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为利用卫星束确定地球表面目标的位置信息具有很多重要应用,例如导航,监控,遥感等。然而,在实际条件下,会有很多因素影响卫星定位系统的精度,比如说信号参数的测量误差,卫星位置误差以及校正源的位置误差。本文基于时差观测量系统分析了多星联合定位的理论性能。首先在基于目标高程约束和高斯误差的假设下,推导四种定位场景下目标位置估计方差的克拉美罗界。第一种场景仅考虑时差观测量误差,并且假设卫星位置精确已知;第二种场景同时考虑时差观测量误差和卫星位置误差;第三种场景假设存在若干位置信息精确已知的校正源,其用于消除卫星位置的影响;第四种场景则假设校正源位置也存在测量误差。此外,文中基于一阶扰动分析和拉格朗日方法推导了两种情形下的定位均方根误差的表达式。第一种情形是假设卫星位置精确已知但实际上却含有误差;第二种情形则是假设校正源位置精确已知但实际上却含有误差。仿真结果验证了文中理论分析的有效性。
There are many important applications for determining the location of a target on the Earth’s surface using satellite beams, such as navigation, surveillance, remote sensing and the like. However, under actual conditions, there are many factors that affect the accuracy of the satellite positioning system, such as the measurement error of signal parameters, the satellite position error and the position error of the correction source. This paper analyzes the theoretical performance of multi-satellite joint location based on the time difference observation system. First, based on the assumption of target elevation constraints and Gaussian errors, the Kerammelo boundary of the target position estimation variance under four localization scenarios is derived. The first scenario considers only the observed errors of the time difference and assumes that the satellite position is precisely known; the second scenario takes into account both the observation error of the time difference and the satellite position error; and the third scenario assumes that there are several calibration sources with exactly known position information, It is used to eliminate the influence of the satellite position; the fourth scenario assumes that there is also a measurement error in the calibration source position. In addition, based on the first-order perturbation analysis and the Lagrange method, the expressions of the root mean square error of the location in the two cases are deduced. The first case assumes that the satellite’s position is known exactly but in fact it contains errors. The second case assumes that the position of the correction source is known exactly but in fact contains errors. The simulation results verify the validity of the theoretical analysis in this paper.