08/21/2015 22:12

Full Spectrum


Well, after a few posts on Radio-activities throughout the Shortwaves, it worths spending a couple of words more on this.

By  FULL SPECTRUM among my group of friends, we mean making traffic occasionally on free frequencies on the Shortwaves. There are a few, inviolable, absolute, rules we gave ourselves: very low power (usually around 100 milliWatts or so), almost unitary gain antennas (wires, essentially), on Radiotelegraphy, far away on ANY other detectable signal, for experimental purposes.

We share many reasons that have brought us to this common choice.

The first is probably that we prefer using very elementary 'wireless sets'. In particular, receivers are regenerative, or signle conversion, or pseudo-domestic ones, like world receivers and so on. Often homemade, but not necessarily. Then, we need ample spaces in the Spectrum so we don't need filters for separating the signals: receivers would be much more simpler and cheaper. We soon discovered that a Direct Conversion receiver is all what is needed to stay in touch on the Shortwaves on moderate distances (a few hundred miles).

We all like going with Very Low Power (QRPp). After some tests, we've seen that about 100 milliWatts are just enough for short-range radiotelegraphy contacts if the proper frequency is choosen. We estimate an effectively radiated power  lower than that of most RF digital lines and devices freely used nowadays.

We all use very humble wires as antennas and if we choose freely our frequencies over the Spectrum, we always can pick up that one which maximizes the reception. It is not uncommon to receive the Correspondent with signals up and above S9!

Eventually, we all can't stand the continuous growing of some bad habits that typically can be encountered on the Radio Amateurs bands. I'm sorry to say that ... but this is a part of the truth.

On the Shortwaves you can hear fishermans talking on frequencies that are not those allocated to the Maritime Service. Pirate beacons. Pirate Broadcasters. Unidentified military stations. Broadcaster jammers (typically the Chinese ones) even though Jamming had been forbidden internationally (have you ever heard about some military expeditions against those jammers ? No, of course). Most of the times, the above transmissions are in conflict with some Institutional user of the Spectrum.

In our group we listen ... listen ... listen ... And then we chose that frequency that for a very short period will be used for our tests. Then the silence falls down again over there.

Till the next experiment. Maybe on another frequency or not. Who knows.

You will not read here not any time nor any frequency. They change of course.

What is of interest here is to let you know that the Shortwaves are nowadays featured by many empty zones, in which you don't hear any signal for weeks or even for months. And the trend is that more and more official users are shutting down their stations or are adopting new communication techniques that more efficiently use the Spectrum.

Put in whatever way you want, the Shortwaves are becoming emptier day after day.

And we decided to make some tests there. Always keeping an eye (or an ear ?) to make sure noone was doing traffic previously.

On whatever frequency will optimize our communication, but also our fun in operating our humble and uncertain equipment.


Try yourself ...


Radioman, August 2015


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