The Patrol Frigate is a Nebulon B modified to carry a 3,000 metre long sensor net with dedicated energy receptors, crystal gravfield traps and hyperspace signal interceptors. Many Imperial Sectors use these vessels to keep watch over their border and to act as a first line of sensor warning against invasion. It carries only half the usual crew and half of its decks are not in use, and its two rear lasers are replaced with towing winches. The array is operated by a crew of three. Controlling the array in flight takes great skill from tangling or disengaging under maneuvering strain. The array is capable of detecting ships entering or exiting hyperspace and can pick up a ship passing by in hyperspace if the ship is massive enough. If this is the case than the frigate can calculate likely vectors and report to its base. The sensor net is also powerful enough to intercept hypercomm transmissions-even holonet communications.