Modifying Polyphase Codes to Mitigate Range Side-lobes in Pulse Compression Radar

Range side-lobes suppression which is responsible for detection ambiguity is a challenging task in pulse compression (PC) radar. Targets generating weak signals tend to hide in undesired side-lobes creating ambiguity. In general, the side-lobes behaviour performance of received signals is observed by their correlation with other contemporary signals. In this paper, a new polyphase code is proposed that exhibits good auto-correlation and cross-correlation properties to reduce peak side-lobe level (PSL) and integrated side-lobe level (ISL). The proposed polyphase code named P43code is produced by combining left and right shifted versions of P4\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$P4$$\end{document} code. The amount of rotation depends upon the overall code length. The optimum rotation combination is the one that produces maximum side-lobes reduction. The proposed design is also applied to multiple-input multiple-output (MIMO) radar, where for the proposed P43\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$P4_{3}$$\end{document} code, orthogonal waveforms are used to minimize cross-interference. Using ambiguity function (AF), the impact of proposed code on the delay-Doppler plane is investigated. Simulation results demonstrate the superiority of the proposed P43\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$P4_{3}$$\end{document} code compared to existing alternatives.