7 Aug 2011

HF noise levels

It is sad how much the noise floor has risen at my QTH in the last few years. Listening on 160 and 80m is now almost impossible on a vertical because of the wideband noise that obliterates the band to an S8-9 level. The noise is there right through to above 17m. Thankfully 10m with the horizontal halo is still pretty clear. Apart from my experiments at VLF and LF I am now tempted to move back to the VHF/UHF bands for serious operation.


Anonymous said...

Sorry to hear your QRM problems.

Could this be the recipe for revival for VHF?

Sad to think that in the not too distant future we may see the HF bands only of use to those in quite rural locations.

Coupled with commercial takeover of our UHF/SHF bands for wireless connected electronic devices during the next twenty years, then maybe there will be more traffic on the 10 - 2m bands.

On the other hand, if the rate of decline in commercial communication and broadcast use of shortwave continues, in twenty years we may have lots of new space to use. Just think - we all become "freebanders" :-)

73 David, G8JGO

Roger G3XBM said...

You may be right David. Certainly lower HF band operation is becoming all but impossible for many now and it can only get worse. So, yes, maybe it's time to dust off the 2m and 70cm SSB gear (and organise some 23cm kit) and rekindle the fun we had back in the 1970s and 80s. Now where's that 9el Tonna?

Julian Moss said...

It's the same here, Roger. I have one strong source of QRN that wipes out 20m but mercifully that comes from one direction and can be drastically reduced with the MFJ noise eliminator. But there has been a steady increase in background QRN that is probably the combined effect of dozens of switched mode wall warts and other electronic paraphernalia in the neighbourhood and there is really nothing that can be done about it. Even the VHF bands are plagued with carriers that make listening for beacons an exercise in frustration. I wonder whether LF/HF/lower VHF amateur radio operation will be possible from urban locations in ten years time?

Roger G3XBM said...

Even on 10m I am getting far more WSPR reports than I give, I think because the local noise here is burying even weak WSPR signals at times. At the moment the noise level on 10m is S7, which is higher than usual.

Anonymous said...

It's also the same here Roger, the QRN is horrific on the low HF bands with noise levels of 9 + On my S meter most of the time. I have traced some of the noise to a local BT broadband modem. Directional Atenas seem to null the noise In some directions. I have had some success with active ferite rod and loop Antenas.
I need to finish off a copy of the S.E,M noise eliminator.
There's a project In SPRAT called the Plazma noise nuller
that looks like another solution to the problem.
It's not just a problem with Radio Ham it affects DAB Radio and WIFI links
If someone can get a 100K Hams and SWL's and radio users to sign a potition to parliament we could get a debate on it.

Kind regards


Anonymous said...

Thinking more about this problem leads me to conclude that we need a new branch of activity.

As part of a national strategy, the RSGB (or other independent group) could construct and install a network of remote, internet connected SDR receivers sited around the country in radio quiet areas and which have the capacity to handle many users.

The technology is all here, right now. What is needed is an engineering approach that puts remote receivers on 24/7 continuous duty on a par with the best of our current repeater network.

If there was such a body responsible for coordinating and designing such a network, then I'm sure funds would be available from fellow radio enthusiasts to assist.

I wonder how many caught up in the increasing QRM problems would be willing to contribute to the costs? Maybe if enough people were willing to pay a small annual subscription towards the operating costs of the network then it would be viable. The more users, the less the annual costs in a true cooperative spirit.

Just a thought.

David G8JGO

Roger G3XBM said...

Hi David

That is an interesting idea. Many would not agree with the use of remote receivers, but if the local noise is unbearably high this might be a solution. As you know there are quite a few internet connected SDRs around and I think you are suggesting a lot more of these be set up and run. I would like a few more on the LF bands (137kHz) as these are SO useful when band activity is low as they allow you to look for your own signal remotely.