| 摘要: |
| 为了提高低轨卫星导航接收机的定位性能，提出了一种顾及卫星运动和突发信号特征的卡尔曼滤波多普勒跟踪方法。以铱星为例，针对铱星信号的高动态和突发特性，设计了一种卡尔曼滤波参数的自适应调整算法，结合铱星轨道动力学和接收机时钟噪声模型优化滤波器噪声协方差等参数，在跟踪过程中依据载噪比动态调整参数，从而显著提高了多普勒频率的估计精度。并且该方法根据历史估计值约束的迭代预测，有效提高了信号中断期间的多普勒估计精度。在信号间断时，利用卡尔曼滤波提供的多普勒频率预测值辅助信号跟踪，提高了环路收敛速度。实测结果表明，多普勒频偏估计值的误差为9.29 Hz，较快速傅里叶变换（Fast Fourier Transform,FFT）方法测量精度提升了67.81%；信号中断期间多普勒频偏的预测误差为13.12 Hz；二维多普勒定位精度达到了100 m以内，相较传统的FFT方法提升了54.6%。 |
| 关键词: 低轨卫星导航 铱星 多普勒频偏 卡尔曼滤波 |
| DOI：10.20079/j.issn.1001-893x.241127001 |
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| 基金项目:湖北省优秀中青年科技创新团队项目（T2022059） |
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| Doppler Tracking Method and Parameter Design of Iridium Signal Based on Kalman Filtering |
| CHEN Xiaoli,ZHU Yitao,GUO Wenfei,FENG Weijun,TIAN Mao |
| (a.School of Electronic Information;b.GNSS Research Center,Wuhan University,Wuhan 430072,China) |
| Abstract: |
| To improve the positioning accuracy of low Earth orbit satellite navigation receivers,a Kalman-filtered Doppler tracking method that considers the characteristics of satellite motion and bursty signals is proposed.Utilizing Iridium as a case study,an adaptive adjustment algorithm for Kalman filter parameters is proposed with considering the highly dynamic characteristics and bursty structure of Iridium signals.It optimizes the filter noise covariance and other parameters by integrating Iridium orbital dynamics and receiver clock noise models.Additionally,it dynamically adjusts the parameters according to the carrier-to-noise ratio during tracking,thereby significantly enhancing the estimation accuracy of the Doppler frequency.Furthermore,the method enhances the Doppler frequency estimation accuracy during signal interruptions by iteratively predicting it according to the constraints of the historical estimation value.During the interruption of the burst signal,the Doppler frequency prediction provided by the Kalman filter is utilized to assist signal tracking,thereby improving the loop convergence speed.The results indicate that the error margin of the Doppler frequency deviation estimation is 9.29 Hz,which is 67.81% better than that of the fast Fourier transform(FFT) method.Furthermore,the prediction error of the Doppler frequency deviation during signal interruption is 13.12 Hz.In addition,the 2D Doppler positioning error reaches down to within 100 m,which is 54.6% better than that of the traditional FFT method. |
| Key words: low Earth orbit satellite navigation Iridium satellite Doppler frequency Kalman filter |
