There Is No Swarm in a Drone Light Show: 200 Aircraft Share One Integer
Grepping all 9,199 lines of Skybrush's open-source light-show firmware for neighbour, collision and swarm turns up nothing: no aircraft knows another exists, and the entire content two hundred of them synchronise is one GPS time-of-week integer plus a millisecond offset, with collision avoidance settled on the ground in the choreography software. Chapter 7 of Taiwan's drone cybersecurity spec — the swarm chapter — leaves the 'drone' column a dash down all twelve items and tests switches and routers instead.