As Felix is learning about the weather as part of his curriculum in school these days, we tried to give it a more practical spin by hunting a weather probe. The weather balloon launches 2 times a day from Stuttgart fully automatic.
The predictor suggested it would land somewhere near Ulm. So we took the car, and drove along the autobahn A8 in direction to Ulm. Apart from temperature, pressure, and humidity, the probe (a Vaisala RS41) also sents its GPS position. So from time to time, we would stop to get a fix on the probe.
The last fix we received shortly before the probe dropped down at Illerberg in 630m height. At this point in time we were about 20 km away. Once the probe is on the ground, the distance from which it can be received drops down from 10th of kilometers to a couple of 100 meters. We quickly drove Illerberg trying to locate the probe to no avail. Assuming that the last GPS position of the probe is reasonably accurate, it should have landed in a nearby field, and we should have received it. Probably, somebody else was faster than us — that is the most likely explanation.
It was still a cool trip that both of us enjoyed. And we unanimously want to give it another go.
Gear:
- Notebook running gqrx (http://gqrx.dk/)
- RS41 software decoder (https://github.com/rs1729/RS)
- TV-Stick
- Yagi Antenna
- Pigtail to connect Yagi antenna to TV-Stick
- Yaesu VX-6 radio
- Predictor (http://predict.habhub.org)
- Inverter (12V->230V) to power the notebook
Hint:
To “connect” the gqrx output to the input of the decoder software, I turned on the UDP-streaming service of gqrx and used netcat to pipe the data into RS41 decoder. Here the command line:
nc -l -u localhost 60000 | sox -t raw -esigned-integer -b16 -r 48000 – -t wav – | ./rs41 –ecc –crc
