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Actually, the trope is Enforced Technology Levels, but I don't see anything there either.
^^ Six of one and half a dozen of the other, I guess. I looked over the Literature section in Enforced Technology Levels but I was also unable to find anything.
^ I do not think it is Safehold. The entry for it on the Kill Sat page reads "the planet Safehold's prohibition on advanced technology is enforced by orbital platforms that, if they detect power sources, will unleash a kinetic bombardment capable of devastating a small continent. Merlin is running extensive tests to determine what counts as a 'power source'. So far, no solution has been found to the main problem, but we're up to steam engines with no response." I'm looking for a system that reacts based on speed, not power output.
Bump ~
Under Medieval Stasis it mentions David Weber's Heir to the Empire, but it doesn't mention that the final book has a planet under quarantine that limits itself to pre industrial. I know they had planetary defences, satellites perhaps, to destroy intruders but I'm not sure if those defences struck industrial technology.
Years ago I read a summary for a book/ series about a world kept at a low level of technology. I do not remember any specifics about the plot, only that the setting was a planet forced into Medieval Stasis by a Kill Sat that destroyed anything moving faster than about 30 miles an hour. (So riding around on horses and carts was alright, but trains and automobiles and projectile weaponry were right out.) Nothing in the Literature sections of the Medieval Stasis and Kill Sat pages rings a bell, so any help tracking down this book would be much appreciated!