Shadow Imaging And Recognition Based On Bistatic Forward Scattering 'Barrier' Radar

The Bi-static Forward Scattering airier Radar (BFSBR) can be used to detect, recognize and track the target with small detection probability in the low altitude sky, on the land or on the sea. The target imaging, recognition and its signal processing method used by BFSBR have been developed in this thesis. Details are described as follows.The background, significance, history and status of BFSBR are introduced in Chapter 1In Chapter 2, the principle of the shadow imaging is induced from the bi-static radar equation. The difference and relationship among shadow image, ISAR image and spectrum analysis of echo are illuminated. The effect of un-even rate rotating induced when target go across radar base line on shadow image is analyzed and the method of overcoming the image aberration is proposed The effect of flight altitude on target shadow image is analyzed and the method of fetching the feature for target recognition is presented.In Chapter 3. the effect of the energy distribution on shadow imaging is developed with the conclusion that it is important for shadow imaging that echo signal of which the Doppler frequency approaches zero. The time-frequency relationship between target echo and clutter is analyzed and two methods of shadow imaging based on time-frequency analysis are presented, which are suitable for the condition of strong direct transmitting signal and clutter.In Chapter 4. the relationship between a phase of shadow image and a phase of midline of shadow profile is analyzed, and method of reconstructed phase of midline of shadow profile by using phase of shadow image is discussed, the effects on phase of midline of shadow profile due to non-constant velocity rotation relative to the target and the azimuth angle of target are examined, and a method of eliminating this effect is presentedIn Chapter 5, based on the mono-pulse angle measurement, the vertical angle and the azimuth angle of the target are measured and the method of estimating target motion parameters is presented by using the instantaneous Doppler frequency of target echo and the azimuth angle of the target, then the length of shadow profile and phase ofmidline of shadow profile are scaled, which is important features for target recognition.In Chapter 6, the target recognition is discussed by using the four kinds of the recognition feature of target, which are the inter-correlation of shadow images for the inhomogeneous target, the auto-correlation between the shadow image and the original shadow image for a kind of the target, the feature of the midline of shadow profile of the target and actual length of the shadow-profile of target. With the analysis of vary of the target auto-correlation with the azimuth angle, the method of target recognition is presented by using inter-correlation and auto-correlation of target shadow images, then two methods of target recognition for shadow image and feature of midline of shadow profile are designed.In Chapter 7, the system construction and the principle of signal processing for BFSBR are developed. The analysis of dynamic arrangement of power ratio of target echo to direct transmitting signal and RCS of target is presented, then the scheme of signal processing for two kinds of continuous wave transmitting sources of continuous wave with constant frequency are described, which are cooperation transmitting source and non-cooperation TV transmitting source.Finally, the conclusions of the dissertation are drawn with some problems to be solved in BFSBR pointed out by the author in Chapter 8.