Category: Satellite

Receiving Starlink Signals with an RTL-SDR and Ku-Band LNB

Over on YouTube, dereksgc has uploaded a new video showing how to receive signals from Starlink satellites using an RTL-SDR and a standard Ku band LNB. Note that this setup simply receives the raw signals, and it does not allow you to connect to the Starlink service.  

In the video, dereksgc first introduces Starlink satellites and explains what signals they transmit, referencing a paper on the structure of the Starlink Ku-band downlink by researchers at the University of Texas. He notes that the signals are strong enough that a single LNB without a dish is sufficient for receiving them. An LNB is a feedhorn antenna, low-noise amplifier, and downconverter all-in-one. It converts the ~10.950 GHz Ku band signal of the Starlink satellites down to a frequency that the RTL-SDR can receive.

In the rest of the video, he shows a timelapse of signals being received. The signal's doppler shift can be seen and heard as the satellite passes over.

Receiving Starlink signals with RTL-SDR

Open-Weather APT: Updates to the Web Based NOAA APT Image Decoder

Dr. Sasha Engelmann and Sophie Dyer, the team behind the Open-Weather project have recently announced the launch of their new version of open-weather apt, a web-based NOAA APT image decoder. The web-based program accepts a WAV file containing a NOAA satellite APT recording, demodulates and decodes it, and displays the resulting weather satellite image.

Sasha writes:

In our recent newsletter, we summarised the updates as follows:

Open-weather apt is the only public, maintained, browser-based decoder for Automatic Picture Transmissions (APT) from satellites NOAA-19, NOAA-18 and NOAA-15. It was developed to improve access to satellite signal decoding for all practitioners.

We are excited to share a new and improved version available here! The new version includes the following updates and additional features:

  • Improved accuracy in decoding and finding sync positions (locates more sync positions than other comparable decoders)
  • Upload a WAV file of any sample rate (no more re-sampling with Audacity!)
  • Option to see the ‘raw’ image without syncing, and to ‘Find the Syncs’
  • Option to Rotate 180 degrees, often useful for viewing images from nighttime passes
  • Go deeper in your analysis: explore Signal Value and Image Value Histograms
  • Upload directly from open-weather apt to the Public Archive

Open-weather apt is co-developed by open-weather with Rectangle (Lizzie Malcolm and Dan Powers), Bill Liles (NQ6Z) and Grayson Earle. We have had a lot of fun testing and experimenting. Please let us know if you have feedback!

Open-Weather APT Web Decoder
Open-Weather APT Web Decoder

Weather Satellite HRPT and LRPT Megaprojection Project Nov 30 – Dec 1

Over on the /r/amateursatellites subreddit, user elmarkodotorg is organizing a group megaprojection project. The Megaprojection Project seeks to create a composite of as much of the earth as possible from weather satellite images captured by hobbyists in a single day, via data from NOAA and Meteor polar-orbiting satellites. They will be accepting HRPT or LRPT data from either Nov 30 or Dec 1 (date yet to be confirmed).

Hobbyists can receive these satellites' LRPT and HRPT signals using an RTL-SDR and appropriate antenna setup.

If you want to contribute, you can join DerekSGC's Discord server, https://sgcderek.github.io, where coordination will be carried out. elmarkodotorg writes that currently, they have confirmed contributors with stations from the west coast of the US all the way over to the western edge of Asia. Currently, they are still hoping to find contributors from the Canary Islands, Turkey, Equatorial Africa, the general area of Indonesia, and Northern Australia. In a more recent Reddit thread, elmarkodotorg provides a link to a Google docs sheet, where you can also register interest.

Recently, on November 16 a test was carried out and they were able to successfully combine 24 images received across the world.

Megaprojection Nov 16 Test: 24 contributors from all over the world submitted HRPT and LRPT images received from their home satellite ground stations.
Megaprojection Nov 16 Test: 24 contributors from all over the world submitted HRPT and LRPT images received from their home satellite ground stations.

SatDump 1.2.1 Released

SatDump is a popular program used to receive and decode images and other data from various weather satellites. SatDump works great RTL-SDR Blog dongles and with our Discovery Dish, an easy-to-use dish and feed for receiving L-band and other weather satellites. Recently SatDump version 1.2.1 was released, which brings several new features including:

  • Meteor-M Calibration - Temperatures and radiances are now available from the Meteor-M infrared channels, including enhancements like Cloud Top IR.
  • Archive Loader & EUMETSAT Archives (and EUMETCAST) Support: Metop, Meteosat, Sentinel-3 and more! - Users can now open data from the EUMETSAT archives in SatDump.
  • Windows ARM64 Support - One of the few SDR programs that has Windows ARM64 support.
  • JUICE Support - JUICE (JUpiter ICy moons Explorer) is an ESA probe tasked to study three of the Galilean moons of Jupiter, namely Ganymede, Callisto and Europa. During a recent Earth slingshot it was possible to receive.
  • AIRS and CERES Support - Hyperspectral sounder and radiation budget instruments on the Aqua satellite
  • Arctic Weather Satellite Support - AWS is a weather satellite recently launched in July 2024 with 1707 MHz downlink and similar parameters to METOP, so it should be accessible to many.
  • IASI (imaging channel) Calibration - Calibration for the hyperspectral sounder onboard METOP satellites.
  • GOES-R L2 Product Support - Pre-processed models from NOAA that include Rain Rate per Quarter Hour, Land Surface Temperature, Sea Surface Temperature, and more.
  • GOME Fixes - True Color for METOP satellites.
  • Miscellaneous AVHRR and MHS Fixes - Calibration stripes and other strangeness is less likely to occur even with a bad signal.
  • Miscellaneous Composites - Many new composites are available.
  • Automatic Filename Templating - Customizable filename templates
  • More Quality-of-Life Features - Various tools and warnings added
  • RFNM Support - Support for the new RFNM SDR
  • Library Directory Fixes on Linux - Fixes SatDump on Gentoo and OpenSUSE among others.
  • Advanced Mode - Lets you change all TLE settings, composite configs, default pipeline settings, and more
  • Themes - Various new themes added
  • More Satellites Support - Initial support for XMM-Newton, VERONIKA and ACE
  • Experimental Windows XP Support - A special version of SatDump now runs on Windows XP SP3.
  • Various Bug Fixes
SatDump Running on Windows XP
SatDump Running on Windows XP

Moving on from WXtoIMG for NOAA APT Weather Satellite Decoding

Thank you to Jacopo (@lego11/IU1QPT) and Robin (@OK2AWO) for writing in and sharing with us his thoughts about how the SDR community as a whole should move on from the use of WXtoIMG, and instead switch to SatDump, which now has full feature parity with WXtoIMG and additional features too. SatDump is available on Windows, MacOS, Linux, and even on Android. An up-to-date guide for receiving APT with SatDump written by @lego11 can be found on his website here.

Historically, WXtoIMG has been the software of choice for the popular hobby of decoding NOAA APT weather satellite images with RTL-SDR and other SDRs. However, the software has unfortunately been abandoned by its authors for several years, and can now only be found on third-party websites which increases the possibility of downloading a virus. Also, a hack involving a proxy, or directly updating via a powershell script is now required to allow WXtoIMG to update its TLE/ Kepler files due to the celestrak.com to celestrak.org domain name change.

Lego11 also notes a whole host of other issues regarding vulnerabilities and bugs with WXtoIMG:

  • The software is ancient and uses obsolete libraries, such as Visual C++ 2002 with .NET. These libraries are the main concern when it comes to WXtoIMG, as I don't find it particularly likely for someone to find an entry point through the software itself. However, a much more likely scenario is a virus abusing the loaded library in memory when WXtoIMG is running and using it to gain an entry point. There are at least 20 vulnerabilities affecting MSVCR70.dll, and all are well known (such as CVE-2007-0025) which makes it even more concerning. CVE-2008-4255 in particular allows for remote code execution on the user's computer, which is very serious. There are certainly many more vulnerabilities that have been exploited regarding MSVCR70, but due to the obsolescence of this software component they are usually not tracked in a CVE.

    In either case, just as nobody would use Windows XP as a daily driver in 2024, nobody should use WXtoIMG as a matter of caution, even if the above mentioned vulnerabilities were not present.

    As for the bugs, there are many. Here's a list of the most important ones:
     
  • Cannot update TLE without external software, complicating the experience for newcomers and adding extra failure points
     
  • Map overlay doesn't work properly most of the times, especially if the user starts to receive the satellite before it is at least at 1° elevation
     
  • WXtoIMG will crash if Microsoft Defender starts a memory scan during a pass. This will lose the recording
     
  • WXtoIMG uses an outdated Win32 API to access audio. This doesn't always work on Windows 11 and Microsoft has stated that it will be removed soon.
     
  • WXtoIMG uses ALSA on Linux. The vast majority of Linux distributions don't support ALSA directly anymore, and WXtoIMG cannot work through an audio server (e.g. Pulseaudio) like all Linux applications are supposed to. Therefore, live recording doesn't work on Linux at all.
     
  • WXtoIMG doesn't run on MacOS anymore, as the system will refuse execution due to security problems and missing libraries.
     
  • WXtoIMG cannot support wav files from e.g. SDR# or SDR++ without using a third party tool such as NOAA-APT.
     
  • If a user moves or copies a recorded WAV file (see above), the map overlay will no longer work.
     
  • WXtoIMG is especially sensitive to concurrent CPU usage, which will result in "tears" on the image (as is evident on the images in the guy's tutorial). It cannot handle multitasking well on systems more modern than Windows XP due to changes in how the CPU scheduler works in more modern kernels.
     
  • WXtoIMG will lock up and then crash if the user starts it without first having updated TLEs due to missing NOAA-17. This is very serious, as it happens to newcomers all the time. It is one of the top support request emails/messages I receive. It is not possible to fix this crash easily.
     
  • WXtoIMG doesn't have updated coefficients for calibration, therefore NOAA-15 will look excessively cold compared to other satellites.
SatDump Receiving APT Weather Satellite Images
SatDump Receiving APT Weather Satellite Images (from @lego11's tutorial)

SignalsEverywhere: Decoding the QO-100 Mid-Beacon with WebSDR and IZ8BLY’s Decoder

In one of her latest videos on YouTube, Sarah from the SignalsEverywhere channel shows how we can use a program called "IZ8BLY Phase 3D (AO-4) Satellite Decoder" to decode the 'Mid-Beacon' on the QO-100 satellite. QO-100 is a commercial geostationary communications satellite that also contains a popular transponder for amateur radio.

However, there is also an interesting beacon called the mid-beacon that can be decoded, which provides some information about the satellite. In the video, Sarah shows how this beacon can be decoded with the software from IZ8BLY. As QO-100 is only visible from Europe, the Middle East and Africa, Sarah uses a WebSDR to receive the signal from the USA, then pipes the audio into the IZ8BLY decoder via Virtual Audio Cable.

Decode QO-100's Mid-Beacon with Virtual Audio Cables and WebSDR

GOES-U Satellite Launched and on the way to Geostationary Orbit

On June 25 the NOAA GOES-U weather satellite was successfully launched on a SpaceX Falcon 9 Heavy rocket. Once it reaches geostationary orbit, this will be a new weather satellite that RTL-SDR hobbyists can receive with an RTL-SDR dongle, satellite dish, and LNA.

From launch, it will take about two weeks for GOES-U to reach geostationary orbit and once it gets there it will be renamed to GOES-19. It is due to be positioned where GOES-16 currently is, and GOES-16 will become the redundant backup satellite. This positioning will make the satellite visible to those in North and South America.

GOES-16 is where GOES-19 will be positioned.
GOES-16 is where GOES-19 will be positioned.

We are anxiously looking forward to the first images from GOES-19 received by hobbyists, but once positioned it will probably take several weeks to be tested and calibrated before hobbyists can receive any signals on L-band. 

Over on X, @WeatherWorks posted a short video showing that the launch plume was visible from GOES-16.

The @CIRA_CSU account has also posted a video from GOES-18 which shows the launch in the water vapor bands

Finally, @SpaceX has also posted a video showing the deployment of the satellite, with an impressive shot showing how far away it is from the Earth.

Scott Manley Explains GPS Jamming & Spoofing and Why & Who is Causing It

In recent years GPS spoofing and jamming have become quite commonplace. Recently popular YouTuber Scott Manley uploaded a video explaining exactly what GPS spoofing and jamming is and explains a bit about who is doing it and why.

In the video Scott explains how aircraft now routinely use GPS as a dominant navigational sensor and how some commercial flights have been suspended due to GPS jamming. Scott explains how ADS-B data can be used to determine the source of GPS jamming (via gpsjam.org) and shows hotspots stemming from Russia. He goes on to show how drone shows have also failed in China either due to GPS jamming by rival companies or due to Chinese military warship jamming. Scott then explains a bit about GPS and how jamming and spoofing work.

GPS Jamming & Spoofing - How Does It Work, And Who's Doing It?