The Tachyon Detection Grid of the game Star Trek: Armada is a means of detecting cloaked ships. Two factions of the game have the capability to cloak their units, making them invisible. To break this invisibility, the player has to either use one of the scout ships or sensor stations along with the Tachyon Detection Grid researched. The research is done at the Modification Center (Borg), Research Facility (Federation), Weapons Center (Klingon) or Covert-Ops Facility (Romulan). It is a passive ability, using no special weapon energy. Every faction has this special weapon at their disposal, although you have to research it for each faction to make their detector units/stations capable of uncovering cloaks. When using the Free Tech Tree, it is already available right from the start.

Cloaked ships have their shields down and therefore are very vulnerable. But without Tachyon Detection Grid you cannot track them or see them approaching. The difference of cloaked and uncloaked ships while seeing them being detected looks like this:

On the left hand side you see the uncloaked Vor'cha ship, while on the right hand side the cloak is running. The difference gets more pronounced, the brighter the color of the player is. So for green or yellow you will see the transparent and slightly glowing effect more intensely.