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A Doppler radar is a specialized radar that uses the Doppler effect to produce velocity data about objects at a distance. [1] It does this by bouncing a microwave signal off a desired target and analyzing how the object's motion has altered the frequency of the returned signal.
Radar is a system that uses radio waves to determine the distance (), direction (azimuth and elevation angles), and radial velocity of objects relative to the site. It is a radiodetermination method [1] used to detect and track aircraft, ships, spacecraft, guided missiles, motor vehicles, map weather formations, and terrain.
Weather radar in Norman, Oklahoma with rainshaft Weather (WF44) radar dish University of Oklahoma OU-PRIME C-band, polarimetric, weather radar during construction. Weather radar, also called weather surveillance radar (WSR) and Doppler weather radar, is a type of radar used to locate precipitation, calculate its motion, and estimate its type (rain, snow, hail etc.).
However, since humans reflect far less radar energy than metal does, these systems require sophisticated technology to isolate human targets and moreover to process any sort of detailed image. Through-the-wall radars can be made with Ultra Wideband impulse radar, micro-Doppler radar, and synthetic aperture radar (SAR). [5] Imaging radar; 3D radar
Continuous-wave radar (CW radar) is a type of radar system where a known stable frequency continuous wave radio energy is transmitted and then received from any reflecting objects. [1] Individual objects can be detected using the Doppler effect , which causes the received signal to have a different frequency from the transmitted signal ...
Pulse-Doppler antenna motion must be slow enough so that all the return signals from at least 3 different PRFs can be processed out to the maximum anticipated detection range. This is known as dwell time. [10] Antenna motion for pulse-Doppler must be as slow as radar using MTI.
For convenience, these figures may also be expressed as 1 nautical mile in 12.4 μs or 1 kilometre in 6.7 μs. (For simplicity, all further discussion will use metric figures.) If the radar pulse width is 1 μs, then there can be no detection of targets closer than about 150 m, because the receiver is blanked.
Pulse Doppler radar may have 50 or more pulses between the radar and the reflector. Pulse Doppler relies on medium pulse repetition frequency (PRF) from about 3 kHz to 30 kHz. Each transmit pulse is separated by 5 km to 50 km distance. Range and speed of the target are folded by a modulo operation produced by the sampling process.