The DOA Estimation Of Two Unsolved Targets Based On XX Monopulse Radar

Amplitude-comparison monopulse radar using a simultaneous lobing technique determines the Direction-Of-Arrive (DOA) of a target. When there is only one target in the same resolution cell of radar, the DOA is estimated with the in-phase part (i.e. the real part) of the monopulse ratio in a received target echo. When the returns from two or more targets interfere (i.e. the echoes are unsolved in the angle, range and Doppler domains), the DOA estimation indicated by the monopulse ratio is incorrect and it can wander far beyond the angular separation of the targets. The failure can be catastrophic for the tracking of monopulse radar using the wrong DOA. This problem will become more prominent as the monopulse radar is applied more widely. Therefore, research on efficient and accurate DOA estimation algorithms are very important for the amplitude-comparison monopulse radar systems.Because the analysis of the returns from more than two targets is of little practical importance and very complicated, a lot of research of two unsolved targets has been done at home and abroad. This paper deeply discusses some classical estimation of it, including the derivation of a formula of the probability density function based on Swerling target models, the analysis of the performance of the estimation and the computer simulation. At last on the base of the current normal monopulse radar multi-channel processing technology, starting from the viewpoint of radar waveform design, this paper proposes a method of transmitting two pulses of energy in one pulse repetition period to estimate the DOA of two unsolved targets, and furthermore, it analyzes the Receiver Operating Characteristic of the false alarm rate and detection probability. The simulation results show that the detection probability and estimation precision of the method are high. So this method can make the normal monopulse radar to track two unsolved targets.The main content of this paper will be described as following:Firstly, this paper introduces the background and the meaning of the DOA estimation of the two unsolved targets in a monopulse radar system, the development history and application status. It also briefly introduces the principle of the main components of XX monopulse radar and angle measure principle of the amplitude-comparison monopulse radar system.Secondly, the detection of two unsolved targets using the complex ratio will be researched and the relations of false alarm probability and detection probability using a pulse will be analyzed in this paper. For the RCS fluctuations are typically characterized as one of four Swerling types, based on three kinds of Swerling types, probability density function derivation is introduced. It is used to detect target multiplicity and estimate the DOA of two unsolved targets. At last the advantages and disadvantages of these algorithms are summarizedFinally, This paper starts from the viewpoint of the radar waveform design, using two pulses in one pulse repetition period to detect target multiplicity and estimate the DOA of two unsolved targets. From the results of computer simulation, the proposed method can effectively solve the problem of the DOA estimation of two unsolved targets, and it is easy to implement in the monopulse radar.