一种QPSK短时数据辅助解调方法

Short-Time Data Demodulation Method for QPSK System based on Data-aided

针对验证复杂QPSK数据帧信号源发射数据正确性和突发数据解调时数据长度过短导致常规同步算法无法实施的问题,提出了一种数据辅助精确同步算法。首先,整个序列经傅立叶变换估计出初始频率点;其次,对相位进行估计,使用定时估计算法估计采样率偏差,并使用插值滤波器改变序列的采样率为整数倍符号速率;最后,通过解调数据反馈迭代的方式对频偏和定时频率进行估计,从而获得较优的数据解调性能。仿真结果表明,在高斯白噪声下,新算法的频率同步和定时同步性能均优于传统算法,且星座图收敛性更好。

To solve the problem of too-short data length for normal algorithm in the complex QPSK data source verification and burst data demodulation, a data-aided precise synchronization algorithm proposed. Firstly, the initial frequency point is estimated by using FFT,then the phase and sampling time estimation and sampling time changing by using interpolation filter is completed,finally,the fairly good demodulation performance is acquired by using the last demodulation result feedback iteration. The simulation results indicate that, in additive white Gaussian noise channel, the frequency synchronization and timing synchronization of the new algorithm are all better than those of the traditional algorithm, and in addition, the converging performance of the constellation is also fairly good.