 Marine Radar, Marine Radars are X-band or F-band radars on ships used to detect other ships and land obstacles to provide bearing end-distance for collision avoidance and navigation at sea. They are electronic navigation instruments that use a rotating antenna to sweep the narrow beam of microwaves around the water surface surrounding the ship to the horizon, detecting targets by microwaves reflected from them, displaying a picture of the ship's surroundings on a display screen. Radar is a vital component for safety at sea and near the shore. Captains need to be able to maneuver their ships within feet in the worst of conditions and to be able to navigate blind when there is no visibility at night or due to bad weather. Radars are rarely used alone in a marine setting. In commercial ships, they are integrated into a full system of marine instruments including chart plotters, SOVNAR, to weight marine radio, satellite navigation GNSS receivers such as the U.S. Global Positioning System GPS and Emergency Locators SA-ART. The integration of these devices is very important as it becomes quite distracting to look at several different screens. Therefore, displays can often overlay charting, radar, SOVNAR into a single system. This gives the captain unprecedented instrumentation to maneuver the ship. With digital backbones, these devices have advanced greatly in the last years. For example, the newer ones have 3D displays that allow navigators to see above, below and all around the ship, including overlays of satellite imaging. In port or in harbor, shore-based vessel traffic service radar systems are used to monitor and regulate ship movements in busy waters.