【摘要】 针对低场磁共振成像系统,该文设计了一种紧凑灵活的信号接收方案,实现对多通道磁共振信号的高速采样与直接数字解调.系统采用高速模数转换器(A/D)对磁共振信号直接采样;以单片数字下变频器(DDC)——AD6636,完成4路采样信号的数字解调;以数字信号处理器(DSP)作为控制器,实现对AD6636的配置以及I/Q数据的读取.信号采样频率可达100 MSPS,适用于1 T以下的系统.实验证明该设计具有结构紧凑,采样速率高,配置方便快速,滤波器设计丰富灵活等特点,为磁共振成像谱仪的研制提供了一种高性能的信号接收方案.更多还原

【Abstract】 In this paper,a compact and flexible signal receiving system mainly designed for low-field MRI systems is presented,which is capable of sampling multi-channel magnetic resonance signals simultaneously at a high speed and demodulating them directly.A digital down conversion chip(AD6636) was used to demodulate and decimate the signals from the four channels in a quadrature way.Digital signal processing(DSP) methods were used to complete the configuration of AD6636 and read out the I/Q data either from all channels at once,or just from one channel of interest.The sampling speed of the system could reach 100 million samples per second,giving high signal-to-noise.The system can be applied in MRI system with magnetic field strength up to 1 T.The performance of the signal receiving system was demonstrated by experimental results.更多还原