MPSK信号载频盲估计

Blind estimation of MPSK carrier frequency

研究了相位编码信号(MPSK)的载频盲估计算法。在没有接收信号先验知识的情况下,首先对MPSK信号载频进行粗估计,然后进行相关运算把信号变成基带调制相位编码信号,接着估计码速率,得到载频和码速率的估计值,就把载频估计问题转化为频偏估计问题。利用基带MPSK信号的相位函数是分段线性函数且每一段直线的斜率均正比于频偏的性质,对接收信号的相位函数进行处理,把分段直线变成一条直线,最后运用最小二乘拟合法得到直线的斜率从而得到频偏估计。仿真表明本算法在没有先验知识的情况下可以对MPSK信号载频进行精确估计。

The blind carrier frequency estimation of multi-phase shift keying （MPSK） signals was discussed. The carrier frequency was coarsely estimated without the prior knowledge of received signals. Consequently the signals were transformed to the baseband-modulated PSK signals by correlation to estimate the symbol rate. With the estimations of the carrier frequency and the symbol rate, the problem of carrier frequency estimation was converted to that of frequency offset. Because the phase of baseband-modulated PSK signal is a piecewise linear function and the slope coefficient of every segment is a linear function of frequency offset, the multi-segment line can be transformed to a straight-line and then the least squares fitting method wasapplied to estimate the slope coefficient. The simulation results show that this method can accurately estimate the cartier frequency without the prior knowledge.