TABLE OF CONTENTS When a radar is mounted on a moving vehicle, the velocity of the vehicle adds vectorially to the radial velocity of the vehicle, mostly aircraft or ships. Some older ground radars allowed a gate to be placed over a patch of rain (or in military radars, window or chaff) and the coherent oscillator signal used for detection was offset by the Doppler frequency of the rain. The rain echo was canceled by the moving target indicator but not the ground echo nor scatterers (aircraft) moving at other radial velocities. The azimuth and range gate that defined the area and the Doppler frequency offset were set by hand. This section provides an introduction and references for some types of processing to detect moving scatters from moving platforms; examples are the TACCAR initially developed by the Lincoln Laboratory for the E2C aircraft for the United States Navy, displaced phase center antenna, and moving target indicators for sideways looking radars. Space and time adaptive processing (STAP) [29, 30] is not covered here.
The main problem is adjusting the reference frequency for coherent detection automatically so that land or sea clutter is canceled. The Doppler frequency of the land or sea clutter depends on the velocity of the aircraft, and the angle in bearing with respect to the aircraft is as in Figure 11.90. If the velocity of the aircraft is v, then the radial velocity of the clutter patch is v cos ?. The radial...
