Thank you to Melan / Alex for submitting news about their project, where they reverse-engineered a second-hand Intellian i4 marine satellite dish, which retails new for around €4000 but which they picked up second-hand for about €200. The dish itself is a 40 cm prime-focus design with a quad LNB, beefy stepper motors, and a motorized sub-reflector implementing Intellian's Dynamic Beam Tilting (DBT) technology, where the small sub-reflector handles fast beam corrections so the main motors only deal with large movements.
The dish normally expects heading data from the boat via NMEA 0183 over RS-422, so Melan solved the "we're not on a boat" problem with an RP2040 and a TTL-to-RS-422 module spoofing $HCHDG compass sentences to the Antenna Control Unit. To avoid being tied to Intellian's Aptus software, they decompiled the C# application to reverse engineer the ACU's text-based serial protocol. They then wrote a shim making the dish appear as a generic rotator to Gpredict, and put it on the roof of Dutch hackerspace NURDspace, pulling in Ku-band satellite TV.
The full write-up includes photos of the internals, an auto-generated protocol document, and a video of the dish doing a test dance.