Vibration signal filtering
- 1. MECHANICAL VIBRATION TASK VIBRATION SIGNAL FILTERING Member : 1. Ibrahim Faqih M 2. M. Nur Ardian 3. Arief Zulfauzi S 4. Petricius Ginting
- 2. INTRODUCTION Fig.1 Fast Fourier Transform used to convert spectrum from time domain into frequecy domain. Filtering is a tool for resolving signals. Filtering can be performed on either analog or digital signals. Furthermore, filtering can be used for a number of purposes. For example, analog signals are typically routed through a lowpass filter prior to analog-to digital conversion. The lowpass filter in this case is designed to prevent an aliasing error. This is an error whereby high frequency spectral components are added to lower frequencies Another purpose of filtering is to clarify resonant behavior by attenuating the energy at frequencies away from resonance
- 3. INTRODUCTION With today’s digital technology, there are two methods that are primarily used: the Fast Fourier Transform (FFT), and digital filtering. Both make use of digitized measurement values. Ideally, filters would block unwanted frequencies and provide a clean cutoff and keep out of unwanted signals. However this is not the case. In reality, there is a transition region where some frequencies will be attenuated, but not blocked. The actual filter designs are shown in Figures. It can be concluded that it’s very important to understand filter types to enable us to look at the data that we are only interested in. Fig.2 Conversion from time domain to frequency domain using FFT
- 4. THE TYPES OF VIBRATION SIGNAL FILTERING The vibration signal filtering have several types, there are : a) Low pass filter b)High pass filter c) Band pass filter d)Band stop filter
- 5. a) Low Pass Filters Antialiasing filtering is also known as low-pass filtering, where the frequency components above the Nyquist frequency in the signal are simply filtered out during data collection. However, depending on the requirements, signals can be low-pass filtered at any other frequency lower than the Nyquist frequency for the collected data during signal processing. THE TYPES OF VIBRATION SIGNAL FILTERING
- 6. a) Low Pass Filters (Continued) The characteristic of low pass filter are : Allow the low frequencies to pass through, but block the high frequencies Low pass filter set at 100Hz will remove the frequency content above 100Hz, but not below 100Hz It follows that a sinewave with a fundamental frequency of 10Hz would not be affected by a 100Hz low pass filter sinewave of 200Hz would be heavily affected by a low pass 100Hz filter as the frequency content above 100Hz would be removed THE TYPES OF VIBRATION SIGNAL FILTERING
- 7. a) Low Pass Filters (Continuous) THE TYPES OF VIBRATION SIGNAL FILTERING
- 8. b) High Pass Filters A HP filter typically removes the frequency content from a signal at and below any particular frequency fHigh. A typical high-pass filter at fHigh = 10 Hz for a signal is shown in Figure 6.4. In many cases, it is required to filter out low-frequency noise, DC components, etc., from the recorded/measured signals THE TYPES OF VIBRATION SIGNAL FILTERING
- 9. b) High Pass Filters (Continued) The characteristic of high pass filter are : The opposite to low pass filters Remove the frequency content below the cut off Frequency. THE TYPES OF VIBRATION SIGNAL FILTERING
- 10. THE TYPES OF VIBRATION SIGNAL FILTERING c) Band Pass Filter This is a combination of both HP and LP filters. For example, a time signal with a sampling rate ( fs) of 1000 samples/s (Hz) can be band-pass filtered in a frequency band of fHigh= 10 Hz to fLow = 200 Hz, as shown in Figure 6.5. This simply means the frequency components below 10 Hz and above 200 Hz will be filtered out from the signal. Typical examples of the above three filters are illustrated through measured data from a rotating machine in Figure 6.6. The characteristic of band pass filter is : Have a low and high cut off and will pass frequencies that fall between these two limits.
- 11. THE TYPES OF VIBRATION SIGNAL FILTERING c) Band Pass Filter (Continued) d) Band Stop filter Block the frequency content between the lower cut off and the higher cut off.
- 12. THE SPECTRUM Fig. 3 Different filters influence on a noise signal’s frequency spectrum when the signal passes through them: (i) Low pass filter (ii) High pass filter (iii) Band pass filter (iv) Band stop filter (Source: Brüel & Kjær, course material.)
- 13. REFERENCES http://www.xyobalancer.com/xyo-balancer-blog/filters-in-the-field-of-vibration http://blog.prosig.com/2011/10/04/understanding-filter-characteristics/ http://nptel.ac.in/courses/112107088/module1/lecture40/lecture40.pdf Jyoti Kumar Sinha. Vibration Analysis, Instrument, and Signal Processing. Boca Raton. 2015
- 14. THANK YOU