Some weeks ago, I presented at FOSDEM my work-in-progress high performance SDR runtime qsdr. I showed a hand-written NEON assembly implementation of a kernel that computes \(y[n] = ax[n] + b\), which I used as the basic math block for benchmarks on a Kria KV260 board (which has a quad-core ARM Cortex-A53 at 1.33 GHz). In that talk I glossed over the details of how I implemented this NEON kernel. There are enough tricks and considerations that I could make a full talk just out of explaining how to write this kernel. This will be the topic for this post.
Month: February 2025
Decoding HYDRA-T
HYDRA-T is a PocketQube developed and operated by the Spanish start-up Hydra Space. It was launched on SpaceX’s Transporter 12 mission on January 12, and according to this news article (in Spanish), it is very similar to HADES-R, another PocketQube also launched in Transporter 12 and developed by Hydra Space and operated by AMSAT-EA, the Spanish amateur satellite society. While HADES-R is an amateur satellite that carries a transponder for amateur radio communications, HYDRA-T is a commercial satellite which according to the news article carries a payload from the 6G-XTREME CON-SAT project from Universidad Carlos III de Madrid related to 6G deployment.
Some days ago, people in the LibreSpace forums started noticing that HYDRA-T was transmitting telemetry on 437.780 MHz, which is a frequency that belongs to the amateur satellite service 435 – 438 MHz band. This was acknowledged by Félix Páez EA4GQS, who is AMSAT-EA’s president and Hydra Space Software and Satellite Operations Manager. Félix expressed that HYDRA-T should not be transmitting in this frequency even if it has a license to do so.
I could delve more and give my opinion about whether HYDRA-T can rightfully transmit on this frequency, specially given the fact that it is doing so under the Earth Exploration Satellite Service (active) allocation (see the frequency allocation tables from ITU, and the ITU Space Explorer entry for this satellite, which for some reason is listed there as HYDRA-A), which is a whole different usage from a telemetry downlink of a communications satellite. Maybe I will do this another time. In this short post I wanted to focus on the analysis of the short telemetry recording shared by Jan van Gils PE0SAT, and show the similarities between HYDRA-T and HADES-R, as well as previous satellites from AMSAT-EA, for which documentation of their telemetry format is publicly available.