Category: Applications

Tutorial on Using xrit-rx to Receive Weather Images from Geostationary Satellite GK-2A

Over on his website VKSDR has recently released a tutorial about his Linux based xirt-rx software which allows RTL-SDR and other SDR owners receive weather images from the geostationary satellite known as GEO-KOMPSAT-2A (GK-2A). GK-2A is a Korean satellite, hence it is positioned over the Asia-Pacific region, covering Asia, Eastern Russia, Australia and New Zealand. 

To receive images from GK-2A you'll need an RTL-SDR, 2.4 GHz WiFi grid antenna and an L-band LNA. We have an earlier tutorial about receiving GK-2A and GOES geostationary L-band satellites that goes into more detail about the hardware required. 

VKSDR's xrit-rx software decodes the Low Rate Information Transmission (LRIT) signal from GK-2A which provides a 64kbps data stream and full disk images of the earth every 10 minutes. His tutorial explains the various image types that are transmitted, shows a few example images, and shows that some smooth animations can be created with the 144 images received over a day. The rest of the tutorial goes into the software setup, and explains the installation and configuration procedure.

We note that the latest version of xrit-rx now also comes with a nice web based dashboard that allows you to view the latest image, as well as the upcoming image schedule.

Full Disk Images Received from GK-2A via XRIT-RX
Full Disk Images Received from GK-2A via xrit-rxThe new web based dashboard for xrit-rx

The new web based dashboard for xrit-rx

GNU Radio TEMPEST Implementation Now Available

TEMPEST refers to a technique that is used to eavesdrop on electronic equipment via their unintentional radio emissions (as well as via sounds and vibrations). All electronics emit some sort of unintentional RF signals, and by capturing and processing those signals some data can be recovered. For example the unintentional signals from a computer screen can be captured, and converted back into a live image of what the screen is displaying.

Until recently we have relied on an open source program by Martin Marinov called TempestSDR which has allowed RTL-SDR and other SDR owners perform interesting TEMPEST experiments with computer and TV monitors. We have a tutorial and demo on  TempestSDR available on a previous post of ours. However, TempestSDR has always been a little difficult to set up and use.

More recently a GNU Radio re-implementation of TempestSDR called gr-tempest has been released. Currently the implementation requires the older GNU Radio 3.7, but they note that a 3.8 compatible version is on the way.

The GNU Radio implementation is a good starting point for further experimentation, and we hope to see more developments in the future. They request that the GitHub repo be starred as it will help them get funding for future work on the project.

The creators have also released a video shown below that demonstrates the code with some recorded data. They have also released the recorded data, with links available on the GitHub. It's not clear which SDR they used, but we assume they used a wide bandwidth SDR as the recovered image is quite clear.

Examples using gr-tempest

GR-TEMPEST: GNU Radio TEMPEST Implementation
GR-TEMPEST: GNU Radio TEMPEST Implementation

Running rtl_tcp over the TOR Network

Over on his DragonOS YouTube tutorial channel Aaron has uploaded a video showing how it is possible to run rtl_tcp over the TOR network. TOR is an "anonymity network" which routes your internet traffic through thousands of volunteer nodes in order to make tracing your internet activity more difficult.

Aaron's tutorial shows how to route rtl_tcp traffic through a TOR connection on his Linux distribution DragonOS (although it should work on any Linux distro), and connect to it with GQRX.

However, a major caveat is that the data streaming result is rather poor with there being lots of data drops, probably due to the slowness of the TOR network. Perhaps running a smaller sample rate, or using a more efficient server like Spyserver might work better.  

DragonOS LTS Remote access RTL-SDR over TOR network (Gqrx, rtl_tcp, OpenWRT)

The 2020 GNU Radio Conference will be held Virtually – Talks Streamed for Free

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.

Call for Participation is now open!

Registration

Registration is available now!

Register Here

Refund Policy

GNU Radio Code for Android Now Released

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., armeabi-v7a and arm64-v8a).
  • 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.

GNU Radio running on an Android phone, usinga USRP B200 SDR as a WLAN transceiver.
GNU Radio running on an Android phone, usinga USRP B200 SDR as a WLAN transceiver.
GNU Radio 3.8 on un-rooted Android receiving FM w/ HackRF (take 2)

Performing a Side Channel TEMPEST Attack on a PC

TEMPEST refers to a technique that is used to eavesdrop on electronic equipment via their unintentional radio emissions (as well as via sounds and vibrations). All electronics emit some sort of unintentional RF signals, and by capturing and processing those signals some data can be recovered. For example the unintentional signals from a computer screen could be captured, and converted back into a live image of what the screen is displaying. We have tutorials on how to do this with a program called TempestSDR available on a previous post of ours.

Recently Mikhail Davidov and Baron Oldenburg from duo.com have uploaded a write up about their TEMPEST experiments. The write up introduces the science behind TEMPEST eavesdropping first, then moves on to topics like software defined radios and antennas.

At the end of their post they perform some experiments like constantly writing data to memory on a PC, and putting the PCs GPU under varying load states. These experiments result in clear RFI bursts and pulsing carriers being visible in the spectrum, indicating that the PC is indeed unintentionally transmitting RF. They note that machine learning could be used to gather some information from these signals.

Their write up reminds us of previous TEMPEST related posts that we've uploaded in the past. One example is where an RTL-SDR was used to successfully attack AES encryption wirelessly via the unintentional RF emitted by an FPGA performing an encryption algorithm. Another interesting post was where we saw how a HackRF was used to obtain the PIN of a cyprocurrency hardware wallet via TEMPEST. Search TEMPEST on our blog for more posts like that.

TEMPEST PC Side Channel Setup: RF pulses from writing to memory and a GPU.
TEMPEST PC Side Channel Setup: RF pulses from writing to memory and a GPU.

YouTube Video Replicates our Galactic Hydrogen Line Detection Tutorial

Earlier in the year we posted a tutorial showing how to detect the Galactic Hydrogen Line at home with less than $200 in components. All that is really needed is a 2.4 GHz WiFi dish, an RTL-SDR and an LNA. With this setup it's possible to do home science like determining the size, shape and rotational speed of our own galaxy. 

Over on YouTube user Nicks Tech Hobby has successfully replicated our tutorial with similar hardware, and has uploaded a time lapse video showing his results. His success confirms that this is a good way to get introduced into radio astronomy. What's also interesting is that it is possible to spot the Hydrogen line energy on the live waterfall even without averaging/integration. 

My first successful attempt to detect galactic hydrogen (Hydrogen line)

CygnusRFI: New RFI Analysis Tool for Ground Stations and Radio Telescopes

Thank you to Apostolos for submitting information about his new open source program called "CygnusRFI". CygnusRFI is a tool designed for analyzing radio frequency interference (RFI) with a focus on how it affects satellite ground stations and radio telescopes. We note that in the past we've posted several times about Apostolos' other project called PICTOR, which is an open source radio telescope platform that makes use of RTL-SDR dongles. 

Apostolos explains CygnusRFI in the following: 

CygnusRFI is an easy-to-use open-source Radio Frequency Interference (RFI) analysis tool, based on Python and GNU Radio Companion (GRC) that is conveniently applicable to any ground station/radio telescope working with a GRC-supported software-defined radio (SDR). In addition to data acquisition, CygnusRFI also carries out automated analysis of the recorded data, producing a series of averaged spectra covering a wide range of frequencies of interest. CygnusRFI is built for ground station operators, radio astronomers, amateur radio operators and anyone who wishes to get an idea of how "radio-quiet" their environment is, using inexpensive instruments like SDRs.

CygnusRFI Screenshots
CygnusRFI Screenshots