摘要: |
深空通信中,星上对载波的主动捕获主要利用频率估计的方法。在实际载波捕获电路
中,精确的频率估计值导入锁相环,使得锁相环捕获带余量充足。在锁相环带宽一定的情况
下,估计精度的提高可以减少FFT实现点数。在FFT频率粗估计的基础上,通过频率精细估计
算法可提高估计精度。为获得估计精度更高的频率精细估计算法,利用最大似然泛函不变性
推导了频率精细估计的最大似然算法。载噪比在5 dB时,估计精度可以提高到FFT分辨率的1
0
-4。仿真结果表明,该算法估计性能优于其他频率精细估计算法。 |
关键词: 深空通信 最大似然频率精细估计 载波捕获 相位最大似然估计 泛函不变性 |
DOI: |
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基金项目:国家高技术研究发展计划(863计划)项目 (2011AA7014053) |
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High-accurate carrier acquisition based on maximum likelihood estimation of refined frequenc |
WANG Le,WANG Zhu-gang,XIONG Wei-ming |
() |
Abstract: |
The carrier initiative acquisition on board is mainly based on the frequency estimation in deep space communications. With the aid of data, the estimator performs well at low SignaltoNoise Ratio(SNR). In the design of carrier acquisition, the accurate estimation of frequency aids the Phase Locked Loop(PLL). If the acquisition bandwidth of PLL is fixed, accurate estimation value helps to decrease Fast Fourier Transform(FFT) size. The refined estimation after FFT coarse estimation is applied to improve estimation accuracy. In order to achieve higher estimation accuracy, a Maximum Likelihood(ML) algorithm of refined estimation is derived via functional invariance. The estimation accuracy can achieve 10-4 when SNR is 5 dB. The simulation results present that the proposed algorithm outperforms other algorithms. |
Key words: deep space communication ML accurate estimation carrier acquisition ML estimation of phase functional invariance |