Abstract
Stepped-chirp signal (SCS) is widely used by wideband high-resolution radars; however, its bandwidth synthesizing suffers from motion-induced phase errors resulting from the radial velocity of the target, especially for high-speed targets. So motion compensation is very crucial in signal processing for this kind of radar using SCS. Based on the cross-correlation inner frame method for velocity measurement of a single-scattering-center target, the multiple cross-correlation method (MCCM) is proposed for measuring the velocity of a complex target with multiple scattering centers (MSC), which is called SCS-MCCM. By this algorithm, not only the radial velocity, but also the real velocity of a target can be measured under the assumption that it is straight moving. After obtaining the velocity, motion compensation is conducted so as to realize high-resolution imaging. Theoretical analysis and simulations show that the proposed method is feasible and effective for an MSC target.
Highlights
To meet the requirements of high-resolution range measurement or imaging, a step frequency technique has been proposed and has already become an important approach for modern radar systems
Because Stepped-chirp signal (SCS) is very sensitive to the radial velocity of target,[4,5,6,7] the synthesized range profile suffers from range migration, energy diffusion, and resolution degradation, and even becomes meaningless if the motion compensation is not well done for high-speed target
We extend the idea of cross-correlation inner frame and propose a new velocity measurement method, which is named the SCS multiple cross-correlation method (SCS-MCCM)
Summary
To meet the requirements of high-resolution range measurement or imaging, a step frequency technique has been proposed and has already become an important approach for modern radar systems. Each of the above-mentioned methods has its limitations, such as the maximum likelihood method and iterative search method need a large amount of computation, the PD auxiliary method and updown stepped-chirp method need an additional transmitting signal besides SCS, the cross-correlation between frames method needs high pulse repeat frequency (PRF) to obtain high measurement accuracy, etc. A preferable method named the cross-correlation inner frame method (CCIFM) was proposed.[19] It can measure the radial velocity of a high-speed target without using an auxiliary signal in a low PRF situation and has the advantages of a small amount of computation and a large unambiguous measurement range. As will be shown later, the SCS-MCCM can keep the advantages of CCIFM while overcoming its disadvantages It focuses on the velocity measurement for a high-speed target in a much more practical situation, i.e., the multiple-scattering-center (MSC) target is considered. Fd[0] is much smaller than fd, and the ratio ðfd0 ∕fdÞ 1⁄4 ðKVTr∕cΔfÞ is usually
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