Research On High Resolution Range Profile Imaging And Detecting Algorithms For Milimeter Wave Seeker

The Radar seeker is a key component of the guidance system, through which themissile can detect the target and get its position and motion parameters relative to themissile. Then the information will be computed and guide the missile in movingtowards the target and destroying it. The millimeter wave seeker has outstandinganti-jamming and anti-stealth performances. It is small in size and light in weight, so itis one of the key military researches of all great powers.The seeker’s role is to achieve precise guidance, which requires the radar signal tohave a high-resolution capability, that is to say the signal must have a very largebandwidth. The stepped frequency modulated signal is a synthetic wideband signal. Ituses coherent chirp pulse-sequence to synthesize high-resolution range profile. So thereceiver doesn’t need a very large instantaneous bandwidth while getting more datafrom the target’s echo. This will improve the real-time signal processing performance ofthe receiver.This paper focuses on the high-resolution range profile achieved by steppedfrequency modulated signal. The main contents are as follows:(1) The mathematical expression of the stepped frequency modulated signal isfirstly introduced, followed by the signal’s ambiguity function according to which howthe signal accomplishes high range resolution is discussed in depth. Then the basicprinciple of HRR profile for LFM-SFW is researched while the implementation of thetwo step pulse compression processing is expounded at the same time. The adverseeffects on the HRR profile caused by the signal’s side lobes and grating lobes isseriously concerned so as to derive the relationship between the bandwidth of thesub-pulse and the fixed frequency step.(2) The Doppler effect on generating a synthetic HRR profile is analyzed in detail.The mathematical expression of the relationship between the offset distance of the HRRprofile and the target’s velocity is obtained in this part, and the accuracyrequirement ofmotion compensation is given later on. Then several velocity compensation algorithmsare researched, their performances are shown in figures. At last, how to illustrate thisdistortion caused by the target velocity in actual cases is discussed.(3) The expectation of the stitching algorithm is extracted after the profileredundancy caused by range mismatch and over-sampling is discussed. Then fourdifferent algorithms are researched, their theoretical performances are verified bysimulations. Because the most significant profile centered extraction algorithm isadaptive to moving target profiling, a new signal processing program is introduced inorder to expand the estimation scope of the target’s velocity. It is verified that this newprogram has very good and stable performance and is suitable for practical applications. (4) The characteristics of the echo of spatially distributed target and the ide a ofspatially distributed target detection are firstly introduced. Then the structure of optimalreceiver and its performance are analyzed. After that, based on the character of thesignal that is mainly discussed in this paper, several detection algorithms for spatiallydistributed target are taken into concern. Their principles are discussed and theirperformances are verified by simulations. Finally, the principles of the determination ofsome important parameters such as the length of detection window are given.