西宁地震台FHD数字化核旋仪从2006年10月安装以来，一直与模拟仪器并行工作。二者采样率不同，所测的量也不相同。在对西宁地震台磁变仪的记录图纸进行数字化转换、生成分钟值的基础上，对FHD仪和磁变仪的观测结果进行对比分析。结果表明：数字FHD仪比三分量磁变仪更加准确地记录了当地地磁场的变化，数字仪器的观测资料明显优于模拟仪器。

Xining digital nuclear spin instrument（FHD）works since it has been installed in October 2006, and working in parallel with the analog equipment. The two instruments have different sample rate, the measured components are also not the same. In order to study the comparability of analog and digital recording, we generate minute values from the record drawings, and then, compared and analyzed the observational data of digital FHD meter and variometer in Xining station. The results showed that the digital FHD instrument is more accurate than the threecomponent variometer for recording the local geomagnetic field changes. The digital instrumentation is much better than the analog instruments.