基于加窗互模糊函数估计的卫星搜救定位技术

Satellite Search and Rescue Localization Technology based on Windowed CAF Estimation

【目的】随着卫星技术的不断发展,将卫星应用于地面信息网络低覆盖区域进行人员搜救已普及,卫星搜救定位技术作为人员和设施位置指示的有效手段,广泛应用于海上、航空和个人遇险救援行动。而全球卫星搜救系统的发展和研究中,搜救源高精度和快速的定位是其主要目标。【方法】针对卫星搜救信号突发特点,采用双星时频差定位作为卫星搜救定位方法,其所需的到达时间差(TDOA)和到达频率差(FDOA)参数估计是提高定位精度的关键。为了提高双星时频差定位技术的参数估计性能和定位精度,文章提出了一种基于时域加窗的互模糊函数(CAF)时频差估计搜救定位技术方案,通过时域加窗CAF来提高时频差估计的精准度,并利用估计值代入双星时频差定位方程组从而解算出搜救信号源位置,即通过高效地提高时频差参数估计精度达到定位精度提高的目的,以准确找到搜救源。【结果】仿真结果表明,加窗下的CAF时频差参数估计方法可用于搜救定位中,能够获得精确时频差估计值,且加入傅里叶变换后可以减少参数估计时间,进而优化定位性能。将时差误差控制在4μs内、频差误差控制在0.2 Hz以内时,定位精度可以达到千米量级。【结论】文章所提方案并入卫星搜救定位技术后定位性能得到改善,能够支持卫星搜救定位技术在搜救系统中的应用,算法结构简单,复杂度低,具有实际可行性。

【Objective】With the continuous development of satellite technology,the application of satellites to low coverage areas of ground information networks for personnel search and rescue is becoming increasingly popular.As an effective means of indicating the location of personnel and facilities,satellite search and rescue positioning technology is widely used in maritime,aviation,and personal distress rescue operations.Therefore,in the continuous development and research of global satellite search and res cue systems,achieving high⁃precision and rapid positioning of search and rescue sources is the main goal.【Methods】In view of the sudden characteristics of satellite search and rescue signals,dual⁃satellite Time Difference of Arrival(TDOA)and Frequency Difference of Arrival(FDOA)positioning are adopted as the satellite search and rescue positioning methods.The estimation of the required TDOA and FDOA parameters is the key to improve the positioning accuracy.In order to improve the parameter esti mation performance and positioning accuracy of dual⁃satellite TDOA and FDOA positioning technology,this paper proposes a search and rescue positioning technology scheme based on time⁃frequency difference estimation of windowed Cross Ambiguity Function(CAF).The method of filtering redundant noise by adding windows in time domain is introduced,and the accuracy of time⁃frequency difference estimation is improved by adding windows in time domain and CAF.The estimated value is substituted into dual⁃satellite TDOA and FDOA positioning equations to calculate the location of the search and rescue signal source.It means that the purpose of improving the positioning accuracy is to efficiently and accurately find the search/rescue source by im proving the estimation accuracy of TDOA/FDOA parameters.【Results】The simulation results show that the method of estimat ing the TDOA/FDOA parameters of CAF with windows can be applied to search and rescue positioning,and the accurate time⁃frequency difference estimation value can be obtained through this method.The method proposed in this paper can effectively im⁃prove the accuracy of time⁃frequency difference parameter estimation,and add Fourier transform to reduce the time of parameter estimation,thus optimizing the positioning performance.When the TDOA error is controlled within 4μs and the FDOA error is controlled within 0.2 Hz,the positioning accuracy can reach the kilometers.【Conclusion】The time⁃domain windowed time⁃fre quency difference parameter estimation scheme proposed in this paper has improved the positioning performance after being incor porated into the satellite search and rescue positioning technology,which can support the application of the satellite search and rescue positioning technology in the satellite search and rescue system.The algorithm has the advantages of simple structure,low complexity and practical feasibility.