NOAA using the SDRplay RSP2 and RTL-SDR for Receiving Weather Balloon Data

NOAA RSP2 setup for Receiving Radiosonde Data
NOAA RSP2 setup for Receiving Radiosonde Data

Over on the SDRplay forums there has been a post by a NOAA engineer showing how they are using SDRplay RSP2 units in the field for tracking their radiosonde weather balloons. A radiosonde is a small sensor package and transmitter that is carried high into the atmosphere by a weather balloon. It gathers weather data whilst transmitting the data live back down to a base stations. You can get data such as temperature, pressure, humidity, altitude and GPS location.

Bobasaurus' coworker launching a weather balloon.
Bobasaurus' coworker launching a weather balloon.

The NOAA engineer on the forum (handle 'bobasaurus') wrote SkySonde, which is the software used by NOAA to decode and plot data from the radiosondes. SkySonde is freely available for public download on the NOAA website. A PDF file showing how to use the SkySonde software with an RSP2 or RTL-SDR can be found here, and the full SkySonde manual is available here. The software consists of a client and server, with the server connecting to the RSP2 or RTL-SDR, and then sending data to the client. Both server and client can run on the same PC.

The hardware setup consists of an RSP2 (can be interchanged with an RTL-SDR), an Uputronics Radiosonde Filtered preamp and a Yagi antenna. Presumably a Yagi and LNA is not completely required, although the receivable range will be less. The RSP2 bias tee is used to power the preamp, and on a V3 RTL-SDR the bias tee should also work.

NOAA appears to use the iMet brand of radiosondes which transmit a Bell 202 signal. Bobasaurus writes that they transmit in the 401-405 MHz range. This video shows an example of such a signal. If you are in the US near an area that launches these iMet weather balloons you should be able to receive them. An alternative piece of software that supports iMet radiosondes is RS. For other radiosondes we have a tutorial that uses SondeMonitor available here.

SkySonde Radiosonde Software
SkySonde Radiosonde Software
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Mark Harris

A bit confused. There is a bold font notice on Skysonde client/server indicating it will not receive NWS radiosonde data, yet the article seems to suggest that is what NOAA is using. Can someone clarify please, thanks.

Tate Schrock

Quick question, has anyone tried this with a colinear, or maybe a di-pole by any chance?
Also, what does NOAA use, antenna wise, for communicating with their sondes?



I’m the one who wrote this software. We typically use a ~400 MHz yagi, as described on our website:

I have used a colinear antenna for our mobile vehicle tracking system.

Steve Barreres

What antenna is used on the radiosonde? Is it within the packaging of the transmitter or a trailing wire arrangement? Is there a picture available of it and do you know if it is linear or circular polarized?

I am going to be working on reception at my amateur radio station in Nassau County at the Suffolk County boarder, center of the island in Plainview.

Steve Barreres, K2CX


Over here in Germany no one uses yagis but simple verticals or just 70cm rubber duckys as a line of sight rx is no problem at all even over several 100miles. To track the sonde down to the ground means you have to be close by (up to 5 miles, most times less. good signals from further away means no good – sonde is way up in a tree for example) and there a vertical is more useful as you can hold your yagi while driving around. And again, the signals are LOUD.

Antennas on the sondes are simple 1/4lambda wire monopoles. Really nothing fancy, power is 50-100mW. Line of sight is the key.

For a map of the sondes in europe go to


I was totally unaware about standards so i received a radiosonde on 404.200 MHz, i installed SkySonde server+client but it did not decode it. Soon i discovered that there are different brands with different standards so i installed SondeMonitor.
Here is what i received a few minutes ago.
Still have to lean how to trace the path on a map


is there a live map showing radiosonde positions in real time?

Tate Schrock

No. Unless you are not from the US.