A radar used on a ship to detect the position of the surrounding target, to implement navigation avoidance, self-positioning, etc.
Navigation radar is an active navigation equipment, which can detect dangerous approaching objects near the route in time while realizing its own positioning, so it is the main maritime collision avoidance equipment of modern ships. Naval navigation radar can detect the sea situation around the ship by transmitting certain frequency electromagnetic wave through the antenna, so as to determine the target orientation and distance, and realize collision avoidance, positioning and navigation. Radar navigation is mainly used to guide ships in and out of ports, through narrow waterways, coastal navigation and collision avoidance at sea, but also for surveillance or finding anchorage, maritime rescue search and weather forecasting.
Navigation radars on naval ships of developed countries are usually integrated with sea search radars to improve comprehensive detection and early warning capabilities. The main index of navigation radar detection and early warning is the maximum and minimum detection distance. The smaller the minimum detection distance, the smaller the radar blind area, and the stronger the early warning ability to small fast approaching ships. For example, the AN/SPS-67(V) sea search radar equipped with the Nimitz-class nuclear-powered aircraft carrier of the United States Navy has a maximum detection range of 104 kilometers, and the minimum detection range can reach 370 meters by increasing the narrow pulse mode, which greatly reduces the detection blind area and realizes the effective detection and resolution of small ships at close range.
Most countries' naval ships and civilian vessels are also equipped with a collision avoidance device called "automatic radar Plotter", also known as collision avoidance radar. Automatic radar plotter is a combination of Marine radar and computer technology, which has the functions of target capture, tracking, display, alarm, ship test control and so on. The device can track and process multiple targets at the same time, and display real-time information such as distance, orientation and speed between the ship and the tracked target. For incoming ships that are in danger of collision, the watchman can simulate avoidance maneuvers on the automatic radar plotter to predict the avoidance effect in advance. At present, the automatic radar plotter has become a necessary equipment for naval ships of all countries.
Although navigation radar plays an important role in collision avoidance at sea, due to the linear propagation characteristics of radar electromagnetic waves, radar detection of targets has shadow areas. In addition, due to the limitations of radar antenna height and vertical beam width, radar pulse width and transceiver switch recovery time, there are still blind areas in radar observation. In particular, the detection ability of targets behind close-range targets and occlusions is limited, and the detection of targets with weak reflected signals is also lacking. Therefore, the automatic radar plotter still has the phenomenon of target loss and mistracking, and can not completely rely on the radar navigation equipment when sailing at sea.