陆探一号卫星SAR载荷关键技术

doi:10.11947/j.AGCS.2024.20230263.

摘要/Abstract

摘要：

陆探一号是我国首个采用差分干涉测量技术实现地表形变监测应用的合成孔径雷达（SAR）卫星星座，其01组双星分别于2022年1月26日和2022年2月27日成功发射并在轨运行。双星在轨后具有双基编队干涉和双星组网两种模式。在双星干涉成像模式下，利用双基InSAR条带模式获取全国高精度DEM；在双星组网成像模式下，双星同轨道间隔180°在轨稳定运行，重访周期由8 d下降至4 d，获取时序相干数据，具备高精度地表形变监测的能力。此外，陆探一号SAR系统具备多模式极化优势，可获取单航过多极化InSAR、混合极化SAR数据，可用于林业、国土资源调查及灾害监测等。本文对陆探一号SAR载荷的关键技术，包括相位同步、模糊抑制与系统定标等进行系统性阐述和分析。陆探一号SAR载荷实现的最高分辨率为3 m，最大幅宽可达400 km，同时干涉模式方位模糊度优于-20 dB，系统性能优良，本文通过地面测试和在轨实测数据对陆探一号多模式成像性能进行验证。

关键词: 陆探一号, 相位同步, 系统定标, 极化SAR, 模糊抑制

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

中图分类号:

P237

邓云凯, 王宇, 刘开雨, 欧乃铭, 刘大成, 张衡, 王吉利. 陆探一号卫星SAR载荷关键技术[J]. 测绘学报, 2024, 53(10): 1881-1895.

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