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为解决低信噪比下直扩信号的参数盲估计问题,提出了一种基于模糊函数的直扩信号载频、码率和伪码周期估计新方法。对直扩信号的模糊函数进行了推导和分析,发现直扩信号模糊函数在特定延时和频率上有明显特征对应载频、码率和伪码周期等参数,给出了直扩信号参数估计的具体算法。仿真实验表明在扩频码长为63及码元数为16条件下,载频和码率估计可工作在-12 dB,扩频周期估计可工作在-6 dB低信噪比条件下。该方法可用于非合作通信中直扩信号的参数估计。
In order to solve the problem of blind parameter estimation of DSSS signals at low signal-to-noise ratio, a new method based on ambiguity function for carrier frequency, bit rate and PN code period estimation is proposed. The derivation and analysis of the ambiguity function of the DSSS signal is carried out. It is found that the ambiguity function of the DSSS signal has some characteristics such as carrier frequency, bit rate and pseudo-code period on certain delay and frequency. The specific algorithm. The simulation results show that the carrier frequency and code rate estimation can work at -12 dB with spreading code length of 63 and symbol number of 16, and the spreading period estimation can work under -6 dB low signal-to-noise ratio. This method can be used to estimate the parameters of DSSS signals in non-cooperative communication.