Design and Implementation of IIR Filters for Power Line Interference Removal in Intramuscular EMG signals

EMG signals, also known as electromyography signals, are often used a lot in biomedical information transmission. They are electric impulses of skeletal muscles, which contain significant body information and objects’ movement intentions. During the transmission of EMG signals, various interferences and noises can accompany the original signal. One of the most common noises is the power line interference. This interference occurs at specific frequencies, so it's important to remove only the signals at these frequencies while preserving the rest of the signal. In this paper, two kinds of filters, FIR filters and IIR filters, are used and compared to do the task of removing interference. In the first part, through an experiment comparing the properties of FIR and IIR filters, this paper demonstrated that IIR filters performed better at removing power line interference. In the next part, with the help of Matlab and a designed experiment, this paper illustrated the suitability of IIR filters for removing interference, including an analysis of their poles, zeros, and overall function. Then in the third part, a Matlab-based experiment demonstrated how a properly designed IIR filter sequentially removed interference at 60, 120, and 180Hz. The experiment results showed that only the noise components were removed, while all the parts containing useful information were preserved in their original form.