Synthesis of Finite Length Multi Level Sequences for Clutter Rejection in Radar

In radar systems the very low side-lobes that can be achieved with amplitude and phase modulated pulse trains make their use particularly attractive in systems requiring a large dynamic range. Moreover, the excellent self-clutter rejection performance is obtained without sacrificing the ability for the separation of close targets (no main lobe widening). The additional expense of encoding and decoding in amplitude and phase may be justified for radars that must cope with land clutter or operate in a dense-target environment. This paper presents a method for generating finite length multi-level sequences of large lengths that have low side-lobe energy in their autocorrelation function. It is shown that energy ratio of multilevel sequences that have low side lobe energy, is improved through the process of clipping. The proposed method generates sequences with low side lobe energy and large energy ratio of any desired length starting from sequences of smaller length.