Windowing for Vibration Analysis

1. WINDOWING FOR VIBRATION
ANALYSIS
ADITYA RINDRA ADHIANTO (15/379026/TK/42968)
AIMAN RIFQI ALTHOF (15/379028/TK/42970)
AKBAR NUR BAHTIAR (15/379030/TK/42972)
ALFIAN YOGA MAHENDRA (15/379032/TK/42974)

2. FAST FOURIER TRANSFORM
The Fast Fourier Transform (FFT) resolves a time waveform into its sinusoidal
components. The FFT takes a block of time-domain data and returns the frequency
spectrum of the data. The FFT is a digital implementation of the Fourier transform.
Thus, the FFT does not yield a continuous spectrum. Instead, the FFT returns a
discrete spectrum, in which the frequency content of the waveform is resolved
into a finite number of frequency lines, or bins.

3. FAST FOURIER TRANSFORM
To achieve the final relevant output, the signal is processed with the following
steps:
• Analog signal input
• Anti-alias filter
• A/D converter
• Overlap
• Windowing
• FFT
• Averaging
• Display/storage.

4. WHAT IS WINDOWING?

5. WINDOWING IN
VIBRATION ANALYSIS
• In FFT (Fast Fourier Transform), Periodicity is one of assumption
used. Windowing is a method used to ensure the periodicity.
Windowing multiply data with window function before the FFT is
used. Window function have a zero value at the start and the end
of the period.
• Windowing used to reduce leakage aberration in the FFT (Fast
Fourier Transform) that are introduced by sudden change of data.

6. CONTINUE
Input Data after multiply in
Window Function always
have a zero value at the start
and at the end of the period.

7. The Principle of Windowing

8. TYPE OF WINDOWS FUNCTION
• Rectangular Window
• Hamming Window
• Hann Window
• Blackman Window
• Bartlett Window

9. Rectangular Window
The rectangular window (sometimes known as the boxcar or
Dirichlet window) is the simplest window, equivalent to
replacing all but N values of a data sequence by zeros, making it
appear as though the waveform suddenly turns on and off:
W(n) = i

10. Hamming Window
The window with these particular coefficients was proposed by Richard W.
Hamming. The window is optimized to minimize the maximum (nearest) side
lobe, giving it a height of about one-fifth that of the Hann window.

11. Hann Window
The Hann window, named after Julius von Hann, is sometimes referred to as
Hanning, presumably due to its linguistic and formulaic similarities to Hamming
window. It is also known as raised cosine, because the zero-phase version, Wo (n) is
one lobe of an elevated cosine function.

12. Blackman Window
Blackman windows are defined as:

13. Bartlett Window
Bartlett Window defined as:
:

14. -THANK YOU-