Researchers have discovered a way to transmit information wirelessly without power, simply by opening an closing a switch that connects a resistor to an antenna. This effect does not violate any physics - it works because the random thermal noise signature of the transmitter changes when the resistor is connected or disconnected.
The researchers used an RTL-SDR with high gain horn antenna and low noise amplifiers to measure changes in the thermal noise signature of the transmitter.
They also compare their idea to backscatter devices, which are another form of passive RF communications that make use of ambient radio signals such as from TV transmitters. They note that their thermal noise approach has a lower data rate and range compared to backscatter, but their next goal is to try and improve this.
Back in August of 2021 we posted about the release of a Russian made portable software defined radio receiver called the "Arinst Dreamkit V1D". The Arinst SDR consists of a portable LCD screen and enclosure, with 16-bit ADC, 5 MHz of bandwidth and 1 - 3100 MHz tuning range. It was released for sale in September 2021 and was priced at only $230 + shipping.
It did have some drawbacks involving a lack of preselector filtering, and there being no digital decoding capabilities implemented in the software.
Fenu-radio is a popular tester of various software defined radios and has recently posted a review of the Arinst Dreamkit V2D. Initially he notes how in 2021 he first received his V1D model from Kazakhstan, and noted some problems with the lack of preselection, but other than that it worked well. His unit also had a display defect, however the manufacturer replaced the entire unit with the newer V2D model.
Fenu-radio notes that a battery is no longer included due to restrictions involving the transport of batteries through airmail, so he had to order a separate battery from Aliexpress. He importantly notes that the polarity of the battery is reversed from what the radio expects, so this has to be manually adjusted by changing the pins on the battery. If this is not done the battery or radio itself could be destroyed.
Other than that, Fenu-radio is impressed with the outer design of the V2D. He goes on to note how the V2D makes use of the R820T2 tuner, the same tuner used in standard RTL-SDR dongles. An up and downconverter is used to expand the range.
Fenu-radio then goes on to show the features of the radio, shows how it is operated, and provides a few audio examples of some stations received. He concludes positively:
The Arinst V2D is almost a "dream kit". It offers amazingly good reception on long, medium and shortwave without immediately clipping. And that on domestic active antennas. If you work with the manual gain control, you largely avoid intermodulation products and noise. The variety of functions is enormous and of high quality. At that point, you realize how hard Arinst has put in. The V2D can also convince above shortwave. What it particularly lacks here is a search function (scanner).
The case is sturdy and of good quality. But unfortunately there is criticism here. The housing shells were painted in places that shouldn't be painted! The painted flanks of the housing significantly worsen the shielding effect, which becomes noticeable with strong interference in reception if the V2D is operated with a telescopic antenna. The interference is particularly strong in the VHF range. Not only that. During the development of the V2D, far too little attention was paid to decoupling the display to prevent interference radiation in the reception branch. The approx. 4 hours Battery life was unfortunately never reached. After almost 3 hours of operation it was over.
Otherwise, the V2D is great fun. Especially with a remote antenna.
Arinst showed itself to be a very committed manufacturer when it came to correcting errors in the software and implementing suggestions.
At the time of this post the Arinst website and their sales platforms on Aliexpress and eBay does not appear to feature the 'Dreamkit V2D' product and we have no further info on the release date or pricing.
PCB boards that combine these two chips can be found cheaply on Aliexpress as LoRa boards, under the name "LILYGO LoRa 32". If you are unaware, ESP32 chips cheaply combine a WiFi and Bluetooth modem with a microcontroller that is capable of hosting a webserver. CC1101 and SC127X are low cost low power hardware transceiver chips made for IOT devices. We've posted about LILYGO boards in the past as they've been used with interesting projects such as Meshtastic, and for weather balloon tracking.
This project could be useful for home automation as a module has been made available for openMQTTGateway. Instead of dedicating a more powerful Raspberry Pi and RTL-SDR, you can now dedicate a much cheaper and much lower power device to the task.
Mahiteam is a Russian company that produces the relatively popular Malahit DSP1/DSP2 and Malahit DDC portable SDR radio which are great for shortwave listening, but can also cover up to 2 GHz. Manuel L. has been following developments and notes that Malahiteam are offering the ability to upgrade their DSP1 (and any DSP1 Chinese clone) into Malahit 2 units by sending the device in for a chip replacement. Manuel writes:
Hi. Recently it is possible to upgrade the Malahit DSP1 (original) and also the China clones (if registered in Russia) of the Malahit with a new CPU and if necessary a new audio codec chip. This upgrade has been officially released by the Malahiteam the developers.
This allows custom DSP2 firmware to run on the DSP1 and clones. This makes the device more powerful and also has the option of installing a Bluetooth board and controlling it via the software, as is the case with the DSP2.
This upgrade can be carried out directly in Russia by the Malahit team.
For Europe this is done by Jochen Köster DC9DD (Malahit Servise Europa) who converted the first DSP1 and China clones outside of Russia.
In the US, the future KD9NXV makes Mark Roy (USA Service Malahit).
I have tested the first conversions outside of Russia and it is a very big upgrade of the devices. They work a lot better now. I have shown this in several YouTube films. More information and contacts to the service teams outside of Russia can be found at Telegram and the Malahit Facebook group
A few weeks ago the tinySA Ultra was released. This is a spectrum analyzer capable of operating between 0.1 - 800 MHz, or 0.1 MHz - 6 GHz with the 'Ultra' mode enabled. A spectrum analyzer is a tool that allows users to visualize signals on the radio spectrum.
Previously the standard tinySA was released back in 2020. The Ultra version brings enhancements to the frequency range, signal generator range, bandpass filter range as well as an optional 20dB LNA, and a larger 4 inch color display.
The TinySA Ultra costs US$119 + shipping direct from the Aliexpress store in China, or $129.95 from R&L in the USA (currently out of stock). The full list of resellers can be found at https://tinysa.org/wiki/pmwiki.php?n=Main.Buying.
We wanted to thank RTL-SDR.com reader Ben for providing us with links to a bunch of reviews of the tinySA Ultra which we are posting below.
During September 26 - 30 GNU Radio Conference 2022 was held in Washington DC. GNU Radio Conference (aka GRCon) is an annual conference centered around the GNU Radio Project and community, and is one of the premier software defined radio industry events. GNU Radio is an open source digital signals processing (DSP) tool which is used often with SDRs.
A few days ago videos of all the presentations were released on their YouTube channels, and all the talks can be found on this playlist. The videos contain a mix of in person and remote talks. A schedule of all talks can be found on the GNU Radio website.
The RX888 MK2 is a software defined radio with 1 kHz - to 1.7 GHz tuning range and up to 64 MHz of real time bandwidth between 1 kHz and 64 MHz and 10 MHz real time bandwidth between 64 MHz - 1.7 GHz. It is available on sites like Aliexpress for about US$170.
Previously we posted about how a number of SDR software developers issued a warning about the RX888, noting that it has very poor driver support, and very poor developer support.
However, in his video Matt reviews the RX888 MK2 and has a favorable opinion of the device. The video begins with an overview of the RX888, shows the driver installation process and then demonstrates the device operating in SDR Console V3 in HF reception mode.
The Red Pitaya is advertised as an open source electronics laboratory instrument, but as it's essentially a software defined radio with built in computing hardware, custom software can be installed allowing it to function as an HPSDR compatible RX/TX capable SDR.
The TRX DUO is a "Red Pitaya compatible" device that comes at a price significantly lower that the Red Pitaya. Its specifications are comparable to the Red Pitaya SDRlab 122-16 which in the official website goes for 625,00€ / US$622. In comparison the TRX DUO can be found on marketplace sites like Aliexpress for almost half price at US$320.
The TRX-DUO has a tuning range from 10 kHz to 60 MHz, 16-bit ADC and 2-RX and 2-TX channels. It also has a built in ARM Cortex A9 processor, and Xilinx Zynq 7010 FPGA SOC. The built in computing means that decoding software can be run directly on the device if desired.
Matt from the TechMinds YouTube channel has recently tested and reviewed the TRX-DUO in his latest video. His video goes over the specifications, software installation, and a demonstration of it receiving HF signals. He goes on to show how it can be used as an 8-band WSPR monitor, and how you can enable WiFi on it and download various Red Pitaya apps.
Matt also notes that the transmit power of the TRX-DUO is very small at 2.5 mW, but of course an external amplifier can be used to boost this. However, it is important to note that band filtering would be required for the emissions to be safe to transmit.
TRX DUO APPLICATION BASED HF SDR TRANSCEIVER (RED PIYATA)
