After a short break Frugal Radio's ongoing series of SDR beginners guide videos is back, and in the latest episode Rob provides part one of a two part overview of some software available to use with software defined radios such as the RTL-SDR.
In the video he demonstrates general Windows based receiver programs like SDR#, SDRUno, SDR-Console V3, HDSDR, as well as multiplatform software such as SDR Angel, GQRX and CubicSDR. He finishes up by explaining the options available for virtual audio cable programs, which are required to pipe audio from general receiver programs to decoders.
GQRX is one of the most popular open source software choices to use with various SDRs on Linux and MacOS. Recently it was updated to version 2.13, bringing in a few new features and several bug fixes and performance improvements. From the GQRX news file, the changes include the following.
2.13.1: Released October 17, 2020
FIXED: Crash when invalid sample rate is specified. FIXED: Decrease minimum size of FFT Settings panel. FIXED: Typos. IMPROVED: More Airspy HF+ sample rates added.
2.13: Released October 16, 2020
NEW: Stereo option for UDP streaming. NEW: Script to generate AppImage. NEW: Allow scroll wheel direction to be inverted. FIXED: FM de-emphasis causing audio to be 20 dB quieter than it should be. FIXED: FM de-emphasis applied incorrectly in WFM stereo receiver. FIXED: Update waterfall time resolution when FFT settings are changed. FIXED: Update waterfall time resolution when window is resized. FIXED: Restore waterfall time span between sessions. FIXED: FFT buffer overlap calculation. FIXED: Crash when launching without device connected. FIXED: Crash when setting invalid RF gains. FIXED: Audio panadapter / waterfall slider direction. FIXED: Clear FFT averages when changing FFT size. FIXED: Crash when source block doesn't support IQ balancing. FIXED: Bookmark labels in FFT draw over each other. IMPROVED: DSP and FFT performance. IMPROVED: Panadapter & waterfall performance. IMPROVED: Smooth panadapter & waterfall redrawing. IMPROVED: Better default values for various settings. IMPROVED: Audio waterfall colormap matches I/Q waterfall. IMPROVED: Use all available display space for panadapter & waterfall. IMPROVED: Updated RDS decoder. IMPROVED: More Airspy HF+ sample rates added.
GQRX is a general purpose GUI based SDR program that is typically used most often on Linux and Mac computers, however it is still possible to install and use it on Windows. Over on YouTube M Khanfar has uploaded a tutorial video that shows a step by step guide on how to get GQRX running on Windows 10.
The process is a little long as it involves an install of Windows GNU Radio, Python, pip and various Python dependencies required by GQRX, as well as setting up the Windows PATH. If you prefer a text guide, the full tutorial is also typed out in the YouTube video description.
Thank you to M Khanfar for submitting another video where he demonstrates and explains how to easily send audio from your Linux PC over to an Android phone. This can be used to monitor the audio output of SDR programs like OP25 and GQRX remotely. The main piece of software used in his setup is the SoundWire Server and SoundWire Android App. SoundWire is described below:
Turn your Android device into wireless headphones / wireless speaker. Stream any music or audio from your PC to your Android phone, tablet, or other PCs. SoundWire does audio mirroring (audio cast). You can use any music player on your PC or laptop like Spotify, YouTube, or iTunes and stream low-latency live sound over WiFi directly to your Android device. Also works over 3G/4G cell networks or WAN.
M Khanfar's full tutorial on how to setup SoundWire can be found in the description of the video.
Piping Op25-GQRX Audio Through LAN to Android Phone
Since mid-January 2020 the popular Linux and Mac compatible SDR program GQRX has seen a number of new code commits over on it's git repository. Some of the updates include moving to GNU Radio 3.8, new color maps, as well as various bug and performance fixes.
At the moment these updates only appear to be available on the latest git code, so to get them you'll need to install GQRX from source via the instructions on the git readme.
Also thank you to @devnulling for providing us with the screenshot posted below which shows off the various new color maps available for the FFT waterfall.
Thank you to Happysat who has shared with us a useful tutorial that explains how we can run Linux only SDR programs on a Windows 10 system using the Windows Subsystem For Linux (WSL) feature. WSL is a feature available on Windows 10 which is a Linux compatibility layer designed for running Linux binaries natively on Windows 10. This means that no Virtual Machine with shared resources is required, instead the full resources of your system are available.
Many people using Windows 10 now since Windows 7 is EOL, and WSL is part of the system kinda "free" so why not use it :)
Together with a X-Server and and Desktop like XFCE4, it can be great for running SDR applications in Linux thru rtl_tcp.
Very fast startup in seconds and not much packet loss thru tcp, quite alot linux sdr applications are working very good.
No allocating resources like a VM.
Sometimes better then Ubuntu on a VM.
Software tested: AX-25 Packet Radio, Dab Radio, DSD, Es-Hail Beacon Tracker, Sat Tracking with Gpredict and Gqrx, NOAA Reception WxToImg, Radiosonde Decoding, Shortwave Reception and some more tips and tricks about WSl and SDR.
The steps appear to be fairly simple. Just enable WSL in the Windows 10 Features panel, download a Linux distro built for WSL and run the .exe file. Then you'll have access to a Linux terminal where you can install a GUI desktop environment, the RTL-SDR drivers, and other Linux SDR programs. Happysats tutorial shows how to install and use various Linux programs via WSL.
It seems that the RTL-SDR cannot be directly accessed via the USB in WSL, however, by the workaround is to simply run rtl_tcp in your Windows environment, and connect to the local IP in the Linux environment. This means that only programs that accept rtl_tcp as an input, or demodulated audio from a program like GQRX can be used.
Thank you to M Khanfar for submitting news about his custom Linux kernel which allows an RTL-SDR and GQRX to run smoothly and with sound on an Intel Compute Stick. The Intel Compute Stick is a full dongle based computer the size of a pack of gum with pricing that starts from US$120. It has a Quad Core Atom Processor, 2GB RAM, 32 GB of built in storage and an HDMI out port. By default the stick comes with Windows 10 installed, but M Khanfar notes that it is very sluggish.
Instead of the sluggish Windows 10 OS, M Khanfar decided that he wanted to run Ubuntu Linux instead. However he found that the standard Ubuntu image did not have support for audio over HDMI or WiFi on the Compute stick. So he built his own custom kernel with some patches to fix this issue. With the issue fixed, GQRX with an RTL-SDR now runs smoothly with full audio support, and rtl_tcp can also be run over WiFi.
Thanks to the work of Lucas Teske, GQRX is now able to connect to SpyServer servers. SpyServer is the IQ streaming server software solution developed by the Airspy SDR developers. It can support Airspy and RTL-SDR devices, and can be used to access these SDRs remotely over a network connection. It is similar to rtl_tcp, but a lot more efficient in terms of network usage, meaning that it performs well over an internet connection. On a previous post we have a tutorial about setting up a SpyServer with an RTL-SDR.
The code modified by Lucas is the gr-osmosdr module, and Lucas' code can be downloaded from his GitHub at github.com/racerxdl/gr-osmosdr. It doesn't yet appear to have been merged into the official osmocom branch. The gr-osmosdr module is a generic block used to access various SDR hardware, so any software that utilizes it (such as GNU Radio) should be able to connect to a SpyServer connection too.