Study Of Key Techniques On Spacial Emitter Non-cooperative Detection System

Non-cooperative bistatic radar systems based on Spacial Motorial Emitter can detect wide distance targets in the ground or in the air. They have the advantages that the receivers are potentially simple and cheap. Bistatic radar may have a counter-stealth capability, since target shaping to reduce monostatic RCS (Radar Cross Section) will in general not reduce the bistatic RCS. In spite of those advantages, they have to face much difficulty such as unknown Emitter's position and velocity and antenna beam direction. All of these make the target detection become hardness and should be solved by corresponding technology approachs. This dissertation includes system design, clutter analyses, target detection, target location and data association. It aims to overcome the interrelated technology difficulties on this spacial non-cooperative background. All of research content may be the reference for the development of Non-cooperative bistatic radar systems.In Chapter 2, AEW (air early warnning) radar signal is chosen to be the emitter. The system design and framework are present on this background. Its performance is analyzed base on certain radar parameters, results reveal the practicability and feasibility of system. At the same time, ground clutter's space-time-frequency characteristic is studied; the result shows that it is not divisible between ground clutter and targets in the time-frequency fields, while they are divisible in the space-time-frequency union fields.In Chapter 3, the algorithm of long-time coherent integration is researched when the range migrations exist in the echo signal. A method of drawing or pulling reference signal is proposed, simulation result shows the method can assemble multi-pulses energy and improve signal-noise-ratio. In order to realizing target detection in clutter and noise background, a target detection algorithm based on mixing product filtering is pointed; it spreads the traditional time-frequency detection to the space-time-frequency union filter. Simulation result shows the effectiveness of the method on the conditional of target signal without covering by clutter in space-time-frequency union fields. In addition, mixing product filtering target detection algorithm relates to a difficulty about range-dependence compensation for bistatic STAP. Because of the RBRDC's (Registration Based Range Dependence Compensation) defect, a method named range-dependence compensation method based on transformation (RBTRC) is proposed. RBTRC omits needless transformation process, reduces the estimate errors and improves operation efficiency. Aim at the existing compensation method's deficiency on the condition of range ambiguity, a new method named range-dependence compensation based on data separation was proposed. Data simulation shows that the new method has the better signal-to-noise upgrading performance for range ambiguity radar signal.In Chapter 4, the application of stochastic resonance (SR) theory in non-cooperative signal detection field is discussed. Fistly, static threshold system and dynamical bistable system's SR phenomena are studied; secondly non-cooperative target detection methods using periodic stochastic resonance or aperiodic stochastic resonance are proposed. Unlike traditional non-cooperative detection, SR can achieve high-point output SNR by harmonizing the nonlinear system, signal and noise.In Chapter 5, the target location about non-cooperative bistatic radar systems is researched. Two location schemes using TDOA (time difference of arrival) are proposed; one is composed of three receiving stations and emitter, the other is composed of four receiving stations. Their multi-target measurement data association methods are also offered. The simulation result shows target location precision is affected by the position of the emitter in the first method, while target location precision is independent of the position of the emitter in the second method. In addition, a restricted total least squares (RTLS) algorithm based on TDOA is applied to multi-station passive location in order to reduce the target position errors. This algorithm takes into account coefficient matrix errors in the process of calculations, so it has better performance than analytical arithmetic.