I need the details of the seminar on the topic as mentioned above.[/size][/font]

Structural behavioral Measurements
This article concentrates on the measurement of the vibration
of mechanical structures and machinery.

Spectral Analysis:
the most convenient way to analyze a vibration
signal is to obtain its frequency spectrum because Resonances are also manifested as peaks in a frequency
spectrum. also because Excitation forces (especially in rotating equipment), often
provide sinusoidal excitation at specific frequencies.

The FFT Analyzer:
The FFT computes
a discretized (sampled) version of the frequency spectrum of
a sampled time signal.Present day FFT analyzers can compute a DFT in milliseconds.

Rules of Digital Measurement:
Time Waveform:The DFT assumes that the sampled time
waveform contains N uniformly spaced waveform samples
Frequency Waveform: The DFT assumes that the digital
frequency spectrum contains N/2 uniformly spaced samples
of complex valued data
Nyquist Sampling: Shannonâ„¢s Sampling Theorem says that
a frequency spectrum can only contain unique frequencies


Zoom Measurements:
A Zoom transform is essentially a digital
filtering operation that takes place after the time waveform
has been sampled and it involves re-sampling, frequency shifting, and low pass filtering of the sampled data.

Digital Measurement Difficulties:
Aliasing
Aliasing of a signal occurs when it is sampled at less than
twice the highest frequency in the spectrum of the signal.In FFT it is solved by passing the analog signals through anti-aliasing
filters before they are sampled.
Leakage:
If a
time signal is not periodic in the transform window, when it
is transformed to the frequency domain, a smearing of its
spectrum will occur. This is called leakage.

for details , refer this pdf:
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