Lime Microsystems chief executive officer Ebrahim Bushehri is to be featured in the next Crowd Supply Teardown Session, diving deep into the LimeSDR family of open-source software-defined radio devices – taking place on the 29th of December at 1700 UTC.

The 40th in an ongoing series of interviews and hands-on sessions with creators, staff, and guests, the Teardown Session closing out 2023 will include Ebrahim on Lime Micro’s creation and crowdfunding of the LimeSDR range – including the LimeSDR USB, LimeSDR Mini and new LimeSDR Mini 2.0, and the upcoming LimeSDR XTRX.

Each of these devices has something in common beyond the use of Lime Micro’s field-programmable radio-frequency (FPRF) technology: they’re open-source, with mass-production of each taking place following crowdfunding campaigns on Crowd Supply.

Interested parties can tune in to the broadcast on YouTube on the 29th of December 16 1700 UTC.

On the topic of crowdfunding, the LimeSDR XTRX project will shortly be delivering the first boards to Crowd Supply ready for onward shipping to backers — starting in January 2024.

Designed as a drop-in replacement for the discontinued Fairwaves XTRX software-defined radio, yet boasting a complete redesign which has brought with it some welcome improvements, the LimeSDR XTRX launched on Crowd Supply back in July. In addition to compatibility with the original Fairwaves driver, the new board boasts support in Lime Suite – and has its gateware and hardware design files released under the permissive Solderpad Hardware Licence v2.0.

Following a successful crowdfunding campaign, focused turned to mass production of the boards for backers – a process which is now reaching a conclusion, with backers to receive their LimeSDR XTRX devices soon. “All the components and the PCBs are with the assembly house and testing will commence immediately,” Andrew Back confirmed in the latest campaign update, “as soon as we receive fully assembled boards back. We now expect to be shipping boards to Crowd Supply at the end of the 2nd week in January.”

Images of the unpopulated PCBs and more information on the production schedule can be found on the project’s Crowd Supply campaign page.

The LibreCellular project, which aims to provide an open-source technology stack for cellular networks, has reached another milestone with the addition of an automated IP Multimedia System (IMS) testing block in its continuous integration platform.

“Assuming that you don’t have a 2G or 3G network to fall back to, native voice calling in 4G and 5G networks – which is to say using the integrated dialler and not an ‘over-the-top’ VoIP service or social media/IM platform – is supported by the IP Multimedia System (IMS),” Andrew Back explains. “This is built on top of SIP, Diameter and IPsec protocols and is moderately complex, hence automated testing of the IMS stack would prove beneficial.

“One way of automating testing is to drive Android handsets via ADB and have them set up and tear down voice calls. Which is probably the only way you can properly test compatibility across different handset vendors and smartphone OS/IMS client releases. However, using LTE modems would be more convenient and should be sufficient for testing IMS basic functionality and stability. The only problem then being that the IMS client is typically integrated at the level of the smartphone OS. Fortunately, there is an exception in the form of the Quectel EC25 modem, which directly supports VoLTE and in fact it has been suggested that this is achieved by it running a minimal Android build.”

The new entry in the CI platform, then, is a device made up of four Quectel EC25 evaluation boards connected to a host controller over a USB hub with software control over downstream USB port power for powering the modems on and off. SIM slots are routed to the front panel, along with USB host and audio connections, with the rear having antenna connectors, a power input, and room for two cooling fans.

More information is available in Andrew’s blog post, while the hardware design has been added to the LibreCellular CI repository under the Creative Commons Attribution 4.0 licence.

Pseudonymous YouTuber “Tech Minds” has published a video which aims to give anyone looking to roll custom software for their SDR a leg-up in getting started using the GNU Radio Companion.

“If you’ve ever wanted to experiment with making your own SDR software, either for fun, learning, or even having a specific big requirement, then GNU Radio Companion is what you want to be looking at,” the YouTuber says by way of introduction. “Now I must admit GNU Radio is extremely new to me, and even though I’ve experimented with it in the past there’s just so much to learn.

“Now I’m no expert at GNU Radio, and the idea of this video is to hopefully spark some interest into experimenting with this software – and it’s another avenue of ham radio that you can learn from in the comfort of your own home.”

The video concentrates on the use of GNU Radio Companion, the visual development environment which allows you to connect blocks together to create flows which can control GNU Radio – demonstrating the concept through the creation of a high-frequency (HF) receiver flow, the source for which has been included in the video’s comments.

The full video is available now on the Tech Minds YouTube channel. has brought our attention to a guide from António Pereira in modifying a cheap 2.4GHz Wi-Fi grid antenna for use on the 1.7GHz band for High-Resolution Picture Transmission (HPRT) signals from L-band weather satellites.

“Wi-Fi grid dishes come in a variety of centre frequencies, yet they are all basically the same Wi-Fi grid made by the same manufacturer and sold under different names,” “USRadioguy” Carl Reinemann explains. “The big difference is the feed and the dipole box.

“António Pereira in Portugal decided to try and see if he could increase the performance of the dipole by modifying it. This increase in performance is beneficial for receiving HRPT transmissions such as Meteor M2-3, NOAA 19, NOAA 18, MetOp-C, and other L-band satellites. This would also work very well for tuning in a dish and dipole feed for LRIT, HRIT transmissions using GOES, GK2A, and other geo sats in L band as well.”

The process, as documented by António and published by Carl, is relatively simple: removing the dipole box and opening it up, then modifying the dipole with new copper strips the correct length for 1.7GHz operation – tuning it with a vector network analyser (VNA), for ideal performance – before closing the box up and putting it back on the grid dish, though 3.5cm further forward to account for the new signal focal point.

The guide is available in full on Carl’s website,

Gabe Emerson, of the YouTube channel SaveItForParts, has been testing an unusual gadget for the radio ham who can’t always be at-key: the Boondock Technologies Echo, an answerphone – or “answerradio” – for when you’re away from your radio.

“The Boondock Echo is essentially a radio answering machine,” Gabe explains. “This gadget uses an ESP32 system to record audio from a two-way radio and act as a time-shift message centre.

“It has a cloud service with speech-to-text and keyword notifications. It can transmit and receive, functioning as a repeater in addition to a recorder. The system has a few features that are still in development, and it still a bit of a prototype, but it’s kind of a cool product!”

Gabe’s testing of the device – or, rather, an early prototype with a 3D-printed enclosure – turned up a few bugs and glitches, including a tendency for the speech-to-text system to interpret static as random words and repeated crashes when using the buttons. Many of the issues highlighted, though, have since been fixed, Boondock Technologies claims.

The full video review is available on SaveItForParts now.

Engineer Angelina Tsuboi has built a tool which aims to detect spoofed ADS-B signals creating fake aircraft on flight trackers – dubbed the Fly Catcher, and deployable on a low-cost Raspberry Pi single-board computer.

“Hackers can easily spoof ‘ghost’ aircraft into the sky,” Angelina explains. “As a pilot and cybersecurity researcher, I developed a device called Fly Catcher to detect instances of aircraft spoofing on ADS-B. I also flew it on a plane over the coast of Los Angeles.

“Fly Catcher monitors the ADS-B 1090MHz frequency to detect spoofed aircraft by ground-based hackers using a custom neural network. The device consists of a 1090MHz antenna, FlightAware SDR, and a Raspberry Pi, and scans nearby ADS-B messages and runs them through a neural network to detect fake aircraft transmitted by bad actors.

“After testing the implementations on multiple flights in a single-engine aircraft throughout Los Angeles and possible attack scenarios in a simulated environment, both the device and the web app have a real-time detection system with an accuracy rate of over 90% and protect against potential flight delays and mid-air collisions caused by fake aircraft signals.”

More information on the project is available on and in Angelina’s YouTube video, with the source code and a research paper on the topic available on GitHub under the permissive MIT licence.

Finally, NASA has become responsible for perhaps the highest-technology cat video in history – transmitting footage of a feline dubbed Taters from 19 million miles away to test its Deep Space Optical Communications (DSOC) system.

“This accomplishment underscores our commitment to advancing optical communications as a key element to meeting our future data transmission needs,” NASA deputy administrator Pam Melroy claims, quietly ignoring the fact there are no known cats in space. “Increasing our bandwidth is essential to achieving our future exploration and science goals, and we look forward to the continued advancement of this technology and the transformation of how we communicate during future interplanetary missions.”

The DSOC test saw a 15-second clip of Taters, recorded in ultra-high-definition, transmitted from the Psyche spacecraft launched in October over a 19 million mile distance using a flight laser transceiver – hitting a bitrate of 267 megabits per second but a speed-of-light-limited lag time of 101 seconds.

“One of the goals is to demonstrate the ability to transmit broadband video across millions of miles. Nothing on Psyche generates video data, so we usually send packets of randomly generated test data,” Bill Klipstein explains of Taters’ involvement. “But to make this significant event more memorable, we decided to work with designers at JPL to create a fun video, which captures the essence of the demo as part of the Psyche mission.”

More information is available in NASA’s write-up, while the video itself can be seen on YouTube.