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Because the external radar causing the transponder to respond is generally not synchronised with your own radar (i.e. different pulse-repetition frequencies), these black dots appear randomly across the display and the operator sees through and around them. The returning image may be much larger than the "dot" or "hole", as it has become known ...
Examples of electronic counter-countermeasures include the American Big Crow program, which served as a Bear bomber and a standoff jammer. [6] It was a modified Air Force NKC-135A and was built to provide capability and flexibility of conducting varied and precision electronic warfare experiments. [ 7 ]
Automatic target recognition (ATR) is the ability for an algorithm or device to recognize targets or other objects based on data obtained from sensors.. Target recognition was initially done by using an audible representation of the received signal, where a trained operator who would decipher that sound to classify the target illuminated by the radar.
A popular example is displaced phase center antenna (DPCA), which is a form of data-independent STAP in the beamspace, pre-Doppler. [7] The goal is to perform beamforming such that the beam appears stationary as the airborne radar is in motion over discrete time periods so the clutter appears without Doppler. [2]
It may also rotate to minimize its cross section exposed to the radar beam. This leads to aircraft being more difficult to separate from the effectively stationary chaff and is known as "notching" as radar typically incorporate a notch of low sensitivity to frequencies associated with low velocity.
MDV determines whether traffic will be detected. A GMTI radar must distinguish a moving target from ground clutter by using the target's Doppler signature to detect the radial component of the target's velocity vector (i.e., by measuring the component of the target's movement directly along the radar-target line).
A pulse-Doppler radar is a radar system that determines the range to a target using pulse-timing techniques, and uses the Doppler effect of the returned signal to determine the target object's velocity.
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.