Side lobe and grating lobe suppression in stepped frequency pulse train using multi-objective optimization algorithms

Linear Frequency Modulated (LFM) pulses are used in radar because of its good range resolution capability. Range resolution can be further improve by introducing a frequency step between consecutive pulses. Resultant signal is known as Stepped Frequency Pulse Train (SFPT). When the product of pulse duration and frequency step become more than one, Autocorrelation Function (ACF) of SFPT shows undesirable peaks, known as grating lobes. Along with grating lobe, the higher side lobes present in the vicinity of main lobe, either can hides the small targets or can cause the false alarm detection. Also, the wide main lobe width deteriorates the range resolution capability of the signal. Many analytic techniques have been proposed in the literature to select the SFPT parameter to suppress the grating lobe, without paying much attention to side lobe and main lobe width. In this paper we have compared three Multi-Objective Optimization (MOO) algorithms to find the optimized parameter of SFPT. The optimization problem is studied in two ways: In first we have taken objective of minimization of grating lobes and peak side lobe level. In second problem, we aimed to minimize the main lobe width, which improves the resolution. Simulations are carried out for different range of parameter values and the result show the potential of the MOO approach.