摘要
针对传统时频差估计方法对时分多址(TDMA)信号进行参数估计时会出现不同用户相互影响、估计精度差,以及计算复杂度高不利于系统实时信号处理等问题,文章提出一种高精度快速时频差联合估计方法。首先,基于循环平稳特征对主站接收数据进行信号检测;然后,基于小波阈值去噪和短时电平和进行TDMA信号时隙分离;在此基础上,基于不同调制信号特征参数设计多级分类器,对每个分离的信号时隙进行调制样式判别,进而分选不同用户对应的信号时隙;接着,利用主站分选的各个用户信号分别与辅站信号进行时频差粗值估计;根据粗时频差估计值减小细化时差搜索范围,以获取精细时频差估计值;最后,利用二阶曲面拟合方法进一步提升参数估计精度。仿真结果表明:文章所提方法能够有效实现TDMA信号高精度快速时频差联合估计,可为后续卫星频谱感知体系的建设提供理论支撑。
When traditional methods of joint TDOA(time difference of arrival)and FDOA(frequency difference of arrival)estimation are applied to obtain the parameters of TDMA(time division multiple access)signals,interactions among different users and poor estimation accuracy will appear.Moreover,traditional joint TDOA/FDOA estimation methods exhibit high computational complexity,which becomes a disadvantage for a real-time processing system.To overcome these problems,a high-accuracy and fast TDOA/FDOA estimation method is proposed for TDMA signals in this paper.In the proposed method,the data received by the main station is firstly used for signal detection based on cyclostationary characteristics.Then,the timeslot of TDMA signals are separated based on wavelet threshold denoising and the sum of short-time electrical levels.Sequentially,the modulation pattern of each separated timeslot is distinguished based on the multi-stage classifier,which is designed by characteristic parameters of different modulation signals.On this basis,the timeslot corresponding to different users are sorted.In the following,the value of TDOA/FDOA is coarsely estimated by using the signals correspon￣ding to each user of the main station and the received signals of the auxiliary station.According to the coarsely-estimated value of TDOA/FDOA,the time-domain search range is reduced and refined to obtain the fine TDOA/FDOA estimation.Finally,based on the fine TDOA/FDOA estimation,the second-order curve surface fitting method is applied to improve the accuracy of parameter estimations.The simulation results show that the proposed method can realize high-accuracy and fast TDOA/FDOA estimation for TDMA signals,which can provide a good theoretical basis for the construction of satellite radiometric spectrum sensing system in the future.
作者
陈潇扬
邱乐德
李帅
李明
辛宁
CHEN Xiaoyang;QIU Lede;LI Shuai;LI Ming;XIN Ning(Institute of Telecommunication and Navigation Satellites,China Academy of Space Technology, Beijing 100094, China)
出处
《航天器工程》
CSCD
北大核心
2022年第1期107-115,共9页
Spacecraft Engineering
基金
国家重点研发计划项目(2020YFB1807900)。
关键词
卫星时分多址信号
互模糊函数
时频差估计
satellite TDMA signal
cross ambiguity function
TDOA/FDOA estimation
