Research On Clutter Simulation Platform And Clutter Suppression Of Space-Based Early Warning Radar

In the modern battlefield,it is especially important to obtain accurate,comprehensive and real-time information from the enemy.Compared with ground-based early warning radar and airborne early warning radar,the flight range of the space-based radar is not restricted by the national airspace and meteorological conditions,and it is not easy to be destroryed,and it can detect targets all day,all night,in a wide range and at a long distance.However,there are some problems that need to be overcome.1.space-based radar has high launch and maintenance costs.And it is often very difficult to modify the system after successful launch.Threrfore various environmental and non-ideal factors should be fully considered in the design stage,and the parameters should be adjusted repeatedly to get the optimal parameters should be adjusted repeatedly to get the optimal parameters and results.A high-precision simulation system is indispensable for this kind of repetitive work;2.Some properties of space-based radar such as high altitude,large detection range,fast satellite flight speed,many blur caused by the clutter Doppler frequency,and too much simulation’s operation and storage volume large and complex;3.space-based radar sclutter,like airborne radar sclutter,has non-smooth and non-uniform characteristics.When the covariance matrix is constructed,the number of samples that satisfy the independent and identical distribution is small,and the clutter suppression effect is poor,so dimensionality reduction processing is required.Therefore,it is very important to develop a high-precision satellite-based radar clutter simulation system,and to study the fast simulation method of satellite-based radar clutter and the dimensionality reduction space-time adaptive processing(STAP)method.In this thesis,we develop a high-precision clutter simulation system for space-based radar,and develop a fast simulation method and dimensionality reduction STAP method for this system.A high-precision space-based radar clutter simulation system is developed,which can meet the simulation requirements under different ground scenarios and different system parameters and provide data for the research of satellite-based radar systems;a clutter fast simulation method is proposed to simplify the calculation process of space-time guided vector for the problem of large amount of operations and storage during clutter simulation.In order to obtain a better spurious suppression effect while reducing the dimension,an array-pulse domain dimensionality reduction STAP method is proposed.The simulation results demonstrate the effectiveness of these two methods.The main work of the paper is summarized as follows.1.A high-precision space-based radar clutter simulation system is developed.The system can artificially set the ground scene information(including three methods of dividing surface type and two methods of setting terrain undulation),and can also generate real ground scene information according to the satellite’s flight status based on the surface distribution type(LCLU)and digital elevation model(DEM),which can meet different ground scenes and different system parameters for low-orbit and medium-orbit long-range early warning and battlefield surveillance radar clutter.2.In order to further improve the simulation speed of clutter,a fast simulation method of space-based radar clutter is proposed.In view of the huge difference between the antenna azimuth resolution and Doppler resolution required by high-precision clutter simulation,the calculation process of the time steering vector and the spatial steering vector of the clutter scattering unit in the range ring are separated,which speeds up the entire range ring.The calculation process of the space-time steering vector of tens of thousands of clutter units in the system significantly shortens the simulation time.3.In order to obtain better clutter suppression performance while significantly reducing the airspace degrees of freedom,an array element-impulse domain dimensionality reduction method suitable for space-time processing of small yaw angle spaceborne radar is proposed.The dimensional structure changes with the pulse.Different pulses use different subapertures to receive echo signals,and sub-arrays are further divided into space channels within the sub-apertures to improve the radar’s ability to resist clutter and anti-jamming.Simulation results confirm the effectiveness of the method and prove that the method is also suitable for some airborne radar situations.