- Last Updated: Monday, 28 March 2022 07:23
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|On January 22, 2022, an automated tracking system for weather balloons, also called radiosondes, was commissioned at the Coti-Chiavari site. The set consists of a Raspberry 3, a USB RTL SDR, a 403 MHz band filter and an omnidirectional antenna. Everything was installed in a rack drawer in the main bay of the site. The first tests are encouraging, the receiver decodes the frames emitted by the radiosondes as soon as they are launched and until the loss of the signal which varies according to the direction taken by the balloon|
Even, if with nowadays smartphone and GPS, it is not as needed as before, it is still very usefull.
You can a nice Web page with a lot of possibilities on Patrick TK5EP's Web page.
Like me, you probably often needed to calculate a gain, loss or SWR when measuring powers or working on antennas. And when you are on the field, you never have the right calculator or forgot the right formula !
It's a long time i wanted to make a chart that could make me the life easier. I was thinking about a circular chart, but i never found the right tool with which i could do it easily. Until i found the GALVA software written by F5BU.
The result of my thoughts is presented below. This tool can calculate gain, loss, SWR and return loss in a second with enough precision for most amateur works.
The principle is simple, the powers are on 4 decade logarithmic scales, for a 40 dB range. The gain and return loss use the same 40 graduations linear scale and the SWR is a special scale responding to the SWR vs power formula.