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Marine radars are X band or S band radars on ships, used to detect other ships and land obstacles, to provide bearing and distance for collision avoidance and navigation at sea. They are electronic navigation instruments that use a rotating antenna to sweep a narrow beam of microwaves around the water surface surrounding the ship to the horizon ...
Marine radars are used by ships for collision avoidance and navigation purposes. The frequency band of radar used on most ships is X band (9 GHz/3 cm), but S band (3 GHz/10 cm) radar is also installed on most oceangoing ships to provide better detection of ships in rough sea and heavy rain condition.
The radar mile is the time it takes for a radar pulse to travel one nautical mile, reflect off a target, and return to the radar antenna. Since a nautical mile is defined as 1,852 m, then dividing this distance by the speed of light (299,792,458 m/s), and then multiplying the result by 2 yields a result of 12.36 μs in duration.
The pulse width ( ) (or pulse duration) of the transmitted signal is the time, typically in microseconds, each pulse lasts. If the pulse is not a perfect square wave, the time is typically measured between the 50% power levels of the rising and falling edges of the pulse. The pulse width must be long enough to ensure that the radar emits ...
A graphical display of AIS data on board a ship. The automatic identification system (AIS) is an automatic tracking system that uses transceivers on ships and is used by vessel traffic services (VTS). When satellites are used to receive AIS signatures, the term Satellite-AIS (S-AIS) is used. AIS information supplements marine radar, which ...
A marine radar with automatic radar plotting aid (ARPA) capability can create tracks using radar contacts. [1] The system can calculate the tracked object's course, speed and closest point of approach [2] (CPA), thereby knowing if there is a danger of collision with the other ship or landmass. Development of ARPA started after 1956, when the ...