Community member Lucas Riobó has, alongside colleagues Francisco Veiras, María Garea, and Patricio Sorichetti, announced a novel use for a LimeSDR: software-defined optoelectronics.

“In this work, we propose a general architecture for the implementation of Software-Defined Optoelectronic systems (SDOs),” Lucas explains in the forum post announcing the early-access publication of his team’s paper. “As an application example, we built a software-defined optical interferometer (SDOI) using the LimeSDR, that was applied to perform optical detection of laser-induced photoacoustic signals.

“In this paper we show that the LimeSDR is suitable for applications in optoelectronic instrumentation and I hope it can be useful for those who want to apply the platform in other scientific applications, in addition to telecommunications.”

The paper, Software Defined Optoelectronics: Space and Frequency Diversity in Heterodyne Interferometry, has been published for early access in the IEEE Sensors Journal. Those without academic access can contact Lucas via Research Gate to request a copy.

Elsewhere on the forum François Lozes has published the source code for iq_toolbox, a suite for processing raw IQ stream data, under the GNU General Public Licence v3.

“The idea is to provide a set of programs that can be plug together to bring an algorithm,” François explains on the forum. “The communication between each program is performed by a simply pipe or files. I give some examples of the application, e.g.: the broadcasting of an audio stream by bringing an FM station with the LimeSDR, with a single shell command.”

The toolbox includes programs for converting the data type of an incoming signal, normalising samples to an arbitrary range, extracting the instantaneous phase or frequency of a signal, frequency modulation of a scalar signal, pre- and de-emphasis of signals, low-pass filtering and downsampling, signal mixing, power spectral density (PSD) display, and spectrogram display.

The iq_toolbox is available from François’ GitHub repository.

The LimeSDR has been demonstrated working with Ground Electronics’ Circumference, a Raspberry Pi-based compute cluster system aimed at developers and educators, to create an all-in-one GSM cellular network.

“We take a look at how you can run a complete GSM network on a Circumference 25, with a base station (BTS) running on one compute node and a base station controller (BSC) on another — plus two media gateways, a signal transfer point (SS7 network router), mobile switching centre (MSC) and a home location register (HLR), each all running on dedicated hosts,” explains Andrew Back by way of introduction for the Circumference project’s latest video update.

“While it would be possible to run all of these components on a single compute node, what Circumference allows us to do is to get a much better experience of a distributed cellular network architecture. In this case GSM, with the Abis protocol being used between the BTS and BSC, SS7 signalling between BSC and MSC, and RTP voice traffic streams, etc. Software control of power sequencing allowing us to then test behaviour when nodes or an Ethernet network switch fails.”

The video is available on the Circumference Crowd Supply campaign page, which has just under a week to run.

Hackaday has brought our attention to a radio telescope project with a difference: rather than looking at the stars, it charts the world around it in terms of Wi-Fi signals.

An ongoing project of the Thought Emporium, the project has been beset with difficulties described in full in a pair of earlier videos, but has finally borne fruit. “This week we mapped the inside of the hackerspace (Foulab) I’ve been working in and then stepped up to taking an image of the whole building,” the video’s description explains. “Not only were we able to see our router, we could see at least half a dozen others, and even one across a courtyard at least 100m away.”

The project’s third and final video is available now on YouTube.

Imperial College London has announced the selection of SignalDoctor, the project of final-year engineering student Jonathan Rawlinson, as one of the top three selected in the UKESF Radio Frequency Competition.

“Future cognitive radio systems will be operating in very signal dense environments, with numerous generations of radio systems in operation utilising different protocols all in the same frequency bands,” Jonathan explains of his project’s inspiration. “The aim of this project is to design and build a radio system that is capable of classifying different radio signals using convolutional neural networks and novel feature extraction methods.

“It is proposed that this technology can be used to build more reliable and more agile Dynamic Spectrum Access (DSA) systems. Overall, a robust classification system for signals in the shortwave radio bands has been designed and constructed using a HackRF Software Defined Radio (SDR) as the data source. The proposed future work options are also presented along with a novel application of this technology (meteor scatter detection).”

More information on the project, and the UKESF competition, is available from the Imperial College London website, though Jonathan’s paper has not yet been released to the public.

The 5G cellular standard has not been officially frozen and ratified, following the completion of earlier milestones in the project – but not before numerous manufacturers have already begun testing 5G networks based on draft standards.

“The freeze of Standalone 5G NR [New Radio] radio specifications represents a major milestone in the quest of the wireless industry towards realizing the holistic 5G vision,” claims Third Generation Partnership Project (TGGP) Technical Specification Group Radio Access Network (TSG-RAN) chair Balázs Bertényi. “5G NR Standalone systems not only dramatically increase the mobile broadband speeds and capacity, but also open the door for new industries beyond telecommunications that are looking to revolutionize their ecosystem through 5G.”

“The agreed completion of the stage 3 freeze milestone for the 5G standalone system has great significance,” adds 3GPP TSG Service and System Aspects (TSG-SA) chair Erik Guttman. “The 5G System specification has now reached its official stage of completion, thanks to the intense efforts of hundreds of engineers over the past three years. A special acknowledgement is due to those who led this remarkable effort in diverse committees. 5G promises a broad expansion of telecommunications, as an ever more central component of our economies, societies and individual activities.”

More information on the finalised 5G standard is available from the 3GPP website.

One such pre-finalised 5G network test was carried out at the tail end of last year in Ljubljana as part of the EU-funded iCIRRUS project – and a recent analysis of the three-year project has declared it a resounding success.

“In the iCirrus project, we were able to demonstrate for the first time an Ethernet-based fronthaul solution for millimetre-wave signals that achieves the high data rates expected for 5G,” explains Fraunhofer HHI’s project manager Kai Habel following the project’s completion. Fraunhofer HHI contributed a 60GHz synchronous fronthaul system with real-time capabilities, proven to operate up to 2.5Gb/s error-free in the test.

More information on the iCirrus project, a backronym which expands to “intelligent Converged network consolidating Radio and optical access aRound USer equipment,” is available on the official website.

Electronics giant Sharp has announced the development of an “invisible” antenna for near-field communication (NFC) use, designed to be integrated into displays up to 42″ in size.

According to a write-up of the company’s announcement on EE News Europe, Sharp’s development uses the company’s metal mesh technology, already in production for capacity sensing on touch-screen devices, to integrated multiple NFC antennas directly into a display. The company’s initial target market: point-of-sale (POS) systems, which can act as both a touch-screen interface and receive payments via NFC without the need for a dedicated reader.

The company has not yet released technical details of the system, but claims it will begin mass production towards the end of its 2019 financial year.

Osmocom, the umbrella project behind a range of open-source mobile communication initiatives, has announced that it is to begin accepting monetary donations through Open Collective to support its work.

“The Osmocom project (if you count its predecessor OpenBSC) has been running for close to 10 years, creating a large number of Open Source projects related to mobile communications,” explains Harald ‘LaForge’ Welte. “We have never needed nor wanted any legal entity for it. It’s a pure/classic FOSS project, open to contributions from anyone. However, we’ve repeatedly getting requests from some individuals who wanted to contribute to the project in an easy way, even if they are not a developer, and/or don’t have time, and/or don’t have the size of a budget to fund development of entire new features or sub-systems.

“Today, Osmocom announces that we have joined Open Collective in order to enable you to make financial contributions, either one-off or recurring. We’ll be using the funds (if we get any!) according to our funding policy outlined at in order to pay for expenses such as hosting costs for our servers / IT infrastructure, travel funding for the annual developer conferences, etc. Any and all expenses paid from those funds will be visible on the Open Collective website. You cannot ask for more transparency than that!”

More information, and the link to donate to the project, is available on the Open Collective website.

Bob Van Valzah has written the second part in an ongoing series of investigations into the use of shortwave radio for long-distance high-frequency trading (HFT).

A performance engineer on gardening leave from Chicago high-frequency trading firms, Bob’s earlier article discussing his investigation into mysterious shortwave equipment was covered back in May’s OTA. “Since I hadn’t anticipated such a diverse audience, I didn’t provide details needed to understand shortwave trading in context so a lot of questions were raised,” Bob writes in introduction to the second part of the series. “I’ll provide some background here, answer the questions, and also document two other shortwave trading sites I’ve found around Chicago. Traders can skip ahead while I fill in the broader audience.”

One particular question answered by Bob in the detailed follow-up should raise a smile: “Are you sure these antenna sites are really for shortwave trading and not a beacon for space alien body snatchers or something else? I’m going to assume that space alien body snatchers wouldn’t bother with FCC licenses for their beacons. The sites I’m documenting here are all licensed to transmit on shortwave frequencies that could cross oceans. Their shortwave antennas are all pointed at Europe. They all have a microwave link to CME. The IEEE Spectrum article on shortwave trading has deep links into the FCC database revealing the name of a trading company owning one of these sites.”

The full article can be read on the Sniper in Mahwah blog.

Members of the forum have been having an interesting discussion on whether a bird perching on an antenna could have an appreciable effect on its standing-wave radio (SWR) measurements.

“I haven’t had the opportunity to actually measure SWR yet, but I do plan to next time I see the bird on the antenna and I can connect my analyser quickly enough,” Frank ‘KE2KB’ Wassner explains by way of introducing the topic. “The Mockingbird likes to sit on the phasing stub of the Ringo Ranger ARX-2B. There are no radials on this antenna (although there are supposed to be), so the stub, and the matching ring are the only horizontal places a bird can sit, although I have never seen him on the ring. I’m not really concerned, either for the SWR or the bird, as the max I put into the antenna is 5W, and my HT will limit the output if the SWR goes too high. Your thoughts?”

Answers in the thread range from “probably somewhat, but not necessarily a lot” to musings on the conductivity of a “burd turd,” while others agree that measuring SWR before, during, and after perching would be an interesting experiment. Naturally, there’s also the age-old question when it comes to birds: “African or European?”

The full thread is open to responses on the forum.

Finally, Hackaday has written up an interesting example of prototypical software-defined radio: a 1975 article on generating AM transmissions from an Altair 8800 microcomputer.

“All the way back in 1975, an article written by Steve Dompier was published in the People’s Computer Company Newsletter and republished in Dr. Dobb’s Journal of Computer Calisthenics & Orthodontia in 1976 that described a very curious discovery,” Tom Nardi explains, having seen the project in action at the Vintage Computing Festival (VCF) East courtesy of Altair enthusiast Bill Degan. “Nearly a decade before a team at Raytheon would coin the term ‘software radio,’ the article showed that with just a few lines of code one could generate AM radio transmissions from their MITS Altair 8800.

“Even 43 years after the discovery that the Altair could perform such a feat, it delighted everyone who stopped by the table. With the LEDs flickering away as the songs came strong and clear through the nearby vintage AM radio, the whole thing seemed almost magical. It’s no wonder Bill Gates was impressed.”

Details of Bill’s implementation of Steve’s transmitter, which Bill affectionately calls his Altair Jukebox, can be found on