Proximity sensor
From Memory Alpha, the free Star Trek reference.
The proximity sensor is a sensor device that determines how close another object is.
[edit] Navigational uses
It was a proximity alarm had warned Cadet Jean Hajar of an impending collision with Cadet Joshua Albert's training craft, allowing herself and her Nova Squadron teammates flying in tight formation to initiate their emergency transporters before their ships were destroyed in the ensuing pileup.
Lieutenant Jadzia Dax had to repair the proximity systems on an abandoned, decrepit Bajoran raider hidden in an underground cavern lest Dax and Major Kira Nerys started "bouncing off the walls". (DS9: "The Siege")
[edit] Military uses
Proximity sensors are commonly used on mines, where they trigger the mine's detonation when it nears or impacts a target. A malfunction in a proximity sensor could cause the mine either to detonate prematurely or to not detonate at all. (DS9: "Call to Arms"; ENT: "Minefield")
