Applications
35 programs on Ubuntu 26.04 LTS, with the version each one has in the 0.1 ISO, and how-tos to get going.
Plug in an RTL-SDR dongle and these hear everything from FM broadcasts to the aircraft overhead. For shortwave, see the stations page.
A software-defined radio receiver with a spectrum display and a waterfall. Click a signal to tune it in. It has AM, FM, SSB and CW demodulators, records audio and raw I/Q, and works with RTL-SDR, Airspy, HackRF, Funcube and USRP devices.
Open Third icon in the dock
On Flathub for Gqrx dk.gqrx.gqrx
The command-line tools for RTL2832U dongles. rtl_test checks one, rtl_fm turns a channel into audio, rtl_tcp shares the dongle over the network and rtl_power sweeps a band.
Try it
rtl_test -tProject site for RTL-SDR tools rtl-sdr
Build your own receivers and decoders as flowgraphs of signal-processing blocks, in GNU Radio Companion or in Python.
Open Run gnuradio-companion
Project site for GNU Radio gnuradio
Digital radio: DAB and DAB+ broadcasts through an RTL-SDR or Airspy.
On Flathub for welle.io io.welle.welle-gui
Decodes the small transmitters on 433, 868 and 915 MHz: weather stations, thermometers, tyre-pressure sensors and doorbells, more than 200 kinds in all.
Try it
rtl_433
# The same, one JSON object per message
rtl_433 -F jsonProject site for rtl_433 rtl-433
Decodes the ADS-B position reports aircraft send on 1090 MHz and shows them as a live table in the terminal.
Try it
dump1090-mutability --interactiveProject site for dump1090 dump1090-mutability
Sound-card modes. Each one decodes audio, from Gqrx or from a receiver plugged into the computer.
FT8, FT4, WSPR, JT65, MSK144 and the other weak-signal modes. FT8 on 14.074 MHz is the busiest corner of the HF bands, and the wallpaper is a picture of it. Needs the clock within a second of the right time; [chrony](#station) sees to that.
Open Fifth icon in the dock
On Flathub for WSJT-X io.sourceforge.wsjt.wsjtx
Keyboard-to-keyboard messaging on FT8’s modulation, with relays through other stations, for signals too weak to hear.
Open Sixth icon in the dock
On Flathub for JS8Call com.js8call.JS8Call
A modem for the older sound-card modes: PSK31, RTTY, Olivia, MFSK, DominoEX, Hellschreiber, Throb and CW.
Open Fourth icon in the dock
On Flathub for fldigi com.w1hkj.fldigi
Slow-scan television: pictures sent as sound, including the ones the International Space Station sends during ARISS events, and digital HamDRM images.
On Flathub for QSSTV net.qsl.QSSTV
A software TNC for APRS and AX.25 packet radio. It decodes position reports, weather and messages, and works as a KISS TNC for the Linux AX.25 tools in ax25-tools.
Try it
# APRS on 144.390 MHz (North America; 144.800 MHz in Europe)
rtl_fm -f 144.39M - | direwolf -r 24000 -D 1 -Project site for Dire Wolf direwolf, ax25-tools
Decodes many digital transmissions from audio: AFSK1200 packet, DTMF tones, Morse, EAS alerts and more.
Try it
# The same APRS packets, decoded another way
rtl_fm -f 144.39M -s 22050 - | multimon-ng -t raw -a AFSK1200 /dev/stdinProject site for multimon-ng multimon-ng
A general-purpose audio FSK modem: Bell 103 and 202 at 300 and 1200 baud, RTTY at 45.45 baud, or any rate you give it.
Try it
# Listen for RTTY on the default audio input
minimodem --rx rttyProject site for minimodem minimodem
Learn it, translate it and play it. fldigi, in the dock, decodes it off the air.
Type text and see it in Morse, or type dots and dashes and see the text.
On Flathub for Telegraph io.github.fkinoshita.Telegraph
Lessons in Morse code, up to high-speed telegraphy.
On Flathub for Morse io.github.teacond.Morse
Plays text as Morse code through the sound card, at the speed you set in words per minute.
Try it
echo "CQ CQ DE N0CALL" | cw -w 18Know when the ISS and the amateur satellites are overhead, and where to point.
Tracks satellites in real time and predicts their passes. Through Hamlib it can correct your radio for Doppler shift and steer an antenna rotator.
Open Seventh icon in the dock
On Flathub for Gpredict net.oz9aec.Gpredict
A 3D globe with the whole CelesTrak catalogue moving on it in real time.
On Flathub for OrbVis io.github.wojciech_graj.OrbVis
The log, the radio’s memory channels, and the clock and position the digital modes rely on.
A logbook for your contacts, with rig control through Hamlib, a DX cluster window, and uploads to LoTW, eQSL, Club Log and QRZ.com.
Open Eighth icon in the dock
On Flathub for QLog io.github.foldynl.QLog
Signs your log for the ARRL’s Logbook of The World (LoTW), where confirmed contacts count toward awards.
On Flathub for TrustedQSL org.arrl.trustedqsl
Programs the memory channels of handheld and mobile radios, hundreds of models from Baofeng to Yaesu, over a USB programming cable. To open the cable, your user must be in the dialout group.
On Flathub for CHIRP com.chirpmyradio.chirp
Controls radios and rotators over CAT. rigctl reads and sets the frequency, and rigctld shares one radio with WSJT-X, Gpredict and QLog at once.
Try it
# Every radio Hamlib knows, with its model number
rigctl -lProject site for Hamlib libhamlib-utils
Keeps the clock right. FT8 and JS8 need it within a second of UTC. The system clock is set to UTC, as radio logs are.
Try it
chronyc trackingProject site for chrony chrony
Reads a USB GPS receiver, for your position and, through chrony, the time without the internet. See gpsd’s time service how-to.
Recordings, internet radio, and the browser that opens on a live map of who hears whom.
Opens on PSKReporter’s map of who hears whom, with bookmarks for WebSDR receivers, the ARRL band plan, QRZ.com, Priyom, The Conet Project and ENIGMA 2000.
Open Second icon in the dock
On Flathub for Firefox org.mozilla.firefox
Records and edits audio. Its spectrogram view shows a recording the way a waterfall does.
On Flathub for Audacity org.audacityteam.Audacity
Records, converts and plays audio from the terminal, with rec, play and sox. Ubuntu builds it from sox_ng, the maintained fork.
Try it
# Ten seconds from the default input
rec -c 1 recording.wav trim 0 10Internet radio, from a directory of over 50,000 stations. Despite the name it does not tune the shortwave bands; Gqrx does that.
On Flathub for Shortwave de.haeckerfelix.Shortwave
For your files and accounts, never for the air: amateur rules forbid messages encoded to hide their meaning. See before you transmit.
OpenPGP encryption and signing from the terminal.
Open Run gpg
Project site for GnuPG gnupg
A window onto GnuPG: make and manage keys, and encrypt, decrypt, sign and verify files.
On Flathub for Kleopatra org.kde.kleopatra
A password manager that keeps everything in one encrypted file.
On Flathub for KeePassXC org.keepassxc.KeePassXC
Encrypts files and folders with XChaCha20 and Argon2id, with optional Reed-Solomon error correction against damaged media.
On Flathub for Picocrypt NG io.github.picocrypt_ng.Picocrypt-NG
Prints only the secret part of an OpenPGP key, short enough to keep on paper.
Try it
gpg --export-secret-key YOURKEY | paperkey --output key.txtProject site for paperkey paperkey
Shamir’s secret sharing: splits a secret into shares so that any few of them, and no fewer, put it back together.
Try it
# Five shares, any three of which recover the secret
ssss-split -t 3 -n 5
ssss-combine -t 3Makes QR codes from text, in the terminal or as PNG images.
Try it
qrencode -t ansiutf8 "CQ DE N0CALL"Project site for qrencode qrencode
How-tos
Short recipes for the things people do first. The commands run in Terminal, which is in the Apps grid.
Plug the dongle into a USB port and check that Number Stations sees it. rtl_test names the tuner it found; press Ctrl+C to stop it.
Terminal
rtl_test -tThen open Gqrx from the dock. The first time, it asks which device to use: pick the Realtek dongle and click OK. Tune to a local FM station, set the mode to WFM (stereo), and press the power button at the top left to start receiving.
Only one program can use the dongle at a time. If one says the device is busy, close the other.
FT8 stations send for about 13 seconds in 15-second slots, so the clock has to be right. Check it first; chrony keeps it there.
Terminal
chronyc trackingConnect a receiver’s audio to the computer, tuned to 14.074 MHz in USB, and open WSJT-X from the dock. In File ▸ Settings, enter your callsign and grid locator, and on the Audio tab choose the input the audio arrives on. To feed it from Gqrx instead, with a dongle that reaches HF, choose the monitor of the output Gqrx plays to.
Decodes fill the Band Activity list every 15 seconds. On the Reporting tab, Enable PSK Reporter Spotting puts what you hear on the PSKReporter map Firefox opens on.
APRS stations report their position, weather and short messages on one VHF frequency: 144.390 MHz in North America, 144.800 MHz in Europe. With a dongle and a VHF antenna, Dire Wolf decodes them in the terminal.
Terminal
# North America; use 144.8M in Europe
rtl_fm -f 144.39M - | direwolf -r 24000 -D 1 -rtl_fm hands Dire Wolf audio at 24,000 samples a second, its default rate. Press Ctrl+C to stop.
Airliners broadcast their position, height and speed on 1090 MHz. With the dongle’s own antenna near a window, dump1090 lists the ones in range and updates the table as they move.
Terminal
dump1090-mutability --interactiveOpen Gpredict from the dock and fetch fresh orbits first, with Edit ▸ Update TLE ▸ From network. Then set where you are in Edit ▸ Preferences, under Ground Stations.
The map and the list show where each satellite is now. Right-click the ISS to see its future passes over you. During ARISS events it sends slow-scan pictures on 145.800 MHz FM, which QSSTV decodes from Gqrx’s audio.
Make an OpenPGP key in Kleopatra or with gpg, then print just its secret part with paperkey. For a passphrase that must survive one lost copy, split it with ssss so that any three of five shares bring it back.
Terminal
gpg --full-generate-key
gpg --export-secret-key YOURKEY | paperkey --output key.txt
# Any 3 of 5 shares recover the passphrase
ssss-split -t 3 -n 5None of this goes on the air; see before you transmit.
On an installed computer, Ubuntu’s packages update with apt and the Flathub apps with Flatpak. Software does both for you, or use the terminal.
Terminal
sudo apt update && sudo apt upgrade
flatpak updateThe source repository also rebuilds the ISO every month with the newest packages and security fixes; those builds are on GitHub Actions.