Usually refers to the 50Hz AC interference signal from the outside world and the power supply of the electrocardiograph itself. This interference signal is regular.
50Hz AC interference is usually divided into the following types:
1. AC magnetic field interference;
2. Leakage current interference;
3. Impedance coupling interference;
4. Electrostatic interference
5. Ground loop interference;
6. 50Hz interference inside the instrument and so on.
In actual work, the usual method to eliminate 50Hz AC interference is to make the ECG machine well grounded (generally, the grounding resistance is required to be ≤4Ω). However, because there are many reasons for 50Hz AC interference and the situation is more complicated, it is often impossible to effectively eliminate the interference only by dealing with the grounding wire.
