Research On Key Technologies Of Radar Signal Interception

In this thesis, some key technologies of the radar signal intercept are researched. This thesis has carried on a deep discussion around the DOA estimation technology for the separation of same time received radar pulses. This thesis mainly includes the technologies of intra-pulse analysis, DOA estimation and multi-parameter joint estimation for radar pulse signal interception.In the aspect of the interception of the radar signal’s DOA parameter, to solve the problem of higher complexity in classical MUSIC algorithm, a DOA estimation algorithm based on the spatial spectrum interpolation was proposed. It implements interpolation by accumulating discrete space spectrum in the time dominate and obtained an efficient estimation of the place of the true spatial spectrum peek. It has advantages both in complexity and hardware implementation. Considering the limitation of the array element interval caused by the wave length of the signal source, the technology of direction-finding phase interformeter was introduced. Firstly, the principle and the phase detection algorithm were presented. Then, the unwrapping phase ambiguity algorithm based on baseline ratio was detailed study. The phase ambiguity numbers were obtained within the unambiguous scope of each double-baseline direction finding system and the unique set of phase ambiguity number could be acquired through the common baselines between those double-baseline interferometers.In multi-parameters joint estimation of radar signal, we first discuss the multiple-time delay ESPRIT algorithm to estimate DOA and frequency as well as its improved method. The improved method overcome the unsatisfactory performances of the original ESPRIT algorithm, but the computational complexity is not improved. Secondly, we propose a DOA, TOA and frequency joint estimation method using spatial filter. When several radar signals receive from different directions at same time, a reference frequency is used to get rough DOA estimation, then space filtering method is used to separate multiple radar source signals, finally we can estimate the frequency and TOA parameter of every signal. When we get frequency, we can calibrate the pre-estimated DOA. This method can realize parameter automatic matching, and less amount of calculation than frequency domain filtering algorithm, which has higher value of application.