非合作直扩信号伪码及信息序列联合盲估计

研究了短码直接序列扩频信号扩频序列及信息序列联合盲估计问题。在已知码片速率和扩频码周期的前提下，对接收信号以2倍伪码周期进行分段构造信号矩阵，然后对其进行奇异值分解，对最大和次大左奇异向量进行线性变换，得到信息序列；利用自相关函数从最大和次大右奇异向量中得到扩频码序列。该算法在失步时间未知的情况下能够同时估计出伪码序列及信息码序列，避免了传统特征值分解盲估计算法利用2个矢量空间组合扩频序列时存在的相位模糊问题。同时，在引入了矩阵的线性变换后，避免了不同时延估计结果存在模糊的问题，提高了盲估计性能。通过理论分析和计算机仿真结果表明：该算法能够有效估计扩频序列，并且具有精确度高、性能不受时延大小影响等优点。

Blind estimation of non-cooperative direct sequence spread spectrum signals and information sequence

Blinding estimation combined spread-spectrum sequence with information sequence of DS-SS signals is studied.The chip rate of the Pseudo-Noise (PN) sequence and the PN sequence period need to be uncovered. Firstly, received signal is sectioned with double pseudo-code cycle to construct the signal matrix, upon which singular value decomposition(SVD) is applied. Then information sequence is obtained by linear transformation of largest and secondary largest left singular vectors , PN sequence is worked out from largest right singular vector with the utilization of autocorrelation function.Without the knowledge of desynchronization time, the proposed method is able to estimate both the spread-spectrum sequence and information sequence blindly. Meanwhile,it avoids solving the problem of the phase ambiguity when useing two vectors to reconstruct spread-spectrum sequence, which is based on EVD blinding estimate algorithm. Furthermore, the ambiguity at different desynchronization time is avoided by using linear transformation of matrix. The theoretical analysis and simulations show that, the proposed method can estimate PN sequence and information sequence effectively, and it has higher estimation accuracy and is not affected by the level of time delay.