Thank you to RTL-SDR.COM reader Aaron, who recently found a Kraken-to-TAK converter made by "SignalMedic" and "dngrssgnls" which converts the KrakenSDR bearing output data to "Cursor on Target" (COT) or XML format, allowing common TAK interfaces to read and display the data. Currently the converter allows a line of bearing to be displayed in a TAK app, with arbitrary length. The converter consists of a single json file for Node Red. The GitHub readme reads:
Convert data from a Kraken SDR to TAK endpoints
The software will parse information collected by Kraken, convert to COT and XML and send to common TAK interfaces. The length of the line is arbitrary. The line is 6km long, but has no correlation besides bearing to the transmitter. Intersecting bearing lines are necessary for determining the geolocation of a transmitter.
Planned improvements include:
Button for persisting the current line and generating a new UID
Work on filtering out by DOA Angle node
Dashboard for easier updating of Kraken and TAK endpoints
We note that most TAK apps may be a little limited for direction finding purposes as they cannot calculate bearing intersections over time, or calculate a bearing grid like the KrakenSDR Android app, and KrakenSDR online web mapper does. However, often a single line of bearing is enough information, especially if there are multiple distributed units contributing bearing data.
If you weren't already aware, KrakenSDR is our 5-channel coherent radio based on RTL-SDRs, and it can be used for applications like radio direction finding. It can be purchased on Crowd Supply.
TAK (Tactical Assault Kit) is software used by the military and other organizations for visualizing geospatial information such as enemy and friendly positions. Civilian versions of TAK also exist, such as ATAK for Android. Previously we posted about how ATAK has the ability to plot aircraft positions via an RTL-SDR receiving ADS-B.
Over on his website "Jacopo's Lair" IU1QPR (@original_lego11) who is also a developer for SatDump has written up many tutorials about weather satellite decoding that involve the use of SatDump. SatDump is a popular piece of software often used with RTL-SDRs and other low cost SDRs for decoding weather satellite images.
With a small satellite dish, feed, RTL-SDR and LNA+filter and the SatDump software it's possible and download beautiful images of the earth from many geostationary and polar orbiting weather satellites. We note that we are currently taking pre-orders on Crowd Supply for our Discovery Dish system, which is low cost hardware designed to help users get started with weather satellite reception.
Over on Reddit IU1QPR has created a listed summary of all the tutorials he's written. These are currently the most up to date and comprehensive tutorials that we have found on this topic. The tutorials cover everything from what satellites are available, what dish sizes you need, what SDRs can be used, what LNA+filter and other hardware you need, and how to use the SatDump software.
Thank you to SDR++ developer Ryzerth who has let us know that RTL-SDR Blog V4 support has recently been added to the nightly build of the APK. With this release, Android is now fully supported by the RTL-SDR Blog V4 via Martin Marinov's SDR Driver app (which many SDR applications connect to), SDRAngel and now SDR++.
A reminder: With SDR++ you may find that you will need to close (using the task manager on Android) and reopen the app a couple of times before it will detect an RTL-SDR dongle.
Job Geheniau was someone whose amateur radio astronomy projects were often featured on RTL-SDR Blog (often referred to as Job's Radio Telescope). It with great sadness that we have recently learned that Job Geheniau passed away from cancer in late December 2023. We would like to take the time share this post to highlight some of his achievements in the amateur radio astronomy field.
Back in 2020 Job first surprised us with one of his first radio astronomy results (Part 1, Part 2) where he was able to image the Milky Way in neutral hydrogen by using a 150cm dish, RTL-SDR, LNA and motorized mount. Over eight nights he recorded hydrogen line readings throughout the Milky Way and ended up creating a 2D Excel sheet that showed an image of the Milky Way at the 1420 MHz hydrogen line frequency.
Job would go on, rapidly evolving and each time showing us that low cost hardware set up in a backyard could be used to unlock many of the secrets of the universe. Using a satellite dishes less than two meters in diameter, RTL-SDRs, LNAs and filters he was able to:
Job's Radio Astronomy website remains up at https://jgeheniau.wixsite.com/radio-astronomy, and many results and writeups of his other experiments can be found there. We will sorely miss posting about Job's achievements, but we hope that his life has inspired you to take a closer look at the amateur radio astronomy hobby.
The ADALM-PHASER is a kit designed to provide experience with phased array beamforming and radar concepts. The kit consists of a PlutoSDR, mixers, LO synthesizer, ADAR1000 beamformer chip, LNAs and array of patch antennas. It operates between 10-11 GHz, has 500 MHz BW FMCW chirps, and has 8 receive channels and 2 transmit channels. It is an open source kit that costs US$2800, and it is produced and available from Analog Devices. Currently the kit appears to not be in stock, but they note that they are working on getting more stock in soon.
Over on YouTube, Jon Kraft who appears to be affiliated with Analog Devices, is working on a series of videos that will ultimately result in a drone tracking radar being built with the ADALM-PHASER. Currently two videos have been released.
The first is an overview of radar concepts, giving an explanation of pulsed vs CW radar, and the various hardware options we have to implement low cost versions of these methods.
The second video covers more radar concepts like range resolution and shows us how to build a CW radar with the ADALM-PHASER system.
The three remaining videos are yet to be released, so keep an eye on his channel for updates.
Build Your Own Drone Tracking Radar: Part 1
Build Your Own Drone Tracking Radar: Part 2 CW Radar
Just recently we posted about the release of some firmware for the AntSDR E200 which allows it to decode DJI DroneID. DroneID is a protocol designed to transmit the position of the drone and operator to authorized entities such as law enforcements and operators of critical infrastructure.
In his latest video Matt from the Tech Minds YouTube channel shows this firmware in action. In the video he first shows how to install the firmware, and how to connect to its serial output. He goes on to test it with his DJI Mini 4 Pro and show some live DroneID frames being decoded.
DJI Drone Hacking Using Software Defined Radio ANTSDR E200
DJI is a major manufacturer of consumer drones and their drones implement an RF protocol called DroneID which is designed to transmit the position of the drone and operator to authorized entities such as law enforcements and operators of critical infrastructure.
Recently the AntSDR team have managed to get DJI DroneID decoding working on the AntSDR's onboard ARM processor. The decoding software runs on board the AntSDR E200 and outputs decoded data via the serial or network port. The AntSDR E200 is an SDR that is based on the AD9361 chip and has a 70 MHz to 6 GHz tuning range, 56 MHz of bandwidth and 12-bit ADC. It has 2x2 full duplex TX/RX channels and has an onboard FPGA with ARM CPU core.
The update from AntSDR shows how to install the firmware onto the device and get it up an running. They note that drones that use Occusync 2 or 3 like the Mini2 or Mini3Pro work best, because other models may be encrypted or have a slightly different protocol which doesn't work with these decoders.
Aaron, creator of DragonOS has also uploaded a video showing the decoder in action.
Over on GitHub user Sultan-papagani has just released a modified RTL-SDR source for SDR++ that enables full manual control of the gain stages, filters and other features on R820T/2/R828D tuner based RTL-SDRs. This includes the Blog V3 and Blog V4. In the standard drivers many of these these features are automatically controlled.
Tweaking the individual LNA, Mixer and VGA gain stages manually can help you to maximize SNR, while adjusting the filters can help block out of band interference.
The modified source also enables the 'Hamonic reception' enhancement from the librtlsdr fork of rtl-sdr, which allows you to tune up to 6 GHz via harmonic mixing. Note that tuning above the standard maximum of 1.766 GHz will most likely require strong band pass filtering and an external LNA as the harmonic mode results in a lot of imaging and weak signals.