Wednesday, March 17, 2010

G4ILO's noise

This afternoon I decided to tune around the HF bands to see how they compared with what I heard when I was out mobile yesterday and at the weekend. It was very depressing. I didn't hear any DX at all. The high noise level obliterated anything interesting and made listening very tiring and unpleasant. From the mobile out in the countryside the only man-made noise was the occasional burst of ignition interference from a passing car and I could copy signals right down to atmospheric noise.



I thought I would use my Pentax digital camera to make a video that demonstrated just what the HF bands sound like from here. It's a ham radio horror movie.

15 comments:

GW0KIG said...

Interesting video Julian. This seems to be a problem of the modern age. I can recall days as an SWL with a 100 metre long wire
and not suffering any problems with band noise. I think those days are gone unless you are lucky enough to live in a rural isolated area.My noise level is quite high on 20 metres even with an external antenna. I also suffer from PLT interference on the non-amateur HF bands although the Wellbrook loop does reduce that to tolerable levels. Is there any possibility of an outdoor "stealth" antenna at your QTH? My Wellbrook loop is a totally different (quieter) beast now it is outside.

73 De Kevin

LY2SS said...

I saw yesterday this post by accident:

http://acomeau.blogspot.com/2010/03/s9-power-line-noise.html

Maybe link above is OT, maybe not...

I'd try to get direction of some of the sources/carriers with the help small loop (+ some small hf rig kind of ft817 hi)...Maybe it's a some device in your own premises. There were some wall switches which produced harsh noise (sparking when turned on. One couldn't even tell that something wrong is with the switch). Ah... these days friend of mine told me that one of _very_bad_ noise source was his own mobile phone charger.

73! de Zilvis

g4ilo said...

Believe me, I've tried all the obvious things. It's not from within my house. I've turned off the power and listened with the FT-817 on its internal battery. For years I have already had the practise of switching on things (TV, satellite receiver, any switched mode PSU or charger etc.) only when needed. I bought a transformer based regulated supply for my mobile phone charger because the original was a noise generator. The network router is probably responsible for some carrier signals, but not the broadband hash - it has a transformer based power supply.

The problem is not because I have attic antennas, because 10 years ago I had attic antennas and I did not have the problem. It isn't possible to trace where the noise comes from and eliminate it, because there is not one noise there is many different noises. And it is not possible to escape the noises from within the confines of my boundaries (which you can see on the satellite view here, which shows how small the plot is and also how many near neighbours there are) which again I have verified by going outside with an FT-817.

Unfortunately moving to a rural QTH would be unacceptable to the XYL, as would the idea of moving anywhere, even if we could afford to.

Dick said...

Sounds familiar, Julian. There are days when my QRN is worse than yours.

Problem is, we can't all operate portable in the great outdoors. Winters here in central New York State can be brutal.

I don't know what can be done. I don't want to spend a half-hour adjusting filters.

Larry W2LJ said...

Julian,

All I can say is you are NOT alone! 30 Meters for me is unusable in the evenings, with 40 Meters a close runner up. 30 Meters at night has an S9 noise level and 40 Meters about S6 to S7. For whatever reason, 80 Meters is relatively quiet.

Too much RF pollution and there is something in a neighbor's house that is cutting into my Amateur Radio lifestyle. Like you, I have had no luck so far figuring it out so far; although I am leaning towards a faulty heating system or perhaps a plasma screen TV.

Larry W2LJ

G4NKX said...

Thats quite amazing - and I thought I had bad noise, 40M was quite bad before christmas, but as the band conditions improved it seems to have gone - now if I get any it runs at about S3-4. Do you have a nursery near you - thermostatically controlled heaters/vents/fans?

g4ilo said...

No, it's entirely a residential area.

QRP Station M6RDP said...

It is sad to hear that this noise is so bad that it makes us wonder whether the hobby is worth continuing.

How wondferful it would be to move to a more rural location. I do not like town life myself particularly, and I think providing I were within walking distance of somewhere to post my mail and buy a pint of milk I would love to move to a much quieter location: quieter in terms of both people and QRN!

The world is getting out of control with technology with which I have a love and hate relationship.

I think the problem, sadly, is destined only to worsen with time.

I guess all we can do is work with it: work the bands that are quieter, work the stronger signals, forget about 2-way QRP - otherwise you're just fighting what I think is a losing battle.

Thanks for the post. Adam

M0JEK said...

Sounds just like my QTH :-( I can sympathise.
The hard rasping noise you had heard before your recording on 15m might have been a plasma TV. If someone switches on the plasma TV at home, it completely blots out 15m for me.

73.

Anonymous said...

I sense a business opportunity here for someone to provide transceivers in rural elevated locations accessible online to folk on a subscription basis. Of course, it doesn't beat actually being in a remote location with your own radio.

As a long-time resident of built-up urban areas, I share your dismay at this kind of noise Julian, and also have a secret dream of living somewhere rural.

Dave
AA7EE

g4ilo said...

Someone actually does provide this, Dave, so it can be done, though for me much of the interest in operating comes from using a station I've put together, which that wouldn't satisfy.

Perhaps some of the wealthier clubs could do this. The trouble with doing it in the UK, apart from the special permission needed to operate an unattended internet-connected station, is that the price of land is so expensive and there are rigid planning controls, so even after you've bought your mountain and paid for the electricity and phone to be laid on there, the local authority will probably refuse permission for the antenna mast.

What I need is someone who already has a bit of land with a mobile phone mast on it, who would be interested in selling it. :)

PE4BAS, Bas said...

Very interesting video Julian. I always tried to imagine why some stations do not hear me while I hear them loud and clear. Now I can. From the comments on your video I learned many stations have a noise level like this. I'm living in a rural location so I guess it's a great advantage when you're a radio amateur. I feel very lucky I do not have noise levels like this. 73, Bas

g4ilo said...

Hi Bas. Yes, this has indeed made me realize that this problem is more common than I imagined. Here in the UK people are trying to campaign against PLT devices, which are certainly a killer if you get one near you. But they are probably no worse than the combined effect of a dozen or so other electrical devices. Death by a thousand switched mode power supplies!

Theodore said...

This seems to be a worldwide problem.

I have a sked with a guy in Vancouver who has to wait for the local plasma TVs' to go QRT before operating.
But Julian is correct, it is thousands of devices which are doing the deed.
With a beam you can locate cities by the rise in noise alone. Perhaps we can get a new award, "Worked all switchmodes".

Like the nuclear arms race, once there are too many devices to stop, the next stage is defensive umbrellas.
Perhaps noise reduction techniques will be the new growth area in ham experimentation.
Luckily DSP and digital modes still gives us a way to operate.
Even digital voice modes are available.
If we can learn morse, we can figure out a solution HI.
Tnx Julian, 73s.

Steve Nichols said...

Hi Julian,

I sympathise - I live in the middle of a modern housing estate and noise is getting worse. To help overcome this I now have a stealthy external antenna mounted and hidden in a tree outside.

I have a run of RG213 coax which goes to an ugly balun of about 10 turns on a four inch former - this helps cut down noise.

The antenna at the moment is a 65ft inverted L with a 9:1 unun from Snowdonia Radio Company. it goes up a 10m fishing pole in the tree and then down at about 45 degrees. it is a great performer on 20m and above.

Noise levels compared with the attic dipoles as as follows:

40m (2 S points better)
20m (1 S point better)
17m (3 S points better)
15m (3 S points better)
10m (2 S points better)

I think outside antennas are going to have to be the way to go as the mains wiring is just reradiating all sorts of stuff from all over the estate.

Steve G0KYA