Radar signal processing is defined as the manipulation of the received signal, represented in digital format, to extract the desired information whilst rejecting unwanted signals. The use of high energy (long pulses duration) permits high detection range, and the time-compressing of a received radar signal permits an increase in the range resolution capability of radar. Pulse compression allowed the use of long waveforms to obtain high energy and simultaneously achieve the resolution of a short pulse by internal modulation of the long pulse. Pulse compression can be accomplished by employing frequency or phase modulation to widen the signal bandwidth, while Amplitude modulation is also possible, but is seldom used.