Category: Applications

Wired Article about Radiosonde (Weather Balloon) Hunting has recently run a short article about Roland F5ZV's hobby of radiosonde hunting. A radiosonde is a small box containing electronic sensors that measure things like wind, temperature, humidity and also give out a GPS location. The radiosonde is carried into the upper atmosphere by a weather balloon, and these probes are usually launched twice a day in many locations around the world by meteorological agencies. The data is useful for weather forecasting and research.

The wired article discusses the hobby of radiosonde hunting, which is the sport of using radios to hunt and collect the radiosonde as it bursts and falls back to earth. He also writes how he was able to convince the Swiss Meteorological agency to allow him to attach a GoPro to a radiosonde which allowed him to capture some interesting images.

We'd like to remind readers that in many places in the world it is possible to receive and decode radiosonde data with an RTL-SDR, and we have a tutorial available here.

Radiosonde in flight captured by a GoPro camera.
Radiosonde in flight captured by a GoPro camera.

Real Time Passive Radar Running Native on the ADALM-PLUTO ARM CPU

The ADALM-Pluto (aka PlutoSDR) is a US$149 TX/RX capable SDR that we have posted about several times in the past. It has a tuning range from 70 MHz to 6000 MHz with a bandwidth of up to 56 MHz (with software hack applied). One additional useful feature on the PlutoSDR is it's built in ARM CPU, which can be used to run programs on board the SDR itself. 

Over on his blog Mike has shown how he implemented simple passive radar code on the PlutoSDR's ARM processor. This means that no PC or other hardware is required to process the data, the entire script can be run via a SSH connection to the PlutoSDR. Mike doesn't seem to have shared his script anywhere, but one of his previous posts explains the process. The script creates the video in real time on board the PlutoSDR's ARM CPU, which is then streamed via ffplay to a PC with a screen. On his second post Mike shows some extra videos of passive radar working with FM Broadcast and DVB-T signals.

Passive radar is a radio technique allows you to detect and track RF reflective objects such as aircraft using strong signals from already existing transmission towers, such as broadcast FM or DVB-T signals.

Viewing Drone Signals with HackRF being used as a Wideband Spectrum Analyzer

Over on his YouTube channel user Andy Clarke has uploaded a video where he demonstrates his HackRF being used as a wideband spectrum analyzer with the HackRF Spectrum Analyzer software. About a year ago the HackRF team released a new firmware update which enabled the HackRF to be able to sweep through the frequency spectrum at a rate of up to 8 GHz per second. This allowed the HackRF to be used as a wideband spectrum analyzer which is able to display an arbitrarily large swath of spectrum. Shortly after the firmware update spectrum analyzer program by 'pavsa' was released on GitHub.

In the video Andy demonstrates the HackRF being used to view the WiFi band and show a 2.4 GHz WiFi connection between a drone and it's controller. He also shows it working with a handheld radio and the uplink of his mobile phone. Andy hopes to use the HackRF to avoid losing his drones due to interference.

SDR# TETRA Plugin Updated: No longer requires MSYS2

Last week we posted about the release of a new TETRA decoder plugin for SDR#. The plugin made setting up a TETRA decoder significantly easier compared to previous methods, but it still required the installation and use of the MSYS2 environment on Windows. 

Thanks to reader Zlati for letting us know that the TETRA plugin has recently been updated once again and now no longer requires MSYS2 to be installed first. Now it is as easy to install as any other plugin, just drop the .dlls into the SDR# folder and add the magicline to the plugins.xml file. We tested it out and decoding worked fine. At the moment the "Net info" button is not working however.

x64 plugin:
x86 plugin:

In the future news and download lines for newer versions will probably be available on the programmers forum thread which is available here (use Google Translate to read):

Updated TETRA Decoder Plugin
Updated TETRA Decoder Plugin

Receiving WSPR with an RTL-SDR V3 and with Automatic Band Changing

RTL-SDR V3 + Raspberry Pi WSPR Receiver
RTL-SDR V3 + Raspberry Pi WSPR Receiver

WSPR (pronounced "Whisper") is short for Weak Signal Propagation Reporting, and is a HF ham mode typically run on very low power levels such as 1W. The data from WSPR reception can be used to determine how good or bad HF propagation is currently around the world as each WSPR message contains a callsign, 6-digit locator and the transmit power level used. Received messages are all reported to the internet and can be viewed on an online map at

With an RTL-SDR V3 running in direct sampling mode it is possible to receive and decode these messages on a Raspberry Pi 3 using the WSPRD software.

Over on his website IT9YBG has uploaded a tutorial for a method that allows the WSPRD software to automatically change bands depending on the time of day. The method simply uses the crontab in Linux to automatically run a script that stops and then restarts WSPRD on a new frequency at certain times of the day. This is useful because different WSPR bands tend to become active at different times of the day due to changing HF propagation conditions.

WSPR messages received from all over the world.
WSPR messages received by IT9YBG from all over the world.

A Guide to Using SDR-Console V3 for Accessing and Creating Remote Servers

Jon Hudson, head of marketing at SDRplay has recently released a helpful tutorial that shows how to access remote servers in SDR-Console V3, and also how to set up your own server too. As you may already know, SDR-Console V3 provides a remote server platform which allows you to access all sorts of SDR hardware remotely over a network connection or over the internet. Some SDR hardware owners even opt to share their radio hardware publicly over the internet for anyone to access. The video description reads:

This video is a screen-by-screen guide to both accessing, and setting up your own, remote SDR radio using the new (Feb 2018) SDR Console V3 software from SDR-Radio. Although the guide uses an RSP2 from SDRplay, this will work with all the popular SDRs

Please note - you need to have a good internet connection since (unlike in V2), the entire I/Q data is being sent over the internet. This also limits how much visual bandwidth you are can see at any one time.

Links referenced in this video:
More videos on

Be careful not to plug multiple SDRs into a single USB2 socket - for multiple SDRs, you may need a powered hub ( like this: )

Once you are up and running - please go to and view your listing - if there is a yellow triangle, then you are not accessible outside your own firewall - attention is needed! Just because you can access it on your own LAN doesn't mean it's accessible via the internet!!!

The RSP family of SDRs from SDRplay cover 1kHz to 2 GHz with no gaps and give up to 10MHz spectrum visibility.

Jon's video first shows how to use SDR-Console V3 to access those publicly shared SDR radios over the internet. The second part of the video demonstrates how to set up your own server that you can use remotely for personal use, or to share over the internet.

The SDR-Console V3 server accepts various kinds of SDR hardware including RTL-SDR, Airspy, SDRplay, HackRF, Elad, LimeSDR and many more SDR units so this is a good way to explore various types of hardware, or simply to explore signals from different areas around the world.

SDR# Plugin: FFT Window Screen Grabber

Recently Eddie MacDonald has been pumping out simple but useful plugins for SDR# including the SDR# Dark Mode and Visual Tuner Knob plugins. Recently he released a new plugin called "FFT Window Screen Grabber". This plugin simply helps you to easily take a screenshot of the FFT and waterfall displays in SDR#. It could be a useful plugin if you are constantly finding interesting signals that you want to document, or upload to

The plugin can be downloaded from his thread in our forums. Note: Updated plugins now available at

FFT Window Screen Grabber example screenshot
FFT Window Screen Grabber example screenshot

RTLSDR-Airband V3 Released

Thanks to reader Lee Donaghy for writing in and little us know that RTLSDR-Airband was recently updated to include SoapySDR support. This allows the software to now work with almost any SDR including the RTL-SDR, Airspy, SDRplay, HackRF, LimeSDR and more. They have also removed the 8-channels per device limitation and applied various bug fixes too. The full changelog is posted at the end of this post.

RTLSDR-Airband is a Linux based command line tool that allows you to simultaneously monitor multiple AM or FM channels per SDR within the same chunk of bandwidth. It is great for monitoring narrowband communications such as aircraft control and can be used to feed websites like, or for use with a Icecast server, or simply for continuously recording multiple channels to an MP3 file locally. It is also very useful for those running on low powered computing hardware who want software that uses less CPU power than a full GUI program like GQRX or CubicSDR.

Version 3.0.0 (Feb 10, 2018):

  • Major overhaul of the SDR input code - now it's modular and hardware-agnostic (no longer tightly coupled with librtlsdr).
  • Support for SoapySDR vendor-neutral SDR library - any SDR which has a plugin for SoapySDR shall now work in RTLSDR-Airband.
  • Support for Mirics DVB-T dongles via libmirisdr-4 library.
  • Support for RTLSDR is now optional and can be disabled at compilation stage.
  • Removed the 8-channels-per-device limit in multichannel mode.
  • Configurable per-device sampling rate.
  • Configurable FFT size.
  • Support for multibyte input samples.
  • Support for rawfile outputs (ie. writing raw I/Q data from a narrowband channel to a file for processing with other programs, line GNUradio or csdr).
  • INCOMPATIBLE CHANGE: removed rtlsdr_buffers global configuration option; buffer count can now be adjusted with a per-device "buffers" option.
  • INCOMPATIBLE CHANGE: removed syslog global configuration option; syslog logging is now enabled by default, both in foreground and background mode. To force logging to standard error, use -e command line option.
  • Added -F command line option for better cooperation with systemd. Runs the program in foreground, but without textual waterfalls. Together with -e it allows running rtl_airband as a service of type "simple" under systemd. Example rtl_airband.service file has been adjusted to reflect this change.
  • Added type device configuration option. It sets the device type (ie. the input driver which shall be used to talk to the device). "rtlsdr" is assumed as a default type for backward compatibility. If RTLSDR support has been disabled at compilation stage, then there is no default type - it must be set manually, or the program will throw an error on startup.
  • Frequencies in the config can now be expressed in Hz, kHz, MHz or GHz for improved readability.
  • Lots of bugfixes.
  • Rewritten documentation on Github Wiki.