高场核磁共振的数字正交检波方法

在核磁共振中,常规的正交检测技术采用两路相敏检波.因为两路相检波的相位和幅度存在不平衡而引起谱失真,所以必须用相位循环来消除.这增加了实验时间.本文提出并在MSL-300 NMR谱仪上实现了一种数字正交检波方法.这种方法使用单路相检波,避免了两路不平衡而引起的谱线失真,因此不需要相位循环技术

DIGITAL QUADRATURE DETECTION IN HIGH FIELD NMR

In conventional NMR, quadrature detection of free induction decay signal employs two channels of phase sensitive detector. With this technique, phase cycling for canceling the spectral distortion due to unbalance between two channels is indispensable. This makes the experiment time longer than necessary when the signal-to-noise ratio is good enough to ensure one scan sampling. In order to overcome this problem, a digital quadrature detection technique is proposed and carried out on an MSL-300 spectrometer in the present article. The method utilizes only one channel of analog-to-digit conversion. Therefore, distortion caused by the unbalance between two channels can be fully avoided. As a result, no phase cycling for canceling the distortion mentioned above is necessary.