Software developer Stephen D. has turned a LimeSDR USB into a device for flooding the airwaves with Taylor Swift songs, covering the whole FM band at once: the Taylorator.

“For the past two weeks or so, I’ve been working on constructing the Taylorator,” Stephen writes of the project. “The Taylorator is a piece of software which allows me to flood the FM broadcast band with Taylor Swift’s music. No matter where you tune your radio, you will only be able to listen to her. Okay, I admit that you could technically use the Taylorator to broadcast whatever music you want, so maybe it’s a bit of a misnomer. But for some reason I figured this would be funnier.

“What do I mean by flooding the FM broadcast band? Well, in Canada and the US (and maybe other places too), the FM broadcast band spans 88MHz – 108MHz. You can’t broadcast wherever, though. Stations will only appear on odd-numbered frequencies, like 88.1MHz, 94.5MHz, 107.3MHz, etc. There’s a technical reason for this – every FM broadcast takes up about 150kHz of bandwidth, and spacing the broadcasts like this allows for an extra 50kHz of wiggle room. This also works out to 100 different frequencies that we need to populate (with 100 different songs).”

The Taylorator is based on a relatively powerful PC connected to a LimeSDR USB software-defined radio dongle – offering wide enough bandwidth coverage to achieve the goal, where all 100 valid FM frequencies are each given their own unique song, all broadcast simultaneously. Wherever you tune the dial, you’ll find Swift.

“Whenever I told someone about the Taylorator during its development, the question I’d consistently get asked is, ‘is this legal?,’ Stephen admits. “This is going to depend on exactly where you live and exactly how you’re using the Taylorator, but in general, I think the answer is… probably not. There are generally cut-outs for very low power FM transmitters, like the ones people use in their car. Usually, though, this requires the transmitter itself to be licensed, and of course, the software I have written has no such license.

“In practice, it’s probably not a huge deal? A few mW spread over 20MHz of bandwidth results in a pretty weak signal. Obviously, don’t do illegal things (and if you do, don’t tell me about it!) If you connected your SDR up to an amplifier you would almost certainly get in a bunch of trouble. So, uh, don’t do that.”

Stephen’s full write-up is available on his website.

Researcher Florian Euchner and colleagues have been working on an array of low-cost Espressif ESP32 microcontroller array, aiming to use their integrated radios for sensing projects – and has shown off an example of how the device can be used to visualise Wi-Fi signals.

“As a research assistant at the Institute of Telecommunications at the University of Stuttgart, I work on multi-antenna systems like (distributed) massive MIMO, with a focus on wireless channel measurement platforms and algorithms for processing channel measurements (classical and deep learning-based),” Florian explains. “One day, my (incredibly talented) colleague Marc Gauger suggested to use ultra low-cost ESP32 chips instead of software defined radios for channel measurements.

“I was highly sceptical at first, but when he showed me a minimalistic prototype he had soldered together, I was intrigued by the idea of being able to demonstrate my algorithms in real time using Wi-Fi signals. In a series of Bachelor’s/Research theses, my excellent students Tim Schneider, David Engelbrecht, and David Kellner helped me develop the ESP32 antenna array ‘ESPARGOS.'”

The ESPARGOS array itself is made up of, in its current incarnation, eight Espressif ESP32 modules arranged in a 2×4 grid. On its own, it can be used to visualise Wi-Fi signals around a room – turning a smartphone or laptop into a glowing blob. With multiple arrays, though, it can deliver more – with one demonstration showing a four-array setup tracking a robot as it moves around the room, locating it in 3D space with a high degree of accuracy.

Following interest in the project, Florian has pledged to begin a manufacturing run for ESPARGOS arrays. “This involves some PCB redesigns to make the design more mass-manufacturable and to get the cost further down,” he notes, “and to get it certified.” Interested parties are invited to sign up on the website for notification when the devices are available to order, while a live demo can be seen on Florian’s YouTube channel.

Radio ham Ben “VE6SFX” Eadie has jumped head-first into the Meshtastic mesh networking craze, quite literally – by building a wearable mesh node disguised as a necktie.

“I don’t normally dress this dapper,” Ben jokes, showing off the wearable system dubbed the MeshTieStick, “but, I’m not going to brag, this is a Meshtastic node, complete, fully-functional. It turns out if you put some iron-on backing onto Faraday cloth and then use the Cricut [vinyl cutter] to cut out the antenna you have something that you can iron onto a ribbon and attach [the] BNC connector that I use for all my other antennas.”

Ben’s project began simply enough: an investigation into flexible antennas, which can be rolled up for ease of transportation. That then expanded to the idea of creating a flexible antenna in the shape of a tie, which could be transported by wearing it around the neck – before finally landing on the idea of also incorporating the surprisingly small microcontroller and transceiver hardware needed to create a node on the community-driven Meshtastic LoRa mesh network.

“It has a better range and it does way better than the stock antenna,” Ben claims of his wearable antenna, which hides the Meshtastic node hardware and a small battery in a pouch at its widest point, “and it will be easier on the electronics hardware that you have.”

The project is documented in full on Ben’s YouTube channel.

Daniel Estévez has written a guide to decoding signals from HYDRA-T, a compact satellite launched in January by Hydra Space and operated by AMSAT-EA – signals which, by right, it shouldn’t be sending on the frequencies it’s currently using.

“Some days ago, people in the LibreSpace forums started noticing that HYDRA-T was transmitting telemetry on 437.780MHz, which is a frequency that belongs to the amateur satellite service 435–438MHz band,” Daniel explains. “This was acknowledged by Félix Páez EA4GQS, who is AMSAT-EA’s president and Hydra Space Software and Satellite Operations Manager. Félix expressed that HYDRA-T should not be transmitting in this frequency even if it has a license to do so.

“The recording shared by PE0SAT is an audio-frequency recording that contains a single telemetry packet. The modulation is 200-baud FSK with a deviation of approximately 560Hz (I haven’t attempted to measure the deviation accurately). After some analysis, I have seen that the coding used in this telemetry packet is the same as the one used by HADES-R.

“The HADES-R telemetry is very similar to the HADES-D telemetry,” Daniel continues. “The only differences are that HADES-D uses 50-baud FSK with 500Hz deviation, while HADES-R uses 200-baud FSK with 562.5Hz deviation, and that the correspondence between packet types and the length and telemetry format of each packet type is different. I had already implemented a HADES-D deframer in gr-satellites. The only thing I have needed to do to extend it to support HADES-R is to define a new list of mappings between packet types and packet lengths.”

Daniel has shared more details, a GNU Radio flowgraph for decoding the signals, and instructions on bypassing a satellite check to have the decoded data further decoded by an AMSAT-EA telemetry parser, on his website.

Researchers from Brown University have hit upon a new approach to filtering out unwanted radio frequencies – after tracking down a noise source in a recording from the Murchison Widefield Array to TV signals bounced off a passing aircraft.

“We said, ‘I bet the signal is reflecting off an airplane,'” physicist Jonathan Prober and US research lead for the Murchison Widefield Array project explains of the team’s puzzling over the noise source. “We’d been seeing these signals for close to five years, and several people had suggested they were airplanes reflecting television broadcasts. We realised we might actually be able to confirm this theory for once.”

Working with student Jade Ducharme, Jonathan was able to confirm that the signals were television broadcasts and also that they were being reflected from the underside of passing aircraft. Further analysis led to the idea to combine near-field corrections with beamforming to track the movement of the aircraft – travelling at around 38,000 feet and almost 500 miles per hour, while acting as a reflector for Australia’s TV Channel 7 – and also to better identify noise sources for later filtering.

“Astronomy is facing an existential crisis,” Jonathan claims. “There is growing concern – and even some reports – that astronomers may soon be unable to carry out high-quality radio observations, as we know it, due to interference from satellite constellations. This is particularly challenging for telescopes like the Murchison Widefield Array, which observes the entire sky simultaneously. There’s no way to point our telescopes away from satellites.

“This [research] is a key step toward making it possible to subtract human-made interference from the data. By accurately identifying and removing only the sources of interference, astronomers can preserve more of their observations, reduce frustrating data loss and increase the chances of making important discoveries.”

The team’s work has been published in the Publications of the Astronomical Society of Australia (PASA) under open-access terms.

Radio ham Matt Miller, of YouTube channel Tech Minds, has shown off the design of an automated NavTex receiver running on a Raspberry Pi with software-defined radio dongle.

“What is NavText, I hear you ask? Well, it’s a navigational Telex,” Matt says, “and it’s an international automated medium-frequency direct-printing server for deliver of navigational and meteorological warnings and forecasts, as well as urgent maritime safety information. The international NavTex messages can be received on 518kHz and national NavTex messages can be received on 490kHz.

“There [are] no fees to receive this information, and of course when this service was introduced you had to purchase specific hardware for receive-decoding-print, either on paper or print on screen, those decoded messages. Yep, some of those hardware receivers had physical printers and could cost up to $1,500 to buy. Now fast forward to the more modern day technology: you can purchase dedicated receivers that show these messages on an LCD for less than $200.”

Matt’s approach, though, is even cheaper: a Raspberry Pi with a low-cost receive-only SDR dongle attached and a software-based decoder running in the OpenPlotter operating system. The resulting low-cost receiver provides a web interface to any device on the same network, listing messages and allowing them to be examined for more information on-demand.

The full video is available on the Tech Minds YouTube channel.

Finally, Bob “W7PUA” Larkin has shown off a ten-watt ten-band homebrew transceiver driven by a Teensy 4.1 microcontroller: the Tiny Ten.

“I wanted a real radio in the sense that the receiver sensitivity, dynamic range and selectivity would not limit the ability to communicate,” Bob explains of the thinking behind the project. “The transmitter needed to be able to generate clean signals and provide enough power output to communicate on CW and FT8 any time and SSB most of the time. The use of CESSB produces clean signals with the effectiveness of a 25 Watt conventional SSB transmitter. The frequency accuracy and stability needed to be right on, with no question as to where we were in the band.

“In addition, the weight and size needed to be back packable by an old guy. The choice of displays gets down to the second purpose for the rig, that being an opportunity to test out various ideas, such as small displays. The main reasons for the small display was low power consumption. But, it is also an opportunity to experiment with ways to make the most of a minimalist control interface. I already knew what could be done with 50 knobs and switches along with a 10-inch display. It is time to see what can be done with 8 lines of 21 characters plus graphics!

“At this time (January 2025) the radio is on the air, but on 80 and 75-meters only,” Bob adds. “The peak output power is just over 15 Watts. The hardware architecture is a single RF frequency converter with quadrature signals fed in and out of the DSP. Switches are used at both the RF and I-F level to go between receive and transmit. A single output of the Si5351A synthesizer is used to drive the converter and set the RF frequency. This is run through a 74ALVC74 high speed divide-by-4 to establish precise quadrature conversion signals. This sets the radio’s operating frequency. A single RD16HHF MOSFET is the transmit output amplifier. The antenna relay is a latching type to save current.”

The project is documented in full on Bob’s website; the design and the ideas behind it are shared under a custom licence which simply asks that “you must never take any steps to restrict their use.”