Scientific & Technical Amateur Radio — Home of EA4GPZ / M0HXM
On 2026-08-02, Peter Gülzow, AMSAT-DL s president, noticed that Tianwen-1 was transmitting very low rate telemetry, in contrast to the usual 16 kbaud telemetry. This is typical of a safe mode configuration, since it allows decoding even when low gain antennas are used and the attitude is unfavourable. Peter made a couple of short IQ recordings. Continue reading Tianwen-1 safe mode telemetry
Open Research Institute has recently published the solutions for a Lunar Descent CTF that they ran at BSides San Diego 2026. The CTF revolves around the Ka-band radio altimeter used by the Chandrayaan-3 lunar lander. The CTF includes a simulation of the radio altimeter and the goal is to discover why the lander is crashing Continue reading ORI s lunar descent CTF
Thomas Telkamp has shared with me an IQ recording of the Tianwen-2 telemetry downlink made with the Bochum 20 metre antenna on June 8. This is part of an ongoing effort led by Peter Gülzow, AMSAT-DL s president, for closely monitoring Tianwen-2 s operations. All the material I have used in previous posts about Tianwen-2 has come Continue reading Tianwen-2 low data rate telemetry
A couple years ago I wrote a post about the paper Controlled-Root Formulation for Digital Phase-Locked Loops, by Stephens and Thomas. In this paper, the authors study digital PLLs by studying the transfer function in discrete time, rather than doing any continuous-time approximations or equivalences. They give values for the loop coefficients that are needed Continue reading PLL coefficients for…
Yesterday I posted about my decoding of some recordings of the X-band telemetry of Tianwen-2 done by the Dwingeloo radio telescope. Today I have some small updates. First of all, I have figured out the format of the AOS insert zone. In the previous post I mentioned that the AOS insert zone contains 8 bytes Continue reading An update about Tianwen-2 telemetry
Tianwen-2 is a Chinese mission that will return samples from the Earth quasi-satellite asteroid 469219 Kamoʻoalewa and rendezvous with the 311P/PanSTARRS comet. It was launched on 28 May 2025 from the Xichang Satellite Launch Center. It is planned to perform its orbital insertion at Kamoʻoalewa on 7 June 2026, and study the asteroid until 24 Continue reading Decoding Tianwen-2
I have a Framework Laptop 13 that has a Ryzen AI 7 350 CPU that includes an NPU. I have started playing with this NPU to understand how to develop software for it. While NPUs are mainly intended as accelerators for inference of ML models, they are fundamentally hardware accelerators for matrix multiplication and other Continue reading Getting peak TOPS on a Ryzen AI 7 350 NPU
Recently I have been posting about V16 beacons, which are car emergency warning beacons that have been introduced this year in Spain, and which use the LTE NB-IoT cellular network to transmit their geolocation data to the traffic authority network when they are switched on. As part of experimenting with these beacons, I made recording Continue reading Decoding the NB-IoT downlink
A few days ago I posted about the fact that AMSAT-DL had not received any signals from Tianwen-1 since 2025-12-23. For months, AMSAT-DL had kept listening to the orbiter s frequency with the 20 m antenna in Bochum and had not detected any signals. Yesterday, AMSAT-DL announced that they had received again the signal from Tianwen-1. Continue reading Tianwen-1 received again by AMSAT-DL
Yesterday, AMSAT-DL published the news that they have been unable to receive any signals from Tianwen-1 with the 20 m antenna in Bochum since 2025-12-23. As you may know if you have been following my posts about Tianwen-1, AMSAT-DL has been using this antenna to receive and decode telemetry from Tianwen-1 almost every day since Continue reading Where is Tianwen-1?