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DIY Satellite Platforms by Sandy Antunes

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Radio Transmission Programming

The FCC rules the spectrum, but the International Amateur Radio Union (IARU) is the entity that actually coordinates satellites. If you are using amateur band, you need to file/coordinate with the IARU to use the amateur band with your personal ham callsign as the satellite’s callsign. Like any regulation, there are many details.

The main IARU requirement is play nice, and be able to turn off your transmitter at a moment’s notice. My approach will be to have the required stop transmit command, of course. To make this really work, however, I will also have all transmissions time out and shut down automatically after an appropriate interval (10 minutes of no contact). Transmission only starts when a start transmitting command is uplinked, with possibly a few orbits that are prearranged to have the satellite automatically turn on based on a clock (if IARU allocates the time).

Since most hams use transceivers (radios that can receive and transmit, for non-hams reading this), it is more fair to only broadcast when someone is willing and able to receive and yet shouldn’t reduce the ability to get picosatellite data down.

From a ground station listener point of view, when you wish to listen, you transmit the start transmitting command to the picosatellite; then it broadcasts for the set time (while you’re in range) and then shuts down. By definition, you can also shut it down earlier (since you’re the one that sent the on and are still in range), so it provides ...

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