【摘要】 该文首先简要介绍了软件无线电的基本原理和基于软件无线电的射频接收系统的3种结构形式:射频全宽开低通采样结构,射频直接带通采样结构和宽带中频带通采样结构;并介绍了磁共振成像(MRI)回波信号接收的基本原理和将软件无线电方法应用于MRI回波信号接收的意义.然后该文重点介绍了采用3种软件无线电结构实现MRI回波信号接收系统的具体设计方案,包括接收系统方框图、工作原理、设计参数的选择和分析、部分功能模块的实现方法、设计和实现中需要注意的问题.最后以一个低场通用MRI回波接收系统为实例,分析比较了3种设计方案并给出了实际系统的测试结果.更多还原

【Abstract】 This paper briefly introduces software-defined radio,as well as three types of radio frequency(RF) receiving system based on the method of software-defined radio: RF sampling with low-pass filtering for fully bandwidth;RF directly sampling with band-pass filtering for narrow band signal and IF sampling with band-pass filtering for broad band signal.Then basic principles of receiving MRI echo with the method of software-defined radio are explained.The actual design of RF receiving system for MRI echo with the software-defined radio was presented,including receiving system diagram,working principle,selection and analysis of design parameters,implementation of some function module,and issues that should be considered during design and implementation.Analysis and comparison of three types of RF receiving system based on software-defined radio for low field MRI spectrometer were given.更多还原