Listening To A Flashlight — Lunar Flashlight - Hackaday

If you’ve been looking for a practical example of using GNU Radio, you should check out [Daniel Estévez’s] work on decoding telemetry captured from the Lunar Flashlight cubesat.

The cubesat is having some trouble, but the data in question was a recording from the day after launch.

The flowgraph for GNU Radio isn’t as bad as you might think, thanks to some judicious reuse of blocks from other projects to do some of the decoding.

The modulation is PCM/PM/bi-phase-L. Nominally, the speed is supposed to be 48,000 baud, but [Daniel] measured 48,077.

[Daniel] speculates that the satellite was correcting its frequency to lock to an uplink carrier from a ground station.

He doesn’t know the complete format of all the telemetry, but he makes some assumptions that seem sound.