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 [3] 4 5 6

Author Topic: Serious interference around 700Khz  (Read 26723 times)

burakkucat

  • Respected
  • Senior Kitizen
  • *
  • Posts: 38300
  • Over the Rainbow Bridge
    • The ELRepo Project
Re: Serious interference around 700Khz
« Reply #30 on: February 22, 2013, 02:42:05 AM »

Surely you will now open up that old PSU and take a look-see, just in case it could be repaired for use in your shed?  ::)
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.

sheddyian

  • Kitizen
  • ****
  • Posts: 1159
    • My Shed Blog
Re: Serious interference around 700Khz
« Reply #31 on: February 22, 2013, 10:54:00 AM »

Surely you will now open up that old PSU and take a look-see, just in case it could be repaired for use in your shed?  ::)

I'm certainly not throwing it away just yet!  :D

I'm curious to see if there's anything obvious - bulging capacitors or something burnt out, but otherwise I'll salvage the fan, possibly the heatsink, and the rest can go to recycling.

I'll probably drop it in the small electronic appliance recycle bin in Sainsbury's car park.  I'm sure they'll find a use for it  :D

Ian

Logged

burakkucat

  • Respected
  • Senior Kitizen
  • *
  • Posts: 38300
  • Over the Rainbow Bridge
    • The ELRepo Project
Re: Serious interference around 700Khz
« Reply #32 on: February 22, 2013, 08:21:52 PM »

Surely you will now open up that old PSU and take a look-see, just in case it could be repaired for use in your shed?  ::)

I'm certainly not throwing it away just yet!  :D

Ah ha! A fellow 'seasoned' adventurer, I do detect.  ;)
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.

sheddyian

  • Kitizen
  • ****
  • Posts: 1159
    • My Shed Blog
Re: Serious interference around 700Khz
« Reply #33 on: February 24, 2013, 06:58:03 PM »

"It's baaaaaaaaaack!"  >:(

Well, something is.

On Monday 18th I found the apparent cause of my high error seconds count and repeated disconnections during the evening - the Dell PSU which was radiating a lot of RF noise, detectable all over the house and in the shed, as already documented at length, above.. 

Since then I've had that computer disconnected from the mains, then I replaced the PSU.  All has been well, no more disconnects, error seconds lower if not perfect.  No problems with web pages not loading.

Then about an hour ago, web pages weren't loading.  Modem still in synch.  Logged in to modem and saw the error seconds climbing as I watched, then the modem lost synch.

Put the AM radio on, and heard this around 612kHz :

http://sheddyian.hopto.org/interference3.mp3

That wasn't there the other day! 

It's not the original interference I heard, which sounded like this http://sheddyian.hopto.org/interference1.mp3

And after I'd isolated the PC causing that noise, the same frequency sounded like this

http://sheddyian.hopto.org/interference2.mp3

Which proves that noise wasn't there a few days ago.

I can hear it at varying levels from 522kHz up to 700+ kHz, peak seems to be just under 612Khz.

This time, switching off all computers, central heating, CFLs, TVs etc doesn't silence it.  And unlike last time, I can detect it in the garden, and a little way up and down the road.  At the very back of the garden it seems to be fading away.

 >:(

Not sure what to do now.  I lost synch, and resynched around 2 meg lower than expected.

This is different interference to before, and isn't coming from the PC that caused the original noise.

Did it cause my loss of synch?  Is it causing my drop in synch speed?

I've had 6 days of trouble-free connection, but haven't listened to 612kHz for about 5 days, so can't be sure when the noise actually appeared.  Naturally I'm assuming the noise has just started, and that's why I just lost synch but I can't know that for certain.

Thoughts?

Ian :rain:
Logged

burakkucat

  • Respected
  • Senior Kitizen
  • *
  • Posts: 38300
  • Over the Rainbow Bridge
    • The ELRepo Project
Re: Serious interference around 700Khz
« Reply #34 on: February 24, 2013, 07:52:34 PM »

Oh dear. That doesn't sound too good.  :(

Just to confirm -- with your incoming mains supply isolated by the 'big switch' being set to off, there is absolutely no change in the observed RFI?

I suspect you are now going to have to print out a scale map of your environs and then, from three physically separate locations measure the bearing for the minima (more accurate), thus the maximum will be +90 degrees of your reading. Plot those three bearings on your map and it should indicate the general area in which to search.
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.

sheddyian

  • Kitizen
  • ****
  • Posts: 1159
    • My Shed Blog
Re: Serious interference around 700Khz
« Reply #35 on: February 24, 2013, 07:57:35 PM »

Just to confirm -- with your incoming mains supply isolated by the 'big switch' being set to off, there is absolutely no change in the observed RFI?

Haven't done that yet - might wait until others don't need electricity  :D

But I have tried individual things that are known for noise - anything with a switch mode PSU, TVs, digiboxes etc.  That made no difference.

It does seem to be mains-borne, up to a point - I've just been up the shed, and found that isolating the power from the shed makes the noise quieter on the radio, but doesn't silence it. 

Will try some more things later

Ian
Logged

sheddyian

  • Kitizen
  • ****
  • Posts: 1159
    • My Shed Blog
Re: Serious interference around 700Khz
« Reply #36 on: February 24, 2013, 08:17:43 PM »

Well, I just happened to switch the radio back on, and the interference is gone.  IN it's place is background hiss / slight static and a very distant foreign station occasionally breaking through.

Earlier, the interference was so strong it was causing the radio's "tuned" light to come on!

So, with the interference gone, I rebooted the modem - and got back my missing speed.  All is well again.

For now  :(

Between me wandering around trying to locate the source of the noise, and me discovering it had gone away by itself, nothing obvious has been switched on or off that I hadn't already tried.

Aren't intermittent problems the absolute worst  ???

Ian
Logged

burakkucat

  • Respected
  • Senior Kitizen
  • *
  • Posts: 38300
  • Over the Rainbow Bridge
    • The ELRepo Project
Re: Serious interference around 700Khz
« Reply #37 on: February 24, 2013, 08:36:42 PM »

Between me wandering around trying to locate the source of the noise, and me discovering it had gone away by itself, nothing obvious has been switched on or off that I hadn't already tried.

Aren't intermittent problems the absolute worst  ???

Indeed they are.  ;)

Just a thought. Could it have been due to a street light which had been energised but failed to light properly? After irritating you, it finally lit and the RFI disappeared (for now)?  :-\
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.

sheddyian

  • Kitizen
  • ****
  • Posts: 1159
    • My Shed Blog
Re: Serious interference around 700Khz
« Reply #38 on: February 24, 2013, 09:05:50 PM »

Just a thought. Could it have been due to a street light which had been energised but failed to light properly? After irritating you, it finally lit and the RFI disappeared (for now)?  :-\

That crossed my mind, which is why I took the radio for a walk up and down the road, but the interference fairly quickly fades out, and doesn't seem as strong at the roadside as it is in the house.  Likewise, at the far back of the garden, where there are more street lights nearby, the interference is practically silent, so I don't think it's street lights.  And I did look to see if any were flickering or unlit, all that I could seel seemed to be working ok

Meanwhile...

Since the last post, the noise is back once more.

I'd switched the radio on again, and recorded the "silence" for research purposes  :graduate:.  When I'd done that, I left the radio on, enjoying it's gentle hissing, and went back to the computer (which had been switched on all the time).  After a short while, the noise started coming back, and lo! web pages started refusing to load. 

I used telnet to connect to the modem and I could see the error seconds rapidly rising, from 80 to 200 in less than a minute.  Shortly afterwards the modem lost synch again, and disconnected. 

The interference is across quite a large swathe of the AM band.  I switched the computers off (to rule out their interference) and made a little Youtube of me scanning the AM band on a portable radio, which you can watch and listen to here http://youtu.be/kzWTGEa-ReU

With everything unplugged from the mains in that room (including the modem), I can still hear the noise, so it's not very nearby electrical equipment there that's causing it.

Edit :

This was the noise at around 6:20pm today : http://sheddyian.hopto.org/interference3.mp3
Then around 8pm I discovered the noise had gone, and recorded this on exactly the same frequency as the above recording. : http://sheddyian.hopto.org/interference4.mp3

But now it's back again again  >:(

Ian
« Last Edit: February 24, 2013, 09:15:49 PM by sheddyian »
Logged

burakkucat

  • Respected
  • Senior Kitizen
  • *
  • Posts: 38300
  • Over the Rainbow Bridge
    • The ELRepo Project
Re: Serious interference around 700Khz
« Reply #39 on: February 25, 2013, 01:06:08 AM »

:hmm:  Hmm . . . one of your immediate neighbours could be suspected -- once you have performed the 'big switch to off' experiment in your own home.

(I wonder if Big Nellie's electropathic belt is showing signs of a corona discharge?  :-X  )
« Last Edit: February 25, 2013, 03:49:35 AM by burakkucat »
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.

sheddyian

  • Kitizen
  • ****
  • Posts: 1159
    • My Shed Blog
Re: Serious interference around 700Khz
« Reply #40 on: February 25, 2013, 05:46:11 PM »

:hmm:  Hmm . . . one of your immediate neighbours could be suspected -- once you have performed the 'big switch to off' experiment in your own home.

Well, on the plus side, the noise seems to be loudest inside this house, though I could detect it outdoors as well.
I did wander up the driveway to the next door neighbour, and whilst I could hear it there, it didn't seem as strong.

If it comes back, I'll do the same again, or I'll ask if I can wander around their house with an AM radio  ???

Not long after my previous posting, I found the noise had gone again, and it hasn't returned since, as far as I can tell (ie the modem has stayed in synch for 20 hours), though the error seconds count was higher than I'd expect (1300+ in 20 hours).

Currently there's no noise, I rebooted the modem and it resynched at 20k.  Error seconds are around 10 an hour.  This is what I'd expect, and how it's been pretty much for the last 14 months, until a few weeks ago.

If anyone can suggest what might cause this sort of noise, please let me know  :ouch:
http://sheddyian.hopto.org/interference3.mp3

(to me, that sounds like putting the radio on top of a CRT TV!  There were no CRT TVs anywhere near the radio when I recorded that, nor monitors, and that noise could be heard throughout the house as I wandered around with the radio)

Ian  :rain:
Logged

sheddyian

  • Kitizen
  • ****
  • Posts: 1159
    • My Shed Blog
Re: Serious interference around 700Khz
« Reply #41 on: February 27, 2013, 01:49:58 AM »

Surely you will now open up that old PSU and take a look-see, just in case it could be repaired for use in your shed?  ::)

I have now had a look at the suspect PSU.  And, lo, there is a bulging capacitor.  (might not be that obvious in the picture, but it's a significant bulging).  Now wondering if it's worth replacing that cap, to bin the whole PSU, or to replace other caps as well. (which ones?)

Still leaves a bit of a puzzle though.

I am confident that this PSU was generating noise on the AM band around 612Khz. I recorded it, and could silence it or create it by switching this PSU off or on.  It could be detected all around the house.

Despite isolating, then removing this faulty PSU, the ADSL disconnections resumed around 7 days later, and continue intermittently.  A different, but strong, noise can be heard on AM at 612Khz nd above, all around the house during the intermittent problem period.

Prior to this, I'd had 14 months problem-free, high speed connection.

Still trying to find current (VERY intermittent) source of noise.

Meanwhile, here's a picture of a bulging cap.  It's quite pronounced in real life (might actually be leaking slightly) but photo doesn't show it as clearly as I'd intended.  All the others seem fine.

Should I try replacing only that one, or others as well?

Ian
Logged

burakkucat

  • Respected
  • Senior Kitizen
  • *
  • Posts: 38300
  • Over the Rainbow Bridge
    • The ELRepo Project
Re: Serious interference around 700Khz
« Reply #42 on: February 27, 2013, 05:03:16 AM »

Oh yes. I can see the bulge.

Erm . . . isn't there a saying "Nothing ventured, nothing gained."?  ::)  If you feel up to it then, as the Nike slogan said, "Just Do It".  :)
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.

sheddyian

  • Kitizen
  • ****
  • Posts: 1159
    • My Shed Blog
Re: Serious interference around 700Khz
« Reply #43 on: March 03, 2013, 06:59:15 PM »


*sigh*  :rain:

Interference is back, pages refusing to load or hanging.  Currently showing 300+ errors in 15 minutes, resynched at much lower speed.

I went to fuse box, and switched EVERYTHING off via the master switch.  House in darkness, silence.  Except for my battery radio.  Which was still buzzing away very loudly.

So, the interference isn't caused by anything in this house.

A wander around the garden and the street shows the noise to be centred on my house and the detached neighbours.  In front of their garage door the noise is very loud  (they have two freezers in there.. I wonder?)  Out in the street, noise less strong.  Up and down the road it quickly fades away.  Standing underneath nearby street lights makes no difference, so it's probably not those.

Will speak to neighbours when they get back.  Seems to be worse on a Sunday evening, even when they're out - so what is it that's different about that day?

Still, I get on well with the neighbours, and I'll have to play it down a bit because they'll be genuinely embarrassed if they think it's their fault!

An hour ago, this post was going to be an update saying it was all going fairly well, and that I'd relocated the modem to be as close as possible to the incoming BT line to the house.  There's no more than 2 metres of cabling above ground to the modem now.  (Previously it was nearer 6, straight up the wall , which I thought might make a good aerial, so I eliminated that).

Hey ho.  Still, I've made progress - next stop, neighbours!

Ian
Logged

sheddyian

  • Kitizen
  • ****
  • Posts: 1159
    • My Shed Blog
Re: Serious interference around 700Khz
« Reply #44 on: March 04, 2013, 01:24:34 AM »

Brief update : Earlier I went around the neighbours house with my radio, explained the situation, switched radio on and they heard the loud buzzing across the bottom end of the MW dial.

Wandered around their house, it did seem loud there, but couldn't pinpoint it.

Loud in the garage which contains two small freezers,  Switched freezers off.  Noise continues.

Loud in their hallway, near cupboard with fuse box.

I ask if I can come back when it's more convenient, they suggest I carry on for a bit, and that I switch mains off.

Switch off the main switch on their fuse board.  Noise continues as before.

So it's not being generated by mains equipment in their house.

And not by mains equipment in my house (also switched off earlier).

Yet the noise seems to centre around these two houses.

Noise is constant whilst present (not pulsing) but comes and goes over a period of hours.

Appeared around dusk

Disappeared around 8pm

Then came back a bit later

By midnight it had gone once more.

But doesn't happen EVERY night (Sunday seems popular!)

The AM radio noise and high error seconds/disconnects seem to be related.  If I cause the modem to resynch whilst the AM noise is present, I get a connection speed around 2K lower than otherwise expected.  Whilst the AM noise is present, the modem records high error seconds, which stabilise once the AM noise has gone.

Anyone have any thoughts as to what to try next?

Ian
Logged
Pages: 1 2 [3] 4 5 6
 

anything