基于时频联合尺度变换的中轨SAR斜视成像方法

doi:10.3969/j.issn.1001-506X.2020.02.08

Abstract

Abstract:

The squinted observation geometry along with long integration time significantly increases the space variance of the medium-Earth-orbit SAR signal. Firstly, in order to solve the range walk of the signal, a variable pulse repetition frequency (PRF) technology was used to receive the echos. Variable pulse repetition frequency is recommended to handle the severe range walk. The existing wavenumber algorithms cannot handle the nonlinear and range-azimuth-coupled space variance over a large scene. We propose a modified Stolt mapping method along with a modified joint time and Doppler scaling for imaging. An azimuth time scale transformation is used to deal with the quadratic space variance of the azimuth frequency modulation rate. A modified Stolt mapping is used to correct range cell migration. To address the range-azimuth-coupled space variance, the Doppler linearization is done in the range-Doppler domain using range-dependent Doppler scale transformation. Simulation results are shown to verify the effectiveness of the developed focusing approaches.

Key words: medium-Earth-orbit (MEO) SAR, 2-D space variance, variable pulse repetition frequency (PRF), joint time-frequency scale transformation

CLC Number:

TN957

Quan CHEN, Guangcai SUN, Wenkang LIU, Mengdao XING. Highly-squinted MEO SAR focusing based on joint time and doppler scaling[J]. Systems Engineering and Electronics, 2020, 42(2): 309-314.

Figures/Tables 7

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Table 1

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References 19

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类型	名称	值
轨道参数	轨道高度/km	7 000
	偏心率	0
	倾角/(°)	90
	近地点幅角/(°)	0
雷达参数	载频/GHz	5.4
	带宽/MHz	200
	PRF/Hz	4 000
	斜视角/(°)	40
	合成孔径时间/s	50
	地面距离/多普勒分辨率/m	2/2
场景参数	地斜角/(°)	60
	方位场景宽度/km	40
	距离场景宽度/km	40

点目标		PSLR/dB		ISLR/dB
点目标		距离向	方位向	距离向	方位向
本文方法	A点	-13.29	-13.22	-10.04	-10.02
	B点	-13.33	-13.28	-10.05	-10.02
	C点	-13.33	-13.24	-10.05	-10.01
文献[6]方法	A点	-13.21	-11.35	-9.71	-8.41
	B点	-13.24	-13.24	-9.76	-10.08
	C点	-13.24	-11.34	-9.74	-8.30

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Highly-squinted MEO SAR focusing based on joint time and doppler scaling

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