Over The Air: Ebrahim Bushehri Interview, ERASynth Update, LimeSDR 4G Repeater, Lime Hackathon Deadline, QB50 Satellites, Drone Hijacking, LTE IMSI Catcher, Chazwazza VNA, Fixing a Bent Antenna, and Focus On Alexandru Csete

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EEWeb’s Paul Dillien has published an interview with Ebrahim Bushehri, chief executive of Lime Microsystems, describing the goal of the LimeSDR and related projects as no less than “to become the Arduino/Raspberry Pi for the wireless engineer.”

Paul’s interview with Ebrahim concentrates primarily, and unsurprisingly, on Lime’s ongoing crowdfunding campaign for the LimeSDR-powered LimeNET all-in-one base station boxes. “Other guys can pick up the designs and offer the product or build it into all sorts of equipment,” Ebrahim explains of the envisioned future where anyone can build a LimeNET-style all-in-one machine. “You see, LimeNET designs aren’t limited to what I’d call conventional applications. Entrepreneurs, system integrators or even other semiconductor companies can add cellular capability onto, I don’t know, say a blade in a server, or perhaps into a vending machine or inside railway carriages — the opportunities are endless.”

One particularly interesting line of questioning came from Paul’s query as to the potential applications of LimeSDR technology in LimeNET systems. “Some countries have started the migration over to LTE [Long Term Evolution] for first responders or emergency services such as fire, police, and ambulances, giving them new capabilities like streaming video and fast data links that can save lives, and LimeNET boxes can be used to set up ad hoc networks. Then, of course, there are huge opportunities in IoT gateways using any of the WAN standards that are being deployed around the world.”

The full interview is available on EEWeb, while more information on the LimeNET boxes can be found from the campaign’s active Crowd Supply page.

The ERASynth open-hardware signal generator project hit a milestone in its own crowdfunding campaign this week, passing its funding goal with eight days left on the clock.

Highlighted in an OTA round-up early last month, the ERA Instruments ERASynth is an impressive signal generator with a 10MHz to 6GHz range on the entry-level model and 250KHz to 15GHz on the Plus model. Those specifications, combined with the promise of open hardware, Wi-Fi-based network control and monitoring, and impressively aggressive pricing have proven popular with the campaign passing its revised $25,000 funding goal – down from the original $40,000 sought by the company – earlier this week.

With funding now guaranteed and eight days left on the clock ERA Instruments looks on-track to begin production and make its September shipping schedule, though its reduced budget may introduce new challenges as the device heads into mass production.

Forum regular Tegwyn Twnfatt has hit a milestone in his project to create a fully-functional 4G cellular repeater using a LimeSDR, successfully rebroadcasting his local Band 20 4G signal.

The last time we checked in on Tegwyn’s 4G repeater project, he had just received a prize in the Hackaday Prize 2017 event. At the time, Tegwyn was working on a dual-pronged approach: a LimeSDR-powered development version for rapid prototyping and experimentation, and a homebrew version built from discrete components. Getting the latter fully functional first, the LimeSDR version proved tricky – until Tegwyn hit a breakthrough late last month.

Tegwyn has uploaded a video of the LimeSDR acting as a functional 4G signal booster, with more details of the project as a whole available on his Hackaday.io project page or forum thread.

As another demonstration of LimeSDR’s capabilities in the telecommunications arena, BT Research Lab director of converged networks Mansoor Hanif has explained how his company is using the platform to work on education and use-cases for future programmable networks.

In a video interview with Telecom TV’s Guy Daniels Mansoor Hanif explains what he sees as the future of telecommunications networks as being centred around software definition. “What’s really clear is that the future of networks is highly programmable networks,” Mansoor claims, “and that’s across fixed and mobile [telecommunications]. Now, if you look at the game-changers of the future in terms of transformation, flexible, programmable, software-based networks, the separation of hardware and software, is a big challenge, because we don’t have the right skills today to have large teams to be able to manage the interface between software programming and networks.

“We’re having a competition over the next three months to give use-cases that are important for our customers today, but also to benchmark the future of this ecosystem today so we know how far away we are from having this new way of working which is very rapid innovation in the same way as the web-scale companies,” Mansoor continues, showcasing LimeSDR hardware at the company’s booth. “It’s the first time we’re having a large-scale benchmark. We hope through this we will have a knock-on effect where universities work with industry to develop that new generation of software-based network engineers that we so badly need, and I’m hoping that can give the UK an extra sprint in this race towards the future networks.”

That competition, if you needed reminding, is the BT and EE LimeSDR Hackathon announced late last month, and if you’re interested but have yet to get your entry across you have only one more day in which to meet the first of several application deadlines.

The competition, as Mansoor explained, centres around using LimeSDR hardware to solve problems in the telecommunications space – either implementing existing functionality onto the LimeSDR, developing new functionality in areas ranging from disaster recovery to entertainment, and finding imaginative and effective uses of the LimeSDR’s programmability. The event culminates in a three-day ‘hack weekend’ from the 1st to the 3rd of September, but interested parties have only until the 9th of June to make the initial application deadline.

Full details and a link to register are available from the official website. For those who do register, a LimeSDR workshop is scheduled for the 21st of June as as precursor to the main hackathon, with more information available on the forum.

Those who enjoy the challenge of receiving extra-terrestrial radio signals should have a look at Daniel Estévez’ tour of the QB50 cubesat constellation, brought to our attention by a post on RTL-SDR.

Launched late last month and early this month from the International Space Station and a PSLV rocket, QB50 is a constellation of 36 compact cubesats built by global universities with the aim of studying the Earth’s thermosphere. While the satellites have differing instrumentation, they all transmit on the 70cm amateur satellite band, and Daniel has been capturing their signals using a seven-element handheld yagi connected to a LimeSDR set to maximum gain but with no LNA attached.

For those who want to repeat Daniel’s detailed analysis of the signals received from the QB50 satellites but who lack an SDR or the time to capture signals themselves, he links to a 16GB IQ waveform recording at the bottom of his blog post.

For a more down-to-Earth use of SDR, security researcher Arthur Garipov’s nullcon presentation on drone hijacking using SDR hardware and GNU Radio has now been uploaded to YouTube.

Although not exclusively focused on drone technology, the ability to intercept signals and take remote control of an in-flight drone is doubtless the most eyebrow-raising portion of Arthur’s 50-minute presentation during the nullcon conference. For those interested more in the underlying technology than its security implementations, the initial portion of the presentation features an overview of available software defined radio hardware and software – including, among others, the LimeSDR.

Those who wish to follow along can download Arthur’s slide deck in PDF format from the nullcon website.

An older talk on using SDR technology to build an open-source Long Term Evolution (LTE) IMSI capture system has also been uploaded to YouTube, courtesy of the official Budapest Hackerspace channel.

Filmed during the Camp++ 0x7e0 event in August 2016, Domi’s presentation discusses changes made between GSM and LTE that make capturing a device’s International Mobile Subscriber Identity (IMSI) more challenging, then highlights the use of a Tracking Area Update Request to capture the IMSI. Domi’s sysmte is built around an Ettus Research USRP SDR, openLTE, OpenAirInterface, srsLTE, and srsUE, with a live demonstration included.

Slides are again available from the official presentation page.

Anyone looking to perform network analysis may want to check out Peter Bevelacqua’s Chazwazza project: a low-cost two-port vector network analyser (VNA) with integrated calibration and a 400MHz to 2.7GHz range.

“What can you do with a VNA,” Peter asks as an introduction on the project’s Kickstarter crowdfunding campaign page. “Most importantly: you can design, tune and validate antennas in the frequency ranges including GPS, GSM/3G/LTE, 2.4GHz Wi-Fi, BT, and more. VNAs enable you to measure the isolation between two antennas, and do RF impedance matching. Transmission line losses, filter responses and LNA gain can be measured as well. The Chazwazza is a 400MHz-2.7 GHz VNA capable of measuring S11 and S21, with display formats VSWR, dB Magnitude, and Smith Charts.”

Priced at $459 for ‘Super Early Bird’ backers rising to a full $549 standard Kickstarter price, the campaign is open now with a $36,000 funding goal and 29 days left on the clock.

Finally, members of the eHam Forum have some great advice on repairing storm damage to a vertical antenna by bending it back into place without risking kinks or other damage.

For those whose antennas have been hit by storms, there are a range of methods suggested for fixing unexpected bends: filling it with sand to prevent kinking and rolling it on a hard, flat surface with gentle ‘persuasion’ from a hammer; using a pipe or conduit bender; or even cutting out the bent section and attaching a new length of aluminium tubing using hose clamps in order to maintain maximum strength.

Focus On: Alexandru Csete

Alexandru Csete

OTA’s Focus On is a new series of interviews with notable members of the Myriad-RF and wider software defined radio community. If you’d like to nominate someone to be interviewed, or would like to be interviewed yourself in a future OTA, send your proposal to ota@myriadrf.org.

A physicist from Aarhus University and making a living in the space and satellite communications sectors, Alexandru Csete is best known in the software defined radio world for the creation of the popular open-source Gqrx software defined radio (SDR) receiver. “I created Gqrx – and many other software packages – because I wanted to have some good ham radio applications on Linux,” Alex explains, “which is my primary computing environment.”

That’s not to say that Alex’s radio experience is entirely software-driven, though his progression from pure-hardware to software defined radio was a natural one. “I always liked experimenting with radio. When I got my ham radio license in 1991 I used to build my own transceivers for shortwaves,” he recalls. “It was great to be on the air with home made equipment. However, as technology evolved it became increasingly difficult and expensive to build my own radios versus buying off the shelf radios.

“SDR changed this. With SDR we have a very cost effective way to experiment with new ideas and technologies; we can use generic hardware to which we write our own software. Of course, for best performance we have to adapt the hardware for specific purposes, but we are no longer limited to the functionality implemented by the radio manufacturers. We are again able to build our own radios, just in a different way than before.”

Alex’s introduction to SDR came with a distinct focus off-planet. “In 2008 I was working with a team participating in the Google Lunar XPRIZE,” Alex explains. “I was researching technologies that could be used for developing our own telemetry and video downlink systems. Software defined radio seemed like a technology with great potential and it didn’t take long before I had my own USRP1 kit and started learning GNU Radio.

“I do have some ‘hardware defined radios’ that I use on the air,” Alex adds, “namely Icom IC-706, IC-910, and Yaesu FT-817ND. A few years ago I also started experimenting with FreeDV, and I am working towards being able to do that using my ‘home made’ SDR – both hardware and software.”

Such projects, combined with a full-time career, make for a very busy schedule, and for anyone using Gqrx Alex offers an invitation to help spread the load. “I am working on new SDR projects at the moment and don’t have time to work on Gqrx, but people are always welcome to send me patches with bugfixes,” he explains. “The list of know issues is on GitHub. It would also be nice to get assistance with some documentation and packaging.”

Like anyone, Alex has a wealth of stories covering both successes and failures – including one which could have been an extremely expensive lesson had things gone just a little differently. “Most recently, I accidentally transmitted 100W RF into a hybrid splitter – designed for low power – with the other output connected to a rather expensive shortwave SDR receiver,” Alex recounts. “The splitter was destroyed, but it protected the expensive SDR receiver. I was very lucky this time!”

Alex’s tip for anyone getting started in SDR is simple: “The only advice I can give is that people should check what software packages are available before buying SDR hardware,” he says, with Gqrx naturally a front-runner for those running Linux.

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