Comparisons of Estimation Methods of Instantaneous Frequency and Examples of its Application to Beam, Engine Block, and Car Door Vibration

순간 진동수 추정 방법론의 비교와 외팔보, 엔진 블록 및 자동차 문 진동에 의 적용예

  • 박연규 (한국과학기술원, 기계공학과) ;
  • 김양한 (한국과학기술원, 기계공학과)
  • Published : 1993.12.01

Abstract

Although a frequency analysis by FFT algorithm has been widely used in the vibration community, this approach has somewhat limited features when an analysist want to see the details of frequency trends because FFT shows only energy contents along frequencies. So the concept of instantaneous frequency that represents the dominant frequency component at each time needs to be introduced. In this paper, to get the instantaneous frequency, two methods are used. Methods using Hilbert transform and evolutionary spectrum are those. One of the problems of estimating instantaneous frequency using Hilbert transform is that it is normally very sensitive to signal to noise ratio(SNR) because of the differentiation. Moving window is applied on the estimation of instantaneous frequency, and instantaneous frequency histogram are used to handle this problem and proved to be very effective. Computer simulations for various signals have been done to understand the characteristics of instantaneous frequency. The usefulness of signal analysis using instantaneous frequency was tested by three simple experiments, which were engine experiment, beam experiment, and car door experiment. The instantaneous frequency analysis is found to be a useful technique to analyze the signals that have time varying frequencies.

Keywords

References

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