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Standard User R0NSKI
(experienced) Sat 15-Dec-12 14:12:04
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Re: Affect of distance on fibre line


[re: timl] [link to this post]
 
I wouldn't make any judgements on the ECI v HG612 just yet, I'm not quite sure what happened when I tried, but with Christmas coming up and some time off work (although less than I thought and I may have to help my brother move house) I will try again and see what happens next time round.

Standard User RobertoS
(sensei) Sat 15-Dec-12 16:41:17
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Re: Affect of distance on fibre line


[re: Chrysalis] [link to this post]
 
In reply to a post by Chrysalis:
Talktalk stated on their forum to a customer their own DLM requires an error rate of 300 per hour for at least 3 consecutive hours then will kick in, so thats a ballpoint although from another isp.
If that's regarding their LLU ADSL2+, fair enough. If it's regarding their Fibre offerings it's twaddle.

My broadband basic info/help site - www.robertos.me.uk | Domains,website and mail hosting - Tsohost.
Connection - Plusnet Extra Fibre (FTTC). Sync ~ 54.0/14.9Mbps @ 600m. - BQM

"Where talent is a dwarf, self-esteem is a giant." - Jean-Antoine Petit-Senn.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Allergy information: This post was manufactured in an environment where nuts are present. It may include traces of understatement, litotes and humour.
Standard User Chrysalis
(eat-sleep-adslguide) Sat 15-Dec-12 18:01:49
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Re: Affect of distance on fibre line


[re: RobertoS] [link to this post]
 
its regarding their own adsl LLU of course.

What we dont know is even tho isp's have no control over the openreach cabinet equipment it may be possible that technical staff at isp's have been informed on the DLM algorithms so would also possibly know when DLM kicks on that as well.

Edited by Chrysalis (Sat 15-Dec-12 18:03:21)


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Standard User Andrue
(knowledge is power) Sat 15-Dec-12 22:21:01
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Re: Affect of distance on fibre line


[re: WWWombat] [link to this post]
 
Actually you can't trust Google Maps for measurement. I happened to keep an eye on my car's display today coming back from the golf range and the distance is slightly more than 0.2 of a mile or 300 metres. And I'm obviously right at the limit of 80Mb/s down although the modem thinks I could have 30 up.

Still - that's better than the 65Mb/s that TBB page suggests.

---
Andrue Cope
Brackley, UK

Just because he could. RIP.

Edited by Andrue (Sat 15-Dec-12 22:22:13)

Moderator billford
(moderator) Sat 15-Dec-12 22:26:20
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Re: Affect of distance on fibre line


[re: Andrue] [link to this post]
 
In reply to a post by Andrue:
Actually you can't trust Google Maps for measurement. I happened to keep an eye on my car's display today coming back from the golf range and the distance is slightly more than 0.2 of a mile or 300 metres.
I think I'd place considerably more trust in Google maps than an odometer in any car...

Bill
[email protected] __________________Planes and Boats and ... __________________BQMs: IPv4 IPv6
The author of the above post is a thinkbroadband moderator but it does not constitute an official statement on behalf of thinkbroadband.
Administrator MrSaffron
(staff) Sat 15-Dec-12 22:28:14
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Re: Affect of distance on fibre line


[re: Chrysalis] [link to this post]
 
You mean they have read SINET like anyone can?

Andrew Ferguson, [email protected]
www.thinkbroadband.com - formerly known as ADSLguide.org.uk
The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Standard User WWWombat
(experienced) Sat 15-Dec-12 22:30:01
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Re: Affect of distance on fibre line


[re: Chrysalis] [link to this post]
 
In reply to a post by Chrysalis:
My attianable rate was 110mbit when I first checked, no idea if it was ever even higher, BT estimated me at 65mbit and my cabinet to socket distance is 200m. Documents I have read on crosstalk consider that with 20 lines active in a bundle on vdsl2 a average loss of sync speed is estimated at 40% so quite significant, 50% of 110mbit is 55mbit, so my 65mbit estimate I guess isnt too far of a 40% loss and I think thats what BT base their estimates on.

Reports from people like Qas who have shorter lines than me but lower attainable speeds the probable reasons are they have more crosstalk, vectoring apparently will get rid of this unpredictability as will get rid of most of interference aka crosstalk.


The graph that I think comes best to showing the effect of crosstalk on UK lines can be found in a Broadband Forum document on Vectoring - See figure 6 on page 12. It covers profile 17a, but is for 26 AWG cable (0.4mm) while BT seems to use 0.5mm, which ought to give better speeds for the same distance (but no idea of the impact on crosstalk).

Ignoring vectoring, the blue crosses show the range of speeds seen at the same distance, and demonstrates how it varies. I imagine that BT's estimator responds with numbers that match either the lowest cross, or the (even lower) inverted triangle.

But seeing the graph leaves me dreaming of the day that vectoring comes in...

I also read in a few places Huawei are quite advanced on vectoring tech but ECI not as much, so I wonder if this will lead to a staggered rollout of the tech or will BT wait for both vendors to be ready, alcatel already rolling it out,

I've seen it suggested that BT's ECI equipment is limited to perform vectoring within the linecard (ie within one card on the shelf of the cabinet), and that new shelves are needed to allow vectoring to work across all lines on all 4 cards.

Perhaps new cabinets, such as the BDUK ones, will come with the upgrade.

No idea about Huawei though.

With this I think lines at 400m will get 80mbit sync (as they can do now with no crosstalk). I hope tho if vectoring is used speeds stay at 80 so people can enjoy healthy snr margins with DLM leaving them alone rather thn pushing for a slightly higher speed product of 100mbit and then have lines fighting with DLM again.

From that graph, it looks like 120Mbps at 400 metres ... but I know what you mean.

I suspect that BT's research guys are playing with this (and DLM) over in Suffolk, working out what is going to work best in reality, rather than theory.
Administrator MrSaffron
(staff) Sat 15-Dec-12 22:42:04
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Re: Affect of distance on fibre line


[re: WWWombat] [link to this post]
 
Vectoring usually also limits the competition to only one firm controlling the FTTC - and sub loop unbundling is something Ofcom fought for so a few years away

Andrew Ferguson, [email protected]
www.thinkbroadband.com - formerly known as ADSLguide.org.uk
The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Standard User WWWombat
(experienced) Sat 15-Dec-12 22:49:06
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Re: Affect of distance on fibre line


[re: Andrue] [link to this post]
 
In reply to a post by Andrue:
Actually you can't trust Google Maps

LOL. Good point...

For completeness, Google say 400m, Bing says 400m, Streetmap says 500m, and Ordnance Survey says 400m.
Standard User jchamier
(knowledge is power) Sat 15-Dec-12 22:54:03
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Re: Affect of distance on fibre line


[re: Andrue] [link to this post]
 
In reply to a post by Andrue:
Still - that's better than the 65Mb/s that TBB page suggests.


I'm at 450m from PCP and my sync is 48945kbps / 10497kbps - but the attainable is 56576kbps / 9551kbps. My estimate was only 44meg/6meg - so I'm slightly above, so happy, but keeping fingers crossed I don't get too many neighbours switching from VM.

I'm expecting "FTTP on demand" to be unaffordable (£1500 to £3000) or completely unavailable due to living in a flat. I'd probably be tempted if it was under £1000.

James BT Infinity 2 19/09/2012 - Estimate 44.6/6.5 - Install 52/12 - Actual 46 / 8 Mbps
13 years of broadband - 1999 ntl:(512k/1M)/BTbusiness(2M)/Metronet(2M)/Bulldog(8M/16M)/BE(19M/16M)/BT FTTC(46M)
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