aha,

Found one - where DS SNRM dropped to very low levels & attainable rate was quite a bit less than sync speed.

Also, there's the attenuation over frequency graph with the dip in it again (right where bits stop being loaded).

Code: [Select]

Max: Upstream rate = 5509 Kbps, Downstream rate = 24820 Kbps
Path: 0, Upstream rate = 5520 Kbps, Downstream rate = 27089 Kbps

       VDSL Port Details       Upstream        Downstream
Attainable Net Data Rate:       5509 kbps         24820 kbps
Actual Aggregate Tx Power:        6.3 dBm          11.9 dBm
============================================================================
  VDSL Band Status        U0      U1      U2      U3      D1      D2      D3
  Line Attenuation(dB): 8.4 53.7 63.9   N/A 21.7 63.8 0.1
Signal Attenuation(dB): 14.2 53.0   N/A   N/A 21.7 63.8   N/A
        SNR Margin(dB): 6.0 6.1   N/A   N/A 1.8 1.9   N/A
         TX Power(dBm): -3.9 5.8   N/A   N/A 11.0 5.2   N/A
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burakkucat

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #468 on: March 27, 2012, 11:44:51 PM »

One or more manky joints in your D-side metallic path seem to be a reasonable assumption.

Knowing how you like to plot (almost) everything against time, I was hoping you would have the data to graph the Line Attenuation (dB) D1, D2 & D3 against time. If you could show me graphs of Line Attenuation v time & SNR v time that both have anomalies present and co-incident with a telephone being used, then I would suggest that you show the same to Alex (of PlusNet).

Putting it another way, show me and, more, importantly PlusNet & Openreach a smoking gun:-\

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Bald_Eagle1

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #469 on: March 28, 2012, 06:12:57 AM »

One or more manky joints in your D-side metallic path seem to be a reasonable assumption.

Knowing how you like to plot (almost) everything against time,

 :lol: :lol:

Quote
I was hoping you would have the data to graph the Line Attenuation (dB) D1, D2 & D3 against time.

If you could show me graphs of Line Attenuation v time & SNR v time that both have anomalies present and co-incident with a telephone being used, then I would suggest that you show the same to Alex (of PlusNet).

Putting it another way, show me and, more, importantly PlusNet & Openreach a smoking gun:-\

Attenuation is the tricky one.
As you know, the HG612 shows zero for overall DS & US attenuation in its GUI & various other xdslxmd info --xxxxx data.
It does show it per band in pbParams, from which I haven't been collecting "Ongoing" every minute data for my graphs.

Maybe I should start collecting that ongoing data too. I was under the impression it was only updated at each re-sync. Hence only obtaining it as & when a "snapshot" graph felt appropriate.

SNRM now seems to have stabilised again since yesterday & doesn't alter when using the phone.

I wonder if the more than normal use of the phone while testing has created a temporary fix by sending pulses of power up/down the copper line?

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Bald_Eagle1

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #470 on: March 28, 2012, 12:03:27 PM »


I wonder if the more than normal use of the phone while testing has created a temporary fix by sending pulses of power up/down the copper line?


Well, if it was a temporary fix, it was very temporary.

The connection re-synced again at 08:30 this morning at only just over 21Mb sync speed.

Attenuation has increased again & now I only get anything at all from DS band D1:-

Code: [Select]
Max: Upstream rate = 6015 Kbps, Downstream rate = 29240 Kbps
Path: 0, Upstream rate = 6004 Kbps, Downstream rate = 21172 Kbps

Discovery Phase (Initial) Band Plan
US: (0,95) (868,1207) (1972,2783)
DS: (32,859) (1216,1963) (2792,3939)
Medley Phase (Final) Band Plan
US: (0,95) (868,1207)
DS: (32,859)
       VDSL Port Details       Upstream        Downstream
Attainable Net Data Rate:       6015 kbps         29240 kbps
Actual Aggregate Tx Power:        6.3 dBm          10.9 dBm
============================================================================
  VDSL Band Status        U0      U1      U2      U3      D1      D2      D3
  Line Attenuation(dB): 8.4 54.0 64.0   N/A 22.1 64.1 0.1
Signal Attenuation(dB): 10.7 53.3   N/A   N/A 22.1   N/A   N/A
        SNR Margin(dB): 6.0 6.1   N/A   N/A 10.3   N/A   N/A
         TX Power(dBm): -4.1 5.8   N/A   N/A 10.9   N/A   N/A

This MIGHT be good news as surely Plusnet/BT now have to accept that my connection has physical faults that need investigating & fixing.

After the re-sync, DS SNRM was around 10dB for a few minutes, then it dropped to 2.5dB & simply picking up the handset caused it to shoot back up to around 10dB.

« Last Edit: March 28, 2012, 12:06:05 PM by Bald_Eagle1 »
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smurfuk

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #471 on: March 28, 2012, 02:50:59 PM »

Pure hunch, but what's the betting an HR fault has been introduced on to the line by some dodgy workmanship previously undertaken by OR, probably close to your premises? I had a case where BT swore blind that couldn't be, spending ££s on everything else then discovering my line cable had been "nipped" in the course of earlier work (after 2 years worth of fault investigation). Nights are still cold with heavy dew. Perhaps they could do worse than check, but I bet they won't.
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Black Sheep

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #472 on: March 28, 2012, 04:10:16 PM »

Ahem .......... trapped (or nipped) wires, does not automatically infer "Dodgy workmanship", Smurf. Does the word 'Accidentally' register in your mind ??

I'm not going 'on one' here, just yet again if some unsuspecting soul reads this, they may make the assumption ALL OR work is dodgy. That is just not the case.

There's only one man that never made a mistake, and they put him on a cross.
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Bald_Eagle1

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #473 on: March 28, 2012, 05:50:06 PM »

@ Black Sheep,

In your experience, does attenuation generally tend to increase during warm, dry weather anyway?

I couldn't see my connection stats last summer, but that was when the problems started (21st July onward).

I didn't seem to do quite as badly during the wet & cold winter months (November until the very recent warm & dry spell).

Paul.
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Black Sheep

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #474 on: March 28, 2012, 06:51:44 PM »

@ Black Sheep,

In your experience, does attenuation generally tend to increase during warm, dry weather anyway?

I couldn't see my connection stats last summer, but that was when the problems started (21st July onward).

I didn't seem to do quite as badly during the wet & cold winter months (November until the very recent warm & dry spell).

Paul.

Again, I'll be honest and say I've not noticed BE. But then again, I wouldn't be looking in that respect anyway.

I have, (on average), just two hours to pick-up, note down, drive to, locate and fix,PQT and Eclipse, make a co-op call to ISP,test and demo to EU, and then fill the job notes in on my laptop. We just don't have the time to perform comparison tests on circuits, regarding their behaviour in differing climates.

When we pick-up the fault, if there has been a 'greater than 6dB' change to the attenuation from original readings, then we are made aware, other than that we just go about our usual business. I've never, ever had or heard of any attenuation issues being caused by heat, especially in this country.

I daresay that, like heat affects resistance readings, it will probably affect attenuation readings as well. To what degree (pardon the pun pal), I've no idea.  :)
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Bald_Eagle1

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #475 on: March 30, 2012, 02:23:52 PM »

Good news - Plusnet now appear to be arranging another engineer's visit as they confirm that SNRM shouldn't drop & cause re-syncs just by picking up a telephone handset.

Bad news - the ongoing but "intermittent" problem appears to have (temporarily?) subsided from 08:30 this morning.
Following yet another (uninitiated by me) re-sync in the early hours of this morning, my sync speed is currently 24999 k - SNRM 8.3dB, which looks suspiciously like DLM has capped it (probably due to all the disconnections over the last few days), needing another reset.

If only an engineer could have visited during this week - when the apparently intermittent problem may well have been a bit/lot easier to track down............................
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Blackeagle

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #476 on: April 02, 2012, 09:25:21 PM »

@ Black Sheep,

In your experience, does attenuation generally tend to increase during warm, dry weather anyway?

I couldn't see my connection stats last summer, but that was when the problems started (21st July onward).

I didn't seem to do quite as badly during the wet & cold winter months (November until the very recent warm & dry spell).

Paul.

Hi BE, BE here  :lol: :lol:

Being quite OCD with my (currently ADSL line but soon to be fibre !), I monitor my stats all the time.  I have to say, I have never seen my attenuation vary at all, but then given that loop loss is approx 13.5dB per Km of cable, the line would have to increase by 800 metres to increase the attenuation by 1dB.  Obviously, this ain't gonna happen !!

In spite of the higher frequencies in use by VDSL, I would hazard that the general principle is the same and that attn should not vary, or not by any significant amount anyway.  Therefore, I would lean towards the 'dodgy joint' scenario in your particular case.  Now, given that you say it is worse in warm weather, I would tend to think it is overhead rather than underground.  Underground I would have thought would have been more susceptible to water ingress during bad weather rather than affected by heat.  Heat would, to my mind anyway, expand a joint slightly and this could be enough to affect the attn.  I've seen this scenario often enough in the field I work in, where a bad solder joint can be perfectly conductive at 10c yet not at 25c.  A can of freezer spray can prove an invaluable tool !!

All this though is based on ADSL systems and observations of many lines.  It may or may not apply to VDSL.  When my line is finally VDSL'd (5th April), I may be able to help you further (assuming that I get the Huawei modem  ;))

Best wishes

Blackeagle
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Bald_Eagle1

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #477 on: April 03, 2012, 07:57:23 AM »

Hi BE,


When my line is finally VDSL'd (5th April), I may be able to help you further (assuming that I get the Huawei modem  ;))


Fingers crossed for you for 5th.

Hopefully, all will be revealed regarding my connection when the engineer visits.
Although not confirmed yet, I am hoping it will be this week & also hoping the issue hasn't disappeared by the time of the visit (the weather is cooler & is expected to get even colder/wetter during the week).

The changes in temperature may just be coincidence though as since being able to see my stats my connection has never been what I would describe as stable (especially when compared against other users' stats - even those with much longer lines than mine).

Cheers,

BE.
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JoshShep

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #478 on: April 03, 2012, 04:24:27 PM »

Hi Paul, sorry for the long delay, I don't really use the graphs because I was supplied with the ECI modem and that doesn't give me any stats, because as you know they can't be unlocked yet.

I have an Engineer coming tomorrow morning, this is the replay I got from my isp via email, "Wed AM slot has been booked for an FTTC1 engineer.
The Service Test failed due to mean time between errors which may indicate just a noise issue to the engineer so I have put notes on job to advise intermittent sync and drops in throughput are being experienced".

Can you or Black Sheep recommend me to request the Engineer to do or run any specific tests? Maybe if I get my connection sorted, It could also help you if they did the same at your end.

Hope it gets fixed for both of us mate,

All the best,

Josh. 

Black Sheep

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Re: FTTC - Distance from the Cabinet - Realistic speed estimate
« Reply #479 on: April 03, 2012, 05:00:16 PM »

Hi Josh. Mean Time Between Errors (MTBE), is basically illustrating that there is a problem somewhere. Be that with the Exchange equipment, OR's plant or your own equipment, I can't say.

I would request the engineer plug his EXFO/JDSU into the circuit and monitor the error-count. I would ask him to ring the landline number at the same time as monitoring. Also request theyperform a 'Quiet Line test', again, at the same time as monitoring for error-count.

You may get an experienced engineer who has the ability to locate a fault without asking ??
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