| 摘要 |
A method and an apparatus for suppressing power frequency common mode interference which are used in a bioelectrical signal measuring system comprising a common mode interference signal extracting circuit and a driving circuit connected to the extracting circuit are provided. The driving circuit changes a phase of a common mode interference signal and amplifies the common mode interference signal, so as to output two-way amplified signals, wherein one amplified signal is selectively outputted to a living body on examination. In particular, the apparatus further includes phase compensating and processing means for receiving both a bioelectrical signal from the living body on examination and the other amplified signal outputted from the driving circuit, determining a phase compensation amount of the other amplified signal outputted from the driving circuit according to a characteristic value of the power frequency interference in the bioelectrical signal so as to phase-compensate the other amplified signal outputted from the driving circuit, and selectively outputting the phase-compensated amplified signal to the living body on examination. The method for suppressing power frequency common mode interference comprises the following steps of: receiving a bioelectrical signal from a living body on examination by phase compensating and processing means; analyzing the characteristic of the bioelectrical signal and determining a phase compensation amount by the phase compensating and processing means; performing a corresponding time delay processing on an amplified signal outputted by the driving circuit; and providing the delay signal to the living body on examination. According to this invention, the capability of the circuit for suppressing power frequency common mode interference is getting improved, and the stability of the analog circuit system and the phase-frequency characteristic of the circuit are maintained. This contributes to the improvement of the quality of the sampled bioelectrical signals.
|
