Anti-interference ability of digital multimeter
Simple digital multimeters generally use the principle of integral A/D conversion. As long as the forward integration time is selected to be exactly equal to the integer multiple of the period of the series interference signal, the series interference can be effectively suppressed. This is because the cross-frame interference signal is averaged out in the forward integration stage. The common frame rejection ratio (CMRR) of medium and low-grade digital multimeters can reach 86-120dB.
