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SNR still high

XenoGuy
Grafter
Posts: 77
Registered: 27-02-2014

SNR still high

I know I asked the same question months ago, but seeing as I won't be getting fibre (ever), I would like to see if I can sort my line out, see why the SNR is a ~12.....
Note:
1. Socket are the old type, so no test socket;
2. I know my wiring is atrocious - for a 29.5 line attenuation, I should be getting ~15mbits;
3. Tried 3 different filters over 5 months - no change;
Ironically, I had a disconnection after ~29 days of uptime!
Quote
Uptime: 0 days, 1:51:44
DSL Type: ITU-T G.992.5
Bandwidth (Up/Down) [kbps/kbps]: 888 / 9,525
Data Transferred (Sent/Received) [GB/GB]: 9.69 / 160.96
Output Power (Up/Down) [dBm]: 11.9 / 0.0
Line Attenuation (Up/Down) [dB]: 14.7 / 29.5
SN Margin (Up/Down) [dB]: 13.3 / 12.1
System Vendor ID (Local/Remote): TMMB / ----
Chipset Vendor ID (Local/Remote): BDCM / IFTN
Loss of Framing (Local/Remote): 9 / 0
Loss of Signal (Local/Remote): 1 / 0
Loss of Power (Local/Remote): 0 / 0
Loss of Link (Remote): -
Error Seconds (Local/Remote): 1,911 / 0
FEC Errors (Up/Down): 618 / 2,111
CRC Errors (Up/Down): 0 / 6
HEC Errors (Up/Down): 0 / 37

It appears that the exchange has set my snr profile to 12 for some reason, would like to find out why.
27 REPLIES
XenoGuy
Grafter
Posts: 77
Registered: 27-02-2014

Re: SNR still high

To follow up, I will be getting someone (ex-BT engineer) to fit 2 x NTE5 replacements and Mark 3 VDSL plate plus wiring check, and maybe move my master socket to my used socket (if it is not a master already)......
Hopefully this will rule out any internal wiring, so I can badger PN/BT if this doesn't improve my line....
I will follow up when it's completed.
Superuser
Superuser
Posts: 11,935
Thanks: 3,301
Fixes: 22
Registered: 22-08-2007

Re: SNR still high

The exchange will have set the SNRM as high as it is to manage errors on the line.  Look at the local error count - that's a lot for a couple of hours  of connection time.
You seem to suspect that the internal wiring might be unhelpful.  That's a good place to start.  Ideally the router should be plugged into the master socket which ought to be where the BT line enters the property, as that is the service boundary point.  From there all extensions should be on twisted pair cable, using only two conductors (no bell wire required) going from one socket to the next, such that no socket has more than two cables connected.  (No 'star' or branch junctions.)
You might find things neater if you invest in a multi hand set DECT phone system.  That can be plugged into the master socket and you can place handsets where you need them without the need to run any phone extensions.  Then (personally) if you really do need Ethernet connections elsewhere, I'd run cat 5 cables from the master socket (in place of phone extensions) or use good quality Ethernet over power adapters which will not interfere with your ADSL seervice.  I've used Devolo adapter tens without issues, note that some people have reported interference problems with some cheaper brands.
Community Veteran
Posts: 5,111
Thanks: 465
Fixes: 17
Registered: 10-06-2010

Re: SNR still high

I don't think that's a lot of errors for a couple of hours, FEC hardly matters. The Error Seconds count doesn't get reset at the start of each DSL uptime. There were a lot of errors in XenoGuy's previous thread however. On that thread, the photo of the inside of the old master socket probably shows what the problem is - the probably not twisted pair cable to that master socket, and it doesn't seem to show where the other socket is connected. Perhaps they are both master type sockets, or the other socket is star wired to the line.
You don't want two NTE5 master sockets on the same line, there should be only one master socket, any other sockets should be extension sockets. Apparently you can convert an old master socket into an extension type socket by removing the capacitor, resistor and surge protector (the components labelled C1, R1 and SP1).
XenoGuy
Grafter
Posts: 77
Registered: 27-02-2014

Re: SNR still high

Quote from: Townman
The exchange will have set the SNRM as high as it is to manage errors on the line.  Look at the local error count - that's a lot for a couple of hours  of connection time.

I had a drop, so the errors do not reset when re-syncing.... Those errors were for ~29 days.
Superuser
Superuser
Posts: 11,935
Thanks: 3,301
Fixes: 22
Registered: 22-08-2007

Re: SNR still high

@ejs - Thank you for the link to the previous thread - I'd forgotten about all of the analysis we did back then.
@Peter - where did all of that lead to?  What happened after 3rd Oct last year - the last (unanswered) post on that thread?
@Mods - is there merit in merging these threads so that we have a clearer history of Peter's issue?
XenoGuy
Grafter
Posts: 77
Registered: 27-02-2014

Re: SNR still high

I actually gave up, but now I know fibre is out of the window, I thought I would come back to it..... Even if a new faceplate doesn't do squat, at least I attempted to do something my end...
I might even turn everything off, bar the router and a laptop 10 feet away, see if it's any interference that's causing the noise/high SNR.... and if it's still a 12db, then I'm not sure what to do apart from asking OR to force a SNR reset to a 6db....  Undecided
XenoGuy
Grafter
Posts: 77
Registered: 27-02-2014

Re: SNR still high

On another note, I just tried a line test via the BT (logged in) site, and my connection went...... hmm... Surely that isnt meant to happen?
Superuser
Superuser
Posts: 11,935
Thanks: 3,301
Fixes: 22
Registered: 22-08-2007

Re: SNR still high

@CRT,
What is the recent stability like on this line please?  Will it "stand" a SNRM reset?  12dB being brought down to 6dB might address the speed expectation gap ... but not if there is a history of instability.
Community Veteran
Posts: 5,111
Thanks: 465
Fixes: 17
Registered: 10-06-2010

Re: SNR still high

@XenoGuy
That line test always knocks out the ADSL, that's entirely normal.
You'd still need the wiring sorted out to get the best speed from an FTTC connection, and most providers only offer FTTC self-install, so you don't usually get a new master socket as part of an FTTC install any more. It's probably not that any interference itself is the problem, it's that wiring that isn't twisted pair is far more susceptible to interference than the proper standard of twisted pair cabling. The master socket and the wiring from the incoming line to it are Openreach's responsibility, and strictly speaking, only Openreach are allowed to replace it.
XenoGuy
Grafter
Posts: 77
Registered: 27-02-2014

Re: SNR still high

Quote from: ejs
That line test always knocks out the ADSL, that's entirely normal.

Then it defeats the purpose of an online test if you get bumped off, unless you have a back up connection, how do you see your results?  Do they automatically log any on your account?
Community Veteran
Posts: 5,111
Thanks: 465
Fixes: 17
Registered: 10-06-2010

Re: SNR still high

With an ordinary router, you just wait a couple of minutes for it to re-connect, then the BT webpage will eventually load with the test result. If your web browser times out loading the page, you can probably just retry loading the page it was attempting to load.
cedlor
Grafter
Posts: 687
Thanks: 2
Registered: 02-04-2015

Re: SNR still high

I think your plan of trying it with JUST the router plugged in via a single filter is a good one.  If you can, connect the laptop via ethernet , making sure the wifi is switched off.
You can then also try it with the laptop on battery ( with the power supply switched off and unplugged.)
If you run a program like routerstats it may help determine of there is any interference from elsewhere.
Do you need to have the outdated tbb and ookla pics in your signature?
XenoGuy
Grafter
Posts: 77
Registered: 27-02-2014

Re: SNR still high

Quote from: cedlor
Do you need to have the outdated tbb and ookla pics in your signature?

The TTB image is dynamic, and the speed test is there to help me remember the good times Tongue
XenoGuy
Grafter
Posts: 77
Registered: 27-02-2014

Re: SNR still high

Did I get a SNR reset or is there a glitch in the matrix?
Lost sync at around 1.40am, woke up 6 hours later to this
Quote
Bandwidth (Up/Down) [kbps/kbps]: 888 / 13,611
Line Attenuation (Up/Down) [dB]: 14.6 / 29.5
SN Margin (Up/Down) [dB]: 13.3 / 3.2

Lowest ever on PN