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目的:为克服高动态弱信号环境下信号的积分峰值受比特符号翻转和频率误差的影响,提出一种基于离散chirp-Fourier变换块补零方法。创新点:与传统闭环捕获和跟踪的接收机结构相比,该方法适用于开环捕获。该方法结合了离散chirp-Fourier变换和块补零思想,能够使后相关信号在剥离比特符号后进行相干积累并同时进行高动态参数精准预测。同时,对所提方法的检测性能进行分析推导捕获概率和虚警概率表达式。方法:首先,后相关信号通过块补零处理被分为一些块,然后这些块通过离散chirp-Fourier变换处理。以这种方式比特翻转对积分峰值的影响可以被削弱,同时后相关信号可以进行相干积累。最后通过阈值检测积分峰值来完成高动态参数的预测,这个阈值是通过设定的虚警概率得出的。仿真结果表明当接收信号长度一定时,本文方法较BASIC方法能在更低的信噪比下检测到高动态参数。结论:本文结合离散chirp-Fourier变换和块补零思想,在弱信号高动态环境下提出基于离散chirp-Fourier变换的块补零方法。仿真结果表明本文方法较BASIC方法在更低的信噪比下预测高动态参数。与利用传统接收机结构的闭环捕获和跟踪方法的相比,这种方法是一种开环捕获的方法,非常适合软件无线电接收机。
Aims To overcome the influence of bit symbol flip and frequency error on signal peak under high dynamic weak signal environment, a new method based on discrete chirp-Fourier transform is proposed. Innovation: This method is suitable for open-loop capture compared to traditional closed-loop capture and tracking receiver architectures. This method combines the discrete chirp-Fourier transform and the block zeroing idea, which enables the coherent accumulation of the post-correlation signal after stripping the bit symbols and the accurate prediction of high dynamic parameters. At the same time, the detection performance of the proposed method is analyzed to derive the probability of capture and the false alarm probability expression. Method: First, the post-correlation signal is divided into blocks by the block zero-padding process, and then these blocks are processed by the discrete chirp-Fourier transform. In this way the effect of bit flipping on the integration peak can be weakened, while the coherent accumulation of the post-correlation signal can occur. Finally, the threshold of integral peak detection to complete the high dynamic parameters of the prediction, the threshold is set by the false alarm probability. The simulation results show that the proposed method can detect high dynamic parameters at a lower signal-to-noise ratio than the BASIC method when the received signal length is constant. Conclusion: In this paper, based on discrete chirp-Fourier transform and block zeroing, this paper proposes a block zeroing method based on discrete chirp-Fourier transform in weak signal and high dynamic environment. The simulation results show that the proposed method predicts high dynamic parameters at a lower signal-to-noise ratio than the BASIC method. This approach is an open-loop capture approach that is well suited for software-defined radio receivers, as compared to closed-loop capture and tracking using conventional receiver architectures.