Pulse repetition interval analysis using decimated Walsh-Hadamard transform
Kamaruddin Abdul Ghani, Ahmad Zuri Sha’ameri, Kaharudin Dimyati, Nik Ghazali Nik Daud · 2017
Radar signal sorting for the identification of radar signals is one of the main tasks for Electronic Intelligence (ELINT). Information derived from the pulse repetition interval (PRI) of a radar signal can be used to identify radar emitters. In this study, classification of PRI type is done based on the power spectrums of the Walsh-Hadamard transform (WHT). The generated spectrums are downsampled to reduce sampling errors and sub-harmonics, resulting in decimated WHT (DWHT) spectrums. A template for DWHT spectrums is developed for the most common PRI modulation types; constant, jittered and staggered. In this template, each pulse sequence is given a unique DWHT spectrum as its identity. A model for the prediction of missing and spurious pulses is developed to estimate their distributions density of occurrences that can be related to the robustness of the PRI classification method. The proposed model is tested for its feasibility using Monte-Carlo simulation. The results showed that the proposed PRI classification model can achieve better than 85% accuracy even in the presence of missing and spurious pulses.