由于非周期性直扩信号破坏了伪码的周期性和相关特性,原周期性直扩信号检测方法将失效或性能严重恶化.本文在信息序列不相关的前提下,利用四阶矩切片能有效抑制高斯白噪声和其循环相关谱具有明显谱峰的特点,提出一种基于四阶矩切片循环相关谱的非周期性直扩信号盲检测方法,该方法同时能精确估计信号载频.这种方法不需要先验信息,计算简单,易于工程实现.仿真结果表明,在虚警概率为1％,信噪比为-21dB时,该方法的检测概率可达到90％以上；当信噪比高于-18dB时,载频估计的归一化标准差低于0.002;该方法的检测和载频估计性能均优于二次四阶矩切片法、平方倍频法和倒谱法.%The non-periodic direct sequence spread spectrum (DSSS) signal damages the periodic and related properties of the pseudo code, so detection methods for the periodic signals are failure or their performance is seriously deteriorated. When the information sequence is not correlative, due to the fourth-order moment chip having good effect in restraining the Gaussian noise and its cycle coherence spectrum having obvious peaks, a blind detection method for non-periodic DSSS signal based on the cycle coherence spectrum of the fourth-order moment chip is proposed, which also could estimate the signal carrier. The proposed method does not need prior information, its computation complexity is low, and it is easy to implement. From the experimental results, it can be concluded that when the false alarm probability is equal to 1%, the detection probability of presented method reaches above 90% at SNR -21dB. When the SNR is higher than -18dB, the normalized standard deviation of carrier frequency estimation is less than 0.003. The performance of the detection and carrier frequency estimation of the proposed method is better than the method based on the quadratic fourth-order moment chip, the double frequency method and the cepstrum method.
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