Hey guess what? I "sonde" you up in a tree!

 

Each year in the United States, there are over 70,000 balloon based "sondes" launched by the National Weather Service.  From locations from around the country, multiple times a day these are launched and they each transmit back weather data back down to ground stations.

It is easy to receive the 400-405 MHz signals from these balloons and this is what we will cover here

It is easy to use an inexpensive RTL-SDR device and a modest antenna to receive the balloon signals line of sight. Before you even get started with building your own ground station, you can check out networks of these stations such as the ARDC backed www.sondehub.org 

Looking at your area you will see launch and receiver sites, plus those interested in tracking them once they land.  Some hunters put some nice stories up once they find them.   

If the weather interests you and you are looking for some other signals to find if you also are interesting in radio direction finding, you may have just found yourself a new side hobby. Here are some of the Grafana based analytics from Sondehub.

Getting Started:   You have the pieces. Now what?

To build a ground station for radiosonde tracking, you will need:

• A Raspberry Pi (3B or later is best)
• An RTL-SDR (Suggest the RTL-SDR V3 or V4)
• A UHF antenna (1/4 wavelength is small. Look it up)
• Auto-RX software
• A place to put your system which will need to be on 24/7

There is a great Wiki for setting everything up from a software perspective, so no need to summarize. It is a big project with great documentation. https://github.com/projecthorus/radiosonde_auto_rx/wiki 

Figuring you are starting with a fresh SD card, once you install Raspberry OS, the rest of the steps should have you up and running in less than an hour or faster.

Give some thought to your antenna though first. If you are an amateur radio person, you do not want to transmit where it may interfere with your new ground station. Some inexpensive filters help here, plus improves the overall results anyway. A nice double benefit.

Here are reception results from the author location for last 24 hours of launches from the Albany NY launch location.  Once balloon has landed and the other is still floating around. 

Not sure what else to share, but beyond using Auto-RX,  you can also use SDRangel to receive radio sonde data too, which is nice if you plan to go portable or mobile.  There was reason to include radiosonde capability in the SIGpi project too, so feel free to look into that also.

Until next time....

Steve K2GOG