Study On DBS Imaging And Moving Target Detection And Relocation Method Under The Mode Of WAS-GMTI

The airborne battlefield surveillance radar system under the mode of WAS-GMTI(Wide Area Surveillance-Ground Moving Target Indication) can offer imaging and moving target detection over a wide area in a relatively short period of time, so we can quickly find valuable targets. Positioning the moving targets accurately can realize the surveillance of moving targets in the battlefield. The system can perform an efficient tracking of the detected targets and detect the same target from different aspect angles. The WAS-GMTI mode is becoming an important way to detect, locate and track moving targets and has important applications in military and civilian fields. This paper focuses on studying the Wide Area GMTI signal processing, such as Doppler Beam Sharpening imaging technology, moving target detection and localization techniques, and deficiencies of the existing methods have been analyzed and improved. Thesis can be summarized as follows:First, for the existing DBS imaging algorithm requiring the estimation of Doppler frequency based on data, an improved DBS imaging algorithm is addressed, which does not estimate the Doppler center frequency but use the INS data directly for DBS imaging. SAR imaging is highly dependent on the accuracy of Doppler center frequency, while we mainly use it to get the Doppler region corresponding main lobe. When the radar system provides high accuracy inertial navigation data, we can directly use the INS data and take advantage of the width of azimuth beam to get the Doppler channels of main lobe for DBS imaging. It obviously simplifies the DBS imaging. In addition, the existence of a distance blur of DBS imaging algorithms was studied.Second, for airborne radar echo which existing stripes interference, we propose a new method of interference suppression based on the distance-frequency domain compensation. Vertical stripes interference can be change into several strengths at a distance of frequency- Coherent Doppler domain. By replacing these strengths with the average of the surrounding cells, and finally converting the data into the range-Doppler domain, we can obtain the effective interference suppression data. Experimental data processing validated the method can effectively suppress the vertical stripes interference, reduce clutter surplus and improve targets detection performance.Third, using the correspondence between the interferometric phase and Doppler frequency, a method of direct calculation the Doppler frequency of the main lobe based on INS data for target location is proposed. Usually we get the interferometric phase of the main lobe by taking conjugated of a two-channel echo data. If the consistency of the two channels is not good, the interferometric phase of the main lobe will affect the location accurancy of the target. Utilizing INS data to calculate interferometric phase of each Doppler channel of the main lobe, avoids calculating it from data fields. And by positioning the target on the DBS image and the electronic map, we verify the accuracy of the positioning method even when the channel characteristic is poor.