MultitaperSpectrum (FPScript)
Computes the Slepian or DPSS Multitaper Fourier spectrum.
Syntax
MultitaperSpectrum(Signal, [ SpectrumType = SPECTRUM_DBNORM ], [ Adjustment = 4.0 ], [ WindowCount = WIN_NORMALIZEAMPLITUDE ], [ FFTLength = 0 ] [ , Peaks ])
The syntax of the MultitaperSpectrum function consists of the following parts:
Part |
Description |
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Signal |
The data to be analyzed. The data must have a constant sampling rate and must not contain void values. Permitted data structures are data series, data matrix, signal und signal series. All real data types are permitted, except calendar time und time span. Void values are not permitted in this argument. For the X component additional restrictions do apply.The values must have a constant positive spacing. Void values are not permitted in this argument. If the argument is a list, then the function is executed for each element of the list and the result is also a list. |
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SpectrumType |
The spectral format to be computed. The argument SpectrumType can have the following values:
Permitted data structures are scalar value. All integral data types are permitted. If the argument is a list, then the first element in the list is taken. If this is also a list, then the process is repeated. If this argument is omitted, it will be set to the default value SPECTRUM_DBNORM. |
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Adjustment |
The one-sided Fourier width as a multiple of the frequency interval. Permitted data structures are scalar value. All real data types are permitted. The value must be greater or equal to 2.0 and less or equal to 5.0. If the argument is a list, then the first element in the list is taken. If this is also a list, then the process is repeated. If this argument is omitted, it will be set to the default value 4.0. |
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WindowCount |
The number of windows to be applied and averaged in the DPSS sequence. The valid range is between 1 and 2 * Adjustment -1. As an option, a constant can be added to select amplitude or power normalization. The default value 0 + WIN_NORMALIZEAMPLITUDE chooses the maximum number of windows and amplitude normalization. The argument WindowCount can have the following values:
Permitted data structures are scalar value. All integral data types are permitted. If the argument is a list, then the first element in the list is taken. If this is also a list, then the process is repeated. If this argument is omitted, it will be set to the default value WIN_NORMALIZEAMPLITUDE. |
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FFTLength |
The length of the Fourier transform. Zero padding applies if the FFT length is greater than the data length. The valid range is from the data length to the maximum limit of FFT. The default value is -1, which sets the FFT length equal to the next highest power of two. The default value is 0, which sets FFT length equal to the data length. Permitted data structures are scalar value. All integral data types are permitted. The value must be greater or equal to -1 and less or equal to 2147483648. If the argument is a list, then the first element in the list is taken. If this is also a list, then the process is repeated. If this argument is omitted, it will be set to the default value 0. |
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Peaks |
If specified, only bin-interpolated peaks in the spectrum are output. The peaks can be specified as a number of peaks, a positive number from 1 to 100, or as an F value, a negative number from -1000 to -0.5. This argument is permitted for one-dimensional data sets only. Permitted data structures are scalar value. All real data types are permitted. If the argument is a list, then the first element in the list is taken. If this is also a list, then the process is repeated. |
Remarks
The data structure of the result is a signal or signal series. If the argument Signal is a data series or data matrix, then the X component of the result contains Nyquist-normalized frequencies.
Available in
Option Spectral Analysis
Examples
MultitaperSpectrum(Signal, SPECTRUM_DBNORM, 3, 0 + WIN_NORMALIZEPOWER, 4096)
Calculates the multitaper Fourier spectrum for the signal 'Signal'. This method is used when a spectral estimation with low variance is required, such as for measuring power. dB is normalized as the spectrum type and 3 is selected as the window adjustment. The number of DPSS windows is set to the maximum value. The FFT length is 4096. This is an example from the Fourier Spectral Analysis Tutorial.