Kitz ADSL Broadband Information
adsl spacer  
Support this site
Home Broadband ISPs Tech Routers Wiki Forum
 
     
   Compare ISP   Rate your ISP
   Glossary   Glossary
 
Please login or register.

Login with username, password and session length
Advanced search  

News:

Pages: [1] 2

Author Topic: National vs local vs micro noise sources  (Read 3685 times)

Weaver

  • Senior Kitizen
  • ******
  • Posts: 11459
  • Retd s/w dev; A&A; 4x7km ADSL2 lines; Firebrick
National vs local vs micro noise sources
« on: May 19, 2018, 06:04:13 AM »

Are people seeing noise source frequencies that are the same across all of the Island of Britain? And solely England, would be useful too. What about reasonably wide area source, say roughly 100 miles radius ? And what about localised sources of radius 5 miles, very localised sources of 1 mile radius and then 100m radius? We would obviously need kitizens and their neighbours and relatives for the latter.
Logged

GaryW

  • Member
  • **
  • Posts: 96
Re: National vs local vs micro noise sources
« Reply #1 on: May 19, 2018, 10:49:02 AM »

Most of mine is AM radio related.  During the day it's mainly local transmitters and high-power less-local transmitters...at night it's also (eastern) European frequencies.  You can find all of the UK frequencies and transmitters at: http://www.mediumwaveradio.com/uk.php

At night I also get a big dip in the tones around 2.6MHz (so around tone 600) - there are maritime/emergency transmissions around those frequencies, but I wonder if it may also be due to my neighbour using cr*ppy powerline adapters and being more active in the evening.  (We're on overhead power and overhead phone lines)
Logged
EE 4G - Huawei B618s-22d - BT WHWF

Weaver

  • Senior Kitizen
  • ******
  • Posts: 11459
  • Retd s/w dev; A&A; 4x7km ADSL2 lines; Firebrick
Re: National vs local vs micro noise sources
« Reply #2 on: May 19, 2018, 10:53:05 AM »

@GaryW - where about are you, Gary? What other (lower) frequencies are you getting?
Logged

GaryW

  • Member
  • **
  • Posts: 96
Re: National vs local vs micro noise sources
« Reply #3 on: May 19, 2018, 11:27:27 AM »

I'm in Kent, between Sevenoaks and West Malling.  I got really bored one day, and created this table  :)  Just tweaked it to reflect the demise (yay!) of some of the local BBC stations.  Quite scary how large the impact of some stations is on SNR...and how much better my broadband might be if we were a nation of sport-hating agnostics who didn't like retro-music :)  (NOTE: I have absolutely nothing against sports-fans or believers, and I love retro-music!)

Logged
EE 4G - Huawei B618s-22d - BT WHWF

GaryW

  • Member
  • **
  • Posts: 96
Re: National vs local vs micro noise sources
« Reply #4 on: May 19, 2018, 11:33:42 AM »

Hmm...and as I've been typing, the SNR has become distinctly nobbly in the 530-770 tone range, with the big dip around tone 600, which makes we think it may indeed by powerline neighbour!
Logged
EE 4G - Huawei B618s-22d - BT WHWF

Weaver

  • Senior Kitizen
  • ******
  • Posts: 11459
  • Retd s/w dev; A&A; 4x7km ADSL2 lines; Firebrick
Re: National vs local vs micro noise sources
« Reply #5 on: May 19, 2018, 11:53:18 AM »

Power line should be banned.

Would filtering on your own mains and dc help at all perhaps? or is it truly radiated? (A radio receiver?)

The offender ought to be legally required to ensure that this crap doesn't leak out over the mains nor into the airspace next door. Just banning it altogether would be the easiest way.
Logged

Weaver

  • Senior Kitizen
  • ******
  • Posts: 11459
  • Retd s/w dev; A&A; 4x7km ADSL2 lines; Firebrick
Re: National vs local vs micro noise sources
« Reply #6 on: May 19, 2018, 01:04:31 PM »

@GaryWFrom your chart, that matches up with my tones 188, 211, 244 and in fact 253 as well, now I think about it in terms of quiet line SNR. But the tones above 162 [!] are not in use anyway as my line is too long at 7300m + 65dB downstream attenuation.

I only have an actual effective dip, one in bits-per-bin at tone 125, 539.0625 kHz with 0 bits as opposed to 2 or 3 bits for the neighbouring tones.
Logged

Weaver

  • Senior Kitizen
  • ******
  • Posts: 11459
  • Retd s/w dev; A&A; 4x7km ADSL2 lines; Firebrick
Re: National vs local vs micro noise sources
« Reply #7 on: May 19, 2018, 01:07:06 PM »

So from your listing, it seems that I can hear
  • BBC Radio Scotland at Burghead (100kW) 810 kHz station, on tone 188
  • Radio 5 Live on tone 211
  • Talk Sport #1 on tone 244
  • Talk Sport #2 on tone 253
but some of the big names that you might expect, for example Radio 4, are not evident.

And none of the above are affecting me as they are all too high.
« Last Edit: May 19, 2018, 11:53:27 PM by Weaver »
Logged

renluop

  • Kitizen
  • ****
  • Posts: 3326
Re: National vs local vs micro noise sources
« Reply #8 on: May 19, 2018, 06:04:46 PM »

GaryW does seem to be in a transmitter hot spot. There's Wrotham, which carries all BBC and Classic, and other Tx, Radio and TV, at Tonbridge, Bluebell Hill, twixt Maidstone and Chatham, to name a few, some being quite powerful.
Logged

Weaver

  • Senior Kitizen
  • ******
  • Posts: 11459
  • Retd s/w dev; A&A; 4x7km ADSL2 lines; Firebrick
Re: National vs local vs micro noise sources
« Reply #9 on: May 19, 2018, 06:14:11 PM »

The 810 kHz signal would seem to be BBC Radio Scotland at Burghead (100kW). It is too high to knock out any of my tones. It sits on top of bin 188 and I stop at bin 136.
« Last Edit: May 19, 2018, 11:52:56 PM by Weaver »
Logged

Weaver

  • Senior Kitizen
  • ******
  • Posts: 11459
  • Retd s/w dev; A&A; 4x7km ADSL2 lines; Firebrick
Re: National vs local vs micro noise sources
« Reply #10 on: May 19, 2018, 08:11:40 PM »

Thanks to that website, http://www.mediumwaveradio.com, good tip -thank you, I looked a frequency or two up.

TalkSport 1053kHz on top of bin 244 would appear to be on the Black Isle peninsula, An t-Eilean Dubh, (it is not an island despite the name), which is on The East Coast, a wee bit further north than me, north of Inverness in fact. So even though they are all the way over on the east coast we have a couple of Broadcast radio stations making trouble for people even a good 70 miles away and there are hills on Skye in the way and then the towering Cinn t-Saile mountains especially Beinn Fhada on the mainland in the way too.

A noise bump of height approx 6dB over bins 204-205 879.75 - 884.0625 kHz went away in the second sync compared with the first.

I dug up the following from http://www.g8dhe.net/ADSL-DSL%20paper%20INTFR-I1.pdf :
8 815-8 965 kHz AERONAUTICAL MOBILE (R) - Civil and non civil aeronautical communication services, including data link services. BT on 8.960 MHz from Rugby. NATS joint use of 8 831 kHz, 8 864 kHz, 8 879 kHz, 8 891 kHz, 8 906 kHz and 8 957 kHz using transmitters located in the Republic of Ireland.

At 882 kHz there is a 100 kW Radio Wales transmitter looking Northwards out over the sea from the Somerset Coast, but even at that power that has to be way way too far away surely at 429 miles [!], and there are the Welsh mountain ranges in the way, if that makes any difference at all.

More realistically we have a source on 883 kHz, weather broadcasts for shipping coming from Tiriodh (anglicised as ‘Tiree’) an island which is 60 miles away to the southwest and a clear line from the house over the atlantic but just over the horizon. I can even just about see Colla which is closer and is next door to Tiriodh. So that is what I will put my money on.

Given that two bins are knocked out, it could be that we have something just on the wrong frequency, straddling two bins or even two disturbers.

Seems that the authorities should over time require new stations or perhaps even existing ones to stick to certain quantised frequencies in future to avoid the two bin zapping / straddling problem. But what frequency grid? What if designers ever want to change the spec of new replacement DSL systems in the distant future? I wonder how enormous the cost would be if designers wanted to have unequal width bins and a territory-dependant map of their frequency allocation. This could perhaps one day optimise performance for some unknown reason or do better at living with the pattern of high power narrow-ish broadcaster disturbers’ centre frequencies and widths.
Logged

burakkucat

  • Respected
  • Senior Kitizen
  • *
  • Posts: 38300
  • Over the Rainbow Bridge
    • The ELRepo Project
Re: National vs local vs micro noise sources
« Reply #11 on: May 19, 2018, 09:16:54 PM »

All uses of xDSL technology is unlicensed use of the RF spectrum. There is no problem with that so long as the xDSL signal does not escape the feeder linking the two transceivers (xTU-C & xTU-R) and radiate into free space.

No user of xDSL technology can demand (nor require) that a licensed radio transmitter cease radiating RF energy. However the converse is not true. If it can be proved that xDSL technology is radiating into free space and is disrupting licensed use of the RF spectrum then cessation of the particular case of problematic xDSL technology is enforcible by the relevant courts of England & Wales, Scotland or Northern Ireland.
Logged
:cat:  100% Linux and, previously, Unix. Co-founder of the ELRepo Project.

Please consider making a donation to support the running of this site.

Weaver

  • Senior Kitizen
  • ******
  • Posts: 11459
  • Retd s/w dev; A&A; 4x7km ADSL2 lines; Firebrick
Re: National vs local vs micro noise sources
« Reply #12 on: May 19, 2018, 09:42:43 PM »

So twisted pairs are supposed to stop dsl copper from becoming effective transmitters? Someone said in a thread somewhere that he believed his drop cable was crappy and not twisted - read that today, memory fails me.
Logged

burakkucat

  • Respected
  • Senior Kitizen
  • *
  • Posts: 38300
  • Over the Rainbow Bridge
    • The ELRepo Project
Re: National vs local vs micro noise sources
« Reply #13 on: May 19, 2018, 10:09:52 PM »

An unshielded twisted pair (UTP) cable, with good balance (both AC & DC), will act as a transmission line and not radiate into free-space.
Logged
:cat:  100% Linux and, previously, Unix. Co-founder of the ELRepo Project.

Please consider making a donation to support the running of this site.

Weaver

  • Senior Kitizen
  • ******
  • Posts: 11459
  • Retd s/w dev; A&A; 4x7km ADSL2 lines; Firebrick
Re: National vs local vs micro noise sources
« Reply #14 on: May 21, 2018, 11:43:49 AM »

I also looked at the current SNR per tone data. Pretty much the same pattern as the QLN.

For those of you who like their numerical analysis, I did a polynomial curve fit on the log of the noise versus tone number, so in what follows y = dB log SNR ( 1 = dB), x = bin number where x = 0 = bin 0, x from 33 upwards compared with the first order. The bin numbers below 33 were meaningless.

And the answer is that the log of the noise level is pretty much a quadratic, with third and fourth power coefficients being really low, down at the order of 10-6 and 10-9 respectively, compared with the first order coefficient :
    y =  -115  −  0.607 x  +  0.00365 x2  −  8.15E-06 x3
« Last Edit: May 21, 2018, 12:42:53 PM by Weaver »
Logged
Pages: [1] 2