天绘二号卫星两种基线定标模型比较分析

Comparison and analysis of two baseline calibration models for TH-2 satellite

天绘二号卫星系统中两颗对等的卫星于2019年7月初形成绕飞编队,采用一发双收体制获取全球雷达干涉数据,精确的干涉基线是实现高精度测绘产品生产的前提。本文给出了主雷达APC坐标系中的基线定义,介绍了一发双收体制下,基于辅雷达距离改化方程和多普勒方程的单景数据基线定标模型和平行基线误差、有效基线误差分步求解的近远波位联合基线定标模型。根据基线误差交会原理给出了控制点选取策略,即在近、远距端子条带内选取控制点的策略。利用天绘二号获取的17次新疆定标场数据开展了单景数据基线定标和近远波位联合基线定标试验,并对两种基线定标模型定标后的地面定位精度进行了分析。结果表明:单景数据模型标出的水平基线误差均值为-2.74 mm,垂直基线误差均值为-5.49 mm,近远波位联合模型标出的水平基线误差均值为-1.95 mm,垂直基线误差均值为-5.84 mm,近远波位联合基线定标后比单景数据基线定标后系统地面定位精度高。

The two equivalent satellites in the TH-2 satellite system formed a flying-around formation in early July 2019, and began to obtain global radar interference data using the one-transmit and double-receiving system. The precise interference baseline is to realize the production of high-precision surveying and mapping products. This article gives the definition of the baseline in the antenna phase center(APC) coordinate system of the main radar. It introduces the single-scene data baseline calibration model based on the slave radar range modification equation and doppler equation under the one-transmit and double-receiving system, and a joint near-far beam positions calibration model of obtaining parallel and effective baseline errors by steps. According to the principle of baseline error intersection, a control points selection strategy is given, that is, the strategy of selecting control points in the near and far sub strips. The 17 times Xinjiang calibration field data acquired by TH-2 was used to carry out single-scene data and near-far beam positions joint baseline calibration experiments, and the ground positioning precision analysis of the two baseline calibration models after calibration was carried out. The experiments show that the average horizontal baseline error is-2.74 mm, and the average vertical baseline error is-5.49 mm calibrated by the single-scene data model. The average horizontal baseline error is-1.95 mm, and the average vertical baseline error is-5.84 mm calibrated by the near-far beam positions joint model. The ground positioning precision of the system after the near-far beam positions joint baseline calibration is higher than that of the single-scene data baseline calibration.