Month: December 2023

Receiving HADES-D

HADES-D is the 9th PocketQube developed by AMSAT-EA. It is the first one that hasn’t failed early in the mission. Among the previous AMSAT-EA satellites, GENESIS-L and -N suffered the launch failure of the Firefly-Alpha maiden flight, EASAT-2 and HADES presumably failed to deploy their antennas, GENESIS-G and -J flew on the second Firefly-Alpha flight, which only achieved a short-lived orbit, with all the satellites reentering in about a week, URESAT-1 had the same kind of antenna deployment problem, and GENESIS-A is a short duration payload scheduled to fly in the Ariane-6 maiden flight, which hasn’t happened yet.

HADES-D launched with the SpaceX Transporter 9 rideshare on November 11. This PocketQube was carried in the ION SCV-013 vehicle, and was released on November 28. The antennas have been deployed correctly, unlike in its predecessors, the satellite is in good health, and several amateur stations have been able to receive it successfully, so congratulations to AMSAT-EA.

Since HADES-D is the first PocketQube from AMSAT-EA that is working well, I was curious to measure the signal strength of this satellite. Back around 2016 I was quite involved in the early steps of AMSAT-EA towards their current line of satellites. We did some trade-offs between PocketQube and cubesat sizes and calculated power budgets and link budgets. Félix Páez EA4GQS and I wanted to build an FM repeater amateur satellite, because that suited best the kind of portable satellite operations with a handheld yagi that we used to do back then. Using a PocketQube for this always seemed a bit of a stretch, since the power available wasn’t ample. In fact, around the time that PocketQubes were starting to appear, some people were asking if this platform could ever be useful for any practical application.

Fast forward to the end of 2023 and we have HADES-D in orbit, with a functioning FM repeater. My main interest in this satellite is to gather more information about these questions. I should say that I was only really active in AMSAT-EA’s projects during 2016. Since then, I have lost most of my involvement, only receiving some occasional informal updates about their work.

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An annotated 5G SigMF recording

For quite some time I’ve been thinking about generating SigMF annotations in some of the Jupyter notebooks I have about signal analysis, such as those for LTE and 5G NR. The idea is that the information about the frequencies and timestamps of the packets, as well as their type and other metadata, is already obtained in the notebook, so it is not too difficult to generate SigMF annotations with this information. The main intention is educational: the annotated SigMF file provides a visual guide that helps to understand the signal structure, and it also serves as a summary of what kind of signal detection and analysis is done in the Jupyter notebook. The code also serves as an example of how to generate annotations.

Another benefit of this idea is that it serves as a good test case for applications that display SigMF annotations. It shows what kinds of limitations the current tools have, and can also motivate new features. I’ve been toying with this idea since a while ago, but never wrote a blog post about it before. A year ago I sent a pull request to Inspectrum to be able to display annotation comments as tooltips when the mouse hovers above the annotation. While doing some tests with one LTE recording I realized that a feature like this was necessary to display any kind of detailed information about a packet. Back then, Inspectrum was the only application that was reasonably good at displaying SigMF annotations in a waterfall. Later, IQEngine has appeared as another good tool to display SigMF annotations (and also add them manually).

I have now updated the Jupyter notebook that I used to process a 5G NR downlink recording made by Benjamin Menkuec. This is much better to show an example of what I have in mind compared to the LTE recordings I was playing with before. The recording is quite short (so it is small), and I already have code to detect all the “packets”, although I have not been able to identify what kind of signals some of them are.

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