一种多速率OFDM测控系统的测距方法

摘要

在多速率OFDM测控系统中,提出一种基于FIR实现结构、联合时域与频域定时估计的高精度测距方法.首先,在时域对接收信号自相关,利用FIR滤波器计算定时度量并获得采样定时估计;在频域对包含残留定时偏差的信号消调制,通过FIR滤波进一步提高估计精度.然后,联合时域与频域定时估计进行精确测距计算.最后,给出该测距方法的理论性能表达式和克拉美罗限.方法利用基于FIR结构的相关计算方法进行测距,实现复杂度较低,其中L0参数可根据性能指标取值.分析结果表明,方法的性能可以达到理论性能限,在高信噪比下的测距精度可达厘米级.%A precise ranging method is proposed in multi-rate OFDM TT&C system based on FIR implementation by combining time-domain and frequency-domain timing estimations. In time-domain, the timing metric is calculated by FIR filtering with the autocorrelation of received signals, and then the timing estimation of samples is obtained. In frequency-domain, the estimation performance is improved by FIR filtering after removing the mapping information of the signals with residual timing offset. The precise ranging is realized by combining these time-domain and frequency-domain timing estimations. Finally, we give the theoretical performance expression of proposed ranging method and its CRB. The proposed method makes use of the FIR implementations to calculate correlations and range with low complexity. Its parameter L0 can be set differently according to the performance requirements. Analysis results show that, the proposed method can get close to the theoretical performance bound and it has ranging precision up to centimeter at high SNRs.