Tagged: gnu radio

GNU Radio World: Browser-Based GNU Radio Flowgraphs

Thank you to Marc Lictman, vice president of GNU Radio, for writing in and sharing with us his new project called "GNU Radio World," which is essentially GNU Radio Companion in a web browser, written in WebAssembly.

If you're not familiar with it, GNU Radio is a very popular free and open-source toolkit for implementing digital signal processing algorithms and applications. It lets you experiment with and build radio receivers, transmitters, and DSP chains through a graphical block-based flowgraph.

Marc Lictman writes:

I thought your readers might be interested in the relatively new website that I put together, https://gnuradioworld.com, as it is starting to have some nice RTL-SDR support, e.g. there is a basic spectrum analyzer and a full ADS-B application with map, but the best part is that it's really just GNU Radio in the browser so you can assemble your own flowgraphs and play around without installing anything, either with live USB SDRs, signal recordings, or simulated signals. It runs entirely client-side and comes with several out-of-free modules (OOTs), including gr-adsb by Matt Hostetter.

The other nice part about GNU Radio World is it comes with dozens of example flowgraphs (see tab on the left) as well as a bunch of example IQ recordings that can be used in place of the typical File Source block, and when you run the flowgraph it streams the IQ to your browser, a lot of the IQ recordings are used in the example flowgraphs to show off various OOTs functionality.

The whole project is free and open source (GPLv3), I think that it will be especially valuable for those learning RF signal processing, and those without a Linux background who want to jump straight into learning GNU Radio. Here are some specific example flowgraphs that may be of interest to RTL-SDR enthusiasts:

If anyone wants to reach out, they can email [email protected] or join the Discord server linked at the top of the site.

We test-drove GNU Radio World with both RTL-SDR Blog V3 and V4 dongles and found it to work well. However, it seems that V4L support has not been added yet. We have forwarded this feedback to Marc, so hopefully it will be supported soon.

GNU Radio World Browser Flow Graph
GNU Radio World Browser Flow Graph
GNU Radio World Running an RTL-SDR Blog V3
GNU Radio World: Running an RTL-SDR Blog V3

Exploring the Art and Science of Spectral Painting with SDR

Thank you to Paul Maine, who wrote in and wanted to share some experiments he and Gary Schafer have been doing with spectral painting. Spectral painting is the art of drawing pictures directly on the spectrum waterfall, which a software-defined radio makes visible. Paul has written the post below:

What happens when radio technology meets digital artwork? The result is something fascinating called Spectral Painting—the ability to create images that appear inside the radio frequency spectrum.

Gary Schafer (@signalgalaxiesunlimited) and Paul “The SDR Guy” Maine (@paulmaine6433) have teamed up to explore this unique combination of software-defined radio, signal processing, and creativity. Together, they have created companion videos on Spectral Painting and released them at the same time, each approaching the topic from a different perspective. For the best experience, it is recommended to watch Gary’s video first, followed by Paul’s practical demonstration.

Gary begins the journey by diving into the theory behind Spectral Painting. Using GNU Radio flowgraphs and GNU Octave scripts, he explains how images can be transformed into signals and displayed within the frequency spectrum.

Paul then takes Gary’s GNU Radio flowgraph and GNU Octave scripts from theory into practice. Using multiple SDR platforms, he demonstrates how to transmit spectral images using both the HackRF and TRX-DUO SDRs. He then completes the process by receiving and displaying the images using several different SDR receivers, including the RTL-SDR V3, RTL-SDR V4, and Airspy HF+.

Together, these videos provide a complete journey—from understanding the science behind Spectral Painting to seeing it come alive on real SDR hardware.

Below is an example screen capture of Spectral Painting in action.

Spectral Painting Example
Spectral Painting Example

Start with Gary’s video to learn the concepts and signal processing techniques:

Creating Spectral Paintings using Gnu Radio Companion (and other open source tools)

Then watch Paul’s video to see Spectral Painting transmitted and received using real SDR equipment:

E30 Spectral Painting

Creating a Spectrum Analyzer with Zoom Capability with an RTL-SDR in GNU Radio

Thank you to Paul Maine "The SDR Guy" for submitting his latest video showing how to create a simple spectrum analyzer with zoom capability, using an RTL-SDR and GNU Radio. Paul writes:

Zoom capabilities are discussed in the 3rd edition of Richard G Lyons “Understanding Digital Signal Processing” book. This is a novel approach when compared to other YouTube videos about creating a Simple Spectrum Analyzer with an RTL-SDR.

Additionally, in the video, Paul explains what a spectrum analyzer is and what it's used for, as well as explaining the use of attenuators and discone antennas. In the video, Paul uses an RTL-SDR Blog V4, but has mentioned that an RTL-SDR Blog V3 would work well too.

E19 Create a Spectrum Analyzer with Zoom Capabilities

Reverse Engineering the RF Communications on a 27 MHz RC Toy with an RTL-SDR and GNU Radio

On his blog, Jacob has recently uploaded an interesting post showing how he used an RTL-SDR to reverse-engineer the 27 MHz RF communications protocol used by his kids' RC toy truck.

To reverse engineer the protocol, Jacob used GNU Radio to visualize and demodulate the signal. He discovered that it was modulated via Amplitude Shift Keying (ASK), and viewing the waveform in a time-domain plot confirmed the on-off nature of the signal. Next, using symbol sync and thresholding blocks, he generated a bit pattern, which was then processed using Python.

Reverse Engineering the RC Toy Truck 27 MHz Signal
Reverse Engineering the RC Toy Truck 27 MHz Signal

An Introduction to SDR’s and GNU Radio using an RTL-SDR

Thank you to Paul Maine for submitting his latest YouTube video titled "Introduction to SDRs and GNU Radio Using an RTL-SDR". The video introduces the RTL-SDR and GNU Radio, and then proceeds to demonstrate how to build a simple FM receiver using GNU Radio. Paul goes on to explain some further concepts, such as sampling, aliasing, interpolation, decimation, upsampling, and finally shows a few more example receivers built in GNU Radio.

E18 Introuction to SDR's and GNU Radio Using an RTL-SDR

Understanding Single Sideband Modulation Through GNU Radio and RTL-SDR

Thank you to Paul Maine for writing in and sharing his latest tutorial video, which explains how Single Sideband (SSB) modulation works. In the video, Paul explains the concept and mathematical principles behind SSB by showing how to create an SSB receiver using GNU Radio and an RTL-SDR.

Paul writes:

Paul Maine “ The SDR Guy” recently released a video about Single Side Band (SSB). 

The SDR Guy shows how to create a single sideband receiver using GNU Radio and an RTL-SDR. He also shows how to modulate SSB signals. Paul collaborated with Gary Schafer in the production of this video. Gary has created a must read blog post on SSB.

Paul answers the question: What is SSB and what’s the advantage when compared to Amplitude Modulation. He used SDR++ to capture an IQ file using an RTL-SDR and his HF antenna and is included in his resources. This allows you to use the resources he has provided to demodulate SSB even if you don’t have an HF antenna.

In fact, you don’t even need to have an SDR. A GitHub link is provided in the video description to all flowgraphs and IQ files discussed in the video. Lastly, The SDR Guy has included a complete Upper and Lower Side Band receiver that’s implemented in GNU Radio using an RTL-SDR!

Be sure to look at his YouTube Channel (paulmaine6433). He has many other SDR related videos.

E17 Create Single Sideband Receivers with GNU Radio and RTL-SDR

An SSB receiver in GNU Radio
An SSB receiver in GNU Radio

Tech Minds: Making your own SDR Software With GNU Radio Companion

In his latest video out on YouTube, Matt from the Tech Minds channel gives us an overview of GNU Radio, and shows a few examples of how it can be used to receive, transmit and decode digital data.

GNU Radio is a popular open source DSP framework for software defined radios. With it you can graphically implement any sort of digital signal processing chain that you like, which can be used for decoding/encoding and demodulating/modulating signals.

GNU Radio can be extremely complex and powerful, but in the video Matt shows some simple starter example flowgraphs like an LSB demodulator, and a simple wav file source transmitter for the HackRF. 

How To Make Your Own SDR Software With GNU Radio Companion

Reminder: GNU Radio Conference 2023 Starts September 5 MST

This is a reminder that GNU Radio Conference 2023 (GRCon23) will be starting tomorrow on September 5 in Mountain Standard Time (MST) and will run until September 9.

GNU Radio conference talks are generally about cutting edge radio research topics and applications that involve the use of GNU Radio, a popular DSP framework for SDRs. If you are interested, previous years talks can be found on the GNU Radio YouTube channel.

The talks at GRCon23 will be livestreamed on YouTube for free, and we have pasted the links to each days live stream link below. We recommend activating YouTube notifications on each video so you won't miss the start.

There is also a virtual conference chat available. Links to the various rooms are available on the participants guide website.