Analysis of human radar echo signal using warped discrete fourier transform

Use of the warped discrete Fourier transform for the time-frequency analysis of the signal on the audio-output of pulse-Doppler radar is examined in this research. The discrete Fourier transform is calculated in points in z-plane that are equidistantly distributed on the unit circle, while the warped discrete Fourier transform is calculated in points that are unevenly distributed on the unit circle. The time-dependent warped discrete Fourier transform for the analysis of the simulated and measured radar signals from a walking human was applied in this research. The results of the time-frequency analysis of radar signals using this transformation are compared with the spectrogram. The results show that the application of the warped discrete Fourier transformation in the radar signal analysis provides a higher concentration of energy around the central Doppler frequency comparing to the spectrogram.

I. Introduction

The main task of sensors in military applications is their usage for situational awareness in the battlefield, [1]. In order to complete this task, sensors that work in different parts of electromagnetic spectrum are used (radars, television cameras, thermal cameras, acoustic sensors, etc.). The advantage of using optoelectronic sensors over radars is a higher resolution and the fact that emitting energy is not needed for their usage. A higher detection range and the possibility to work in complex atmosphere conditions are advantages of radar sensors for ground surveillance purposes.