Skywave Linux
Software Defined Radio for Global Online Listening

What is Skywave Linux?
Supported SDR Types
Decoders and Digimodes
Usage and Installation
Apps for Coders
Command Line Tools
Technical Notes
Acknowledgements
System Integrity and Authenticity
Disclaimer
Special Notes and Bug Fixes
Apps in this Version of Skywave Linux

Skywave Linux... What's That?

Skywave Linux is an operating system using bleeding-edge technology to robustly access broadcast, utility, military, and amateur radio signals from almost anywhere in the world, including countries with restrictive internet environments. Skywave Linux is set up to connect easily to a large network of state of the art software defined radio (SDR) servers, making it possible to enjoy high performance SDR operation without putting up your own large antennas or on-site radio hardware. All you need to do is boot the system on a computer with internet connectivity, find a remote SDR server in your region of interest, and tune across the spectrum to find signals. Skywave Linux can also operate numerous types of SDR hardware, plugged into the your computer or on the local network. Downloading, installing and configuring SDR software can be difficult for many computer users; Skywave Linux eliminates the hassle by including several applications installed, configured, and ready to run.

Supported SDR Types

Several types of software defined radios are supported by Skywave Linux:

1. WebSDR servers are located all over the world and provide easy access to the global airwaves through the web browser. In Skywave Linux, the web browser is packed with a curated set of bookmarks linking to the best servers. Thus, a moderately broad internet connection is all one needs to enjoy clean, stable, AM / FM / SSB reception using this cutting edge technology. WebSDR servers at the University of Twente (NL) and G4FPH, Stafford (UK) are particularly good, for example.
2. KiwiSDR servers are a popular type of internet accessible radio, with hundreds operating at any time. Use the curated set of web browser bookmarks to access several excellent sites around the world, such as the server in Victoria, British Columbia (Canada).
3. RTL-SDR devices used on the local computer system. Just plug-and-play! CubicSDR, Gqrx, and SDRPlusPlus are the main applications for receiving AM / FM / SSB modes. Dump1090 (FlightAware version) is for monitoring aircraft ADS-B transmissions. ADS-B mapping is available with the help of Python3 libraries. ADS-B data is also logged to an SQL compatible database for further analysis if desired. ACARSDec and VDLM2dec are multichannel decoders for aeronautical VHF data modes. Each is capable of simultaneously monitoring several channels at once without scanning and also logging the data to an SQLite database file. RTLSDR-Airband is a hardware agnostic, multichannel monitor for AM or FM voice modes (not limited to airband), capable of simultaneously monitoring several channels without scanning, mixing and streaming audio locally (via PulseAudio) or to the internet (via Icecast server).
4. Ettus Research USRP devices, offering advanced features and high performance. Their hardware can cover frequencies from DC through 6 GHz in a diverse array of signal modes.
5. RemoteSDRClient connects to a network of shared RFSPACE SDRs. These are high performance radios, with advanced filtering and noise reduction software. Like the shared HPSDRs mentioned above, they require broadband internet connectivity for smooth operation.
6. SDRplay, Airspy, and BladeRF offer higher performance than RTL-SDR dongles. These devices feature stable and clean oscillators, sensitive front end circuitry, superior RF filters, broader RF bandwidths, and higher resolution ADC chipsets. CubicSDR and Gqrx are the applications built for running these devices.

The key to getting most SDR devices and software to function on Linux is having proper drivers installed. Skywave Linux broadly supports these with SoapySDR and Gr-OsmoSDR packages.

Decoders and Digimodes

For decoding RTTY, CW, PSK, WSPR, WSJT, RDS, and other digital radio transmission modes, use the Fldigi, JS8Call, and WSJT applications. Weather satellite decoding is possible with Noaa-apt for APT and Glrpt for LRPT. Gpredict provides real-time satellite tracking data and doppler corrected tuning control for Gqrx. In some cases it may be necessary to use the PulseAudio Volume Control application to select the best audio source and levels. Basic trunked radio systems may be monitored using SDRTrunk.

Conventional radio and video broadcast streams are also supported in Skywave Linux. VLC Media Player provides global access to music, talk, news, free-speech, and religious stations around the world. Editable playlists of IPTV and IPRADIO stations are located on the internet - available through most search engines. There is a sample radio playlist in the ~/Music folder.

Usage and Installation Options

Skywave Linux is intended to run as a live Linux environment, bootable from an iso image. The system may be installed as a persistent, uncompressed filesystem on your hard drive. Consider these options:

1. In Linux or Windows, create a bootable USB or SD card using Ventoy or Etcher. Ventoy is capable of creating multiboot drives, so you can set up multiple operating systems for different computing environments. See the Ventoy site for details!
2. Clone it to the hard drive as a regular, uncompressed operating system with the included linux-clone script.
3. Run the iso in a virtual machine under Virtualbox, VMware, or in Qemu.
4. TimeShift is installed. From the live environment, back up the system to a separate medium. Thence, restore the backup as an uncompressed filesystem to the medium you want to operate from in daily computing. Systemback is another option, with the same method: back up to a separate medium then restore onto your working medium.

Persistence: You may enjoy keeping files and settings through reboots by creating a persistent image file, with the name writable. It is also possible to create a whole partition, labeled writable, for persistent data.

It is not recommended to burn an actual DVD to run any live computing environment. It is far, far too slow! Use a flash drive or SSD. For ultimate performance, clone the environment to a regular uncompressed file system.

The Skywave Linux Desktop and Rofi menu.

Tiling a web browser and CubicSDR window.

Receiving BBC Radio 4 Longwave via official
stream and actual longwave on an SDR.

Enjoy fewer hassles and more automation
in Skywave Linux 4.

Apps for Coders

Python, Go, Bash, Perl, and Ruby are installed and Neovim is the editor for coding. It looks great. It is functional and streamlined for friction-free workflow. Jupyter Notebook is also installed, and it supports creation, testing, and sharing of applications written in Python, Go, and Bash. Just do it! Make the next leap in software defined radio by writing the next generation of DSP and firmware applications. Beginners and advanced coders will all enjoy the software creation tools available in Skywave Linux.

Command Line Tools

Skywave Linux contains a plethora of efficient and fast command line tools.

• Neovim and Nano are a pleasure to program in, in part, because they are so fast.
• Browsing the web is a breeze in text mode with W3M. Navigate pages with Vim-like keys and enjoy cleaner, stripped text using the Readability utility.
• Surfraw is a search tool providing well over a hundred different websites to access for information not easy to find on the major portals. You can look for aircraft in flight by registration or ADSB hex code, find answers to computing or math problems, or even do lookups of slang phrases or rumors appearing in the news.
• TwitGrid pulls multiple Twitter feeds and displays them as a broadsheet in Firefox. here, it is set up in "topics." You select a topic and watch five feeds, updated at regular intervals.
• Irssi is a terminal based internet relay chat (irc) application for anyone wanting to go "old school" in text based communication.
• lf is a fast and efficient terminal file manager. Navigate with Vim-like keys, with previews and user configurable management commands.
• fzf, ripgrep, and fd are tiny yet very effective tools for searching and organizing files or text. With these, you can reach into dozens or hundreds of files to recursively find words, phrases, code, or even terminal command history.

Technical Notes

Skywave Linux is a 64 bit system, built on a base of Ubuntu 20.04 LTS, with a few MATE Desktop applications and a very riced i3 Window Manager. It is the additional digital signal processing, networking, and signal decoding applications that set Skywave Linux apart from its original base distro. The default username is skywave and there is no password in the default system.

It is sometimes necessary for users to make encrypted connections which provide stronger privacy, security, and ability to circumvent censorship. For that purpose, Lantern, Psiphon, Sshuttle, Outline, and Wireguard client applications are installed. Skywave Linux intends to bash holes in censorship barriers.

Acknowledgements

Skywave Linux thanks the talented developers who create Ubuntu, Gqrx, Cubic SDR, Dump1090, Fldigi, WebSDR, and the many other components which help this distribution to exist. Skywave Linux also thanks the end users for selecting this distribution and hopes it is an asset to their radio monitoring endeavors.

Integrity and Authenticity of Skywave Linux

Great effort goes into making Skywave Linux safe and free of malware. To verify that your copy of the iso image file is authentic, undamaged, and unaltered, check the sha256sum against the official authentication document and verify the digital signature of Skywave Linux. The authentication document is available by the download link at Skywave Linux.com. Use the "Passwords and Keys" or equivalent application to check the signature. Import the Skywave Linux public key from pool.sks-keyservers.net or keyserver.ubuntu.com.

Disclaimer

Skywave Linux is provided as-is. No guarantees or warranties are applicable to Skywave Linux. Skywave Linux is derived from Ubuntu Linux, but not endorsed by or affiliated with Ubuntu or Canonical Ltd. End users bear all responsibility for compliance with applicable regulations relating to communications monitoring.

Special Notes and Bug Fixes

See the bugfixes page.

Integrated Changes for this Version of Skywave Linux

For older changes, visit the DOWNLOADS page.