Category: RTL-SDR

Taylor Swift Threatens Legal Action Against Owner of X Account that Tracks her Private Jet via ADS-B

Jack Sweeney is a student who operates various social media and websites dedicated to tracking the private jets of celebrities and notable persons. In the past he's drawn the ire of Elon Musk who banned his @ElonJet account in 2022 which used to provide live updates on the location of Elon Musk's private jet. These days he operates the @ElonJetNextDay account which tracks Elon's jet with a 24 hour delay on X, but continues to track the jet live on other platforms.

Recently the legal team for global superstar Taylor Swift threatened legal action against Jack Sweeney for running the various social media accounts that track her private jet including @SwiftJetNextDay on X with a 24 hour delay, or live on alternative platforms like Mastodon. Swift's legal team claim Sweeney's live tracking accounts pose an “imminent threat to the safety and wellbeing” of Swift.

Jack notes that he makes use of legal live ADS-B flight data from public data aggregators like Airplanes.live and AirFramesIO. ADS-B data is most commonly provided from contributors with RTL-SDR dongles running on Raspberry Pi single board computers. 

Even without Sweeney's social media accounts anyone can legally look up this live public flight data data, or even receive it themselves directly from the aircraft if they are close enough. Although a point can be argued that the social media accounts run by Sweeney make it significantly easier for this information to be obtained and shared by anyone.

An example notification from @SwiftJetNextDay for Taylor Swift's private jet flight.

FOSDEM 2024 Videos now Available: Synthetic Aperture WiFi RADAR, GPU DSP Acceleration and more

FOSDEM (Free and Open Source Developer’s Meeting) is a yearly conference that took place in Brussels, Belgium on 3 - 4 February 2024. This conference featured a room on Software Defined Radio and Amateur Radio.

Recently the videos of most the talks have been uploaded to their website. Some interesting talks include:

Covert Ground Based Synthetic Aperture RADAR using a WiFi emitter and SDR receiver

Link to Talk Page

Using a WiFi emitter as radiofrequency source illuminating a scene under investigation for slow movement (e.g. landslides), a Ground-Based Synthetic Aperture RADAR (GB-SAR) is assembled using commercial, off the shelf hardware. The dual-channel coherent Software Defined Radio (SDR) receiver records the non-cooperative emitter signal as well as the signal received by a surveillance antenna facing the scene. Spatial diversity for azimuth mapping using direction of arrival measurement is achieved by moving the transmitter and receiver setup on a rail along a meter-long path -- the longer the better the azimuth resolution -- with quarter wavelength steps. The fully embedded application runs on a Raspberry Pi 4 single board computer executing GNU Radio on a Buildroot-generated GNU/Linux operating system. All development files are available at https://github.com/jmfriedt/SDR-GB-SAR/

Synthetic Aperture RADAR with WiFi and USRP SDR

Using GPU for real-time SDR Signal processing

Link to Talk Page

GPU processors have become essential for image or AI processing. Can they bring anything to real-time signal processing for SDR applications? The answer is yes, of course, but not all classic algorithms (FIR, DDC, etc.) can be used "as is", sometimes a different approach must be taken. In this presentation, I will share the solutions that I implemented to achieve multi-channel DDC on NVIDIA Jetson GPU and will make a comparison with "classic CPU" approaches.

Using GPU's for Real Time Signal Processing

Maia SDR: an open-source FPGA-based project for AD936x+Zynq radios

Link to Talk Page

Maia SDR is an open-source project with the main goal of promoting FPGA development for SDR and increasing the collaboration between the open-source SDR and FPGA communities. Currently it provides a firmware image for the ADALM Pluto and other radios based on the AD936x and Zynq. This firmware can display a real-time waterfall at up to 61.44 Msps in a WebSDR-like interface using WebGL2 rendering, and record IQ data in SigMF format in the SDR DDR. The FPGA design is implemented in Amaranth, an Python-based HDL, and the software stack is implemented in Rust, targetting the embedded ARM CPU and WebAssembly.

The first firmware version was released in February 2023, and the project was presented in June in the Software Defined Radio Academy. In this talk we cover the progress since the summer, including the addition of support for devices such as the Pluto+ and AntSDR. We focus on the technical details of the project and the possibilities for re-using some of the components in other projects.

Maia SDR

DAPNET: Bringing pagers back to the 21st Century

Link to Talk Page

When talking about pagers, most of us will think about an object of the past, often seen in TV shows from the 90s, used by medical staff and businessmen. However, they're an interesting way to get simple data broadcast over amateur radio frequencies, with receivers that can be built for less than 20€. We'll explore this and understand how an extensive network can be deployed with simple equipment and using open source hardware and software.

DAPNET Talk

A KrakenSDR to TAK Interface Converter

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
  • Simplified deployment

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.

KrakenSDR bearing data displayed on a TAK app.

Multiple Comprehensive Tutorials on Weather Satellite Decoding

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.

Satellite reception and decoding

Automated stations

SatDump usage

All have been moved to SatDump's documentation page

Satellite data processing and usage

From the HRPT tutorial: What various HRPT signals look like on the spectrum.
From IU1QPR's HRPT tutorial: What various HRPT signals look like on the spectrum.

SDR++ Android APK now supports the RTL-SDR Blog V4

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. 

If you enjoy SDR++ please consider supporting the developer on Patreon.

Blog V4 Receiving Broadcast FM on Android with SDR++
Blog V4 Receiving Broadcast FM on Android with SDR++

A Tribute to Amateur Radio Astronomer Job Geheniau (Job’s Radio Telescope)

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.

A tribute to Job will also be published in the next membership journal from the Society of Amateur Radio Astronomers.

Building a Drone Tracking Radar with the ADALM-PHASER and PlutoSDR

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.

The ADALM-PHASER a phased array kit for implementing radar and other phased array experiments.
The ADALM-PHASER a phased array kit for implementing radar and other phased array experiments.

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

Modified RTL-SDR Source for SDR++ with Manual Controls for R820T/2/R828D Tuners and Harmonic Reception

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. 

A new RTL-SDR Source for SDR++ with Manual Gain/Filter and Harmonic Mixing Controls
A new RTL-SDR Source for SDR++ with Manual Gain/Filter and Harmonic Mixing Controls