The Lime Suite software bundle has received a significant update, to version 20.01.0, bundling new support for the LimeRFE software-defined front end, improved tuning and PLL locking, and other improvements.

In its latest release, the open-source Lime Suite library comes with support for the LimeRFE front end, following on from last year’s addition of support for the final LimeNET Micro design. The new release also includes improvements and bug-fixes for PLL locking during calibration, optional Rx phase alignment, improved SXT/SXR tuning with automated bios current increases, more efficient FIFO buggers, and avoidance of unwanted transmissions during calibration, among other changes.

The Lime Suite update also includes upgrades for SoapyLMS, including a new oversampling setting and fixes for potential crashes when two receive channels are used simultaneously, and the LimeSuite Octave plugin. Finally, the LimeSuiteGUI package now includes a panel for Lime Suite API function testing and the option to play WFM files directly within the software.

Full details on the improvements are available in the changelog, while the latest version is always available to download from the GitHub Releases tab.

Over on the Lime Micro blog, details have been posted on the use of the cuSignal Python library to improve SDR performance by offloading work onto a CUDA-compatible graphics processor – including on embedded systems like the Nvidia Jetson Nano.

“GPUs are increasingly being used in applications outside of graphics and have been popular for some time in both high performance computing (HPC) and machine learning,” writes Andrew Back. “Thanks to technologies such as the CUDA parallel computing platform from NVIDIA and the Numba high performance Python compiler, the barriers to using GPUs are being lowered all the time, enabling their blistering performance to be harnessed in ever more compute-intensive applications.

“CuSignal is a port of the signal processing modules in the Python SciPy library, which is developed by NVIDIA and builds on top of Numba and CUDA, along with CuPy. It comes provided with a number of examples, such as polyphase resampling, WFM demodulation, and even using machine learning to ‘predict’ the number of carriers in a signal.”

A month after demonstrating the potential for cuSignal in SDR applications, Luigi Cruz, interviewed below for Focus On, released an FM/AM desktop radio app accelerated with cuSignal and an assortment of Python scripts demonstrating other capabilities – including the ability to demodulate 35 FM stations simultaneously.

More information is available on the Lime Micro blog, while a guide to installing and using cuSignal in your own projects can be found on GitHub.

Videos of LimeSDR-related presentations made at the SDR Makerspace Conference, a joint initiative of the European Space Agency (ESA) and the Libre Space Foundation, late last year have now been published.

“We were invited to participate at the SDR Makerspace Conference back in November, where makers, researchers, experts and industry came together for two days of talks and workshops,” writes Andrew Back. “At this we presented an Introduction to LMS7002M, LimeSDR and Lime’s roadmap to 100GHz,” which was given by Drs. Danny Webster and Dušan Grujić.

“At the conference we also had the pleasure of being joined by Portsdown lead developer Dave Crump of the British Amateur Television Club (BATC), who gave a presentation on LimeSDR as an enabler for Satellite TV Transmissions.”

The presentations were followed by a hands-on workshop, held on the second day of the event, in which attendees were presented with a LimeSDR Mini and walked through the building of a DVB receiver which could be used to pick up a live transmission from a Portsdown system in the same room using a Snap-packaged app from the SDR Satcom app store.

More information on the event is available on the Lime Micro blog.

AMSAT, the organisation for amateur satellite operations, has officially declared AMSAT-OSCAR 85 (AO-85) as having reached “end of mission” – nearly five years after it launched.

“After a long decline in the health of its batteries, AO-85 has gone silent,” writes AMSAT vice president for operations Drew Glasbrenner. “Having not been heard throughout the most recent period of full illumination, it is reasonable to believe the batteries have deteriorated to the point of no longer being able to power the transmitter.

“AO-85 was conceived as the first AMSAT cubesat, and was designed to be a successor to the popular AO-51 microsat. Accepted into the NASA CubeSat Launch Initiative in February 2012, AO-85 was launched October 8, 2015. AO-85’s success led to further Fox satellites AO-91, AO-92, AO-95, and RadFxSat2 / Fox-1E which will be launched later this year. The Fox-1E transponder was also spun off into a radio system now in orbit onboard HuskySat-1, and soon to be in several other university cubesats.”

While it is possible that AO-85 may begin transmitting again if a cell recovers to hold enough charge, it is now official to be considered end-of-mission, Drew confirms.

Researchers from Ruhr University Bochum and New York University Abu Dhabi have warned of vulnerabilities in 4G Long Term Evolution (LTE) and early 5G cellular networks which open them up to the possibility of impersonation attacks on both uplink and downlink connections.

“In mobile networks, mutual authentication ensures that the smartphone and the network can verify their identities. In LTE, mutual authentication is established on the control plane with a provably secure authentication and key agreement protocol,” the researchers explain of their discovery. “However, missing integrity protection of the user plane still allows an adversary to manipulate and redirect IP packets.

“The IMP4GT (IMPersonation Attacks in 4G NeTworks) attacks exploit the missing integrity protection, and extend it with an attack mechanism on layer three which allows an attacker to impersonate a user towards the network and vice versa. We conduct two IMP4GT variants in a LTE commercial network and demonstrate how this completely breaks the mutual authentication of the user plane LTE and early 5G networks.”

Tested using the open-source srsLTE software stack and in a shielded housing to prevent interference with live networks, the vulnerabilities have been confirmed as affecting both 4G LTE and early 5G networks operating in non-standalone modes; 5G networks operating in standalone mode are not affected, so long as they implement optional user-level data integrity protection functionality.

More information can be found on the official website.

Separately, security specialists from IOActive have published a white paper detailing serious security failings in LoRaWAN low-power long-range wide-area networks – though admits these are due to implementation issues, rather than inherent to the protocol.

“LoRaWAN is fast becoming the most popular wireless,low-power WAN protocol. It is used around the world for smart cities, industrial IoT, smart homes, etc., with millions of devices already connected,” the researchers write. “The LoRaWAN protocol is advertised as having ‘built-in encryption’ making it ‘secure by default.’

“As a result, users are blindly trusting LoRaWAN networks and not paying attention to cyber security; however, implementation issues and weaknesses can make these networks easy to hack. Currently,cyber security vulnerabilities in LoRaWAN networks are not well known,and there are no existing tools for testing LoRaWAN networks or for detecting cyber attacks, which makes LoRaWAN deployments an easy target for attackers.”

As well as detailing these vulnerabilities in the white paper (PDF warning), the researchers have released a bundle of tools dubbed the LoRaWAN Auditing Framework (LAF) under the permissive BSD 3-Clause licence.

RTL-SDR has brought our attention to José Carlos Rueda’s work on creating an automated signal fingerprinting system for radio signals, building on a tool originally developed by Joseph Balikuddembe to create an open-source equivalent to song-recognition platform Shazam.

“SIGID (Signal Identification) is a strange hobby. A lot of people (including myself) are constantly searching for radio signals, trying to identify them through example sounds and images using waterfall software defined radio (RTLSDR, Airspy, SDRPlay, HackRF, etc.),” José explains.

“So first I have downloaded all audio samples from Signal Identification Wiki database and generated a SQLite database for the Python script. [After] about 5 to 10 seconds for listening, the script can now Identify a lot of Known Signals (About 350)!”

Instructions for installing the required tools, the audio fingerprinting system, and the hashed signal identification database plus running the tool across live audio or saved audio files can be found on José’s blog.

RTL-SDR has also highlighted a useful tool for anyone working on satellite communications and who has an Android device to hand: Look4Sat, an amateur radio and weather satellite tracker and pass predictor.

“The very app creation and design is hugely inspired by the open-source Gpredict desktop satellite tracking application, created by Alexandru Csete, OZ9AEC and contributors, supported by the Libre Space Foundation,” writes author Arty Bishop. “The Libre Space Foundation team is also behind the epic SatNOGS project that provides an extremely easy to use API and DB with a huge amount of information about satellites, their telemetry and transmitters, which the app uses under the hood.

“For TLE data calculation and passes prediction Look4Sat uses the mavenized version of predict4java library, created by David A. B. Johnson, G4DPZ and Dave Moten. Thank you guys for your hard work making this lib efficient and easy to use! The app is built using Dagger2, Retrofit2, Kotlin and Kotlin coroutines, Architecture Components and Jetpack Navigation.”

The tool is available to install now from the Google Play store, with source code available under the GNU General Public Licence 2 from GitHub.

For those interested in the basics of radio-frequency security, Dark Reading’s Curtis Franklin Jr. has penned a beginner’s guide with input from a selection of industry experts.

“It’s almost impossible to think about modern IT and networking without bringing radio frequency energy (RF) into the picture. That means it’s equally impossible to fully consider IT security without thinking about the implications of radio as both a Layer 1 component and a critical attack vector,” Curtis explains. “The problem for most IT and security professionals is that RF is all wibbly-wobbly and squishy.

“Rather than the neat, clean, on/off, one/zero of the digital domain, radio tends to be described in terms of frequencies and amplitudes, reflection and refraction, all of which are measured and described in the analogue domain. So for security professionals the questions become, why should they take the time to learn about this mysterious transmission layer, and where do they begin?”

The full article can be read over on Dark Reading.

Finally, researchers from the Massachusetts Institute of Technology have developed a means of boosting mobile phone signals by 1,000 percent – by adding antennas to the walls, rather than the device or transmitter.

“The core goal here was to explore whether we can use elements in the environment and arrange them to direct the signal in a way that we can actually control,” explains Professor Hari Balakrishnan, senior author on the paper describing RFocus. “If you want to have wireless devices that transmit at the lowest possible power, but give you a good signal, this seems to be one extremely promising way to do it.”

The RFocus system itself is a two-dimensional surface covered in thousands of antennas capable of either passing then signal through or reflecting it. Placed under software control, these antennas concentrate the signal where it needs to be – and in doing so boost the signal strength at the mobile phone side by 1,000 percent.

“The biggest challenge was determining how to configure the antennas to maximise signal strength without using any additional sensors, since the signals we measure are very weak,” says Venkat Arun, lead author of the paper. “We ended up with a technique that is surprisingly robust.”

More details are available on the MIT website, with the work to be presented at the USENIX Symposium on Networked Systems Design and Implementation (NSDI) in Santa Clara, California later this month.

Focus On: Luigi Cruz

Luigi Cruz

Can you tell us about some of the projects that you are working on what they are, how they started, and why they are interesting and/or important?

PiSDR: This project started when my friend Luciano Gasparini (PT9KK) asked me for a Raspberry Pi image with the LimeSuite pre-installed. I realized that a lot of people in the SDR community don’t have experience with Linux and therefore struggle to install the required packages. With this in mind, I installed the toolkits of every SDR I owned on a Raspbian image and made it available for everyone. Today, the latest PiSDR image was downloaded more than four thousand times.

CyberRadio: The main purpose of the application is to simplify the SDR experience by mimicking an analog radio. Modern and straight forward GUI with minimal controls and no FFT. Despite its apparent simplicity, the radio makes use of cool tricks like GPU powered DSP using cuSignal and statically linked SDR interfaces for an easier installation.

What attracts you to SDR and RF/wireless in general?

I’m fascinated with radios because it is one of the most important inventions of all time. It drastically changed the way the human race live and interact. Today, we can access an unlimited library of knowledge with our phones. Something unheard of only two generations ago. I find really rewarding to contribute with something with such a high impact upon society.

How did you get started – what were your first experiences?

I bought my first Software Defined Radio four years ago to receive the ADS-B signal. At first, I didn’t realize the endless list of applications offered by such an inexpensive device. I started to read more and more about it and by the time it arrived at home I already had a full list of cool experiments to make. I started simple with the ADS-B receiver and one project lead to another. Eventually, I was decoding NOAA satellites and contributing to a project like the Open Satellite Project created by Lucas Teske (PU2NVX). This whole experience with radios motivated me to became a licensed radio amateur PU2SPY.

What recent developments are you most excited by?

The performance of the latest generation of Single Board Computers is finally good enough for real-time Digital Signal Processing. In combination with a low-cost SDR, remote solutions can be deployed at a super low cost. This democratization of field solutions helps accelerate the development and research of new technologies.

I’m also excited about projects that take advantage of highly parallelized code to perform DSP. This kind of code will be critical to take advantage of future CPU with the growing number of cores. A project developed by Adam Thompson called cuSignal is a good example of such an optimized code being tailored to run in the GPU using CUDA.

What is on the horizon that you are particularly looking forward to?

I’m particularly excited by the recent advancements of open-source software to decode robust Forward Error Correction codes such as Low-Density Parity Checks developed by the Phase 4 Ground project. This type of FEC is used by newer generations of the Digital Video Broadcast to reduce the Signal to Noise Ratio required to successfully receive the MPEG Transport Stream. Unfortunately, this algorithm requires a lot of computational power to be decoded at lower SNR. I think this technology can be highly beneficial to the HAM community and would take DATV transmissions to a whole new level.

What do you see as some of the biggest challenges for experimenters/enthusiasts/hams?

I noticed that the SDR community constitutes of mainly two groups, the radios amateurs experimenting with new technology and the programmers exploring a new dimension of possibilities. This strange confluence of different skill sets into a common goal resulted in two opposite challenges. The programmers understand the software side really well and struggle with signal processing and hardware concepts. On the other hand, radio amateurs often dream with Smith Charts but wrestle with simple programming problems. This is why sharing your experience with the community is so important.

What would you most like to see from future SDR solutions?

I can’t decide which one is the most important, so I’m listing three things that I think will make the SDR solutions even better than they are today:

  • Affordable SDR solutions with alternative data interfaces like PCIe and Ethernet. The former would be useful for high-speed low latency applications and the latter for remote deployments where reliability is key.
  • Wideband SDR with a tunable frontend filter to improve performance with faint signals. This is increasingly important because EMI is becoming unbearable in densely populated areas.
  • More SDR solutions like the LimeNET and PlutoSDR. Sometimes is important to run your DSP locally. Running Linux on the SDR with custom software is the easiest way to get this done.

How important is it to you that projects are released as open-source?

For me, it’s crucial for the small SDR and HAM community. All the projects I develop in my free time about radios are and always will be open-source. This contribution is the least I can do to make justice to the radio amateur core value of helping each other and the community.

How can people get involved with the projects you are working on?

It’s easy, all you need is a GitHub account! All types of contributions are welcome. People can contribute even without coding experience by reporting bugs, unexpected behaviours and requesting new features. I’m recently giving special attention to documenting my repositories. All my projects are listed on my GitHub Profile. My Twitter is also a great place to find my projects being used in practice.

Have you ever had any major failures, such as accidentally shorting something out that shouldn’t have been shorted?

Fortunately, not recently. But a long time ago, I somehow shorted the heatsink to the chipset of my Compaq laptop and it died. It’s sad, but it taught me an important lesson to be always being cautious with ESD.