Hi everyone
What is the frequency step size in the process of calculation of furier amplitude spectra in the seismosignal? And this step in this software, how and by what criteria is obtained? Can the frequency step size be selected less or more?
Thanks
frequency step size in fourier amplitude spectra
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seismosoft
- Posts: 1246
- Joined: 06 Jul 2007, 04:55
Re: frequency step size in fourier amplitude spectra
The Frequency Step is calculated as follows:
Fstep=Fmax/(FFTsize)
where:
Fmax equals to the sampling frequency
FFTsize is the number of FFT bins taken equal to the closest power of 2 which is found higher than the number of points of the imported accelerogram
The residual points between the number of FFT bins and the number of points of the accelerogram are filled using zero-padding.
Currently there is no possibility to use a frequency step different than the one calculated as above.
In the following version of Seismosignal a correction will be implemented so that Fmax is equal to Fsampling/2 and FFTsize/2 will be considered. This change does not affect the calculated frequency step.
Seismosoft Support
Fstep=Fmax/(FFTsize)
where:
Fmax equals to the sampling frequency
FFTsize is the number of FFT bins taken equal to the closest power of 2 which is found higher than the number of points of the imported accelerogram
The residual points between the number of FFT bins and the number of points of the accelerogram are filled using zero-padding.
Currently there is no possibility to use a frequency step different than the one calculated as above.
In the following version of Seismosignal a correction will be implemented so that Fmax is equal to Fsampling/2 and FFTsize/2 will be considered. This change does not affect the calculated frequency step.
Seismosoft Support