YAAC is not Yak

YAAC is not Yak but Gnu, you really ought to k-now wa-who's wa-who. YAAC is - Yet Another APRS Client written in Java under GNU license. YAAC, I'm quoting here - "can be used as a stand-alone APRS client, an APRS RF-Internet gateway (I-Gate), or as a AX.25 digipeater". It doesn't matter what does this even mean but this app can actually be used to display multiple weather sondes at the same time on a map.

How to receive and decode multiple weather sondes with only one RTL-SDR receiver (Part 2)

As I finished the first article I got a tip from Zilog80 that he has finished a preliminary version of his iq_server concept. iq_server is a kind of a channelizer that allows clients to connect over TCP and request decimated baseband IQ stream of floats for a specific frequency offset. I was really excited to learn about his work because it would allow to allocate/dispose decoding processes upon request dynamically!

How to receive and decode multiple weather sondes with only one RTL-SDR receiver

Note: there's part 2 to this article with the script updated for performance

It could sound strange but I haven't seen a simple solution that would allow me to receive and decode multiple weather sondes at the same time with only one receiver. dxlAPRS software has a channelizer if I'm not mistaken but the software itself is too complex and is designed for things I'm not even interested in. auto-rx on the other hand would require a receiver per frequency. But is it a problem to get me more RTL-SDR dongles to receive as many sondes as I like at the same time? No, getting an RTL-SDR dongle is not a problem, the problem is the antenna - each dongle would require one. So either I would have to install as many antennas as dongles or I would have to use an antenna splitter. And without an amplifier (LNA) a splitter would reduce signal power by a number of its outputs. So both solutions would require additional hardware and investments. But then I had an idea that it should be possible to build a very simple (and very inefficient of course) channelizer even in bash by multiplexing IQ samples baseband stream into multiple decoding processes.

Radiosonde Hunting

There are over hundred of weather sondes sent over the Europe each day from different locations for weather forecasts and other scientific or military purposes. Weather sondes are expendable electronic devices to measure wind speed, air temperature, humidity and pressure. Sondes attached to a balloon filled with hydrogen or helium ascent up into the stratosphere where the balloon bursts and the sonde falls down back to earth with a parachute.