Twitter user @d0tslash was watching news helicopter footage of the BLM protests on the 28th of May when he heard something that sounded like an RF telemetry feed in the background audio on the helicopter's video feed. Having seen this previous success at decoding similar helicopter telemetry, he contacted his friend proto17 who proceeded to reverse engineer and figure out how to decode the telemetry, in the end discovering that it was providing location data for the helicopter.
Over on GitHub proto17 has documented the complete process that he took in reverse engineering the telemetry. He first explored the audio in Baudline discovering that there was a 1200 Hz wide FSK signal. Next he used GNU Radio to further analyze the signal, discovering it's baud rate, resampling the signal and then using a GFSK block to demodulate the signal into 1's and 0's.
Finally he used some clever terminal tricks and a Python script to discover the bit pattern and convert the bits into ASCII characters which reveals the helicopter coordinates. The coordinates decoded indicate that the helicopter was indeed circling the protest area.
We looked into the news helicopters in use during the protests and found that Denver news stations all share one helicopter with registration N6UX. Plugging that into adsbexchange.com and looking at the helicopter ADS-B history on the 28th gives a good match to proto17's decoded data.
The yearly GNU Radio Conference (GRCon) is a conference all about the development of GNU Radio and projects based on GNU Radio. GNU Radio is an open source digital signal processing (DSP) toolkit which is often used in cutting edge radio applications and research to implement decoders, demodulators and various other SDR algorithms.
This years 2020 GNU Conference is to be the 10th one ever held and was supposed to take place in Charlotte, NC. However due to the ongoing pandemic the organizers have now decided that it will be held entirely online this year. The starting date is September 14 and the talks and events will probably run for several days. All talks will be streamed for free, however, registering for US$50 will get you access to the live workshops and other events.
There is a great line up of keynote speakers, and if you have a talk that you'd like to submit, submissions are now open. For ideas on what GNU Radio talks are like, you can see full recordings from previous GNU Radio conferences on their YouTube channel playlists.
GNU Radio Conference (GRCon) is the annual conference for the GNU Radio project & community, and has established itself as one of the premier industry events for Software Radio. It is a week-long conference that includes high-quality technical content and valuable networking opportunities. GRCon is a venue that highlights design, implementation, and theory that has been practically applied in a useful way. GRCon attendees come from a large variety of backgrounds, including industry, academia, government, and hobbyists.
GRCon20 will be held starting September 14, 2020 online as a virtual event. The organizing team is hard at work to create a fun and interactive experience.
Our keynote speakers include: Becky Schoenfeld W1BXY, managing editor of QST magazine, Oona Räisänen [ windytan ] hacker of signals and computer programmer, and Jim St. Leger, Director Open Source, Intel.
With an annual program that has broad appeal, GRCon attracts people new to Software Radio just looking to learn more, experts that want to keep their finger on the pulse & direction of the industry, and seasoned developers ready to show off their latest work.
Registration is available now!
Back in November 2019 we posted how Bastian Bloessl (@bastibl) had teased us with his ability to get GNU Radio running on an Android phone. Now he has officially released his code to the public on GitHub. This is quite a remarkable development as you can now carry a full DSP processing suite in your pocket. In addition to the code, he's put up a short blog post explaining a bit about the port. He notes some highlights of the release:
- Supports the most recent version of GNU Radio (v3.8).
- Supports 32-bit and 64-bit ARM architectures (i.e.,
- Supports popular hardware frontends (RTL-SDR, HackRF, and Ettus B2XX). Others can be added if there is interest.
- Supports interfacing Android hardware (mic, speaker, accelerometer, …) through gr-grand.
- Does not require to root the device.
- All signal processing happens in C++ domain.
- Provides various means to interact with a flowgraph from Java-domain (e.g., Control Port, PMTs, ZeroMQ, TCP/UDP).
- Comes with a custom GNU Radio double-mapped circular buffer implementation, using Android shared memory.
- Benefits from SIMD extensions through VOLK and comes with a profiling app for Android.
- Benefits from OpenCL through gr-clenabled.
- Includes an Android app to benchmark GNU Radio runtime, VOLK, and OpenCL.
- Includes example applications for WLAN and FM.
He's even included demonstration code that turns a USRP B200 SDR connected to an Android phone into a WLAN transceiver which can run in real time on faster devices.
Installing it may not be easy for most, but Bastian has included full build instructions on the GitHub page, and makes use of a Docker file which should simplify the installation a bit.
GQRX is a general purpose GUI based SDR program that is typically used most often on Linux and Mac computers, however it is still possible to install and use it on Windows. Over on YouTube M Khanfar has uploaded a tutorial video that shows a step by step guide on how to get GQRX running on Windows 10.
The process is a little long as it involves an install of Windows GNU Radio, Python, pip and various Python dependencies required by GQRX, as well as setting up the Windows PATH. If you prefer a text guide, the full tutorial is also typed out in the YouTube video description.
A few days ago we posted about DragonOS, which is a Linux ISO file with several built in SDR programs that the creator Aaron has been working on during his COVID-19 lockdown period. We've now got a second lockdown inspired Linux distribution called "gorizont-rtlsdr" which was submitted by Steve Cox. The distro is based on Xubuntu 18.04 and focuses only on software for RTL-SDRs. Steve writes:
gorizont linux 1.0 is a live, USB bootable or VM .iso image, and my first attempt at sharing a project like this. It's built specifically for rtl_sdr/ RTL2832U family dongles, no other devices will be supported in the future (although drivers can be installed if required). It's meant for the cheapest, most available hardware out there.
I think there's a useful niche for this distro, Skywave Linux is getting a bit long-in-the-tooth and un-updated, and the recently reviewed DragonOS, whilst good, is a little complicated for beginners to use. gorizont concentrates on purely terrestrial HF/VHF/UHF analogue and digital signal exploration and decoding, hence the name. It also provides instant DAB+ and FM radio reception for emergency information using RTL V3 stock antennae.
It's built for customisation and compilation of evolving software, hence it's rather portly size. A pretty full suite of dev libraries and repos come as included. Users can also create a bootable USB image or .iso of an updated system using Systemback if gorizont is run as a VM.
We didn't see a list of programs preinstalled, but from the Readme it appears to have at least GNU Radio, GQRX, multimon-ng, DSD+, welle.io, PyBOMBs, wine32, sox, as well as a preset Virtual Audio sync set up through pulseaudio for piping audio between programs. We expect that many more programs will also have been preinstalled.
Last month we posted about Aaron's "DragonOS" project, which is a ready to install Linux ISO aimed to make getting started with SDR software easy by providing several programs preinstalled, as well as providing multiple video tutorials. Recently he's updated the build, this time basing it on Lubuntu 18.04 allowing for Legacy and UEFI support, along with disk encryption. The OS supports RTL-SDRs as well as the HackRF and bladeRF and probably supports most other SDRs via the SoapySDR interface.
In terms of software he's also added OP25 and bladeRF support. Other programs pre-installed include rtl_433, Universal Radio Hacker, GNU Radio, Aircrack-ng, GQRX, Kalibrate, hackrf, wireshare, gr-gsm, rtl-sdr, HackRF, IMSI-catcher, Zenmap, inspectrum, qspectrumanalyzer, LTE-Cell-Scanner, CubicSDR, Limesuite, ShinySDR, SDRAngel, SDRTrunk, Kismet, BladeRF.
His DragonOS YouTube tutorial channel is also growing fast, with several tutorials showing you how to use DragonOS to perform tasks like listen to trunked mobile radios, use QSpectrumAnalyzer with a HackRF, receive NOAA APT weather satellite images, retrieve cellular network information via a rooted Samsung Galaxy S5, create a ShinySDR server with rtl_433 and how to capture and replay with a HackRF.
Thank you to Aaron for submitting news about his latest project called "DragonOS" which he's been working on while in COVID-19 lock down. DragonOS is a Debian Linux based operating system which comes with many open source software defined radio programs pre-installed. It supports SDRs like the RTL-SDR, HackRF and LimeSDR.
Aaron's video below shows how to set up DragonOS in a VirtualBox, and he has two other videos on his channel showing how to set up ADS-B reception with Kismet, and how to run GR-RDS in GNURadio. He aims to continue with more tutorial videos that make use of the software installed on DragonOS in the near future.