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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The Open-Weather Project’s Year Of Weather: June 15 NOAA EOL Nowcast Scheduled

Dr. Sasha Engelmann and Sophie Dyer, the team behind the Open-Weather project have recently announced a NOAA end-of-life nowcast to be recorded on June 15 2025. An open weather nowcast is a collaborative effort with users all around the world sending in weather satellite images that they have received locally with their home SDR setups.

NOAA satellite weather image APT transmissions have long been a staple of RTL-SDR hobbyists as they are among the easiest and cheapest satellite transmissions to receive. A simple V-dipole, RTL-SDR, and a computer are all that is required.

Sadly, it was recently announced that the NOAA satellites will be classified as end-of-life (EOL) on June 16 2025. However, the good news is that APT and HRPT data transmissions are expected to continue as usual. The end-of-life status indicates that NOAA will cease its own collection of data from these satellites and, hence, will no longer be distributing the datasets online. It also means that the satellites should no longer be used for mission-critical or scientific purposes and that no attempt will be made to fix a failing satellite.

These satellites have been operating well past their operational life, and given their advanced age, failure could come at any time. So the Open-Weather nowcast on June 15 2025 remains a nice way to honor their service to humanity.

You can see the last Year of Weather map created by the Open-Weather team and contributors here https://open-weather.community/yow/map/

The recent newsletter from the Open-Weather team explains how to participate in the June 15 nowcast.

OpenWeather Current Screenshot
OpenWeather Current Screenshot
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Saveitforparts: Taking Videos of Geostationary TV Satellites via a DIY Radio Telescope

In a recent video on the saveitforparts channel Gabe shows how he used a DIY radio telescope to take a video of geosynchronous TV satellites. The system works by using a motorized dish to scan the sky at Ku-band frequencies. An SDR is used to receive the signal strength at each dish position, and this data is used to create a heatmap image.

Each scan takes an hour to scan the sky, but by running a scan every hour, Gabe is able to create a video of the geosynchronous satellites wobbling. While still mostly fixed at one position in the sky, unlike geostationary satellites, geosynchronous satellites can appear to move in a figure-eight pattern from the ground, and this wobbly movement is apparent from Gabe's video.

The video also shows the sun passing by every 24 hours as the sun emits some RF energy in the Ku-band, as well as brief blips from Starlink satellites. The video also shows the effect of rain fade, as Gabe shows how the heatmap power was attenuated during poor weather.

Videos Of Satellites In Space Made With DIY Radio Telescope

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