Cyclostationary and correlation based signal detection for harmonic radar systems

Abstract

In recent times, a significant interest in detection of nonlinear scatterers in various applications has appeared. One of these applications is detection of passive objects of artificial origin containing electronic circuits or other non-explosive elements incorporated into the firing train of hidden explosive hazards means. Prior research has shown that a single frequency RF signal is well suited to the task of illuminating such scatterers to excite their nonlinear response and commercially available devices based on this principle have appeared since the 1970s. However, this basic approach without any carrier modulation may limit efficiency of energy transmission to the nonlinear scatterer. Therefore, investigation of appropriate modulation schemes can reveal their potential benefits in harmonic radar detection systems. This paper presents an initial concept of novel detection method using binary phase-shift keying (BPSK) modulated signal for simultaneous detection of nonlinear scatterers with both quadratic and cubic characteristics. The use of BPSK signal brings interesting benefits to the fundamental detection of components at multiples of the carrier frequency and, at the same time, allows achieving significant reduction of transmit signal power at the carrier frequency. The proposed algorithms use cyclostationary features of linear digital modulations along with correlation based processing in some parts and are implemented using MATLAB.