Satellite navigation systems used in ships are usually integrated systems of satellite positioning, identity identification and communication, rather than a single navigation satellite signal receiver. The integrated system is usually referred to as the ship automatic identification system". This system was born in 1990s, is a high-tech marine navigational equipment integration of communication, network and information technology, with the help of the global positioning system (GPS) dynamic parameters of ship speed, location, destination, heading and heading change rate, and the name of the ship, ship type, draught and dangerous goods such as static data broadcast to the waters near the ship, and the shore station by VHF, the adjacent ship and shore station near the sea can grasp all the ship's dynamic and static information, in order to quickly call each other coordination, take the necessary action to avoid collision. The first function of ship automatic identification system is ship identification, in addition, it can provide more information so that both sides can understand each other's operation intention clearly, and make avoidance more timely and effective. The international maritime organization is mandatory for all 300 tons and above international sailing civilian ships, 500 tons and above the non International Sailing civil ship, and all passenger ships are equipped with the ship to the automatic identification system, to reduce the risk of collision at sea. Whether the military ships install the automatic ship identification system, the IMO has not made the compulsory request. Most military ships are equipped with the system, but because of the action, confidentiality and other factors, even if the installation of the system is not often used, mostly in emergency when enabled. When some naval ships use the automatic identification system of ships, they will turn off the signal emission function and only enable the signal reception function.