How Do You Calculate Spectral Density from FFT in Fortran 90?

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In summary, spectral density is a measure of the power or energy distribution of a signal at different frequencies. To obtain spectral density from a fast Fourier transform, the magnitude square of the FFT needs to be calculated, along with a scaling factor. Tom Irvine at VibrationData.com has resources and papers on this topic. It is also equivalent to calculating the Fourier transform of the autocorrelation function.
  • #1
Przem
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Spectral density?

How to get spectral density (e.g. of voltage noise) from a fast Fourier transform of a signal?
 
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  • #2
Are you doing this by hand or via some kind of software? A PSD is pretty much an equivilent to doing an RSS of the signal.

If you contact Tom Irvine at VibrationData.com, he has some great papers and references on this subject.
 
  • #3
i presume you mean power sprectrum or energy spectrum which is the Fourier Transform of the autocorrelation function. no?

i think you want the magnitude square of the FFT (there's another scaling factor involved.). later i'll post a more exact relationship.

gotta go.

r b-j
 
  • #4
I want to do it via Fortran 90 and I have main problem with this scaling factor.
 

What is spectral density?

Spectral density is a measure of the distribution of power or energy in a signal over a range of frequencies. It is commonly used in the analysis of signals and systems in fields such as physics, engineering, and statistics.

How is spectral density calculated?

Spectral density can be calculated using various methods, depending on the type of signal and the desired results. Some common methods include Fourier analysis, autocorrelation function, and power spectral density estimation. These methods involve transforming the signal into the frequency domain and analyzing its components.

What is the significance of spectral density?

Spectral density provides valuable information about the frequency content of a signal or system. It can be used to identify dominant frequencies, detect periodicity, and characterize noise or interference. It is also used in the design and analysis of filters and other signal processing techniques.

What are the units of spectral density?

The units of spectral density depend on the type of signal being analyzed and the method used to calculate it. In general, spectral density can have units of power per frequency, energy per frequency, or power per frequency per unit time. These units can vary, and it is important to specify the units when reporting spectral density values.

How is spectral density used in practical applications?

Spectral density has a wide range of applications in various fields. In physics and engineering, it is used in signal processing, spectrum analysis, and noise reduction. In statistics, it is used in time series analysis and forecasting. It is also used in fields such as telecommunications, astronomy, and geology for analyzing signals and systems.

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