中文摘要：

核磁共振回波信号幅度微弱,容易受到来自电子器件和外部环境噪声的干扰,要求回波检测方法既能实时采集回波数据,又能较好的抑制噪声.对比分析不同微弱信号检测方法的优缺点,归纳出DPSD（Digital Phase-Sensitivity Detection）方法在回波检测应用中的优越性.通过仿真计算,提出适用于回波信号检测的最佳滤波器窗函数.在自制的核磁共振仪器上进行实验,结果表明,DPSD方法在满足回波信号实时测量的同时,有效压制了噪声,能准确的提取出低场核磁共振回波信号的幅度和相位信息.

英文摘要：

In NMR logging,amplitude of NMR echo train is often weak,and vulnerable to noise contamination originated from either electronic devices or external environment.Both real-time acquisition and noise suppression are critical to echo envelope detection.In this paper,advantages and disadvantages of various echo envelope detection methods were reviewed.The superiority of DPSD（digital phase-sensitivity detection） for NMR echo detection was discussed.The optimal filter window function was obtained from simulation of the echo envelope.Experimental results showed that not only real-time measurement and noise reduction could be achieved by DPSD,but also the amplitude and phase could be extracted accurately.