Am Intereference Issue

[Harry1503559513]

Hi this is not a TV issue as my digital TV reception is fine , but since some of you guys are experts in EMI then maybe you can help.

I get inteference like crackling for long periods of time on AM stations such as ABC News radio 585Khz. Usually OK after midnight and most of day Monday to Friday but at weekends starts in the mid morning usually but sometimes later ...suspect neighbour perhaps.

This also increases the noise on my Internet ADSL connection , causing resync at a lower speed.

I turned all the power off to my house and checked by using a portable radio but the interference is still there.

My first assumption is that is must be a neighbour's electrical equipment BUT as soon as I move the portable radio away from my house the interference drops rapidly indicating the source must be in my house.

I am now stuck and need some technical advice.

Could it be that my TV Antenna and /or Foxtel dish are picking up this noise and re broacasting it ?, I was about to disconnect them but thought I would check first if possible with those that may know.

Is there any other way that my house could amplify a noise signal ?

I have a cement tile roof but my immediate neighbour has a metal roof,, can that transmit interference ?

Any thoughts and suggestions welcome. I have checked the ACMA site but no obvious solution there.

[mtv]

Harry,

Have you tried walking around with your AM radio near your neighbour's house?

The interference may be entering via the mains power, so mains filtering may help and also fitting some ferrite core clamp-on suppressors to your equipment (ADSL modem etc)

Are your phone cables in the street overhead, or underground?

The consistent timing of the interference suggests it's some form of equipment only used during those times.... kids next door only on weekends?

Some wireless devices in use at those times?

CB radio's?

I have seen a couple of instances of faulty modulators in sat boxes causing issues for neighbours, the same with spurious signals from faulty masthead amps.

As for your antenna or dish picking up the interference.... sure.. anything's possible.. process of elimination.

A walk-around with a spectrum analyser should quickly locate the source if it's local.... but the AM radio is a useful tool to do this... the noise will increase the closer you get to the source.

[DrP]

Going for a walk with your radio off station may let you track it down too. Rotate the radio left to right to peak the signal etc.

Edited November 1, 2008 by DrP

[Harry1503559513]

Thanks you guys , will check further..btw phone cables are underground and to my wall from where it goes up the cavity into my roof space for about 5 metres.

Edited November 1, 2008 by Harry

[Harry1503559513]

Hi I have uploaded three attachments , hope I did that right and you can access

http://www.dtvforum.info/index.php?act=Att...ost&id=5619 a .wav file recording of ABC News Radio showing before and when the interference kicked in , interestingly it happened @ 12.30 when they went to a news break. I had to to "save link as" in order to play it

http://www.dtvforum.info/index.php?act=Att...ost&id=5621 graph of my ADSL noise margin show9ng correlation the onset of the interference.

http://www.dtvforum.info/index.php?act=Att...ost&id=5620 data that produced the graph

btw Alan I received your email, I am in Edgewater

Edited November 2, 2008 by Harry

[digitalj]

Harry,

None of the links work.

[Harry1503559513]

Harry,

None of the links work.

I do not think I understand how to do this , I uploaded the 3 files (and they are still there) using the attachment forum ( http://www.dtvforum.info/index.php?showforum=145) but then it said I need to register the post and I could not see how to do that , so I assume that because I had uploaded them that they are accessible but obviously not. Any help appreciated.

[digitalj]

you need to make a post in the attachments forum where it's uploaded, then link to that post from here.

[Harry1503559513]

you need to make a post in the attachments forum where it's uploaded, then link to that post from here.

Thanks ...looks as if it would not let me post before as I did not put any nohting in the text.......done it ....here is the link hope that works

http://www.dtvforum.info/index.php?showtopic=72423

[DrP]

Major arcing going on somewhere by the sounds of that. How is the electricity delivered there via poles or underground? How did you turn all power off at your house? Via the breakers at your fusebox? Did you turn your hot water off too?

Edited November 4, 2008 by DrP

[Harry1503559513]

Major arcing going on somewhere by the sounds of that. How is the electricity delivered there via poles or underground?

Underground.

[DrP]

How did you turn all power off at your house? Via the breakers at your fusebox? Did you turn your hot water off too?

[Harry1503559513]

How did you turn all power off at your house? Via the breakers at your fusebox? Did you turn your hot water off too?

Thanks for the reply

Hot water is gas.

I turned off via the breakers at the fuse box.

This problem I first noticed about 6 months ago as my ADSL kept losing sync

I have just had a thought, I had some electrical work done about 6 months ago , I had an outside power point installed (works fine) , I watched the electrician do it, he used a "snake" (as he called it) to locate and pull the existing cable so he could get at it. He routed a new cable length from a power point on the inside of the wall where I wanted the external power point fitted.

Also my telephone cable runs fairly close in parallel to the modified power cable (say 15cm) up the cavity wall ( so arcing here could explain the ADSL problem. I have also installed 6 to 5 months ago Aluminium Backed Insulation Sarking partially in the roof (cement tile) which I understand may reduce externals signal radio strength.

What do you think ? BUT for many hours there is no interference on radio or noise on the ADSL for very long periods of time even if the power circuit near there is being used.

I think we may be on the right track possibly.

[DrP]

If everything was really turned off when you flicked the breakers then it can't really be anything inside your house doing it. I guess you could confirm that when you switch off via the breakers, that outlet goes dead. Plug in a desk lamp or something and see if it still lights up.

[Harry1503559513]

If everything was really turned off when you flicked the breakers then it can't really be anything inside your house doing it. I guess you could confirm that when you switch off via the breakers, that outlet goes dead. Plug in a desk lamp or something and see if it still lights up.

Thanks

Actually may not have been, I might have left one light circuit on which for whatever reason I did not think would be involved. Anyway I now have everything off, running off laptop battery and have put my ADSL modem on SLA powered battery and battery powered radio. And now I wait and see.

Currently no noise on Radio and ADSL reports 7 SNR and am syncing at max rate. If it does not fail before dark then we could be onto the solution.

Told the missus that no power until I say (if she wants the Melbourne cup she can go to neighbour's place).

[Harry1503559513]

Thanks

Actually may not have been, I might have left one light circuit on which for whatever reason I did not think would be involved. Anyway I now have everything off, running off laptop battery and have put my ADSL modem on SLA powered battery and battery powered radio. And now I wait and see.

Currently no noise on Radio and ADSL reports 7 SNR and am syncing at max rate. If it does not fail before dark then we could be onto the solution.

Told the missus that no power until I say (if she wants the Melbourne cup she can go to neighbour's place).

Unfortunately due to family pressure had to abort the test , will reschedule soon and let you know what transpires

[Harry1503559513]

Unfortunately due to family pressure had to abort the test , will reschedule soon and let you know what transpires

Test complete...definitely NOT any electrical equipment in my house. I now suspect neighbour it may be a coincidence but noise spike seems to coincide with time he comes home and is louder closer to his property but appears to be "amplified" by my house. He had a steel pergola installed about the same time I noticed the issue, could that act as amplifier/transmitter ? Will monitor his movements and see whether just a coincidence or not.

Times that the noise starts are mid afternoon usually Mon to Friday and earlier @ weekends (mid morning) so does coincide with times that he and also school kids in the area are home. I did notice that during recent school holidays that the noise started earlier in the day but my current suspect neighbour does not have any school kids. Most other houses in the street do.

There are two other neighbours at the back who also work hours that may coincide with the noise starting.

Apart from finding the source and stopping it by asking them to fix their equipment what other remedies do I have ?

Edited November 6, 2008 by Harry

[DrP]

Its best to keep it friendly if at all possible. There's nothing worse than being on poor terms with your neighbours. Do a bit of polite door knocking explaining the problem and seeing you can do a walk around their house / land when the problem is ocurring to attempt tracking it down. It might be a faulty thermostat on an airconditioner.

[Harry1503559513]

Its best to keep it friendly if at all possible. There's nothing worse than being on poor terms with your neighbours. Do a bit of polite door knocking explaining the problem and seeing you can do a walk around their house / land when the problem is ocurring to attempt tracking it down. It might be a faulty thermostat on an airconditioner.

I was sniffing around with my AM radio and got this sound around 628Khz when no severe crackling interference on News Radio and ADSL fine,

http://www.dtvforum.info/index.php?showtopic=72501

Anyone know what it is ?

Maybe when whatever it is is turned off that the shorting/crackling/arcing occurs etc , waiting for my neighbour to return home to see what happens

[alanh]

Harry,

You need to get 3 other adjacent houses to all complain to the ACMA

Then the ACMA can locate the source for free.

Also ABC. On this one let me know what happens. They are slow to respond.

AlanH

[Harry1503559513]

Harry,

You need to get 3 other adjacent houses to all complain to the ACMA

Then the ACMA can locate the source for free.

Also ABC. On this one let me know what happens. They are slow to respond.

AlanH

thanks , once I get more evidence I will contact them

[Harry1503559513]

The interference may be entering via the mains power, so mains filtering may help and also fitting some ferrite core clamp-on suppressors to your equipment (ADSL modem etc)

Hi mtv , In desperation I have bought the following and applied to the telephone input lead to my modem and for the time being at least it appears to have stopped the degradation of my ADSL service. Many thanks for the tip.

http://www.altronics.com.au/index.asp?area=item&id=L4644

I do not understand why the problem continued before even when I turned off all power to the house is it some sort of static in the wiring ?

[alanh]

Harry,

Are you sure that there is nothing arcing in your wiring? You may be able to hear a buzzing sound from the wiring or intermittent operation of electrical equipment.

AlanH

[Harry1503559513]

Harry,

Are you sure that there is nothing arcing in your wiring? You may be able to hear a buzzing sound from the wiring or intermittent operation of electrical equipment.

AlanH

I cannot rule it out but there is no consistency with the "spike" or "arc" i.e. when I have suspected something turned things off and on to try and recreate but there is nothing.

It seems as if I get an initial very loud "spike" followed by a continuous lower level interference for quite some time (hours afterwards).

The Ferrite filter appears to be doing its stuff for my ADSL ie. a lot better SNR margin but the "spike" still occurs. e.g. yesterday I turned on the TV /and STB and got the problem and had a Archimedes moment , but subsequent testing did not recreate. A previous day my wife turned on the vacuum cleaner and it happened but again turning it off and on again did not recreate and 20 minutes before she had it on plugged into the same circuit with no effect.

Today with no devices on in the house other than my computer and ADSL modem, the spike occurred when the postman delivered a letter !!!! the other day it happened when a courier delivered a parcel to me.

atm I am putting all these things down to coincidence and not possible to recreate any of them.

anyway will keep on trucking

[DrP]

Given that you said the problem (arcing) was still audible even with your house 'off' its unlikely to be anything actually in your house (ie, your side of your fusebox).