多频段信号抗混叠接收算法研究与硬件实现

发布时间：2018-11-06 08:40

【摘要】：软件定义无线电作为一种通过软件实现不同器件功能的射频通信技术,旨在实现无线传输系统由模拟向数字的转变。软件无线电采用可升级、可重构的应用软件实现无线电功能,解决了传统无线电台功能单一、扩展性差等问题。近年来由于A/D采样技术的发展,采样速率和精度不断提高,带通采样被广泛应用于软件无线电接收机中。然而,在采样过程中,采样后信号镜像混叠和有用信号间的混叠问题普遍存在,影响了多模式、多频段信号在同一平台上的正常接收。因此研究实现同一硬件平台对多频段、多制式信号的无混叠接收问题,在无线通信,尤其是多模式、多频段的软件无线电接收机中,具有很好的理论与应用价值。本文基于二阶带通采样和多频段信号采样频率规则对多频段信号抗混叠接收进行研究:首先,针对多频段信号采样后混叠问题,基于二阶带通采样原理及软件无线电抗混叠接收机的理论基础,提出了一种分离两路混叠信号的相位调整滤波算法,设计了一种抗混叠滤波器。并在仿真过程中分析了时间延时、采样信号位置索引差值、群延时、滤波器tap数对抗混叠滤波器性能的影响,为实现多频段抗混叠硬件平台提供了最优化参数设计方案。其次,基于现有的多频段信号最小采样频率搜索算法,对多频段信号的采样频率方法进行了研究,对采样频率约束条件进行改进,提出了一种允许采样后同一位置存在两路混叠信号的采样频率搜索算法。通过仿真分析验证了算法的有效性,该算法约束条件较传统多频段信号采样算法更广泛,有效降低了计算复杂度,更利于硬件实现和工程应用。最后,设计了一个可实现对多频段信号无混叠接收的软件无线电硬件平台。通过自定义模块实现了该平台和GNU Radio的连接。该平台验证了本文所提采样频率方法与相位调整算法的正确性,最终实现多路混叠信号的分离与接收。该基于GNU Radio的带通采样无线电处理平台无需修改硬件就可以实现多种信号接收并消除混叠。为基于软件无线电的无线通信系统的开发工作和多带通采样等相关实验提供了更加便捷的硬件平台。
[Abstract]:Software defined radio (SDR) is a kind of radio frequency communication technology which realizes the function of different devices by software. It aims to change the wireless transmission system from analog to digital. Software radio uses scalable and reconfigurable application software to realize radio function, which solves the problems of single function and poor expansibility of traditional radio station. In recent years, due to the development of A- / D sampling technology, the sampling rate and precision have been improved, and band-pass sampling has been widely used in software radio receivers. However, in the process of sampling, the problem of aliasing between image images and useful signals after sampling is common, which affects the normal reception of multi-mode and multi-frequency signals on the same platform. Therefore, it is of great theoretical and practical value to study and implement the same hardware platform for multi-band and multi-standard signal receiving without aliasing in wireless communication, especially in multi-mode and multi-frequency software radio receiver. In this paper, the anti-aliasing reception of multi-band signals is studied based on second-order bandpass sampling and multi-band signal sampling frequency rules. Based on the second-order bandpass sampling principle and the theoretical basis of software radio anti-aliasing receiver, a phase-adjusted filtering algorithm for separating two-channel aliasing signals is proposed, and an anti-aliasing filter is designed. The effects of time delay, sampling signal location index difference, group delay and filter tap number on the performance of the aliasing filter are analyzed in the simulation process, which provides an optimal parameter design scheme for the anti-aliasing hardware platform in multi-frequency band. Secondly, based on the existing minimum sampling frequency search algorithm of multi-band signal, the sampling frequency method of multi-band signal is studied, and the sampling frequency constraint condition is improved. This paper presents a sampling frequency search algorithm that allows two aliasing signals to exist at the same location after sampling. The simulation results show that the algorithm is more effective than the traditional multi-band signal sampling algorithm, which reduces the computational complexity and is more convenient for hardware implementation and engineering application. At last, a hardware platform of software radio is designed, which can receive multi-band signals without aliasing. The connection between the platform and GNU Radio is realized by custom module. The platform verifies the correctness of the proposed sampling frequency method and phase adjustment algorithm, and finally realizes the separation and reception of multichannel aliasing signals. The bandpass sampling radio processing platform based on GNU Radio can realize multiple signal reception and eliminate aliasing without modifying hardware. It provides a more convenient hardware platform for the development of wireless communication system based on software radio and related experiments such as multi-bandpass sampling.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN92

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