In reply to a post by adslmax:

Plusnet GEA test say my line length are 243.6m.

Do you have an exchange nearby? Could that be the distance to the exchange rather than the cabinet?

You must be joking? My property to the nearer telephone exchange in High Street, Madeley - Cuckoo Oak Exchange is approx 1 mile away (1,609m away)

Actually it is my mistake, I wasn't paying enough attention. https://www.geekzone.co.nz/forums.asp?forumid=49&top...
This is from New Zealand, so the comparison won't be relevant.

You can test your line length by locating your cabinet on google maps and then selecting your property after that click on the walk button then press details.

So for example my Bishopsgate cabinet 20 is located in 46 Frostic Walk, Shadwell, London E1 5LT and to my home which is around 0.2 miles. But actually I did some other measurements by measuring it straight to one other restaurant bar next to my building which adds to 197 meters. And from there to rest of my residential block is another 53 and add some more meters up to my flat.

I don't want to give my full details here of my property, for privacy and security. But this is how I measured my line length. 196.8 meters from cabinet to the restaurant direct straight line route+53 meters to entrance of my block+approximately another 40 or so meters up my building.
196.8+53+40=289.8 meters. Now my measurement is probably not 100% accurate. Direct route on google maps from cabinet shows as 0.2 miles roughly 321 meters.

If these measurements are true then my line length is between 290-321 meters to cabinet.

But it all depends whether the blue dotted lines actually follows the straightest direct path. If the line is artificially extended then this can add up several more meters of copper which I will assume will be the case. There will be further cabling inside the building which will definitely extend it to a greater than 290 meter length, maybe another 10 meters and a few more meters if we add the line to our master telephone socket. Depending on what floor of the building you live on.

If you live in a house or low rise building then the measurement via google maps will be more accurate as you won't have to do further calculations of internal copper wiring. When I spoke to one of the BT Openreach engineers who came to my flat to install the VDSL Faceplate he showed his device and said 70Mbps to 83Mbps is what his device reading is showing for my flat. He said 500 meters to cab, but I said google maps is showing 321 meters, he said "maybe you are right". So I take it that, it's not going to be 500 meters as that's way too long and I wouldn't be syncing at 80Mbps with that kind of line length that would be impossible.

My google map say distance walking from my property to the fibre cabinet 486 ft (3 minutes walk) around 148m away (add another 100m because of cable route from the back to the cabinet) where two next doors is at the front cable route to the cabinet so they getting less than 150m for full 330/50 on G.fast while next doors on mine get another 100m addition to the cabinet to get G.fast 220-230/30-35. So, the GEA test are much spot on for 243m away.

Edited by adslmax (Fri 24-Apr-20 20:14:58)

Then this measurement is more or a less accurate.

The fact that you are getting the top sync speeds last 6 years suggests that your cabinet should be less than 250 meters. You also have 6.5dB SNR which shows there is very little crosstalk.

Generally 3dB SNR is for people who either have very long copper length or crosstalk where speeds are being overstretched to their limits.

You don't appear to be suffering from neither crosstalk or a very long line.

My google map shows around 4 minutes walk to cabinet. My cabinet only went live 6 months ago. But I have FTTC only last 2 months. Previously I had EO Line and my Exchange is 1300 meters. But as we all know BT Exchange length is irrelevant when it comes to FTTC as Fibre travels from exchange to cabinet.

I'm not too concerned about the accuracy of the line length, as long as we are getting a solid and reliable connection that is all that matters.

Yeah, I am not too fussy as I am happy with 80/20 for time being. Not bother with G.fast. Need a lower budget FTTC for now. paying monthly £16.25 for 80/20 fibre with line only. Can't complaint.

Edited by adslmax (Fri 24-Apr-20 22:55:57)

In reply to a post by BLaZiNgSPEED:

Then this measurement is more or a less accurate.

The fact that you are getting the top sync speeds last 6 years suggests that your cabinet should be less than 250 meters. You also have 6.5dB SNR which shows there is very little crosstalk.

How does it suggest that? That's absolute nonsense I'm sorry.
Where did you pick the arbitrary 250m figure from?

6.5dB doesn't suggest anything about crosstalk, at all.
I have a line length of just over 1km and with over 600 active connections on my cabinet.
It's a safe bet my line suffers from crosstalk.
It connects at 6.3dB.
That simply means it's connecting as high as it can with no spare SNRM.

HAVING A 6dB SNRM simply means the line is connecting near the target SNRM, which means it's near the maximum the line can handle with a 6dB target.

Generally 3dB SNR is for people who either have very long copper length or crosstalk where speeds are being overstretched to their limits.

No it's not.
3, 4 and 5dB is for any line that doesn't achieve full sync with a 6dB SNRM.
It's nothing to do with line length as such.

You can have a 300m line that gets 80Mb sync and you can get a 300m line that gets 60Mb.
Crosstalk is extremely variable and no 2 lines of the same length will perform the same.

Different modems report attenuation in different ways. You can't just read an attenuation and pick a distance to the cabinet from that.
My attenuation has varied between 19dB and 22dB over the years using various different modems.

You throw far too many generalisations about.
You compare FTTC to ADSL too often. Forget about ADSL.

Your Google maps line length calculation doesn't work either.
Type line is longer than 290-320m, quite a bit longer.
The attenuation suggests nearly double that length.

Your assuming your line goes the shortest route, most lines don't.
It may go the other direction around the block, it may go 50m past your property and back down the other side of the street.
There are many quirks and oddities in how the OpenReach network is laid out.
The engineer who visited your property to activate FTTC didn't read his line length figure from some random sheet of paper.
He connected specialised telecoms equipment that cost a pretty penny. They are very accurate.
If he said 500m then it will be around that.

So, it likely my 243m are spot on anyway. Like Openreach engineer did stated my line are 250m away.

Thank you John, well said.

I'll have you know my Google Map to my cabinet was spot on.

However, as a result of the campaign we did in 2012, I did have the full wiring map for the entire estate so knew the exact route it took.

A Google Maps check via the most direct route would've put the line at 150m. It was actually 460m+ due to the most direct route being undeveloped land at the time the line was put in place.