基于LFM信号的超声信道估计均衡算法研究

发布时间：2018-04-28 08:16

本文选题：Chirp + 线性调频信号　；参考：《华南理工大学》2015年硕士论文

【摘要】：超声探测作为当下运用最为广泛的探测技术,因其无损特性,被广泛应用于工业探伤,医疗、交通运输等领域。线性调频信号是数字信号处理领域的一种非常重要的信号,因其大时宽带宽积特性,被经常应用到超声探测中。在现实情况下信道都是非理想的,通过超声探头检测得到的接收数据已经受到了其探头自身信道的干扰,使得接收数据并不精准,所以研究信道的估计与均衡算法并将其应用在超声探测系统中,对提高检测系统的数据精度具有重要意义。本文基于线性调频信号提出一种新的信道估计与均衡算法并将其进行仿真与实验验证。本文首先对传统的LMS信道均衡算法做了理论分析和研究,并对最优解的三种求解方式做了综述。接着本文重点研究针对于线性调频信号提出的基于频域的信道估计均衡算法和基于频域加窗的时延估计改进算法。本文通过分别对以上两种算法进行数学上的理论推导,并且通过仿真,证实了其有效性。同时,对影响基于频域的信道估计均衡算法的性能参数:步长、迭代次数、初始值的设置进行的比较和分析;在不同信噪比下对基于频域加窗的时延估计改进算法的效果与原算法进行对比,通过仿真证实改进算法的有效性。在本文的最后一章中,运用第四章提出的基于频域的信道估计均衡算法进行实验,用来提高超声检测系统的检测精度。不同的探头具有不同的物理特性,通过检测发射与接收探头直接对接时的数据可以对探头自身信道进行估计,从而对接收数据进行均衡处理,使实际接收数据与理想接收数据的误差降低,提高检测系统的精确度。在本文中,对基于线性调频信号的信道估计与均衡算法从理论推导到仿真结果整个过程中,算法的有效性得到充分的验证,并且通过实验结果表明,本文提出的信道估计与均衡算法具有实际的效用。
[Abstract]:As the most widely used detection technology, ultrasonic detection is widely used in industrial detection, medical treatment, transportation and other fields because of its nondestructive characteristics. Linear frequency modulation signal is a very important signal in the field of digital signal processing. Because of its large time broadband and wide product characteristics, it is often applied to ultrasonic detection. The channel is not ideal. The receiving data obtained through the ultrasonic probe has been disturbed by the channel of its probe, which makes the received data imprecise. Therefore, it is of great significance to study the estimation and equalization algorithm of the channel and apply it to the ultrasonic detection system. This paper is based on linear analysis. FM signal presents a new channel estimation and equalization algorithm and carries out simulation and experimental verification. Firstly, this paper makes a theoretical analysis and Research on the traditional LMS channel equalization algorithm, and summarizes the three ways of solving the optimal solution. Then, this paper focuses on the frequency domain based channel proposed for linear FM signals. The estimation of the equilibrium algorithm and the improved algorithm based on the frequency-domain window based time delay estimation. In this paper, the theoretical derivation of the above two algorithms is mathematically deduced and its effectiveness is verified by simulation. At the same time, the ratio of the performance parameters of the channel estimation equalization algorithm based on the frequency domain: step length, iteration number and initial value are compared. Compared with the analysis, the effectiveness of the improved algorithm based on the frequency domain plus window based time delay estimation is compared with the original algorithm, and the effectiveness of the improved algorithm is verified by simulation. In the last chapter of this paper, the experiment based on the channel estimation equalization algorithm based on the frequency domain proposed in the fourth chapter is used to improve the detection of the ultrasonic detection system. Measurement accuracy. Different probes have different physical characteristics. By detecting the data of the probe directly connected to the receiving probe, the probe can estimate the channel of the probe itself, so as to balance the received data, so that the error of the actual received data and the ideal received data is reduced and the accuracy of the detection system is improved. In this paper, the base In the whole process of the channel estimation and equalization algorithm of LFM signals from theory to simulation results, the effectiveness of the algorithm is fully verified, and the experimental results show that the proposed channel estimation and equalization algorithm has practical utility.

【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN911.5

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