Larson Davis SoundAdvisor 831C Reference Manual page 146

Sampled Sound
Sampled Sound
Sampled Sound
SoundAdvisor Model 831C
FIGURE 18-2
Example- Rectangular Windowing
Window Shape
Samples
Flat Top: The Flat Top window shape descends below zero at the end of each
time record and allows for wider-spaced peaks in the frequency domain. As a
result, this method may more accurately show the true amplitude of peaks, but
possibly with less detail in the signal overall.
FIGURE 18-3
Example- Flat Top Windowing
Window Shape
Hanning: This windowing method forces the ends of the time record to zero
and changes the wave form to a curve with side lobes to reduce any spectral
leakage. The spectral leakage sometimes results when a sine wave signal is
captured non-periodically.
The Hanning window is the G4 default and the most commonly used method,
because it provides the most accurate levels with the least spectral leakage. It is
also the windowing method required to meet the ISO Tonality standard. If
you're not sure which window to apply; choose Hanning.
FIGURE 18-4 Example- Hanning Windowing
Window Shape
Samples
Samples
Creating an FFT Setup File On the Meter
Waveform With Windowing
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Waveform With Windowing
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Waveform With Windowing
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