摘要
提出了一种用于盲估计四相编码(Quaternary phase shift key,QPSK)载波频率的改进MAT(M-MAT)算法,并给出了一种新型QPSK信号码元估计方法。在没有接收信号先验知识的情况下,首先对QPSK信号粗估计出其载频重心和3dB带宽,并适度滤除带外噪声,之后利用MAT方法估计载频。在此基础上,利用每个码元带宽内相位幅度不变的特性,通过相邻码元的相位差值来估计码元变化。仿真结果表明,该载频估计方法估计精度高于传统的MAT方法,解码方法可以在低信噪比条件下,达到较高的解码精度。
A modified MAT （M-MAT） method for estimating the blind carrier frequency of the quaternary phase shift key （QPSK） signal is presented and a novel code estimation algorithm of the QPSK signal is proposed. Firstly, carrier frequency center and 3 dB-bandwidth of the QPSK signal are estimated coarsely without the prior knowledge of received signals, and the noise out of the bandwidth is filtered appropriately. Then, the carrier frequency can be estimated ac- curately by using the MAT method. Furthermore, considering the phase is constant in every code period, the code change can be estimated by analyzing the phase difference of adjacent codes. Finally, simulating results indicate that the proposed method for carrier frequency estimation is more accurate than the traditional MAT method and validate the high decoding accu- racy under low signal-to-noise radio （SNR）.
出处
《数据采集与处理》
CSCD
北大核心
2011年第5期553-558,共6页
Journal of Data Acquisition and Processing
关键词
四相编码
频率估计
载频
MAT
码元估计
quaternary phase shift key
frequency estimation
carrier frequency
MAT
code estimation
