Category: Satellite

Receiving US Nuclear Detection Satellite Signals with RTL-SDR, Discovery Dish and Discovery Drive

Over on the Saveitforparts YouTube channel, Gabe has documented how he accidentally discovered signals coming from the GPS-satellite-based US nuclear detection system.

While scanning the GPS L3 frequency around 1381 MHz with his RTL-SDR, Discovery Dish, 1420 MHz Hydrogen line Discovery Dish feed, and Discovery Drive, Gabe caught short intermittent data bursts instead of the usual navigation signals. It turns out L3 is used by the GPS constellation for nuclear detonation detection, as the satellites double as arms-control sensors. When one detects a possible event, it relays the message across the network, the only time this frequency sees activity.

Later in the video, Gabe also swaps the dish feed to compare against a regular GPS L1 signal at 1575.42 MHz, and notes that radio astronomers are reverse-engineering L3 to filter it out, since it sits close to the protected 1420 MHz hydrogen line.

I Found The US Nuclear Detection System In Space

Further Tutorials on SatDump Map Projections

Thank you to Paul Maine, who has submitted to us two new SatDump tutorials that he has uploaded to his YouTube channel. These two tutorials follow on from his previous tutorials that we posted a month ago.

His SatDump V2.x Part 5 video demonstrates Recording and Processing. Paul shows his hardware setup and then shows GUI Live Processing, CLI Live Processing, CLI Recording and how to use the GUI to process recorded files.

E28 SatDump v2.x Part5 Recording & Processing

His SatDump V2.x Part 6 video on Projections introduces Map Projections. Paul uses things covered in earlier SatDump videos and builds upon them to create very interesting map projections. For his first example, he uses the Load First Party feature to download a GOES-19 CONUS image. Next, he shows how to add a shape file and a Severe Storms image expression. Lastly, he shows how to create an equirectangular map projection. In the video, Paul also shows how to create three other types of projections.

Before SatDump Projection
Before SatDump Projection
After SatDump Projection
After SatDump Projection
E29 SatDump v2.x Part 6 Projections

Saveitforparts: Seeing Satellites with the Discovery Drive and Discovery Dish

Over on YouTube, Gabe from the saveitforparts channel has uploaded a video where he tests out his Discovery Drive and Discovery Dish with L-Band feed for creating sky heatmaps of L-band satellites.

If you were unaware, Discovery Drive is our sister company KrakenRF's most recent successful crowdfunding campaign, which was successfully funded a couple of weeks ago. Discovery Drive is a portable antenna rotator with low power requirements, designed for use with Discovery Dish and other antennas of similar size and weight.

In the video, Gabe writes a custom script that has the Discovery Drive sweep the sky while simultaneously taking RF power readings with the Discovery Dish and L-band feed. The result is an image showing where L-band satellites are in the sky. He goes on to conduct experiments with the hydrogen line and sun imaging, as well as with satellites at UHF frequencies.

Seeing Satellites With The Discovery Drive

SatDump V2 Image Product Expressions YouTube Tutorial

Thank you to Paul Maine, who has submitted a new SatDump tutorial to us that he has uploaded to his YouTube channel. The new tutorial is the fourth in a series focused on SatDump V2.x. In an earlier post, we showed Paul's three previous tutorials.

His SatDump V2.x Part 4 video provides an introduction to SatDump’s “Image Product Expressions”. The video begins with satellite calibration units and descriptions, and includes Albedo, Brightness Temperature, and Radiance. The video then discusses satellite sensors, providing examples. The GOES-19 Satellite and its Advanced Baseline Imager are used in the examples.

Color RGB Images can be created using various satellite bands and Image Product Expressions to produce very beautiful and useful satellite imagery.

Image Product Expression Examples
Image Product Expression Examples
E 27 SatDump v2.x Part4 Image Product Expressions

L-Band Weather Imagery Soon Coming Back to Western Europe via Elektro-L3

Thanks to weather satellite enthusiast 'Heja Ali' who wrote in to share some welcome news. On February 12, 2026, Roscosmos successfully launched Elektro-L No.5 aboard a Proton-M rocket from Baikonur Cosmodrome, the fifth in the Elektro-L series of Russian geostationary weather satellites (following No.1 in 2011, No.2 in 2015, No.3 in 2019 and No.4 in 2023). Like its predecessors, it carries an unencrypted 1691 MHz L-band downlink with both LRIT and HRIT imagery.

The interesting consequence for amateur satellite enthusiasts is what happens next. Per SatDump's satellite list, L5 is now commissioning at 76°E (L3's old slot), L4 is operational at 165.75°E, and the European slot at 14.5°W is currently held by L2, which has lost its L-band transmitter to a power supply failure. Once L5 is fully operational, L3 is expected to drift west to 14.5°W to replace L2, finally restoring an unencrypted geostationary L-band downlink to the UK, Ireland, Iceland, Portugal, western France, and Spain for the first time since EUMETSAT switched off Meteosat HRIT in 2018.

The Electro-L 1691 MHz signal is easily received by an RTL-SDR Blog V3 or V4, LNA, and a modest 65 cm dish. Our Discovery Dish with the L-band weather satellite feed is a good choice, with existing users in southern Europe routinely pulling Elektro-L3 at 5 to 6 dB SNR using SatDump (which only needs around +1 dB to decode).

There is no firm public timeline yet for L3's drift west, but if you are in far-western Europe and have been waiting on a geostationary L-band satellite to become available, now is a good time to start planning for the receive hardware.

Receiving Electro-L Satellite Imagery With SatDump
Receiving Electro-L Satellite Imagery With SatDump

Build a Cubesat Reviews a Discovery Drive Prototype and Sets up SatNOGS

Over on YouTube Manuel from the 'Build a Cubesat' channel has uploaded a video testing a prototype version of our Discovery Drive antenna rotator. If you are unaware, Discovery Drive is our new antenna rotator product for applications like satellite tracking and general antenna positioning that is currently being crowd-funded over on Crowd Supply. There are two days left in the campaign.

In the video, Manuel overviews the Discovery Drive, shows the internals, and walks us through the web UI. He goes on to show how it can be set up with the SatNOGS project. The SatNOGS project has volunteers set up ground-based satellite stations, and anyone can use those stations to log an observation anywhere in the world.

We note that he mentioned some trouble with getting SatNOGS to rotate the Discovery Drive over zenith. We have added a note to our Wiki showing how this can be fixed by specifying the correct rotational limits for the Discovery Drive.

Discovery Drive Antenna Rotator Preview

Hacking a Secondhand Marine Satellite Dish to Track Satellites with Gpredict

Thank you to Melan / Alex for submitting news about their project, where they reverse-engineered a second-hand Intellian i4 marine satellite dish, which retails new for around €4000 but which they picked up second-hand for about €200. The dish itself is a 40 cm prime-focus design with a quad LNB, beefy stepper motors, and a motorized sub-reflector implementing Intellian's Dynamic Beam Tilting (DBT) technology, where the small sub-reflector handles fast beam corrections so the main motors only deal with large movements.

The dish normally expects heading data from the boat via NMEA 0183 over RS-422, so Melan solved the "we're not on a boat" problem with an RP2040 and a TTL-to-RS-422 module spoofing $HCHDG compass sentences to the Antenna Control Unit. To avoid being tied to Intellian's Aptus software, they decompiled the C# application to reverse engineer the ACU's text-based serial protocol. They then wrote a shim making the dish appear as a generic rotator to Gpredict, and put it on the roof of Dutch hackerspace NURDspace, pulling in Ku-band satellite TV. 

The full write-up includes photos of the internals, an auto-generated protocol document, and a video of the dish doing a test dance.

The Intellian i4 Marine Satellite Dish Platform
The Intellian i4 Marine Satellite Dish Platform

New YouTube Tutorials for SatDump V2.x.x

Thank you to Paul Maine, who has submitted to us new SatDump tutorials that he has uploaded to his YouTube channel. The new tutorials focus on the new SatDump V2.x.x alpha version.

The first tutorial shows how to install SatDump 2.x.x, and how to obtain an EUMETSAT API key and use the 'Load First Party' feature to view and analyze satellite data downloaded from the internet. The second tutorial focuses on the nbew DSP Flowgraph feature, and the third discusses how Look Up Tables (LUTs) are used with satellite imagery.

E24 SatDump v2.x wip Part1

E25 SatDump v2.x wip Part2 DSPflowgraphs

E26 SatDump v2.x wip Part3 LUTs