The GPS Device is a gadget featured in Tom Clancy's Rainbow Six: Vegas 2.
It scans the adversarial battle map for enemy and friendly locations. Dots appear on your mini-map (and your allies' tactical map, if they pull it up) as red and green dots, just like in Story mode. However, the scanner only picks up individuals with a successful pass. Quick enemies can be far away by the time you track down their last position