The British Amateur Television Club (BATC)’s Portsdown digital TV transmission platform has received an update, bringing with it drop-in support for the using the new LimeSDR Mini 2.0.
“The previous facilities that worked with the LimeSDR Mini V1 and the LimeSDR USB now also work with the LimeSDR Mini V2,” Dave “G8GKQ” Crump, chair of the BATC, explains of the update. “These include the generation of DVB-S, DVB-S2 and DVB-T amateur television signals, a signal generator and sweep generator covering 30 MHz to 3.5 GHz, and a spectrum viewer covering any 20 MHz span between 30 MHz and 3.5 GHz.”
For those who have not come across the project before, Portsdown was created to offer an easily-accessible platform for experimenting with digital TV transmission for those amateur TV enthusiasts who had previously worked with analog signals. Powered by a software-defined radio connected to a Raspberry Pi 4 single-board computer, Portsdown is designed to be both affordable and accessible.
More information on the new release of Portsdown is available on the BATC website, while LimeSDR Mini 2.0 boards are available to order through Crowd Supply now.
RF’s Not Magic (RFNM) is preparing to launch an ambitious modular software-defined radio platform, based around an NXP Semi LA9310 baseband processor and with interchangeable RF front-ends – including one built around the Lime LMS7002M field-programmable RF IC.
“The [LA9310 is] the star of the show,” the company explains of its design. “Eight ADCs [Analogue to Digital Converters] and two DACs [Digital to Analog Converters] running at 12 bit[s] and 153 MSPS [Megasamples Per Second], plus 80 GFLOPS of VSPA-2 DSP [Digital Signal Processing] power. [The] Si5510 [offers] 47 femtoseconds of RMS jitter, 18 outputs, and a digitally controlled oscilliator for zero-ppm frequency errors. [The] i.MX 8M Plus [includes] Arm Cortex-A53 and M7 [cores] for real-time applications, the latest-generation NXP processor to foster an ecosystem of onboard applications.”
Aside from the integrated hardware, what is most interesting about the RFNM is its modular nature. Two high-density connectors, dubbed the RFNM Interfaces, offer connectivity to daughterboards, including a model built around the LMS7002M – the same part as used in the LimeSDR family of devices. “We are working closely with Lime Micro, the makers of the LMS7002 chip and manufacturers of the LimeSDR,” the company explains, “to develop a RFNM board using their silicon. It will cover 10 to 3500 MHz.”
Full technical details are available on the company website, with RFNM offering a waitlist for those interested in ordering hardware from the first production batch.
The call for participation in the GNU Radio Conference 2023 (GRCon ’23) has opened, along with ticket sales, with those interested in speaking at the event advised to get their submissions in by the 5th of June.
“We invite developers and users from across the GNU Radio Community to present your projects, presentations, papers, posters, and problems at GNU Radio Conference 2023,” the event’s organisers explain, “so start thinking about what great work you would like to present at this year’s conference.
“GRCon attendees come from a large variety of backgrounds, including industry, academia, government, and hobbyists. Offering an annual program with broad appeal, GRCon attracts a variety of participants: people new to software radio who are interested in learning more, seasoned developers ready to show off their latest work, and experts who want to keep their finger on the pulse and direction of the industry.”
This year’s GRCon takes place at the Arizona State University Memorial Union in Tempe, Arizona, on the 5th to the 9th of September 2023. Those interested in presenting, or attending as a guest, can find out more on the event website.
The Internet Archive has announced a milestone for its Digital Library of Amateur Radio & Communications (DLARC) collection, which has passed 60,000 items since its launch six months ago.
“Launched just five months ago, Internet Archive’s Digital Library of Amateur Radio & Communications has expanded to more than 61,000 items related to amateur radio, shortwave listening, and related communications,” program manager Kay “K6KJN” Savetz says of the collection. “The library’s newest additions include deep historical resources and contemporary reporting about the world of radio.”
Among the items most recently added to the DLARC collection include scripts for the Amateur Radio Newsline bulletin reaching back to the mid-1990s, 2,300 issues of DX Listening Digest, and the niche Numbers & Oddities and Enigma 2000 newsletters. The DLARC Lending Library, meanwhile, now offers more than 400 books for controlled digital lending, along with “thousands of issues” of magazines and trade journals.
“The Digital Library of Amateur Radio & Communications is funded by a grant from Amateur Radio Digital Communications (ARDC) to create a free digital library for the radio community, researchers, educators, and students,” Kay explains. “DLARC invites radio clubs and individuals to submit collections of material, whether it’s already in digital format or not.”
More information on the collection is available on the Internet Archive blog.
Gabe Emerson has been hard at work trying to turn old satellite dishes into a compact version of New Mexico’s Very Large Array – which, he admits, “didn’t turn out all that successful,” but which is interesting nevertheless.
“I keep acquiring these old dish Tailgater units, which are designed to be portable satellite dishes for use at a tailgating event at a sportsball game, or out at your cabin, or camping, or fishing,” Gabe explains. “Honestly, I don’t know if anyone has ever taken one of these out on the lake while wearing waders.”
Featuring a weatherproof housing hiding a small satellite dish and aiming hardware, the low-cost second-hand Tailgaters proved a great source of parts for a VLA-inspired antenna array in miniature. “By combining signals between the antennas,” Gabe says, “we can sort of synthesise an aperture equal to the diameter of the largest distance between the two antennas.”
In testing the array, which was admittedly cobbled together by someone who self-admittedly has little knowledge in “antenna theory and proper tuning,” the results weren’t great. “It seems to be actually getting a little bit less signal [than a single dish],” Gabe found. “The most I can combine is two antennas, but again I’m still not getting any benefit from having multiple antennas on this circuit.”
The full video is available on Gabe’s YouTube channel, Save It For Parts, with suggestions in the comments as to how the array could be made functional.
Students from the University of Arizona are preparing to launch a student-led CubeSat into space, bringing with it an unusual payload: an antenna which inflates like a beach ball.
“Following a successful launch, this inflatable antenna will be the first of its kind in space,” says Hilliard Paige, a systems engineering student at the University of Arizona and the lead systems engineer on the CatSat project. “If it works, it will be a pathfinder for future missions.”
Designed by Freefall Aerospace, which was spun off from the University of Arizona’s commercialisation arm, the spherical antenna is designed to take up as little room as possible during launch then inflate with a mixture of helium and argon once the satellite has reached orbit. A transparent lower surface and a reflective upper surface combine into what is, effectively, a satellite dish, offering a larger surface area than rival designs.
“This technology could drive down the cost of high-quality scientific measurements in space,” says mechanical engineering student Aman Chandra, “by enabling the use of lightweight, low-cost antennas with very high data rates.”
More information on the project is available on the University of Arizona website.
Researchers from the Nagoya Institute of Technology, ROMA TRE University, the University of California at San Diego, the University of Nottingham, and the Japan Science and Technology Agency (JST) have published a paper detailing what they say could be a “new antenna paradigm” based on waveform-selective metasurfaces.
“Classic antennas are incapable of varying their performance, for example, its radiation pattern, at a fixed frequency,” explains project lead Hiroki Wakasuchi, PhD. “In our study, we introduced a new degree of freedom to change antenna performance and control electromagnetic waves/signals even at the same frequency by using ‘metasurfaces,’ artificially engineered electromagnetic structures that can produce electromagnetic properties based on the signal received. In particular, our metasurfaces show unique behaviour that selectively transmits incoming signals in response to their pulse width, which is applied to the antenna design.
“With our technology advancing towards 6G and 7G networks, cyber spaces and physical spaces are becoming more closely associated. Using multiple IoT devices, we would be able to create a digital twin for each physical space. Such a concept of cyber-physical space will require a substantial number of IoT sensors to be deployed in physical spaces to collect information without severe electromagnetic interference occurring between these devices to ensure real-time time update. Our study contributes to this future by providing a way to harmonize wireless communications while increasing the number of communication devices at the same frequency.”
The team’s paper is available under open-access terms in the journal Nature Communications, with an explainer video available on YouTube.
The UK Government is preparing to test a new nationwide emergency alert system, with the first transmission taking place on the 23rd of April 2023.
“We are strengthening our national resilience with a new emergency alerts system, to deal with a wide range of threats – from flooding to wild fires,” explains Oliver Dowden MP of the government’s new system. “It will revolutionise our ability to warn and inform people who are in immediate danger, and help us keep people safe. As we’ve seen in the US and elsewhere, the buzz of a phone can save a life.”
“This year is the 70th anniversary of the 1953 east coast surge, one of the worst flood events in our recent history which saw over 300 people perish in England,” notes Caroline Douglass, executive director for flood and coastal erosion risk management at the Environment Agency. “While our ability to warn and inform has come on leaps and bounds since then, Emergency Alerts is a fantastic addition to our toolbox that we can use in emergency situations.”
The first national test transmission, which follows smaller trials in East Suffolk and Reading, will appear on mobile phones throughout the UK, with an audible siren even if the device is placed in do-not-disturb mode – but not if it’s disconnected from the network in aeroplane mode or switched off.
More information is available on the government’s website.
Graphics card maker turned high-performance computing specialist Nvidia has announced the launch of a source-available platform tailored specifically for 5G and 6G cellular research projects: the Nvidia Aerial Research Cloud.
Described by the company as “the first fully-programmable 5G and 6G network research sandbox,” the platform – which is powered by the company’s CUDA general-purpose graphics processing unit (GPGPU) cores – marks what Nvidia says is the first time a standards-compliant gNodeB (gNB) has been provided with its full source available.
“Everything from Layer 1 and Layer 2 through to the Core Node is defined in C++,” Nvidia’s Anupa Kelkar and Chris Dick explain in a joint statement, “enabling researchers with the ability to bring their innovations to reality in a fully programmable network testbed.
“Aerial Research Cloud intends to win the hearts and minds of innovators, and we look forward to hearing about your use cases, extensions, and innovations. The possibilities are boundless with this accelerated full-stack and ML-ready platform for innovators.”
More information on the Aerial Research Cloud is available on the Nvidia Developer blog.
A research team in China has unveiled a “disruptive” framework for dynamic spectrum sharing in 6G cellular networks, based on blockchain technology: SpectrumChain.
“The sixth-generation (6G) wireless network will support ubiquitous connectivity and diversified scenarios to satisfy the requirements of various emerging applications. Full spectrum is a key enabler for 6G to achieve the ambitious goal of a Tbps-scale [terabits-per-second scale] data rate,” the researchers explain. “SpectrumChain [is] a blockchain-based dynamic spectrum-sharing (DSS) framework for 6G.”
SpectrumChain uses a similar blockchain system to cryptocurrencies like Bitcoin or Ethereum, but for a very different purpose: providing a decentralised spectrum-sharing system to encourage fair use of available resources. A main chain offers spectrum resource trading and regulation publishing services, while subchains are used for local spectrum sharing.
“Compared with the existing SAS [Spectrum Access System] architecture, the hierarchical SpectrumChain architecture can achieve a consensus-based fault-tolerant decision process at the global level and the local level,” its creators claim. “This capability not only facilitates the DSS processing efficiency but also guarantees certain isolation between different services with flexible scalability.”
The team’s paper is available under open-access terms in the journal Science China Information Sciences.
Finally, students at the Rochester Institute of Technology turned the campus’ Sentinel statue into a functional antenna – transmitting over an “amazing range” for what was never designed as a functional piece of art.
“A few members of K2GXT, the Rochester Institute of Technology’s ARC [Amateur Radio Club], hooked a coax cable up to RIT’s ‘Sentinel’ statue in front of the campus centre building,” an anonymous club member explains. “We ran 5 watts from a Yaesu FT-991 into the statue on 20m to achieve an amazing range with such low power!
“We were able to be heard almost across the entire eastern half of the US (at least according to PSKReporter) despite some less-than-amazing band conditions! We were originally going to run WSPR but we weren’t quite set up for that today and hope to try again, as well as get some more conclusive results as to the SWR and other electrical characteristics of the statue. (All we really did today was hook up a NanoVNA to make sure it wouldn’t blow up my radio!)
“We’ve had this long-running meme in our club for at least as long as I can remember,” the club member continues, “and with help from our university’s health and safety team, we did this today! Needless to say, we’re all really impressed with the results, and we hope to do this again with better band conditions, or maybe make more contacts with more people!”
More information is available in the project’s Reddit post.