This is a great story from over at the Silicon Graybeard blog: https://thesilicongraybeard.blogspot.com/2021/03/a-couple-of-things-i-couldnt-resist.html
[A] Scott Manley story I came across during the week. When SpaceX launches a Falcon 9 mission, they recover the booster about 9 minutes into the mission. The upper stage that actually deploys the satellites is left in a higher orbit and is currently not considered recoverable. I believe they are put into a destructive de-orbit, using some onboard thrusters or perhaps some residual fuel, so that they reenter the atmosphere and are destroyed. During the couple of days this takes to have its affect, the second stage is still operating on battery power and transmitting telemetry, including video.
It seems a group of hams in Europe figured out how receive the Telemetry and decode the video.
Scott does an OK job of describing what the hams did. The “gizmo” he mentions at around 3:28 or 3:29 is called a downconverter. Fundamental, essential technology, and if you have a typical house, you’re probably surrounded by half a dozen of them. In my talk about superheterodyne receivers, every block diagram starts out with a downconverter.
All that aside, it’s a fun story. It comes down to SpaceX using open standards for their telemetry and a bunch of hams willing to try lots of stuff.
The data collection from telemetry is pretty awesome!
Sounds like a project for hams line-of-sight from the trajectory.