Repulsor Towers, otherwise referred to as Wildlife Repulsor Towers or Dog Whistle Towers, are massive pieces of technology developed by the Interstellar Manufacturing Corporation, for the purposes of security and defence against alien fauna such as Leviathans and Flyers. They emit sound at a frequency inaudible to human ears, that is extremely loud and piercing to animals that can hear it - this keeps the animals away from critical IMC installations.
Repulsor Tower technology was pioneered at Base Golden, otherwise known as the Boneyard. Here, the tower served as a prototype that future models would be based on. However, it was abandoned decades before the events of the games. Eventually, the facility would come under attack by the Marauder Corps, led to the site by Robert "Barker" Taube. The Miltia would hope to recover data from the site, in anticipation of sabotaging the towers situated at the defence of Airbase Sierra.
The Militia would recover enough information on the towers to pose a threat, and soon launched an assault on the fourth moon of Demeter. IMC Orbital Defense Cannons and the fleet stationed there would make a frontal assault impossible, so instead a covert strike team was used; Pilots and Titans would strike the base proper, as a distraction for a covert operation led by Sarah Briggs to destroy the towers, allowing wildlife to overrun the base and do the Militia's dirty work. This would be achieved by a special modification to the Data Knife known as the Icepick, which uploaded a special program to the IMC's Goblins and Phantoms, resulting in the autopiloted aircraft destroying the towers. Leviathans soon overran the base.
Many years after the war, it would appear that the Repulsor technology is still in use, as an additional tower was situated at the King’s Canyon arena, with dormant Leviathans and Flyers on the outskirts of the island, away from the tower and thus allowing the Apex Games to take place. During Season 2 of Apex Legends, Crypto remotely triggered an EMP in the Tower itself, bringing it down. With the Leviathans and Flyers intruding the arena, just like Base Golden, the Legends were evacuated and transported to another arena, World's Edge, where the Apex Games continued.