As a result of brain electrical signal is a very weak signal, the signal acquisition, amplification, processing and other process is very prone to interference, when the motor is disturbed, the performance of the waveform is not smooth, jitter, will affect the clinical diagnosis. The interference of EEG machine can be divided into external interference and internal interference. The main performance of interference calibration waveform is normal, in EEG time interference occurs. The reason is that the ground is bad, the input is short, the skin, the contact resistance of the electrode is too large and the surrounding environment.
Machine fault caused by interference performance is either fixed or the underlying EEG timing disturbance has existed, the detection can be the gain switch placed in the "0", the preamplifier input shorted to ground, to see whether the existence of interference, the main reason is component aging, differential amplifier tube symmetry and power supply filter circuit fault and so on, to exclude the interference, we have to use from the outside to the inside, from the simple to the complex method to think.
Should first check whether there around other appliances at work, to as far away as possible from these can produce equipment of electromagnetic waves, and view the electrode box and lead wires and the patient is met metallic bedstead or an instrument shell, to testing machine ground is good, but also pay attention to the internal modules of the ground.
Interference occurs in the detection of EEG recordings, should pay attention to check signal acquisition amplification processing pathway, check with scalp electrodes are connected properly, electrode box all sockets and lead wire plug contact is good. Also check all parts of the circuit board, because there are a lot of the same amplifier, so can be used to replace the method to find, pay attention to check the power filter, voltage regulator circuit, in particular, to pay attention to filter capacitor, voltage regulator, three terminal regulator block, etc..