CAJ | 학술논문

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10-4.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.
심공통신중,성상대재파적주동포획주요이용빈솔고계적방법.재실제재파포획전로중,정학적빈솔고계치도입쇄상배,사득쇄상배포획대여량충족.재쇄상배대관일정적정황하,고계정도적제고가이감소FFT실현점수.재FFT빈솔조고계적기출상,통과빈솔정세고계산법가제고고계정도.위획득고계정도경고적빈솔정세고계산법,이용최대사연범함불변성추도료빈솔정세고계적최대사연산법.재조비재5 dB시,고계정도가이제고도FFT분변솔적10-4.방진결과표명,해산법고계성능우우기타빈솔정세고계산법.
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 Signal-to-Noise Ratio(SNR). In the design of carrier acquisition,the accurate estimation of frequency aids the Phase Locked Loop(PLL). If the ac-quisition 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 pre-sent that the proposed algorithm outperforms other algorithms.