单载波GMSK信号的高精度频偏估计算法  

High-Precision Frequency Offset Estimation Algorithm for Single-Carrier GMSK Modulation Signals

作　　者：高静 桑田 罗韬[3] Gao Jing;Sang Tian;Luo Tao(School of Microelectronics,Tianjin University,Tianjin 300072,China;Tianjin Key Laboratory of Imaging and Sensing Microelectronic Technology,Tianjin 300072,China;College of Intelligence and Computing,Tianjin University,Tianjin 300350,China)

机构地区：[1]天津大学微电子学院,天津300072 [2]天津市成像与感知微电子技术重点实验室,天津300072 [3]天津大学智能与计算学部,天津300350

出　　处：《天津大学学报（自然科学与工程技术版）》2020年第12期1301-1307,共7页Journal of Tianjin University：Science and Technology

基　　金：天津市科技计划资助项目(17ZXRGGX00030).

摘　　要：在接收机中,频偏估计的精度决定了信号解调的准确性。GMSK调制作为深空通信的调制方式之一,复杂的空间环境对高精度频偏估计的实现带来了大的挑战.为了进一步提高GMSK信号频偏估计的精度,本文提出了一种基于快速傅里叶变换(FFT)的高精度插值估计算法.该算法是一种非数据辅助类算法,不需要依赖导频序列,可以与数据辅助类算法结合使用.在GMSK信号的传输过程中,复杂的大气环境导致传输信道具有很低的信噪比。在低信噪比的信道环境中,估计算法要达到理想的精度,需要提高其抗噪声干扰能力.在本文中,高精度插值估计算法首先对接收信号进行FFT运算,得到接收信号的频谱信息,实现对信号频率的初步估计.之后将得到的FFT最大幅值谱线与其相邻谱线中心点的谱线值进行比较,将具有最大幅值的点作为峰值谱线.最后,对峰值谱线进行数学计算,得到估计的频偏值.本文提出的频偏估计算法可以提高抗干扰能力,降低噪声对有用信号的影响并减少误判情况,提高估计精度.利用计算机模拟该频偏估计算法的估计性能,仿真结果表明:所提出算法的频率估计精度优于其他现有算法,具有更加平稳的估计效果,降低了算法工作的信噪比门限,可用于各种环境下GMSK信号的载波频偏估计.In receiver,the accuracy of frequency offset estimation determines the accuracy of signal demodulation.GMSK modulation is one of the modulation methods for deep space communication.The complex space environment brings great challenge to the realization of high-precision frequency offset estimation.In this study,a high-precision interpolation estimation algorithm based on fast Fourier transform(FFT)is proposed to further improve the accuracy of GMSK signal frequency offset estimation.The algorithm is a non-data-aided algorithm,which does not need to rely on pilot frequency information,and can be used with the data-aided algorithms.In the transmission process of GMSK signal,the complex atmospheric environment leads to a very low signal-to-noise ratio transmission channel.In the low SNR channel environment,the estimation algorithm needs to improve its anti-noise capability to achieve the desired accuracy.In this paper,the high-precision interpolation estimation algorithm first performs FFT operation on the received signal,obtains the spectrum information of the received signal,and realizes the preliminary estimation of the signal frequency.After that,the maximum FFT spectral line is compared with the spectral line value at the center of its adjacent spectral line,and the point with maximum FFT value is taken as the peak spectral line.Finally,the estimated frequency offset is obtained by mathematical calculation of the peak spectral line.Simulation results show that the proposed algorithm has better estimation accuracy than other existing algorithms,has a more stable estimation effect,reduces the signal-to-noise ratio threshold,and can be used for the carrier frequency offset estimation of GMSK signals in various environments.

关 键 词：频偏估计 快速傅里叶变换 低信噪比门限 高精度 

分 类 号：TN914[电子电信—通信与信息系统]