[Milsurplus] Less stations or more noise?

[Ray Fantini]

What seemed like years ago I attended a school for ATSC training for Digital Television technology. The engineers from Zenith would demonstrate the ability of the digital signal to lock up and work at just twelve or so Db above the noise floor by using a calibrated digital (ATSC) source mixed with the output of a wide band noise source and instead of decreasing the signal source increase the noise floor until the signal was no longer decoded. At the time I thought that was crazy coming from the two way radio world where you decreased the output of the signal source to read sensitivity and seeing how they played around with the noise floor instead.
Think the important thing in all this is the idea of the noise floor and what's been going on with that. With the advent of all the modern sources of wide band RF noise out there the real affect is that the noise floor on the HF bands has increased several fold. Twenty or so years ago the noise floor was considerably less than it is today. In many developments and subdivisions the noise floor is so high due to RF pollution it's almost impossible to receive anything on the HF bands. Try listening to AM radio and see how much TI (terrestrial Interference) is on that band, It's a huge problem for the AM Broadcasters. In the last several years I have seen a migration of wide band noise that in some cases extends up to 100 to 120 MHz from a lot of the cheap solid state ballast used for florescent lighting.
The rising noise floor has a direct effect on your ability to receive and unless you live away from everything it's hard to escape. I live at least a five hundred feet from my neighbors but between the TV sets, devices like the latest generation of washing machines and other intelligent appliances I find operating from the home QTH not very satisfying. At least on the HF bands.
Maybe this is why I find that I have been operating more from remote locations with the mutt and find that to be more satisfying then the home QTH?
Noise floors at VHF, UHF and above are still somewhat quite with the exceptions of the non-licensed Wi-Fi channels. The FCC had a big push to eliminate all the old wireless microphone systems and other devices that operated in the old high sections of the UHF broadcast band to avoid any possibility of interference to the G3 and other new cell technologies that now live there. With the current proposed TV repack and all TV broadcasters being restricted to below channel 40 expect to see more new services
Coming soon. But don't think the FCC has any interest in protecting the noise floor in the HF band. Hate to give the ARRL credit for anything but maybe they are the only one helping to protect that resource?


Ray F/KA3EKH

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