The LibreCellular project has reached another milestone with the development of a low-cost 1,800MHz medium power amplifier design targeting 4G Long Term Evolution (LTE) Band 3.
“While suitable low power RF amplifiers are available at a modest cost, as the power output increases to a watt or more the cost starts to increase significantly,” Andrew Back explains of the need for a medium power amplifier. “Meanwhile in rural areas of the UK it is now possible to obtain a spectrum licence under the Ofcom Shared Access scheme which permits operation with up to 42dBm EIRP. Hence an affordable power amplifier solution for those with smaller budgets would prove quite useful.”
The amplifier is based around a BGY2016 three-stage UHF amplifier module, chosen for its low cost and ready supply, and targets a minimum modulated power output of 32dBm (1.6W). In testing, the initial design showed the potential to offer a maximum useful power output of 34dBm (2.5W) – exceeding the target minimum by a comfortable margin.
Launched in May last year, LibreCellular is an effort which aims to provide a fully-tested and validated hardware platform and software stack for 4G Long Term Evolution (LTE) networking building atop open-source projects including srsRAN (formerly srsLTE) and Open5GS, OsmoGSMTester, the LimeSDR family, and LimeRFE.
A pair of navigation technology experts, Cillian O’Driscoll and the European Space Agency’s Gianluca Caparra, have designed a test-bed platform for embedded navigation authentication, building atop the LimeNET Micro platform.
“Nautilus [is] a low-cost, lightweight, and highly configurable platform for assessing GNSS [Global Navigation Satellite System] authentication schemes,” the pair explain of the project. “Nautilus consists of a commercially available board integrating a u-blox GNSS receiver, a Raspberry Pi Single Board Computer (SBC), and an LMS7002M Software Defined Radio (SDR).
“A range of custom software has been developed to enable both system side (NMA [Navigation Message Authentication] and SCE [Spreading Code Encryption]) authentication, and user-side defences, such as clock modelling, secure time transfer and IMU [Inertial Measurement Unit] consistency checks.”
The idea behind Nautilus: A proven, low-cost platform for testing protections against GNSS spoofing, with a focus on NMA and SCE. In its creation, the pair performed some modifications to the LimeNET Micro: Updated FPGA firmware for closer tight alignment between data collection and GNSS timestamps and the re-routing of the u-blox’ PPS signal to the Raspberry Pi for time synchronisation alignment, made possible through the open-source nature of the LimeNET Micro’s gateware, plus the unlocking of a USB connection between the Raspberry Pi and the u-blox module. A serial IMU and combined Wi-Fi and cellular modem were added alongside the changes.
The paper detailing Nautilus is available on ResearchGate under open-access terms.
Adrian “YO8RZZ” Musceac has shown off a multi-carrier, multi-standard base station for amateur radio work powered by a LimeNET Micro and LimeSDR Mini.
“Using LimeSDR equipment (LimeNET Micro/LimeSDR Mini) and MMDVM + GNU radio as core components,” Adrian explains, “[this] implementation of a full duplex SDR base station was created in order to support the DMR, System Fusion, D-Star, and M17 amateur digital voice standards in a multi-carrier configuration, with up to seven transmitted carriers within 200kHz bandwidth, in any combination of operating modes and with a configurable channel separation. The channel/mode matrix is entirely user configurable by using multiple MMDVM instances, each of them dedicated to one operating channel.
“The long term goal is to continue software development and combine LimeSDR equipment with the LimeRFE front-end and capable computing hardware to supply a self-contained, easily deployable base station in NITB style. The end-user should only need to supply their own antennas, power amplification, and duplexing hardware for a complete SDR base station solution.”
At the time of writing, the project had successfully proven its capabilities for DMR and System Fusion standard operation, though D-Star and M17 had not yet been tested. “All credit for the work supporting this project goes to Jonathan Naylor, Peter Rakesh and all the people who created or contributed to MMDVM and GNU Radio along the years,” Adrian notes.
Lime Micro has announced the release of Lime Suite v22.09.0, which brings with it bug fixes and the first support for LimeSDR Mini v2 hardware – and a third-party build for FreeBSD, too.
Released earlier this month, Lime Suite v22.09.0 brings with it a fix for a crash in the fast Fourier transform viewer if using the software over an SSH connection via X11 forwarding, a workaround for another crash in libusb-1.0.25, and fixes for wxWidgets which could result in sub-optimal GUI rendering.
The biggest change, though, comes in support for the upcoming LimeSDR Mini v2. Designed to replace the LimeSDR Mini, the LimeSDR Mini v2 was created to work around component shortages with the original’s designs FPGA – but takes the opportunity to upgrade to a considerably larger chip with more resources and an open-source toolchain.
The latest Lime Suite is available to download now on the project’s GitHub repository, and is a recommended upgrade for all LimeSDR users. Those using LimeSDR hardware with FreeBSD rather than Windows, macOS, or Linux, meanwhile, can find third-party builds on Fresh Ports.
Developer Dale Ranta has released a new version of SdrGlut, the portable software defined radio software, which brings with it “remote speaker” functionality for streamed audio.
“The new SdrGlut V1.31 has a remote speaker option where the audio can be sent to any machine on the local network running the listen program,” Dale explains of the software’s latest feature. “This permits shortwave programs from the SDR connected to an outside antenna to be heard in other rooms. SdrGlut and the listen program both work nicely with LimeSDR devices.”
The new build of the software, which is built around the OpenGL Utility Toolkit (GLUT) and aimed at simplicity and portability, follows on from a rapid development process which has seen the software gain a range of features since its original launch including improved visualisations, enhanced recording capabilities, I/Q stream over TCP/IP transmission, and a seven-channel audio equaliser.
The latest version of SdrGlut is available on the project’s GitHub repository, along with the source code under the permissive MIT licence. A video demonstrating the new remote speaker functionality is available on YouTube.
RadioStack’s upcoming Maverick-603 is a software-defined radio with a difference: The receiver at its heart is open-source silicon, built as part of the OpenMPW shuttle program under Google’s sponsorship.
“Maverick-603 is the first affordable FT8 receiver board built around an RF receiver chip that was designed using fully open source tools and fabrication,” its creators explain. “It is capable of acquiring FT8 signals between 7 MHz and 70 MHz. With this frequency range, you will be able to receive signals from around the world with high accuracy. The use of our Low Noise Amplifier (LNA) will also give the chip the ability to amplify very low-strength signals, which is necessary for an effective FT8 receiver.”
While the SDR board itself is controlled by an off-the-shelf Microchip ATmega1608, the receiver chip is entirely custom – and has been created as a physical silicon chip as part of the OpenMPW program which sees open silicon projects invited to tape out their designs using the Efabless platform for production at a SkyWater fab entirely free of charge, with Google footing the bill.
“It is difficult for open source practices to thrive in the chip-design industry, but Maverick-603 demonstrates that open source chip design can produce products that equal or surpass their closed-source counterparts,” the RadioStack team claims. “With this project, we aim to gather interest and support, both for amateur radio and for open source chip design.”
More details are available on the project’s Crowd Supply page, where assembled boards will be put up for sale in the near future; the source files for the receiver have been published to GitHub under the permissive Apache 2.0 licence.
Those working with unknown radio signals have a new tool in their arsenal: FISSURE, an SDR-based framework for signal analysis and reverse engineering.
“FISSURE [Frequency Independent SDR-Based Signal Understanding and Reverse Engineering] is an open-source RF and reverse engineering framework designed for all skill levels with hooks for signal detection and classification, protocol discovery, attack execution, IQ manipulation, vulnerability analysis, automation, and AI/ML [Artificial Intelligence/Machine Learning],” the Assured Information Security Inc. team explains of the tool, brought to our attention by RTL-SDR.
“The framework was built to promote the rapid integration of software modules, radios, protocols, signal data, scripts, flow graphs, reference material, and third-party tools. FISSURE is a workflow enabler that keeps software in one location and allows teams to effortlessly get up to speed while sharing the same proven baseline configuration for specific Linux distributions.”
ETSI, the European Telecommunications Standards Institute, has announced that it has adopted the first open radio access network (open RAN) specification as a formal Technical Specification (TS), ETSI TS 103 859.
“Recognition of O-RAN specifications by ETSI is another major step in enabling broad adoption of Open RAN,” claims Claire Chauvin, O-RAN Alliance Board member and directory for strategy architecture and standardisation at Orange. “Having the O-RAN specification available as an ETSI specification adds further endorsement desired by commercial and public sector entities in a range of countries.”
“The O-RAN specification has been approved as an ETSI specification after a thorough review and requested revisions by our experts,” adds ETSI Mobile Standards Group Technical Committee chair Dominique Everaere. “When specifications go through the ETSI PAS [Publicly Available Specification] process, they need to comply with the ETSI rules, and the ETSI committee in charge of these specifications works with the organisation to ensure they align with existing procedures for approval as ETSI standards.”
ETSI TS 103 859 is based on the O-RAN Alliance’s Fronthaul Control, User and Synchronisation Plane Specification v7.02 covering open fronthaul for both 4G Long Term Evolution (LTE) and 5G New Radio (NR) networks. A PDF copy of the standard is available for public download.
Embedded engineer Johnny Wu has designed a motorised antenna rotator for satellite communication projects, dubbed the AntRunner – and is selling initial prototypes
“AntRunner is a portable antenna rotator designed and made by Muse Lab,” Johnny writes of the project, brought to our attention by Hackaday. “It can be used for real-time automatic racking of satellites with corresponding open source software which is available on Windows/Linux/Mac/Raspberry Pi/Android.
“The rotator and the host computer can communicate via wired (serial port) or wireless (Wi-Fi 2.4GHz). It can install various types of antennas (usually Yagi antennas), support 360-degree azimuth and 180-degree elevation control, and can support antennas up to 5kg. It can be powered by a 12V battery or by a fast charging power bank with a 12V fast charging trigger cable. It’s easy to carry as its weight is relatively light and very convenient to use in the wild for HAM.”
Johnny has published the software for, but not the design of, the AntRunner to GitHub under the reciprocal GNU General Public Licence 3; for those looking to try it out, he has made a number of prototypes available on Tindie at $325 (around £295).
ARRL, the National Association for Amateur Radio, has published an article showing just how vital radio communications and software-defined radio can be – after hams guided a disabled sailboat back to port.
“Jeanne (Jan) Socrates, VE0JS/MM/KC2IOV, and her sailboat, the SV Nereida, set sail from Cape Flattery, the north-westernmost point of the contiguous US. She was on her way to visit friends in San Francisco, California, but two days of 35 knot winds and storms left her sailboat disabled and her onboard radio equipment marginally operational,” the ARRL explains. “Amateur operators in New Mexico, California, and Canada, and members of Group 7.155 heard her requests for assistance.
“Gil Gray, N2GG, was able to contact Socrates on 40 meters. ‘Her power was extremely low, and she was unable to communicate on 14.300 MHz to notify the monitoring group on that frequency,’ said Gray. ‘She needed help with wind and sea conditions, and tidal data for San Francisco Bay,’ he added. Low-power output on the HF radio made it very difficult to get Q5 copy, which would typically be Q2 or Q3. With the help of several software-defined radio (SDR) operators in Utah, California, and Maui, Hawaii, they were able to glean enough copy to understand her situation and answer questions for her navigation.”
The full story is available on the ARRL website.
Finally, Harald “LaForge” Welte has published an update on the Osmocom Community TDM over IP (OCTOI) retro-networking project, detailing the deployment of a dedicated and powerful community hub.
“So far, the central hub of [the] OCTOI network has been operating in the basement of my home, behind a consumer-grade DOCSIS cable modem connection. Given that TDMoIP is relatively sensitive to packet loss, this has been sub-optimal,” Harald explains. “Luckily some of my old friends at noris.net have agreed to host a new OCTOI hub free of charge in one of their ultra-reliable co-location data centres.
“I’m already hosting some other machines there for 20+ years, and noris.net is a good fit given that they were – in their early days as an ISP – the driving force in the early 90s behind one of the Linux kernel ISDN stacks called u-isdn. So after many decades, ISDN returns to them in a very different way. Now that the physical deployment has been made, the next steps will be to migrate all the TDMoIP links from the existing user base over to the new hub. We hope the reliability and performance will be much better than behind DOCSIS.”
Harald’s full post is available on his website, while more information on the OCTOI project – which aims to bring functionality back to TDM/ISDN/SS7 equipment by connecting them over modern IP networks – is available on the Osmocom wiki.