Kitz Forum

Broadband Related => Broadband Technology => Topic started by: canon on August 28, 2008, 10:30:40 AM

Title: Line length from exchange
Post by: canon on August 28, 2008, 10:30:40 AM
Can someone please tell me the latest information to use the BT 17070 number to get your line length. When I dialled it today, the options are different from when I used it a year or so ago.
Thanks,
terry.
Title: Re: Line length from exchange
Post by: roseway on August 28, 2008, 11:06:28 AM
I don't think you can get that information now.
Title: Re: Line length from exchange
Post by: canon on August 28, 2008, 11:37:39 AM
That's what I suspected when Listened to the new options  :(
However, I can use the utility on this site  :)
Terry.
Title: Re: Line length from exchange
Post by: roseway on August 28, 2008, 11:42:05 AM
None of the line checkers available to the public (including Kitz' one) give actual line length, only geographical distances.
Title: Re: Line length from exchange
Post by: Ezzer on August 28, 2008, 12:08:56 PM
Within openreach we can only get line lenght either by doing some thing called a RATS test which isn't avalable outside bt or by physicaly measuring it with a mole/hawk.

The 17070  :-X tool is strictly speaking a for use by bt only. (it can get annoying when working on a line and you can't get on the thing because it's too busy) a lot of the options will only work in conjunction with a bt engineers company supplied mobile.

The other thing about line lenght is it's relative to the type of cable which your fed from.
Title: Re: Line length from exchange
Post by: lodge on September 08, 2008, 07:39:05 AM
You can get the line distance information here:

http://www.dslzoneuk.net/distance.php
Title: Re: Line length from exchange
Post by: roseway on September 08, 2008, 07:47:13 AM
Like all the other checkers, that one just gives geographical distances, not the actual line length.
Title: Re: Line length from exchange
Post by: IDH on September 08, 2008, 03:17:51 PM
Gives me as being 383.23kms from my exchange which is the middle of the Irish Sea  ??? :no:
Title: Re: Line length from exchange
Post by: canon on September 08, 2008, 08:05:22 PM
Re.
Quote
You can get the line distance information here:
http://www.dslzoneuk.net/distance.php
It is as the crow flies so not very helpful.
By using Google maps and "directions" from -to it's possible to simulate various routes - you can drag the route to wherever you like on the map.
Taking the most obvious cable route, that gave me a distance very close to what I recall from dialling 17070, when it was allowed.
To get the distance that is apparently on the BT database (according to BeThere), the route would have to be very, very circuitous. From my current stats and this information, I can only assume the BT database is wrong.
Terry.
Title: Re: Line length from exchange
Post by: kitz on September 12, 2008, 01:33:35 PM
Quote from: lodge on September 08, 2008, 07:39:05 AM
You can get the line distance information here:

http://www.dslzoneuk.net/distance.php

As eric says - thats just "as the crow flies" and is highly unlikely to be any real indication of the true line distance.


This sites checker (http://www.kitz.co.uk/adsl/adslchecker.php) displays both as the crow flies and road distance.
Since most BT wiring, green cabs, and telegraph poles tend mostly to go along side the road, then that of the 2 is likely to be the nearest.  However, it cant ever take into account that some cabling may take the long way round.

You could also look at the maximum speed checker (http://www.kitz.co.uk/adsl/max_speed_calc.php), which attempts to calculate your line length based on loop loss from your routers attenuation figure.  However this is best guess based on the average UK looploss and doesnt account for the fact that BT may use thicker gauge cable on some lines or that their may be some aluminium on the line etc etc.

Everything is intended to be a guide based on best information available and the true figures can only be obtained by BT as Ezzer says :/
Title: Re: Line length from exchange
Post by: Maturecheese on October 05, 2008, 01:48:29 PM
"The other thing about line length is it's relative to the type of cable which your fed from."



Ezzer do you mean it could be  Aluminium or Copper?
Title: Re: Line length from exchange
Post by: orainsear on October 14, 2008, 08:40:59 AM
Like for like, Aluminium will be about 50% more resistive than the same diameter of copper conductor, and will attenuate the signal more.

Increasing the diameter of cable of either material should result in less attenuation, as will using a solid core rather than strands.
Title: Re: Line length from exchange
Post by: Kiro on October 16, 2008, 05:39:32 PM
Also don't forget BT's dirty little secret, lead in the lines ;) Anyway, as previous posters have said the only way to get a reasonable accurate line length is from a RAT test. Also your ISP may be lucky and have a copper line test on BTWS.com. Incidentally BTWS' new KBD tool will perform a copper line test as part of its diagnostics. That said they're basing the line length on resistance. Different cable types will affect it, as will a stretched wire or a dodgy joint.
Title: Re: Line length from exchange
Post by: tallp on May 18, 2009, 03:27:43 PM
A quick question on this subject:  :o

The physical lines carry signal up and down as in a network cable style or port [house] by port in a token ring fashion.

I have just have an ISP tell me that even though I am 600m as the crow flies and 850m via road from the closest exchange that my line length is; wait for it, 5780m away from the exchange.

For that to be the case, they will have to travel all the way into the city and then back out again and still have distance to spare!

I am stuck between BT and the ISP. ARGH>>>

btw, thanks for the fab info and link on the forum already. checked them all out but am still stuck, hence the question.

Look forward to a speedy reply to get this sorted before I lose cable internet!

cheers

Paul
Title: Re: Line length from exchange
Post by: roseway on May 18, 2009, 04:08:11 PM
It's not unknown for the line to take a very roundabout route, so what the ISP has told you isn't impossible. But it's only a figure in a database, and even if it's wrong it doesn't affect actual performance. I think that the only way to be (fairly) certain is to subscribe to a BT-based ADSL service and get the connection stats from the router.

If I understand you correctly, you're currently with a cable provider and you want to change to a BT-based service. Depending on the ISP you *may* be able to get the line length checked some other way, but you would probably need to go with one of the more expensive, more professional ISPs such as Zen.
Title: Re: Line length from exchange
Post by: tallp on May 18, 2009, 04:24:39 PM
Quote from: roseway on May 18, 2009, 04:08:11 PM
It's not unknown for the line to take a very roundabout route, so what the ISP has told you isn't impossible. But it's only a figure in a database, and even if it's wrong it doesn't affect actual performance. I think that the only way to be (fairly) certain is to subscribe to a BT-based ADSL service and get the connection stats from the router.

If I understand you correctly, you're currently with a cable provider and you want to change to a BT-based service. Depending on the ISP you *may* be able to get the line length checked some other way, but you would probably need to go with one of the more expensive, more professional ISPs such as Zen.


I can understand a roundabout route, but that would cover half of Bristol! I cant really afford an expensive line investigation to be told that some "muppet" has entered the wrong figure in the database. BT stated that I was only 600m from the exchange but more importantly I think that I should get upto 6Mb download speed. the ISP are stating that they will not even connect me with that [5780m] distance as it is outside of their service deliverables.

I dont know who to believe; chance it and go with the ISP and be stuck with no service or crawl back to my Cable company?

oh the uninformed decision we have to make!

Thanks for your speedy response btw.

Cheers

Paul   :)
Title: Re: Line length from exchange
Post by: orainsear on May 18, 2009, 04:51:27 PM
That seems an awfully long line length in comparison to your geographical distance from the exchange.  Do you have any neighbours who use ADSL that you could possibly speak to?

Which ISP was it that you spoke to?  Have you tried any others?

Title: Re: Line length from exchange
Post by: tuftedduck on May 18, 2009, 04:51:40 PM
Paul, go to the Kitz adsl checker page at  http://www.kitz.co.uk/adsl/adslchecker.php , enter your phone number and postcode in the appropriate boxes and you will get all sorts of info including your actual line length.

If nothing else it will give you a reliable figure on which to base any further debates with BT/ISP

 :)
Title: Re: Line length from exchange
Post by: roseway on May 18, 2009, 04:59:56 PM
Quote
you will get all sorts of info including your actual line length.

No, sorry TD, but the Kitz checker, like all other publicly accessible checkers, only provides geographical distances, not actual line lengths.
Title: Re: Line length from exchange
Post by: tuftedduck on May 18, 2009, 05:06:16 PM
 :-[
Title: Re: Line length from exchange
Post by: HPsauce on May 18, 2009, 05:22:39 PM
I thought it accessed the BT database.
Title: Re: Line length from exchange
Post by: orainsear on May 18, 2009, 05:39:13 PM
It uses the Samknows database API.

Edited: Oops my bad!
Title: Re: Line length from exchange
Post by: kitz on May 18, 2009, 07:48:58 PM
The approx line length is based on geographic figures on the assumption that most of BT's cabling tends to follow main roads.. I use google maps and a rather complicated algorithm (http://www.ngs.noaa.gov/PUBS_LIB/inverse.pdf) to get the figures.
Another slightly better indication is if you have any line stats and taking the figure from your attenuation.

The estimated speed is taken from the BTw database, and will likely be the same results as all other ISPs/checkers.

One thing that does occur.. you mention coming over from cable..  in which case is this a brand new telephone line?

If so then its likely that the figures are based on the location of whom ever had that phone no before you.
It can take a while before the BTw database update..
Some ISPs are more understanding than others if you mention that it is a brand new phone line, and highly likely that the BTw database hasnt yet been updated.
Title: Re: Line length from exchange
Post by: waltergmw on May 18, 2009, 08:52:57 PM
If you have a modem compatible with DMT tools there is sometimes an electical line length estimate on the right hand side written in grey in the third panel down before you start the noise monitoring. The picture below is from a netgear DG834V4 (Broadcom chip set).
I do not know how accurate it is but this value was similar to the figures provided by Zen on this line.

If you happen to live in Surrey the SCC provide quite a good interactive map at:-

http://www.surreycc.gov.uk/sccwebsite/sccwspages.nsf/LookupWebPagesByTITLE_RTF/Surrey+Interactive+Map#

and then click on the green writing. The suite contains a road distance measuring tool but again this will only be an estimate as it's almost impossible to know the exact cable route.

Kind regards,
Walter

[attachment deleted by admin]
Title: Re: Line length from exchange
Post by: kitz on May 18, 2009, 11:01:47 PM
>> line length estimate on the right hand side written in grey in the third panel.
>> I do not know how accurate it is but this value was similar to the figures provided by Zen on this line.

It's a broad estimate based on the attenuation (loop loss).

My maximum speed calculator (http://www.kitz.co.uk/adsl/max_speed_calc.php) tool based on Consultels (http://www.consultel.com.au/) survey for adsl loop loss, a graph of which can be seen here (http://www.internode.on.net/media/images/internode-adsl2-dist07.jpg).  It involved much plotting of figures and adjustments for UK gague cable and provides an estimations for line length v attenuation.  Obviously it cant allow for such things as aluminium joints etc, but it is generally recognised as being one of the most accurate without physically being able measure it from the EU premises. 
Leo may confirm for sure,  but I think Zen (and a few other ISPs) use it if they cant get a  BT measure.

>> The suite contains a road distance measuring tool

Nice tool :) Notice its done by the Ordnance Survey who also approve and use the  Vincenty inverse formula for geodistic calculations. 
Quick note..  from what I saw it uses straight line between 2 points which is the calculation often provided by most sites.
Driving distance as per the road and curvatures is a bit more complicated..(hence the combo of the google maps and the inverse Vinventy formula which was a PITA to code) and afaik this site was the first and only (aside from one that copied my code) adsl site that does so.
Big thanks and credit must be given to Sam though, cause I pull on his data for the exchange info and location.
Title: Re: Line length from exchange
Post by: waltergmw on May 19, 2009, 06:53:12 AM
@ Kitx

>>>>>> from what I saw it uses straight line between 2 points ............

That is correct but if you have the patience (you'll certainly need it for accurate measurements !) and zoom in to a reasonable resolution on a large screen you can join as many straight lines as you like.

Kind regards,
Walter
Title: Re: Line length from exchange
Post by: Azzaka on July 27, 2009, 12:38:38 PM
What is the ISP Paul.

At the end of the day I have provided a line where no other ISP would and fought to keep it. As they have all stated thus far, the line distance is an estimate and the BTW database does take awhile to get updated.


Any more modem info, stats wise, would certainly help us help you.

Kindest Regards,

Leo
Title: Re: Line length from exchange
Post by: asbokid on September 27, 2011, 12:27:47 PM
Quote from: waltergmw on May 18, 2009, 08:52:57 PM
If you have a modem compatible with DMT tools there is sometimes an electrical line length estimate on the right hand side written in grey in the third panel down before you start the noise monitoring. The picture below is from a Netgear DG834V4 (Broadcom chip set).

I do not know how accurate it is but this value was similar to the figures provided by Zen on this line.

Hi... I managed to get DMT-UX, the DMT port for Unix [1] working with the Huawei HG612, the OpenReach VDSL2 modem. Once it's more stable, I will upload the patches to some webspace.

The source code for the function that calculates line length is replicated below. It doesn't look very complicated.

dsl_chancharlog.data is the Hlog value for each tone, as parsed from the output of xdslcmd info --Hlog.

But what does the Hlog metric actually capture? And why does the function pluck out tone number 231? What's special about that tone?

Code: [Select]
char* linelength() {
int tone231;
int linelength_min;
int linelength_max;

char* text;
tone231=(int)dsl_chancharlog.data[231];
if (tone231>0) {
//search minimum chancharlog value
unsigned int i;
int chancharlogmin;
chancharlogmin=100000;
for (i=DROP_TONES; i < dsl_chancharlog.last; i++) {
if ((int)dsl_chancharlog.data[i]>0) {
if ((int)dsl_chancharlog.data[i]<chancharlogmin) {
chancharlogmin=(int)dsl_chancharlog.data[i];
}
}
}
//(MD_CHANCHARLOG_TABLE[232]*1000)/20.5 *((low_Misc_Value - 50)+100)/100)
linelength_min= (int)(tone231 * 10/20.5 * (chancharlogmin + 50));
//(MD_CHANCHARLOG_TABLE[232]*1000)/13.4)
linelength_max= (int)(tone231 * 1000/13.4);

char* text;
text=dmalloc(sizeof(char)*(8 + log(linelength_min) + log(linelength_max)));
sprintf(text, "%im - %im",(int)linelength_min,(int)linelength_max);
return text;
} else {
text=dmalloc(sizeof(char)*(26));
sprintf(text, "couldn't estimate line length");
return text;
}
}
The function returns a line length of 239m - 428m for our line which sounds about right.

It would be good to port this version of the DMT tool (back) to Windows, if anyone fancies a challenge?

Naturally, it would remain Open Source for others' benefit.  I would anticipate building it under minGW [2].
In Windows, the major hurdle would probably be the RRDtool data logging and graphing library used in DMT-UX.[3]

Are there any interested parties up for doing that?

Cheers, a

[1] http://www.spida.net/projects/software/dmt-ux/index.en.html
[2] http://www.mingw.org/
[3] http://oss.oetiker.ch/rrdtool/index.en.html
Title: Re: Line length from exchange
Post by: trantore on October 03, 2011, 10:43:44 PM
Quote from: asbokid on September 27, 2011, 12:27:47 PM
Hi... I managed to get DMT-UX, the DMT port for Unix [1] working with the Huawei HG612, the OpenReach VDSL2 modem. Once it's more stable, I will upload the patches to some webspace.
Hi Asbokid,

I'm also interested in refactoring the DMT-UX tool!

My suggestion is port all the code to the Qt framework, to make it platform-independent. This simplifies the interface, the socket control and other aspects of the program. Additionally simplifies the compile environment. Also, to make more simple the port to Windows, you don't need to exclude the RRDtool library, you can link to some of the two native versions:

http://www.gknw.net/mirror/rrdtool/
http://oss.oetiker.ch/rrdtool/pub/?M=D

My interest is for support more modem/routers... because the original DMT tool is close-sourced, and also the good OrbMT. So, I prefer to focus on add support to other devices.

What you think about it? When you publish the patched DMT-UX version?
Regards.

Title: Re: Line length from exchange
Post by: Bald_Eagle1 on October 04, 2011, 08:02:30 PM
@ kitz,

Hi Kitz,

We have not spoken before, & I don't wish to hijack someone else's thread, so just a very quick query:-

Do you have any current proposals to introduce a similar checker for FTTC connections?

We all seem to be struggling to understand what SHOULD be achievable for given line lengths etc.

Paul.
Title: Re: Line length from exchange
Post by: asbokid on October 05, 2011, 07:00:11 PM
Quote from: trantore on October 03, 2011, 10:43:44 PM
Hi Asbokid,

I'm also interested in refactoring the DMT-UX tool!

My suggestion is port all the code to the Qt framework, to make it platform-independent. This simplifies the interface, the socket control and other aspects of the program. Additionally simplifies the compile environment. Also, to make more simple the port to Windows, you don't need to exclude the RRDtool library, you can link to some of the two native versions:

http://www.gknw.net/mirror/rrdtool/
http://oss.oetiker.ch/rrdtool/pub/?M=D

My interest is for support more modem/routers... because the original DMT tool is close-sourced, and also the good OrbMT. So, I prefer to focus on add support to other devices.

What you think about it? When you publish the patched DMT-UX version?
Regards.

Hi trantore,

You have some very good plans  :)

A basic GUI client for DMT-UX has been built using GTK+ (see below), but I wouldn't know where to start with QT.  It sounds like QT has its own functions for network socket programming? Yikes!

The scraping and parsing code used by all of these tools could do with throwing on the fire. There are much cleaner ways of obtaining the data..

The 63xx xDSL device driver can be queried directly using ioctl() system calls. The driver responds by returning the data in a well-defined structure of xDSL MIB data objects. Those objects are defined according to RFC2662.  This method of obtaining line characteristics data avoids all that string chomping used by existing tools.

However, that better method of data retrieval comes at a price.  It requires a MIPS32 binary to be available on the modem to execute the ioctl() calls.  Where possible, the binary could be uploaded to the modem via tftpd/ftp/sftpd.  If the modem isn't running a file server then the 'telnet upload trick' could be used instead.  Ideally, though, the code to retrieve the line data from the xDSL driver would be built into new firmware.

What modems do you plan to get DMT-UX working with? And what xDSL chipsets do those modems use?

I will soon post the source code very soon. A new parser was built for the Huawei HG612 (pretty much the only VDSL2 modem used in Britain). But otherwise, I hardly changed DMT-UX at all.. Just a few tweaks for the larger tone maps and extra bands used by VDSL2.  And the magnitudes of some elements of the VDSL2 channel data were too big to be stored in a char, so the signs of the readings were being reversed as they 'rolled round'.

Cheers,
A

(http://huaweihg612hacking.files.wordpress.com/2011/10/vdmtscreenshot1.png)