Research On The Method Of Hypersonic Target Velocity Measurement In Two Dimensional Frequency Domain

In recent years, with the rapid development of fighter jets, missiles, aircraft and other modern war fighting tools, the flying speed of near space hypersonic target continues to accelerate, which leads to across range unit migration when the long time coherent is accumulated. Thus, the conventional coherent accumulation technology has been unable to accumulate. How to realize the effective accumulation of the target echo has become a hot research by many scholars at home and abroad.This thesis focuses on the velocity of hypersonic target based on the Pulse Doppler radar. We describe the basic principle of radar speed measurement, from the linear frequency modulation signal generation, pulse compression, to the coherent accumulation and the incoherent one. The emphasis is the model establishment of the hypersonic target of uniform linear motion. And the influence of the across range unit migration on the target detection is analyzed.To solve the problem of velocity ambiguity and across range unit migration, in long time coherent integration in the near space hypersonic target detection, this thesis proposes an incoherent integration algorithm in two dimensional(2-D) frequency domain. With this algorithm, we complete pulse compression processing of linear frequency modulation echo signal received by radar. Then the processed signal is written in a fast-time/slow-time domain, and then the 2-D time domain signal obtains 2-D frequency domain representation through 2-D Fourier transformation. In view of the 2-D frequency domain, different target speed corresponding to slashes with different slope and intercept. We can obtain the target velocity corresponding to incoherent accumulation according to slash. Finally, after the points in the line which the target speed corresponding to are picked up, the distance information of the target can be obtained by using the inverse Fourier transform. On this basis, the MATLAB simulation is carried out to verify the correctness of the proposed algorithm. The two dimensional frequency domain method solves the influence of high speed target across range unit migration when long time coherent accumulate, which can also solve the velocity ambiguity.