A Three-Dimensional Localization Method for Multistatic SAR Based on Numerical Range-Doppler Algorithm and Entropy Minimization

Abstract

Abstract:In traditional localization methods for synthetic aperture radar (SAR), the range sum estimation and Doppler centroid estimation (DCE) are required. The DCE error can influence the localization accuracy greatly. In addition, the target height information cannot be obtained by these methods. In this paper, a three-dimensional localization method for multistatic SAR based on the numerical range-Doppler (RD) algorithm and entropy minimization principle is proposed. In this method, the raw data from each transmitter and receiver (T/R) pair are focused by the numerical RD algorithm with the initial location value of the reference target. Then, Newton iteration is used to solve the target location value with the information of the bistatic range sum (BRS) in different SAR images with respect to different T/R pairs. Generally, the initial location value of the reference target is not accurate, and it can influence the imaging quality and accuracy of other target locations. We use entropy to measure image quality and iterate imaging with the new location value of the reference target, until the entropy gets the minimum value. Therefore, we can get the optimal location value of the reference target, which can make image entropy reach the minimum. Finally, all targets can be located by the Newton iteration method with their BRS in each T/R pair that are obtained from the images with minimum entropy. Compared with traditional localization methods for monostatic SAR, the proposed method not only effectively eliminates the influences of DCE errors, but also can get the target height information. Therefore, it improves the localization accuracy and can achieve three-dimensional localization. The effectiveness of the localization approach is validated by a numerical simulation experiment.

Focusing High-Resolution Highly-Squinted Airborne SAR Data with Maneuvers

“…However, the results may not be generalizable. Thus, a judgment is added in the processes to determine whether the interpolation is necessary or not according to Equations (25) and (26). The judgment flowchart is given in Figure 9.…”

“…and thus the impacts on the final image could be ignored. With simulation parameters in Table 1, the maximum phase errors of Equations (25) and (26) are 0.02 π and 0.7 π , respectively. Clearly, the azimuth interpolation is still necessary whereas the range one is not in this case.…”

“…Concerning the focusing algorithm for the SAR with maneuvers, methods performed in the frequency domain include the range-Doppler algorithm (RDA) [19], chirp scaling algorithm (CSA) [20], omega-K algorithm (OKA) [21], and their extensions [11][12][13][22][23][24][25]. Eldhuset [11,12] suggests a fourth-order processing algorithm by 2-D exact transfer function (ETF) for spaceborne SAR with curved orbit.…”

An Imaging Algorithm for Multireceiver Synthetic Aperture Sonar

“…In this paper, we present an imaging algorithm, which was also based on the accurate time delay of the transmitted signal. With the numerical evaluation method [23], we first calculated the PSP and azimuth PSP. The PTRS and azimuth modulation can be easily obtained based on their respective numerical PSPs.…”

Editorial for Special Issue “Radar Systems for the Societal Challenges”

“…In [13], a three-dimensional localization method based on multistatic SAR, exploiting the numerical range-Doppler (RD) algorithm and the entropy minimization principle, is presented, which also offers improved localization accuracy in the 3D case. The paper from Yu et al [14] deals with the problem to analyze the internal structure of objects and to identify and classify their shapes based on ultra-wideband signals, by proposing and exploiting a reconstruction approach directly in the time domain.…”