The LMS8001 Companion Board’s crowdfunding campaign is now live, and the response has been fantastic – including with questions from backers eager to use the device on the 3cm/10GHz amateur radio band for Earth-Moon-Earth communication, satellite tracking, radio astronomy, and more.
“Years after the initial release of engineering samples of our LMS8001A frequency-shifting RFIC [Radio-Frequency Integrated Circuit], Lime is proud to announce its transition to production and continuous availability,” Lime Microsystems’ chief executive officer Ebrahim Bushehri explained at the campaign’s opening. “To mark the occasion and help developers get started extending their SDRs up to 10GHz, we are releasing a new version (3.1) of the LMS8001 Companion Board that includes the production chip and functional upgrades, such as a USB Type-C connector and retuned bands.”
Interest in the new board, which is being made available at a time-limited price of $350, has been high, with many backers interested in one particular application: the 3cm/10GHz amateur radio band, which extends to 10.5GHz – officially slightly out-of-range for the new LMS8001 Companion Board per its formal specification.
Any disappointment should be washed away, however, by the news that initial testing shows that the board can indeed be used up to 10.5GHz – with, benchmarks have shown, “excellent performance across the 10-10.5GHz band” with “relatively small degradation” even towards the upper end of the range. For further details please see the campaign update.
Those interested in picking up an LMS8001 Companion Board for themselves can back the campaign on Crowd Supply now.
Google’s Mike Burton has built a tiny desktop “Watch Tower” – not to keep an eye on his pens, but to serve as a short-range WWVB time signal transmitter for a watch collection.
“There are some beautiful radio-controlled watches available these days from Citizen, Seiko, Junghans, and even Casio,” Mike says of the need for the gadget. “These timepieces don’t need fiddling every other month, which is great if you have more than one or two and can never remember what comes after ‘thirty days hath September…’
“In the US, these watches work by receiving a 60-bit 1Hz signal on a 60kHz carrier wave broadcast from Fort Collins, Colorado called WWVB. The broadcast is quite strong and generally covers the entire continental US, but some areas of the country can have unreliable reception.
“I live in the SF Bay Area,” Mike continues, “in an area with high RF noise and my reception can be spotty. My watches sync often enough that it’s not an issue 363 days out of the year, but sometimes they can miss DST shifts for a day or two. The east coast is known to be even more challenging. And people who live in other countries such as Australia have generally been out of luck. Wouldn’t it be great if anyone anywhere in the world could set up a home transmitter to broadcast the time so their watches were always in sync?”
That’s exactly what the Watch Tower is: a 3D-printed plinth on which a watch can sit, and inside which is an Espressif ESP32 microcontroller linked to a ferrite rod antenna via an H-bridge amplifier. “The FCC requires a license to transmit,” Mike admits, “but has an exemption for 60kHz transmitters as long as the field strength is under 40μV/m at 300 metres. You will definitely not exceed this limit.”
Full details, source code, and the 3D-print files for the enclosure are available on GitHub under the permissive MIT licence.
Jacopo Cassinis has written a guide for satellites to look for in the wake of the scheduled decommissioning of the Polar Operational Environmental Satellite (POES) constellation – and there’s still plenty in the sky to keep you occupied.
“After the eventual decommissioning of the last POES satellite (NOAA-15, known as The King), many satellite amateurs are worried about the end of the hobby, given the apparent lack of satellites to receive imagery from,” Jacopo writes. “However, this is far from the truth!
“Contrary to popular belief, the LRPT transmission [of Russian Meteor-M satellites] is not much harder to receive than APT and only needs the same hardware and software (SatDump). No other adjustments are needed, other than perhaps the purchase of an inexpensive SAW-filtered LNA from Aliexpress to improve the reception in interference-prone areas (APT was a bit more resilient to that, as for example VDL2 bursts caused thin lines on APT that were barely visible).
“Arctic Weather Satellite and STERNA […] satellite series transmit microwave radiometric data on the L band at 1707MHz with parameters similar to Metop. While less ‘shiny’ and ‘sexy’ than visual imagery, this data is nevertheless quite important and can be used to complement Meteor data for weather forecasting,” Jacopo continues.
“Elektro-L […] geostationary satellites transmit easily receivable signals on the L band, on 1691MHz (HRIT and LRIT). The system employs three satellites, covering most of the globe except the Americas. People in the Americas will be pleased to know that GOES-U (GOES-18 and GOES-19) satellites will continue to operate and transmit HRIT and GRB well into the 2030s.”
The full write-up, with considerably more satellites than included above, is available on Jacopo’s website.
Mononymous radio amateur Meti, meanwhile, has launched an archive of historical satellite data – totalling 430GB and rising.
“The ultimate goal of this archive is to provide historical data from weather satellites for educational and scientific purposes, [and to] store it for the sake [of] preservation,” Meti writes of the project. “Many of these satellites are lost to the sands of time because nobody figured they’d ever need the data again or the recordings they had eventually decayed to the point of non-recoverability.
“I currently host this archive on a spare HDD on my primary server, maintain it for fun. It helps others and takes minimal time to do so, I believe it’s a worthwhile cause! 430 gigabytes of data from 30+ contributors is stored. I currently classify every dataset into one of five processing levels, each of which is a processing step ranging from raw baseband to processed imagery.
“Initially,” Meti adds, “this project started as a place to store sample imagery for my satellite reception guide, shortly after adding the imagery I decided I could save whole sample passes – I had a whole spare HDD after all. A reason for doing so is allowing people to view datasets from satellites they can’t receive – I still fondly remember the amazement when I first loaded in an HRPT dataset and seeing the volume of data!”
The archive is available on its dedicated website now, under the Creative Commons Attribution ShareAlike 4.0 licence.
SatDump’s developers have set out a roadmap to the software’s 2.0.0 release – promising a complete overhaul of key parts of the satellite data decoding tool and improved documentation.
“Development never stopped,” the project’s maintainers promise in their latest update, “but has rather been focused on another large rewrite meant to finally fix design mistakes and completely overhaul several parts of SatDump (featuring Documentation!!!!!).
“By design, sure, a large rework will make the software absolutely unusable for a little while,” the developers admit, “therefore all the work had to be performed on another branch in the meantime. However, it can’t last forever and has to be merged back in master at some point. The way we decided to do it was to keep it separate until the bulk of the rework that would impact the user most & break compatibility the most was done, and from there start releasing alpha releases until the full thing is done to finally release 2.0.0.”
Improvements promised in the new version include a more flexible calibration system, a completely reworked viewer inspired by geographic information system (GIS) standards and which replaces the original graphical user interface, a simplified pipeline format, the ability to directly open first-party products and xRIT files, support for external shapefiles, the option to script in Angelscript for improved performance, and initial – but experimental – decoder for slow-scan television (SSTV) signals.
A longer list of changes coming in SatDump 2.0.0 is available on the project website.
Researchers from the Massachusetts Insitute of Technology (MIT) have designed a family of “meta-antennas” which can be expanded and retracted in order to tune them to particular frequencies.
“Usually, when we think of antennas, we think of static antennas,” lead author Marwa AlAlawi explains of the team’s work. “They are fabricated to have specific properties and that is it. However, by using auxetic metamaterials, which can deform into three different geometric states, we can seamlessly change the properties of the antenna by changing its geometry, without fabricating a new structure. In addition, we can use changes in the antenna’s radio frequency properties, due to changes in the metamaterial geometry, as a new method of sensing for interaction design.
“In order to trigger changes in resonance frequency, we either need to change the antenna’s effective length or introduce slits and holes into it. Metamaterials allow us to get those different states from only one structure. The beauty of metamaterials is that, because it is an interconnected system of linkages, the geometric structure allows us to reduce the complexity of a mechanical system.”
The team’s rubber-and-conductor metamaterial is laser-cut under the control of a design program which calculates the finished product’s resonant frequency range. To prove its functionality, the researchers built a range of devices featuring the meta-antennas – including curtains which adjust smart lighting systems when opened and closed and headphones which can switch between noise-cancelling and transparency modes.
The team’s work is available on the MIT Computer Science and Artificial Intelligence Laboratory website under open-access terms.
Two members of the Institute of Electrical and Electronics Engineers (IEEE) have published a paper detailing how in-memory computing (IMC) can be used to deliver more energy-efficient signal detection in massive multiple-input multiple-output (MIMO) systems.
“SRAM-based IMCs are the state-of-the-art for executing deep learning workloads in terms of energy efficiency and compute density,” the pair write in the abstract to their paper. “However, given the more stringent accuracy requirements of massive MIMO signal detection compared to deep learning, it remains an open question whether the energy efficiency benefits of IMCs can be preserved while meeting these accuracy requirements.
“This paper systematically explores the energy-accuracy trade-off in massive MIMO signal detectors designed using SRAM-based IMCs. Through transistor-level behavioural modelling and simulations in 28nm CMOS process, we evaluate the energy per information bit (Eb), error vector magnitude (EVM) and symbol error rate (SER) of linear detectors designed using SRAM-based IMCs for various wireless channels. We perform extensive design space exploration to determine the design parameters and operating conditions under which IMC-based linear detectors achieve significantly better energy efficiency than conventional digital implementations, while maintaining comparable accuracy.
“Our results show,” the team concludes, “that IMC-based detectors can meet 3GPP EVM specifications for QPSK, 16-QAM, and 64-QAM across both real-world (Argos) and synthetic (WINNER-II) wireless channels, achieving 7.2× to 11.7× better energy efficiency than digital detectors while incurring <0.1dB penalty in receiver signal-to-noise ratio (RX SNR). We present extensive simulation results that provide insights into how parameters such as MIMO dimension, modulation scheme, precision of detection matrix, IMC bit-cell capacitance, IMC ADC precision, and ADC thermal noise impact the energy efficiency and accuracy of massive MIMO signal detection.”
The full paper is available in the journal IEEE Transactions on Circuits and Systems under open-access terms.
Finally, scientists have spotted the brightest fast radio burst ever recorded – dubbed RBFLOAT, or the “radio brightest flash of all time”, and originating in the Ursa Major constellation some 130 million light-years from Earth.
“Cosmically speaking, this fast radio burst is just in our neighbourhood,” co-author Kiyoshi Masui, associate professor of physics, explains. “This means we get this chance to study a pretty normal FRB in exquisite detail.”
The burst, a flash of radio-frequency emissions lasting for mere milliseconds yet strong enough to drown out all other radio sources in its vicinity, was captured by the Canadian Hydrogen Intensity Mapping Experiment (CHIME), one of around 4,000 bursts captured since it started its observations in 2018 – but the first which has been pinpointed to an exact location, thanks to the recent addition of “CHIME Outriggers” to increase its precision.
“But the precise localisation of this burst is letting us dive into the details of how old an FRB source could be,” Masui explains of the reason the team was so excited at their discovery. “If it were right in the middle, it would only be thousands of years old – very young for a star. This one, being on the edge, may have had a little more time to bake.”
The team’s work is available under open-access terms in The Astrophysical Journal Letters.