Peak Side Lobe Reduction analysis of NLFM and Improved NLFM Radar signal with Non-Uniform PRI

Abstract

Abstract—The problem of determining a good radar signal

with the objective of minimizing autocorrelation sidelobes with
non-uniform PRI is addressed. Linear Frequency Modulated
signal (LFM) is frequently used pulse compression waveform but
the LFM signal results in first side lobe of -13dB corresponding
to the main lobe. Conventional uniform Pulse Repetition Interval
(PRI) systems suffer from limitations like blind speeds, jamming
etc. These limitations can be overcome by using non-uniform PRI
waveforms. Further the range resolution of these waveforms can
be improved by reducing the Peak Side Lobe Ratio (PSLR) and
this can be done by appropriately choosing the PRIs and basic
pulse shapes. In this paper, an attempt is done to design a radar
signal to attain low autocorrelation PSLR which exhibits low side
lobes and high range resolution. In order to maintain good
resolution and to get suppressed side lobes of the signal, one can
use a improved Non-Linear Frequency Modulation (NLFM)
polynomial signal with Non-Uniform PRI. The proposed NLFM
polynomial with Non-Uniform PRI is compared with LFM,
NLFM, Two Stage ,Tri-Stage sweeps NLFM and a Polynomial-I
NLFM. The quality of the overall best radar signal is assessed
through the parameter Peak Side Lobe Ratio(PSLR) for different
values of BT and PRI. From this analysis, it is found that the
NLFM with Non-Uniform PRI with BT=200 gives the very low
PSLR value of 69dB . Simulation results shows the reduction in
the sidelobe level from LFM to Polynomial-II NLFM with
Uniform and Non-Uniform PRI.