Hackaday Supercon 2024: Tracking Down Radio Transmissions

Talks from the Hackaday Supercon 2024 conference have recently been uploaded to YouTube, and one interesting talk by Justin McAllister and Nick Foster is about tracking down radio transmissions.

The talk focuses on using SDR hardware such as the RX888, RTL-SDR, and Airspy devices combined with directional antennas for radio direction finding. Interestingly, they also discuss using ultrasonic microphones to find power line noise from bad transformers or insulators. The talk also focuses on ensuring that your SDRs receive real signals and what noise might look like on the spectrum.

This talk provides a comprehensive guide to identifying and locating radio transmitters. Learn about practical techniques, common tools, and methodologies from decades of combined experience finding, squashing, and mitigating against radio frequency interference.

Supercon 2024: Justin McAllister and Nick Foster - How to Track Down Radio Transmissions

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SkyRoof: New Ham Satellite Tracking and SDR Receiver Software

Recently VE3NEA has released a new Windows program called "SkyRoof". SkyRoof is both a satellite tracking and SDR receiver program. It supports the RTL-SDR as well as Airspy and SDRplay devices.

The software is designed for tracking and receiving ham radio satellites, and it can provide detailed information about all ham satellites, tracking them in real time, and provide pass prediction. It also shows a skymap and SDR waterfall display. The receiver software supports demodulation of SSB/CW/FM, and it automatically compensates for doppler. It can also interface with antenna rotators that support hamlib.

SkyRoof Satellite Tracking and SDR Receiver Software Screenshot
SkyRoof Satellite Tracking and SDR Receiver Software Screenshot

Over on YouTube Johnson's Techworld has also recently uploaded a video showing him testing out Skyroof, which may be of interest to some.

Brief review of SkyRoof, the latest satellite tracking software!

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Open-Source 0.1–3 GHz Network Analyzer using ADALM Pluto SDR

Thank you to RTL-SDR.COM reader MAKA for writing in and sharing his project with us, an open-source 0.1 - 3 GHz network analyzer using an ADALM PlutoSDR and a $15 RF bridge. The system allows you to measure S21 (insertion loss/gain) and S11 (return loss) with real-time visual feedback. MAKA writes:

Key features include:

  • FFT-based FIR filter for precise measurements
  • Simple S21 and S11 calibration workflows (LOAD & OPEN)
  • Real-time plots with smoothing and raw-data toggles
  • Interactive markers for easy dB/frequency annotations
  • Automatic export of calibration data to .xlsx for offline analysis
  • Fully open-source

The complete open-source code for the project is available on GitHub at  https://github.com/fromconcepttocircuit/pluto-network-analyzer

Over on his YouTube channel, MAKA has also uploaded a video demo and walkthrough.

RF Bridge Turns Your Pluto SDR into 0.1-3GHz Network Analyzer(Pt.1: S11/S21 Fund. & Filter Test)

Pluto Network Analyzer Pt. 2: S11 Calibration, Python Code & RF Bridge Performance

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AEDA: Crowd Sourced RTL-SDR Spectrum Analysis and TDoA Direction Finding Platform

Recently, we've seen posts on X about a new service called "AEDA" (Advanced Electromagnetic Detection Application). This crowd-sourced web service utilizes RTL-SDR dongles as the RF reception hardware. The software can use multiple RTL-SDRs distributed around a city area for spectrum analysis and TDoA (Time Difference of Arrival) radio direction finding.

The service uses RTL-SDR dongles connected to Raspberry Pis as RF monitoring hardware. In the web UI, a user can initiate a spectrum scan using any of the distributed RTL-SDR nodes available to them. It can also automatically detect popular modulation types such as WBFM, NBFM, DMR, and P25.

A user can also initiate a TDoA scan to localize the source of a particular signal. This requires at least three RTL-SDR nodes to be distributed with good geometry around the signal source. The service synchronizes time via external wideband noise-like signals such as TV signals, cell towers, and DAB, so one of these signals must be available to be received by all RTL-SDRs used in the TDoA calculation.

For now, the service and features appear to be free. However, it looks like they will monetize the platform in the future by renting the crowdsourced RTL-SDR nodes to companies and persons that need to do band studies, radiolocation, and interference detection. They also hope to pay node owners for any time the nodes are rented.

More information about the AEDA service is available on their documentation page.

AEDA Scan with Modulation Detection
AEDA Scan with Modulation Detection
AEDA TDoA Hyberbolas from Three Distributed RTL-SDRs
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NOAA18 to Begin Decommissioning Steps Immediately

In April, we posted news that the NOAA satellites would be classed as 'end-of-life' on June 16, 2025. According to the statements, the satellites were expected to remain in orbit and continue transmitting data that radio hobbyists could use, but no attempts would be made to rectify failures.

However, recent news from Carl Reinmann's usaradioguy.com blog has indicated that NOAA 18 will begin decommissioning steps immediately on June 3, 2025. The steps involve disabling batteries and transmitters, depleting remaining propellants, transitioning data and operations, and finally deorbiting, or moving the satellite to a safer orbit.

NOAA-18 may have been chosen to be decommissioned earlier than NOAA-15 and NOAA-19 as the S-band downlink transmitter failed last month, resulting in severe image degradation. The satellite has also been running on backup gyros since 2017, and has suffered various transmitter and sensor failures over the years. 

NOAA-18
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Obtaining an Antenna Radiation Pattern with a Large Field, Android Device and RTL-SDR

An antenna's radiation pattern tells us how it radiates or receives electromagnetic energy in different directions, indicating the strength, directionality, and coverage area of its signals. These days, this is easy to simulate on a PC. However, getting real-world results can still be essential to ensure an antenna is constructed well. For commercial antennas, real-world testing is typically done in an RF anechoic chamber.

Over on Hackaday, Jenny List shows us an alternative method for measuring an antenna's radiation pattern: setting up an antenna in a large field and taking RF measurements at various locations around it using an RTL-SDR.

In the post, List tests an HB9CV two-element 144MHz Yagi antenna. As expected, the resulting polar plot from the measurements indicates that the HB9CV is a directional antenna.

We've seen a similar setup in the past, as shown in this post, where a NanoVNA was used to measure the antenna power.

Antenna Field Test Setup
Antenna Field Test Setup

 

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AI Cloud Detection for GOES Weather Satellite Images on a Raspberry Pi

Over on his blog account at Hackser.io Justin Lutz has uploaded an article describing how he uses AI object detection to automatically detect clouds on weather satellite images that he's downloaded from GOES satellites via an RTL-SDR.

Lutz's blog post first describes and shows his RTL-SDR GOES reception setup. Then, it explains how he used Edge Impulse on his Raspberry Pi 4 to create an AI model that automatically detects the clouds in the image.

The process begins by importing 100 images into Edge Impulse, manually labelling the clouds in each image, training the model, and testing it. The result was an average detection accuracy of 90%.

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SDR Television: DATV TX and RX Software for the PlutoSDR

Recently, Simon Brown (G4ELI), best known for being the author of the popular SDR-Console software, has released a new program called "SDR Television (Beta 2)". SDR Television is a program designed for transmitting and receiving Digital Amateur TV (DATV) signals.

At the moment, the software supports DATV on the QO-100 satellite, but in the future, further terrestrial DATV support has been promised. The software is designed to be used with a PlutoSDR (or PlutoSDR clone or spinoff), but also supports Airspy or SDRplay for receive only.

Over on YouTube, Tech Minds has also posted a great video demonstrating the software's setup and use.

SDR TELEVISION V1.0 - Game Changing DATV Software From G4ELI!

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