多谐波脉冲星信号时延估计方法

发布时间：2018-07-25 08:29

【摘要】：针对脉冲星导航技术中延时估计这一关键问题,提出了频域上直接使用脉冲星信号测量到达时间集合进行时延估计的方法——多谐波脉冲星信号时延估计(MHSPE)方法.该方法建立在频域上相位时延的极大似然估计的基础上,通过高次谐波对脉冲星观测信号提取出各谐波相位的极大似然估计,然后取频谱上各谐波的幅值进行归一化作为各谐波相位的权值,最后取各谐波相位的加权平均作为该时刻的相位估计.理论上证得MHSPE算法对相位的估计是无偏、一致的,相比于频域上一次谐波的极大似然估计,MHSPE方法的信噪比随谐波数m的增加而增加,当各谐波幅值相同时,信噪比可提高m1/2倍;与脉冲星信号时延的克拉美罗界比较,脉冲星信号时域的导数在频域上的反映就是各谐波分量的数量,因此随着谐波次数的增加脉冲星信号时延估计可极大趋近克拉美罗界.采用RXTE航天器对Crab脉冲星的实测数据检验MHSPE方法的性能,实验结果表明,针对低信噪比的脉冲星信号,MHSPE可获得高精度的相位估计,随观测时间增加,估计精度快速收敛于克拉美罗界.
[Abstract]:Aiming at the key problem of time delay estimation in pulsar navigation technology, a method of time delay estimation using pulsar signal measurement and arrival time set in frequency domain is proposed, which is called multi-harmonic pulsar signal time delay estimation (MHSPE) method. Based on the maximum likelihood estimation of phase delay in frequency domain, the maximum likelihood estimation of each harmonic phase is extracted from the observed signal of pulsar by high-order harmonics. Then the amplitude of each harmonic in the spectrum is normalized as the weight of each harmonic phase, and the weighted average of each harmonic phase is taken as the phase estimation at that time. It is proved that the phase estimation of MHSPE algorithm is unbiased and consistent. Compared with the maximum likelihood estimation of the first harmonic in frequency domain, the SNR of the MHSPE algorithm increases with the increase of the harmonic number m, and the signal-to-noise ratio can be increased by 1 / 2 times when the amplitude of the harmonics is the same. Compared with the Clemero bound of pulsar signal time delay, the derivative of pulsar signal in frequency domain is reflected by the number of harmonic components, so the time delay estimation of pulsar signal can approach Clemero bound greatly with the increase of harmonic frequency. The performance of the MHSPE method is tested by the measured data of the RXTE spacecraft on the Crab pulsar. The experimental results show that the phase estimation of the pulsar signal with low signal-to-noise ratio (SNR) can be obtained with the increase of the observation time. The estimation accuracy converges rapidly to the Clemero bound.
【作者单位】：哈尔滨工业大学卫星技术研究所;哈尔滨理工大学电气与电子工程学院;
【基金】：国家高技术研究发展计划(863计划)(批准号:2008AA8051602)资助的课题~~
【分类号】：P128.4

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