Key technologies for spaceborne SAR payload of LuTan-1 satellite system

doi:10.11947/j.AGCS.2024.20230263.

Abstract

Abstract:

LuTan-1 (referred as LT-1) is China's first civil synthetic aperture radar (SAR) satellite mission to monitor the ground deformation with high precision by differential interferometry technology. The LT-1A and LT-1B have been success-fully launched on January 26 and February 27, 2022, respectively. The data acquisition schedule of LT-1 mission is divided into two stages, which corresponding to two specific orbit configurations. In the first stage, two satellites fly in a compact formation to get the digital elevation model (DEM) using the bistatic InSAR strip mode. In the second stage, both satellites fly in a common reference orbit with 180° separation. The revisit time of the individual satellite is 8 days, and it can be reduced to 4 days with two satellites. LT-1 satellite constellation can stably obtain time series data, so that we can monitor the ground deformation with high precision. Moreover, the multi-mode polarimetric payload will be utilized to obtain single-pass multi-polarimetric InSAR and hybrid polarimetric SAR data for forestry, land resource surveys, disaster monitoring, etc. In this paper, the key technologies of the LT-1 SAR payload, including phase synchronization, ambiguity suppression and system calibration, are systematically described and analyzed.The maximum resolution of LT-1 is 3 m, and the maximum swath width is 400 km, respectively. The azimuth ambiguity-to-signal ratio (AASR) of the interference wave position is better than -20 dB.The performance is partially demonstrated by ground testing and on-orbit actual measurement data.

Key words: LT-1, phase synchronization, system calibration, polarimetric SAR, ambiguity suppression

CLC Number:

P237

Yunkai DENG, Yu WANG, Kaiyu LIU, Naiming OU, Dacheng LIU, Heng ZHANG, Jili WANG. Key technologies for spaceborne SAR payload of LuTan-1 satellite system[J]. Acta Geodaetica et Cartographica Sinica, 2024, 53(10): 1881-1895.

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参数	数值
轨道高度/km	607
载频/GHz	1.26
带宽/MHz	最高84
调制模式	LFM(常规模式)/NLFM(试验模式)
天线尺寸/m	9.8(方位向)×3.4(俯仰向)
分辨率/m	3~30
幅宽/km	50~400
系统灵敏度/dB	优于-28
方位和距离模糊度/dB	≤-20(干涉波位)
内定标精度/(°)	≤3
相位同步精度/(°)	≤10(3σ)
极化模式	单极化/双极化/全极化/简缩极化

成像模式	分辨率/幅宽	极化方式
条带模式1	3 m (A)×3 m (R)/50 km	条带模式，双/单基成像，方位双通道，单/双/简缩极化
条带模式2	12 m (A)×12 m (R)/100 km	条带模式，单基成像，单/双/简缩极化
条带模式3	3 m (A)×3 m (R)/50 km	条带模式，单基成像，方位双通道，双/简缩极化
条带模式4	6 m (A)×6 m (R)/30 km	条带模式，单基成像，全极化
条带模式5	24 m (A)×24 m (R)/160 km	条带模式，单基成像，单/双/简缩极化
扫描模式	30 m (A)×30 m (R)/400 km	扫描模式，方位双通道，单/双/简缩极化

精度	类型
精度	水域	裸土	道路	高层建筑	其他建筑	温室大棚	植被	苗圃
全极化	96.2	91.6	95.3	92.5	82.5	90.2	92.3	92
简缩极化	95.9	88.8	86.1	88.9	64.2	76.3	82.5	80.5