Cross‐range scaling method of inverse synthetic aperture radar image based on discrete polynomial‐phase transform

Abstract

The cross-range scaling of inverse synthetic aperture radar image depends on both the radar wavelength and the rotating angle of the target relative to the radar line-of-sight. After compensating the translational motion, the second-order phase coefficients of the range echoes are a linear polynomial of the rotating angular velocity and range geometry. In this study, a novel method for estimating the rotating angular velocity of the targets with dominant scatters is proposed. The range cells where the amplitudes have smaller normalised variances are selected, and then frequency domain windowing is applied to extract echoes of dominant scatters. Based on the discrete polynomial-phase transform, the second-order phase coefficients of the strong scatter echoes are estimated, and thus the rotating angular velocity can be obtained through the least-square-error method. Simulated and real-data results have shown the effectiveness and robustness of this method.

Isar rotational motion compensation algorithm using polynomial phase transform

“…In general, an amplitude normalized variance (ANV) has been used to evaluate the existence of a dominant scatterer in a certain range bin. The ANV of the n ‐th‐range bin is defined as where E (×) represents the expectation operation.…”

“…However, the estimated parameters can be easily trapped into local minima especially when the initial searching boundary is large; this inaccurate estimation of h l (t) causes poorly focused ISAR images. In order to resolve this problem, we introduce the PPT which is an algorithm that determines the polynomial phase signal, because it implements accurate estimation of the polynomial phase coefficients in a fast computational time.…”

“…In order to resolve this problem, we propose a new ISAR RMC method using the polynomial‐phase transform (PPT) to formulate the polynomial phase signal of the dominant scatterer. Because the PPT does not suffer from the local minima problem as in , the focal quality of the compensated ISAR image using the proposed method is much better than those using conventional RMC methods.…”

A Study on the Rotational Motion Compensation Method for ISAR Imaging

“…번 째 레인지 빈에 대한 ANV는 식 (5)와 같이 정의된다. [8] . 따라서, 모든 레인지 빈에 대한 ANV를 계산한 후, ANV의 값이 가장 작은 레인지 빈   을 선택한다.…”

ISAR Imaging of Maneuvering Targets Based on the Modified Discrete Polynomial-Phase Transform

“…[9,10,11]. In the past three decades, many useful results have been obtained by scholars all around the world [12,13,14,15,16,17]. The high resolution in the range coordinate is achieved by transmitting a large bandwidth coded signal, and the high cross range resolution is achieved by the coherent integration of echoes collected at different viewing angles between the radar and target [18].…”