Thank you to Ihar Yatsevich for writing in and sharing his open source project called "rpitx-coax-pcb" which is an expansion board for the Raspberry Pi that converts the GPIO pin used by RPiTX into a coaxial SMA connector for easily connecting the output to an antenna. He notes that there are two revisions. One includes a filter in the in the GP1212 / GP731 case and the other does not. Filters in this type of enclosure can be found from Minicircuits. Finally he notes that he has not yet fully tested the design, but believes that there will be no problems.
The GitHub contains the EasyEDA design files, schematics and gerbers which you can use to print and build the PCB yourself.
If you are unfamiliar with it, RPiTX is a program for Raspberry Pi single board computers that allows you to transmit almost any type of signal on frequencies between 5 kHz up to 1500 MHz with nothing more than a wire connected to a GPIO pin. However, it is highly recommended that appropriate filtering be used if you are transmitting with an amplifier or longer range antenna as the RPiTX contains harmonics that can cause interference with other devices.
RPiTX Coaxial PCB Expansion Board for the Raspberry Pi
A few weeks ago we posted about "LikWidChz"'s work on using GNU Radio to channelize multiple NRSC-5 HD-Radio transmissions for simultaneous decoding with GNU Radio and an RTL-SDR. He has now also submitted a way to channelize pager traffic. He writes:
Quite a while ago I wanted to decode pager traffic, specifically Flex. When I started doing some basic poking around I figured out that there were multiple pager transmissions going on at once. Thinking about GnuRadio and its ability to chop up signal.. I was curious if anyone tried to decode them all at once.. I didn't get a whole lot of answers on the subject and It didn't seem like people used GnuRadio to pass MultiMonNG data.. I had my work cut out for me.
In my area all of the flex transmissions were between 928Mhz and 932Mhz and quite strong... You don't need much of an antenna to RX these transmissions. A simple wire of appropriate length will do nicely.
My plan was to design a graph and tune into the center of the range I was interested in and somehow channelize it. The remaining steps are required to format the data to allow MultiMonNG to process that audio stream. This is done a couple times depending on how many you want to decode in parallel. Have fun!
This this zip file we have uploaded his GRC file, and his full PDF description of the flowgraph. Again we note that to get in touch with the author you can log on #gnuradio and ##rtlsdr on freenode IRC and fine him under the nickname "LikWidChz".
Over on his YouTube channel CWNE88 has posted how he has been using and RTL-SDR with the rtl_433 software to explore the data coming in from various 433 MHz ISM band devices in his neighborhood. In the video he explains how he has set up rtl_433 on his Raspberry Pi, and what sort of data he is receiving. Some examples of devices he's received include various weather stations, doorbells, remotes and car tyre pressure monitors.
He also mentions how these signals are unencrypted, noting that in a future video he will show on GNU Radio how a false signal could be synthesized.
Thank you to Evuraan for writing in and sharing his new browser based HD Radio / NRSC-5 interface for the nrsc5 decoder which he has called yellowShoes.
NOTE: We have been informed by some users that yellowShoes may contain a Trojan virus. This is likely to be a false positive which is a very common problem with antivirus software falsely detecting viruses on newly released niche software via heuristics. We have removed the above link out of an abundance of caution, however if you wish to continue the yellowShoes Github is here. If you want the software, but are concerned you can check the code compile it yourself.
NOTE UPDATE: The author of the software has contacted us regarding the virus concerns and written "I wanted to write in clarify that it is indeed a false positive, please see https://groups.google.com/g/golang-nuts/c/Au1FbtTZzbk and also https://golang.org/doc/faq#virus - this false positive occurs when you cross compile go binaries - This is a common occurrence, especially on Windows machines. Commercial virus scanning programs are often confused by the structure of Go binaries, which they don't see as often as those compiled from other languages."
HD Radio is a digital broadcast protocol replacement for analogue broadcast FM. It is only used in North America and is easily recognized as the two rectangular blocks on either side of a broadcast FM station signal on a spectrum analyzer/waterfall display. Together with an RTL-SDR and theori's command line nrsc5 decoder, the HD Radio signal can be decoded and listened to. Evuraan writes:
I wrote yellowShoes - an nrsc5 player which you can control from your browser. (Should work on Windows, Linux etc. Player F/E also works on Android Phones.)
Its sole dependency is that the nrsc5 binary must be available in the path.
Over on YouTube Adam Łoboda has uploaded a video showing the full steps that he's taken to reverse engineer and clone a wireless garage door key using an RTL-SDR and Arduino.
He starts by using the Universal Radio Hacker software to record a copy of the wireless signal generated by the garage key. Using the software he can then analyze the signal, and determine the preamble data, payload data and pulse width which he can then input into some Arduino code. The Arduino can then generate an identical signal, and transmit it via a cheap FS1000A 433 MHz RF module. Finally, at the end of the video Adam shows the cloned Arduino based garage key working as expected.
hacking & clonning my garage key with URH ( Universal radio Hacker ) and ARDUINO DIGISPARK + FS1000A
Thank you to Ramiro Utrilla Gutiérrez a PhD Candidate researcher at Universidad Politécnica de Madrid for writing in and sharing his research groups work on a low power SDR radio platform called "Migou". The basic idea is to combine software defined radio which is flexible but power hungry, with less flexible but power efficient hardware radios. The design files and BOM are creative commons licensed, and free to download. The radio is capable of operating in the 433 MHz, 868 MHz and 2.4 GHz bands at sample rates of up to 4 MSPS in SDR mode. Ramiro writes:
I'm the main developer of the MIGOU platform. This platform uses the Microchip AT86RF215 transceiver (like TinySDR and iotSDR) and a Microchip SmartFusion2 flash-based FPGA SoC.
The particularity of our work is what we have called the hybrid radio approach, which proposes to provide low-resource devices with the ability to operate both as a current mote, using a hardware transceiver, and as an SDR system. This is possible using only the AT86RF215 transceiver. With these capabilities, hybrid radio end-devices can exploit the SDR hardware flexibility for those sporadic tasks that strictly require it, and still benefit from the energy efficiency of hardware transceivers for all other tasks.
Our platform is not a commercial product, it is an open-source research tool. If you are interested, you can read more about our work in this article in Sensors journal, where we present the hybrid radio approach and the MIGOU platform, and in this article in IEEE Access journal, where we approach a Cognitive Radio problem from the perspective of our hybrid radio platform. Both articles are also open access.
MIGOU is a low-power wireless experimental platform designed to simultaneously address the energy-efficiency requirements of resource-constrained end-devices and the hardware flexibility demanded by the current Cognitive Radio (CR) and edge computing paradigms. This platform relies on the SmartFusion2 SoC that integrates an ARM Cortex-M3 processor and a flash-based FPGA, where high-speed processing tasks can be offloaded and computed more efficiently via hardware acceleration. In addition, at the radio level, the platform can operate both as a traditional node, which demands lower energy resources and development time, and as a Software-Defined Radio (SDR) system, which allows for the implementation of custom CR features. Moreover, the ability to dynamically switch between these two modes of operation opens the possibility for developing new hybrid strategies, taking advantage of both the flexibility offered by the SDR and the efficiency of the transceiver’s highly optimized baseband cores.
The power consumption of our platform was measured in transmit, receive, and sleep modes. These measurements were compared with the corresponding ones of other representative tools and systems: YetiMote, a traditional IoT end-device; MarmotE SDR, a low-power SDR system; and B200mini and B210 USRPs, two widely used high-performance SDR platforms. Moreover, all these devices were compared in terms of their hardware features. The results obtained confirmed that a state-of-the-art tradeoff between hardware flexibility and energy efficiency was achieved. These features will allow researchers to develop appropriate solutions to current end-devices’ challenges, and to test and evaluate them in real scenarios.
Over the past few months we have posted a few times about the beta of CENOS, a new antenna modelling and simulation design package. Recently CENOS has exited it's beta testing phase, and they have put out a press release about the first release.
Of most importance is that the software is affordable for hobbyist's, with a 10-day free trial and subscription price of €20 (US$25) per month for hobbyist use (no live engineering support).
Electromagnetics simulation software company CENOS (Riga, Latvia) continues on its mission to democratize simulation software by releasing its newest application designed for radio frequency and antenna design engineers. CENOS released its first electromagnetics simulation software focused on the induction heating applications in 2017 and it proved to be a success - mainly because of the simple and straightforward user experience and the specialization and focus on a single industry. After a year of development and testing in close cooperation with its avid beta-tester community, the Antenna Design simulation software was finally released for public use at the end of April, 2021.
CENOS Antenna Design is an intuitive FEM-based software that helps engineers to speed up RF antenna design, it solves Maxwell’s equations directly with no simplifications or limitations. Therefore, the results provided by CENOS are accurate for wide ranges of geometries and antennas, including very complex geometries. For instance, the software is good for high Q, multi-port simulations with arbitrary 3D structures. It is specialized for the simulation of microstrip- and wire-type antennas that include various geometries (fractal, helix, horn, loop, slot, patch, spiral, and others), as well as dipole and monopole antennas.
CENOS co-founder Dr. phys. Mihails Scepanskis: “Two years ago we launched a specialized induction heating simulation software to cover the growing demand in the SME sector - smaller equipment manufacturers, tooling shops, and production plants. Following the success in the low-frequency applications, we decided to move to the microwaves with the same mission - to democratize the simulation software, make it accessible for every engineer. I believe, it is an awkward situation in the market - engineers have to choose either to pay tons of money for enterprise-type generic simulation packages to utilize just a fraction of their functionality or to use over-simplified 1D approximations with the hobbyist-level software. With CENOS we have leveraged the power of open-source algorithms to break the status quo - to deliver a full-functionality FEM software for price-sensitive business users and individuals.”
CENOS Antenna Design is free to try for 10 days, after which the users can choose from the two subscription plans - for an individual or business use, starting from 20 euros per month ($25). The business version includes the features that help to automate and speed up simulation processes and has more integrations with the existing software and, most importantly, it has a live customer support through the chat and video calls. More features are planned to be added in 2021 and thus the prices may be increased over time, so now it is a good moment to subscribe and get all the future updates for a lower price.
The company name CENOS stands for “Connecting ENgineering Open Source” highlighting the new software approach they invented. It is a platform that connects the best of community-driven open-source algorithms into one seamless user experience and since it is a desktop software - the data do not leave the owner’s computer. CENOS was founded in 2017 by 3 PhDs in physics and mathematics who committed themselves to the democratization of the simulation software by making it easy, affordable, and secure for every engineer. CENOS is a startup, funded by the leading San Francisco early-stage investor ‘500 Startups’, the leading B2B European accelerator Startup Wise Guys, and the cohort of the Baltic business angels.
Raspberry-NOAA is open source code and a set of scripts that allows you to set up a Raspberry Pi as an automated NOAA and Meteor weather satellite station with an SDR like an RTL-SDR. The software makes use of the Raspberry Pi version of WXtoIMG and meteor_decoder for decoding the satellites, a program called predict for predicting satellite passes, and various automatically generated cron scripts to schedule recording and processing.
Recently V2 has been released by Justin Karimi who builds on the work of the original creators. It seems that the webpanel has been upgraded and made mobile friendly, as well as many more enhancements that can be seen on the Release page notes.
