低信噪比场景下全相位FFT载频估计改进算法  

Improved Carrier Frequency Estimation Algorithm Based onapFFT in Low Signal-Noise Ratio Scene

作　　者：吴呈瑜 张红斌 占敖 WU Chengyu;ZHANG Hongbin;ZHAN Ao(School of Information Science and Engineering,Zhejiang Sci-Tech University,Hangzhou 310018,China)

机构地区：[1]浙江理工大学信息科学与工程学院,浙江杭州310018

出　　处：《无线电通信技术》2023年第6期1073-1080,共8页Radio Communications Technology

基　　金：浙江省2023年度第一批“尖兵”研发攻关计划项目(2023C01041)~~。

摘　　要：对比传统的快速傅里叶变换(Fast Fourier Transform, FFT),全相位FFT(all-phase FFT,apFFT)加入了全相位信号预处理过程,拥有相位不变特性和较好的抑制频谱泄漏的性能,对调幅(Amplitude Modulation, AM)信号的载频估计能达到较高的精度。但在无线电监测和通信信号识别等特定场景下,解调需要在低信噪比(Signal-Noise Ratio, SNR)下进行。然而在低信噪比环境下,信号往往遭受严重的干扰,为了解决低信噪比环境下AM信号的载频估计问题,提高载频估计精度,提出了基于apFFT的均值修正样条插值结合的AM载频估计算法。分别模拟了添加高斯噪声的低信噪比情况下带正弦干扰与不带干扰的实验环境,对比了样条插值与其他插值方法的优势。仿真结果表明,样条插值能够得到更平滑的插值曲线,提出的载频估计方法具有良好的抗干扰能力,并且对低信噪比环境下载频估计数据有较好的校正作用,得到的载频估计结果对比原始方法有3~5 dB的提升。Compared with traditional Fast Fourier Transform(FFT),all-phase FFT(apFFT)has added all-phase signal pre-processing process and possesses phase invariance characteristic,better performance in suppressing spectrum leakage.It achieves higher accuracy in carrier frequency estimation of Amplitude Modulation(AM)signals.However,in specific scenarios such as radio monitoring and communication signal recognition,demodulation needs to be carried out under low Signal-Noise Ratio(SNR).In a low SNR environment,signals often experience severe interference.To address the problem of carrier frequency estimation of AM signals under low SNR conditions and improve estimation accuracy,an AM carrier frequency estimation algorithm based on all-phase FFT combined with mean-modified spline interpolation is proposed.Experimental environment simulates scenarios with sinusoidal interference and without interference under low SNR conditions with Gaussian noise,respectively.Comparing the advantages of spline interpolation with other interpolation methods,Simulation results demonstrate that spline interpolation can generate smoother interpolation curves,and the proposed carrier frequency estimation method exhibits good anti-interference ability.It also provides effective correction for carrier frequency estimation data in low SNR environment,resulting in carrier frequency estimation improvements of 3~5 dB compared to the original method.

关 键 词：低信噪比 全相位快速傅里叶变换 调幅 载频估计 样条插值 

分 类 号：TN911.72[电子电信—通信与信息系统]