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For an observer standing on a hill or tower 100 metres (330 ft) above sea level, the horizon is at a distance of 36 kilometres (22 mi). For an observer standing on the roof of the Burj Khalifa, 828 metres (2,717 ft) from ground, and about 834 metres (2,736 ft) above sea level, the horizon is at a distance of 103 kilometres (64 mi).
Without taking into account the refraction through the atmosphere, the radar horizon would be the geometrical distance from the radar to the horizon only taking into account the height of the radar above sea-level, and the radius of the earth (approximately 6.4·10 3 km):
Assuming a perfect sphere with no terrain irregularity, the distance to the horizon from a high altitude transmitter (i.e., line of sight) can readily be calculated. Let R be the radius of the Earth and h be the altitude of a telecommunication station. The line of sight distance d of this station is given by the Pythagorean theorem;
Marine radar has performance adjustment controls for brightness and contrast, also manual or automatic adjustment of gain, tuning, sea clutter and rain clutter suppression, and interference reduction. Other common controls consist of range scale, bearing cursor, fix/variable range marker (VRM) or bearing/distance cursor (EBL).
Horizon distance graphs: Image title: Graphs of distances to the true horizon on Earth for a given height above sea level, h by CMG Lee. s is along the surface of the Earth, d is the straight line distance, and ~d is the approximate straight line distance assuming h << the radius of the Earth, 6371 km. In the SVG image, hover over a graph to ...
MADRE over-the-horizon radar at the NRL's Chesapeake Bay Detachment U.S. Navy Relocatable Over-the-Horizon Radar station. The most common type of OTH radar, OTH-B (backscatter), [3] uses skywave or "skip" propagation, in which shortwave radio waves are refracted off an ionized layer in the atmosphere, the ionosphere, and return to Earth some distance away.
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Consider the following example : if the radar antenna is located at around 15 m above sea level, then the distance to the horizon is pretty close, (perhaps 15 km). Ground targets further than this range cannot be detected, so the PRF can be quite high; a radar with a PRF of 7.5 kHz will return ambiguous echoes from targets at about 20 km, or ...