Sky chart

[hb9tmc]

Living in an alpine valley, I don't have a very good view on balloons, because the mountains reach high into the sky, up to 40° elevation.

So I was quite surprised to see that I can receive balloons which are actually behind the mountains, with no direct line of sight. I suspect it could be from reflections off mountains, or mountaintop-scattering (knife-edge diffraction).

To understand the phenomena better, i hacked together this python script, to plot the SNR in relation to the position in the sky.

Maybe someone finds this useful or interesting. I would be interested in plots from other receivers. Just set the path to log file and set your latitude/longitude/altitude.
If you merge log files, you have to remove the header lines from the succeeding log files.
It might contain bugs or errors, I'm quite new to this.

73
Stefan

[thebaldgeek]

Stefan,

This is awesome. Thanks so much for posting this.
When I got my auto_rx station up and running I wondered about how optimized it was and what the antenna gain pattern was.
I wrote some Node-RED code to take the Chasemaper output and using some code that Mark pointed out, normalized the SNR and distance over a curved earth.
In short, like you, I sort of built a giant antenna test range using 100's of sonde flights to build a profile of my antenna and radar plot of my stations coverage.

If I get some time, I look forward to testing your script out.

Thanks again.

Ben.

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