Monday, 29 April 2013

RFI in the shack

Not much to say to be honest, this seemed to creep up on me and was only evident when I became interested in aviation frequencies after looking at PlanePlotter as an interesting application. More  on my web site ( www, ).

I have been running a dual monitor system here for use with HRD mainly, however with my Planeplotter monitoring on the top screen I had the bottom screen available for other stuff. bottom monitor was full HD @1920 x 1080, the top being 1680 x 1050. As there was a format / size change to windows when I moved them between screens I was getting a bit fed up with the slight change of aspect ratio and the visible data in HRD when going to the lesser screen.

I have set up my system to receive data from aircraft transponders on 1090 MHz which I feed into the PlanePlotter servers, and thus leave my station on 24/7. To save power I reduced the power saving settings on my monitors to 20 minutes. Nothing special there.

An aircraft I was interested in came through Scottish ATC and control was passed to a local frequency to which i tuned my Icom IC706MkIIG. Noise on that frequency was horrendous. At that point the power saving cut in and switched off my monitors, and also switched off the noise. A quick test of each monitor showed the top beast was the troublesome on.

As I had won a raffle, the prize being £200 of Amazon vouchers the way forward was clear. I had another full HD monitor on another PC so I checked this for RFI - clear, so I ordered a new one. It arrived today and I swapped them over. WHAT A DIFFERENCE. even on the bands I thought were unaffected the background noise dropped dramatically. I had thought my monitors were all OK as I had checked them within the ham bands for spikes, however the general hash was missed.

All my monitors are LG, I stuck to this manufacturer to try and match colour balances, not really come to pass, the replaced monitor will now be coupled up to my new Raspberry Pi which I hope to receive for my birthday (Kids - hint hint).

I also checked using a SDR as a waterfall display and the main band of interference was right on the frequency I was interested in. I had planned to use my Funcube Dongle Pro + as a radio source with SDR-Radio to hunt down RFI, however I left in in my hotel room in the USA as on the final day of my holiday got gastro enteritis which cost me $297.00 for a doctor's visit and knocked me for 6. Needless to say it was not found and handed in by their housekeeping.

Said more than I thought - will stop rambling now