Researches On Key Techniques Of Wide Band/Ultra-wide Band Radar Detection And Signature Extraction Of Locomotor Human Targets

Detection of human target is an important issue in antiterrorism and search-and-rescue situations after emergencies, and detection technique of human target based on radar has been a research hotspot for a few years. In this paper, scientific researches have been made on radar detection theory and techniques of locomotor human targets. The main attention have been paid to key theory and techniques of radar echo model and wide band (WB) or ultra-wide band (UWB) radar signature extraction of locomotor human targets, interference and clutter suppression algorithms of UWB through the wall radar (TWR), and real data processing and analysis of experimental radar system.Firstly, radar echo model of locomotor human target is analyzed. The movement of human target is abstracted as composite motions composed of typical movements, and the model of human marking time and the model of human walking are established and improved based on linear-rigid structure, respectively. The characteristic of models discussed in this paper are that models fit well with real human's movement, parameters of models can be adjusted conveniently, and the process of modeling is simple. Therefore, these two models can be applied to various radar signals. The radar echoes of locomotor human targets are acquired under the condition of continuous wave (CW) signal, instantaneous Doppler signatures and instantaneous movement signatures of targets are analyzed in theory, and the characteristic of radar echoes under different detection conditions are discussed by simulations in order to establish the theoretical foundation of signature extraction of locomotor human targets.Secondly, WB/UWB radar signature extraction of locomotor human targets is analyzed. First of all, signature extraction of human marking time is discussed based on the simplified model of vibrating targets. WB/UWB radar echoes of vibrating target are obtained based on stepped frequency continuous wave (SFCW) signal, and a micro-motion signal separation method is brought forward with pulse canceller, high-pass filter (notch filter), or adaptive time-frequency representation(ATFR)algorithm. Then after the periodic laws of time-range profile and time-frequency profile of the target being analyzed, two improved micro-motion signature extraction algorithms based on time-range profile are carried out to improve the precision of the period estimation of vibrating target, a micro-motion signature extraction algorithm based on amplitude threshold detection is carried out to extract signatures directly from time-frequency profile, and the influence of time-frequency transforms onto the micro-motion signature extraction algorithm based on amplitude threshold detection is investigated. Studies indicate that micro-motion signature extraction algorithms put forward in this paper can be applied to other periodic moving targets such as rotary targets.Signature extraction of pedestrian is discussed based on the simplified model of a complex motion with translation and vibration. WB/UWB radar echoes of a target with complex motion are obtained based on SFCW signal first, and then after the characteristic of the target's time-range profile being analyzed, a novel signature extraction method based on summation and difference sequence of ranges is proposed. The method can be utilized to deal with the problem of parameter estimation of the target with different vibrating amplitudes, and has specialties of easy implementation and high resolution of estimation results. A novel signature extraction method based on motion compensation is carried out after the characteristic of the target's time-frequency profile being analyzed. The method can be utilized to deal with the problem of trend extraction and processing of multi-scatterers, and has specialties of good real time processing characteristic and high resolution of estimation results. Studies indicate that signature extraction methods discussed in this paper can be extended to analyze other targets with complex motions composed of general translation and other periodic motions.Lastly, human target detection and signature extraction based on real experimental data of UWB-TWR are investigated. The characteristic of UWB impulse radar echoes is discussed first, and then the structure and basic configurations of the UWB-TWR developed by NUDT are presented. Interference suppression and clutter suppression are the key factors to human target detection, and a novel coupling suppression algorithm based on the compensation of amplitude and delay within frequency domain is put forward, which can partly deal with the problem of time-variant coupling suppression. A novel clutter suppression algorithm based on adaptive background subtraction is brought forward in order to reduce clutter, and the algorithm can be applied to complex clutter environments and multiple movements of targets. In theory, the clutter suppression algorithm discussed in this paper can be regarded as common form for conventional clutter suppression algorithms such as pulse canceller, and background subtraction, and enriches the theory and methods of through the wall radar clutter suppression. TWR experiments are performed under different conditions of detection and movements. After data processing, experimental results validate interference and clutter suppression algorithms, signature extraction algorithms of locomotor human targets, and the good detection performance of the radar system. Some important issues are pointed out in order to improve the system further at last.Radar echo model of locomotor human targets, WB/UWB radar signature extraction of locomotor human targets, and key signal proceesing algorithms of UWB-TWR discussed in this paper can enrich the radar detection theory and signature techniques of human target, and be much valuable in theory and in application for development of TWR.