Community member Godfrey L has published a multi-part series on using a LimeSDR and the ODR-mmbTools software bundle to transmit Digital Audio Broadcasting (DAB) signals.
“My journey on the reason to use LimeSDR and ODR-mmbTools for DAB/DAB+ transmission started from the announcement that Raspberry Pi could transmit FM station all by itself,” Godfrey explains. “I said alright, let me try with LimeSDR then since it can transimit and receive almost everything. Well on that front it took me to OCR-mmbTools. From there my path lead me to Open Digital Radio and their fantastic ODR-mmbTools.
“Over the next articles, I will go through how I got it to work, what challenges I faced and how I resolved them and many other information on broadcasting DAB/DAB+ using LimeSDR and ODR-mmbTools.”
The series starts over on Godfrey’s first Medium post.
Ronald Nicholson has released an IQ server for the LimeSDR Mini, designed to run on a Raspberry Pi 3 and compatible with the rtl_tcp protocol.
“There are multiple SDR applications, available for Linux, macOS, or Wintel systems that can connect to a local or remote SDR radio peripheral via the rtl_tcp protocol. This server allows using many of those applications with a LimeSDR Mini.”
The software is available now on Ronald’s GitHub repository, under the Mozilla Public Licence v1.1.
Luigi Cruz has released a desktop operating system image for the Raspberry Pi which comes pre-loaded with a range of drivers and supporting software for SDRs including the LimeSDR family.
“I created a Raspberry Pi desktop image pre-loaded with RTL-SDR, Airspy, and LimeSDR (with VNA & GRC support) software. Including GNU Radio, Soapy, GQRX, and SDR Angel,” Luigi writes via Twitter. “The idea is to support all SDR but I just have these three.
“I created this image for @luciangasparini to upgrade his LimeSDR. After that I decided to make it publicly available and people seem to like it. But I didn’t had the time yet to write a proper documentation and stuff. It’s basically Raspbian with a lot of SDR software pre-loaded.”
The image, which can be flashed to a microSD and booted in a Raspberry Pi 3 or higher single-board computer, can be downloaded from Luigi’s website. A roadmap outlining upcoming enhancements can be found on Notion.so.
Software developer perillamint, meanwhile, is aiming to be the first to use a LimeSDR on a Nintendo Switch handheld console – though warns there are final touches to be made.
Effectively a high-performance Arm-based single-board computer featuring an Nvidia Tegra system-on-chip, the Nintendo Switch is – as with most modern consoles – designed to run only the software approved by its creator. The L4T Ubuntu project, however, has found a way to install and run a variant of the Ubuntu Linux operating system on the device – unlocking its potential for non-gaming use.
“It’s almost ready to run LimeSDR on Nintendo Switch,” perillamint writes on Twitter. “It may require some final touch[es] but I think I can run GNU Radio with some OpenCL blocks.”
Those interested in following perillamint’s progress should follow them on Twitter.
Hackaday has highlighted a clever project which combines a home-made electromagnetic interference (EMI) probe with a camera to produce a heat map of a device’s emissions.
Created by Charles Grassin, the project attempts to automate the process of measuring emissions and presenting the results in as easy-to-understand a format as possible. “The near-field probe is moved above the device under test while a camera tracks its current position,” Charles explains. “A Python script does all of the signal processing: tracking in the camera stream, computing the RF power and generating an EMI heatmap.”
Charles describes the system as simple and fast, high resolution, and inexpensive, though warns that it has limitations for real electromagnetic compatibility testing including issues with repeatability owing to the difficulty in keeping the probe a set height from the device on test and limited bandwidth from the entry-level SDR used in the prototype.
Full project details are available on Charles’ website.
RTL-SDR has published a write-up of an effort to receive and decode imagery from the geostationary COMS-1 weather satellite.
“COMS-1 LRIT decode chain is finally complete,” Sam writes on his Twitter account. “COMS-1 is a geostationary meteorological satellite operated by the Korean Meteorological Agency’s (KMA) National Meteorological Satellite Center (NMSC). It broadcasts meteorological data to end-users via two L-band (~1.69 GHz) downlinks. These downlinks can be received with an inexpensive hardware setup and some open-source software.”
Eric Sorensen has been working with weather satellite data too, creating full disk images of earth from the US National Oceanic and Atmospheric Administration’s GOES-17 weather satellite.
Using a parabolic dish antenna, a low cost SDR, bandpass filter and LNA, and some cables, Eric receives the data and passes it to the open-source goestools software for decoding. His guide also goes into antenna alignment and image processing.
The highlight of Eric’s post, though, is the video and animation created by processing 48 consecutive full disk images – offering an amazing view of the planet as the weather changes and it transitions from day to night.
Semtech Corporation has announced it is opening up the LoRaWAN Academy, previously available only to universities, to all in an effort to encourage the adoption of the open low-power wide-area network standard.
“Developers are the most important part of any modern technology platform, and the LoRaWAN Academy is there to help them get up to speed on one of the fastest growing IoT-enabling technologies out there today.The LoRaWAN Academy will enable developers to get their LoRa-based solutions to market faster as well as simplify development,” claims Steven Hegenderfer, senior director of the Developer Ecosystem in Semtech’s Wireless Sensing and Products Group.
““We are working with the LoRaWAN-based ecosystem to develop and drive material that is beneficial to the community. Providing completely free modules focused on building LoRa-based applications gives students, engineers, developers, and enterprises the jump-start they need to build robust, innovative IoT applications.”
The LoRaWAN Academy materials can be found on the company’s LoRa Developer’s Portal.
For those who prefer to jump right in, Hackaday has highlighted a project by high-altitude balloonist Dave Akerman to build a simple low-cost LoRa repeater in under an hour.
“Sometimes it’s handy to have a repeater to extend the range of a radio transmission. The particular usage I have in mind is to be able to receive telemetry from a landed payload that is too far away (or hidden by buildings or geography) to receive directly, but could possibly be received via a repeater up on a mast or flying on a drone,” Dave explains. “LoRa makes it easy to make a repeater, so that’s what I’ve done here. And to make it more generally useful, the repeater is programmable for frequency etc. via a Windows program, with the configuration stored in the repeater’s EEPROM.”
Full details on the repeater project, which is based on an Arduino Pro Mini microcontroller board, a compatible LoRa radio module, and a lithium-polymer battery, can be found on Dave’s website.
Finally, the videos from the OsmoDevCon 2019 conference have been made available via the Chaos Computer Club (CCC) media portal.
Presentations available in video form cover topics including a frequency-hopping GSM mobile station built using an SDR, software-defined E1, an introduction to the iCE40 field-programmable gate array (FPGA), a dissection of the Aastra/Mitel DECT base station, a look at the Osmo-GSM-Tester, and a project to create long-distance digital links using the high-frequency radio band, as well as updates on various Osmocom initiatives and projects.