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A typical case is wave measurements from an offshore platform in deep water, where swift currents could make mooring a wave buoy enormously difficult. Another interesting case is a ship under way, where having instruments in the sea is highly impractical and interference from the ship's hull must be avoided.
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).
AN/APN-179 Doppler navigational radar by Bendix Corporation for EC-47; AN/APN-182 improved AN/APN-130 Doppler navigational radar system by Teledyne used with AN/AYK-2 for SH-3H CH-46, HH-46A/D SH-2D, UH-2C and RH-53; AN/APN-185 Doppler navigational radar by Singer Corporation for FB-111A A-7D and B-1A; AN/APN-186 Doppler radar system for A-6 ...
Ships and planes are metal, and reflect radio waves. The radar measures the distance to the reflector by measuring the time of the round trip from emission of a pulse to reception, dividing this by two, and then multiplying by the speed of light. To be accepted, the received pulse has to lie within a period of time called the range gate. The ...
Regardless, radars that employ the technique are universally coherent, with a very stable radio frequency, and the pulse packets may also be used to make measurements of the Doppler shift (a velocity-dependent modification of the apparent radio frequency), especially when the PRFs are in the hundreds-of-kilohertz range. Radars exploiting ...
SARs produce a two-dimensional (2-D) image. One dimension in the image is called range and is a measure of the "line-of-sight" distance from the radar to the object. Range is determined by measuring the time from transmission of a pulse to receiving the echo from a target. Also, range resolution is determined by the transmitted pulse width.
The range and velocity of a target are detected through pulse delay ranging and the Doppler effect (pulse-Doppler), or through the frequency modulation (FM) ranging and range differentiation. The range resolution is limited by the instantaneous signal bandwidth of the radar sensor in both pulse-Doppler and frequency modulated continuous wave ...
A 1976 United States NOAA chart of part of Puerto Rico A nautical chart of the Warnemünde harbor shown on OpenSeaMap. A nautical chart or hydrographic chart is a graphic representation of a sea region or water body and adjacent coasts or banks.