选项DSOXDVM（DVM）不为零

当输入接地时，InfiniiVision 3000上的DVM选项（DSOXDVM）不会显示零伏特。
在DC刻度上，它通常显示-273 mV或大约，这不是一个不可忽视的偏移。
据推测，有一些方法可以为此测量设置参考电压，但我在手册中找不到它。
任何帮助将不胜感激。
谢谢，汤姆



     以下为原文

  The DVM option (DSOXDVM) on our InfiniiVision 3000 does not show zero volts when the input is grounded. On the DC scale it typically shows -273 mV or there abouts, which is not an inconsiderable offset. Presumably there is some way to set the reference voltage for this measurment, but I can't find it in the manual. Any help will be greatly appreciated.

Thanks,
Tom