Frequency tracking power frequency digital filtering method

Abstract

A method for filtering power frequency digit by frequency-tracking includes switching power frequency reference signal into signal input end of phase locked loop, outputting eight frequency multiplier signal of power frequency by said loop when eight frequency division signal of power frequency outputted by central processor is switched into comparison input end of said loop, using said frequency multiplier signal as sampling signal sequence, using comb filtering algorithm to realize trop of power frequency and its frequency multiplier, finally controlling and outputting filtered signal by central processor.

Description

technical field [0001] The invention relates to a digital filtering method, in particular to a power frequency digital filtering method for frequency tracking. It belongs to the technical field of electronic circuits. Background technique [0002] In the detection of industrial measurement and control systems and biomedical signals (such as ECG, EEG, etc.), the detected signal is easily affected by the power frequency interference generated by the surrounding external 50Hz electric and magnetic fields. In severe cases, the effective signal will be overwhelmed by such interference . Therefore, in the detection of various electrical signals, especially biomedical signal detection, suppressing power frequency interference is one of the most important issues. At present, there are many mature methods for eliminating 50Hz power frequency interference signals. The adaptive filter has a strong suppression effect on power frequency interference, and can automatically adjust its s...

AI Technical Summary

Problems solved by technology

In 1975, Bernard Window et al. proposed the linear least square estimation (LMS) algorithm. Its shortcoming is that for the A / D process of the power signal and its higher harmonics, A / D converters are required respectively. In addition to the power frequency and its second harmonic, four A / D converters are required, and the amount of calculation is large at the same time

Since the origin is also a zero point of the filter, the filter will filter out the DC component of the signal, which can be used in the process of extracting bioelectrical signals such as ECG, because the low frequency component will be extracted from a certain To a certain extent, it can cause interference phenomena such as baseline drift, but it is not suitable for situations where slowly changing signals need to be retained, so its application range is limited to a certain extent

[0004] Through literature retrieval of the prior art, it was found that Wang Zhizhong et al. published "The Realization Method of Digital Notch Filter" in "Journal of Shanghai Jiaotong University" 1995 Supplement I, P21-25, in which the digital comb filter method was proposed , the specific method is: use the comb filter to completely suppress the fundamental frequency and some harmonic components, the transfer function is: H ( z ) = 1 - z - 1 1 - α z - 1 ), its shortcoming is that this technology does not involve the parameter setting of the filter and hardware details, nor does it give a specific solution

Images