Coherent Radar
Volume 18, Number 3 (July–September 1997)
This issue of the Technical Digest examines coherent signal processing techniques as applied to radar systems. A coherent radar compares the phase or frequency of a target echo with a stable oscillator or reference signal source. Natural objects, such as trees or islands, tend to be relatively steady in phase or frequency. (An important exception is the Doppler-shifted frequency of echoes from weather phenomena.) However, moving targets such as aircraft or ships cause echoes that vary compared with the stable source. These variations can be used to detect the presence of a moving target, measure the target speed relative to the radar, or determine other characteristics of the target such as the type ofjet engine it is using.