HRV FFT Spectrum VI

Owning Palette: HRV Analysis VIs

Requires: Biomedical Toolkit

Extracts frequency-domain measurements of the heart rate variability (HRV) from RR intervals by using the fast Fourier transform (FFT) method.

You must manually select the polymorphic instance to use.

Example

HRV FFT Spectrum (Array Unevenly Sampled RR)

	RR specifies the RR intervals that this VI uses to calculate the power spectral density (PSD).
	raw RR specifies the raw RR intervals. This VI interpolates raw RR intervals to an evenly-sampled time series.
	FFT settings specifies the FFT parameters, including window settings, frequency bins, and frequency band settings. window settings specifies the information of the sliding window that divides the time series into subsequences. window specifies the time-domain window that this VI applies to the time series. 0 None 1 Hanning (default) 2 Hamming 3 Blackman-Harris 4 Exact Blackman 5 Blackman 6 Flat Top 7 4 Term B-Harris 8 7 Term B-Harris 9 Low Sidelobe length specifies the length of the window. A large window generates a PSD with small bias but results in a coarse PSD plot. A small window generates a smooth PSD plot but leads to large bias. The default is 1024. overlap specifies the overlap, in percentage, of the moving window that this VI applies to the time series. overlap determines how much data this VI reuses for the signal space matrix. A large overlap reduces the variance of the resulting power spectrum but increases computation time. The default is 50, which specifies that the overlap is half of the window length. dB on? specifies whether this VI returns the PSD in decibels or in a linear scale. If dB on? is TRUE, this VI returns the PSD in decibels. If dB on? is FALSE, this VI returns the PSD in a linear scale. The default is FALSE. frequency bins specifies the number of frequency bins for which this VI computes the single-sided PSD. The length of the single-sided PSD is (frequency bins/2+1). The default is 1024. frequency bands specifies the frequency ranges of very low frequency (VLF), low frequency (LF), and high frequency (HF) to calculate the FFT measurements. VLF high specifies the high limit of the VLF frequency band, in hertz. The default is 0.04. VLF low specifies the low limit of the VLF frequency band, in hertz. The default is 0. LF high specifies the high limit of the LF frequency band, in hertz. The default is 0.15. LF low specifies the low limit of the LF frequency band, in hertz. The default is 0.04. HF high specifies the high limit of the HF frequency band, in hertz. The default is 0.4. HF low specifies the low limit of the HF frequency band, in hertz. The default is 0.15.
	error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
	interpolation rate specifies the rate of interpolation, in hertz, for converting raw RR intervals into an evenly-sampled time series. The default is 2.
	FFT spectrum returns the FFT spectrum of the input RR intervals. f0 returns the lower boundary, in hertz, of the frequency range. df returns the frequency increment, in hertz. S(f) returns the magnitude of the PSD at each frequency. The value of dB on? determines the unit of measurement for S(f).
	FFT measurements returns the VLF, LF, and HF information of the input RR intervals. VLF peak frequency returns the peak frequency of the PSD estimate in VLF bands, in hertz. VLF peak amplitude returns the peak amplitude of the PSD estimate in VLF bands, in milliseconds squared. LF peak frequency returns the peak frequency of the PSD estimate in LF bands, in hertz. LF peak amplitude returns the peak amplitude of the PSD estimate in LF bands, in milliseconds squared. HF peak frequency returns the peak frequency of the PSD estimate in HF bands, in hertz. HF peak amplitude returns the peak amplitude of the PSD estimate in HF bands, in milliseconds squared. VLF power returns the absolute value of power in VLF bands, in milliseconds squared. LF power returns the absolute value of power in LF bands, in milliseconds squared. HF power returns the absolute value of power in HF bands, in milliseconds squared. LF norm returns the normalized unit of power in LF bands, which represents the relative value of LF power in proportion to the total power minus the VLF power. HF norm returns the normalized unit of power in HF bands, which represents the relative value of HF power in proportion to the total power minus the VLF power. LF/HF returns the ratio of LF power to HF power. VLF returns the distribution of power in VLF bands. LF returns the distribution of power in LF bands. HF returns the distribution of power in HF bands.
	error out contains error information. This output provides standard error out functionality.

HRV FFT Spectrum (Waveform Evenly Sampled RR)

	RR specifies the RR intervals that this VI uses to calculate the power spectral density (PSD).
	FFT settings specifies the FFT parameters, including window settings, frequency bins, and frequency band settings. window settings specifies the information of the sliding window that divides the time series into subsequences. window specifies the time-domain window that this VI applies to the time series. 0 None 1 Hanning (default) 2 Hamming 3 Blackman-Harris 4 Exact Blackman 5 Blackman 6 Flat Top 7 4 Term B-Harris 8 7 Term B-Harris 9 Low Sidelobe length specifies the length of the window. A large window generates a PSD with small bias but results in a coarse PSD plot. A small window generates a smooth PSD plot but leads to large bias. The default is 1024. overlap specifies the overlap, in percentage, of the moving window that this VI applies to the time series. overlap determines how much data this VI reuses for the signal space matrix. A large overlap reduces the variance of the resulting power spectrum but increases computation time. The default is 50, which specifies that the overlap is half of the window length. dB on? specifies whether this VI returns the PSD in decibels or in a linear scale. If dB on? is TRUE, this VI returns the PSD in decibels. If dB on? is FALSE, this VI returns the PSD in a linear scale. The default is FALSE. frequency bins specifies the number of frequency bins for which this VI computes the single-sided PSD. The length of the single-sided PSD is (frequency bins/2+1). The default is 1024. frequency bands specifies the frequency ranges of very low frequency (VLF), low frequency (LF), and high frequency (HF) to calculate the FFT measurements. VLF high specifies the high limit of the VLF frequency band, in hertz. The default is 0.04. VLF low specifies the low limit of the VLF frequency band, in hertz. The default is 0. LF high specifies the high limit of the LF frequency band, in hertz. The default is 0.15. LF low specifies the low limit of the LF frequency band, in hertz. The default is 0.04. HF high specifies the high limit of the HF frequency band, in hertz. The default is 0.4. HF low specifies the low limit of the HF frequency band, in hertz. The default is 0.15.
	error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
	FFT spectrum returns the FFT spectrum of the input RR intervals. f0 returns the lower boundary, in hertz, of the frequency range. df returns the frequency increment, in hertz. S(f) returns the magnitude of the PSD at each frequency. The value of dB on? determines the unit of measurement for S(f).
	FFT measurements returns the VLF, LF, and HF information of the input RR intervals. VLF peak frequency returns the peak frequency of the PSD estimate in VLF bands, in hertz. VLF peak amplitude returns the peak amplitude of the PSD estimate in VLF bands, in milliseconds squared. LF peak frequency returns the peak frequency of the PSD estimate in LF bands, in hertz. LF peak amplitude returns the peak amplitude of the PSD estimate in LF bands, in milliseconds squared. HF peak frequency returns the peak frequency of the PSD estimate in HF bands, in hertz. HF peak amplitude returns the peak amplitude of the PSD estimate in HF bands, in milliseconds squared. VLF power returns the absolute value of power in VLF bands, in milliseconds squared. LF power returns the absolute value of power in LF bands, in milliseconds squared. HF power returns the absolute value of power in HF bands, in milliseconds squared. LF norm returns the normalized unit of power in LF bands, which represents the relative value of LF power in proportion to the total power minus the VLF power. HF norm returns the normalized unit of power in HF bands, which represents the relative value of HF power in proportion to the total power minus the VLF power. LF/HF returns the ratio of LF power to HF power. VLF returns the distribution of power in VLF bands. LF returns the distribution of power in LF bands. HF returns the distribution of power in HF bands.
	error out contains error information. This output provides standard error out functionality.

HRV FFT Spectrum (Array Evenly Sampled RR)

	RR specifies the RR intervals that this VI uses to calculate the power spectral density (PSD).
	FFT settings specifies the FFT parameters, including window settings, frequency bins, and frequency band settings. window settings specifies the information of the sliding window that divides the time series into subsequences. window specifies the time-domain window that this VI applies to the time series. 0 None 1 Hanning (default) 2 Hamming 3 Blackman-Harris 4 Exact Blackman 5 Blackman 6 Flat Top 7 4 Term B-Harris 8 7 Term B-Harris 9 Low Sidelobe length specifies the length of the window. A large window generates a PSD with small bias but results in a coarse PSD plot. A small window generates a smooth PSD plot but leads to large bias. The default is 1024. overlap specifies the overlap, in percentage, of the moving window that this VI applies to the time series. overlap determines how much data this VI reuses for the signal space matrix. A large overlap reduces the variance of the resulting power spectrum but increases computation time. The default is 50, which specifies that the overlap is half of the window length. dB on? specifies whether this VI returns the PSD in decibels or in a linear scale. If dB on? is TRUE, this VI returns the PSD in decibels. If dB on? is FALSE, this VI returns the PSD in a linear scale. The default is FALSE. frequency bins specifies the number of frequency bins for which this VI computes the single-sided PSD. The length of the single-sided PSD is (frequency bins/2+1). The default is 1024. frequency bands specifies the frequency ranges of very low frequency (VLF), low frequency (LF), and high frequency (HF) to calculate the FFT measurements. VLF high specifies the high limit of the VLF frequency band, in hertz. The default is 0.04. VLF low specifies the low limit of the VLF frequency band, in hertz. The default is 0. LF high specifies the high limit of the LF frequency band, in hertz. The default is 0.15. LF low specifies the low limit of the LF frequency band, in hertz. The default is 0.04. HF high specifies the high limit of the HF frequency band, in hertz. The default is 0.4. HF low specifies the low limit of the HF frequency band, in hertz. The default is 0.15.
	error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
	sampling rate specifies the sampling rate of the input RR intervals, in hertz. The default is 1.
	FFT spectrum returns the FFT spectrum of the input RR intervals. f0 returns the lower boundary, in hertz, of the frequency range. df returns the frequency increment, in hertz. S(f) returns the magnitude of the PSD at each frequency. The value of dB on? determines the unit of measurement for S(f).
	FFT measurements returns the VLF, LF, and HF information of the input RR intervals. VLF peak frequency returns the peak frequency of the PSD estimate in VLF bands, in hertz. VLF peak amplitude returns the peak amplitude of the PSD estimate in VLF bands, in milliseconds squared. LF peak frequency returns the peak frequency of the PSD estimate in LF bands, in hertz. LF peak amplitude returns the peak amplitude of the PSD estimate in LF bands, in milliseconds squared. HF peak frequency returns the peak frequency of the PSD estimate in HF bands, in hertz. HF peak amplitude returns the peak amplitude of the PSD estimate in HF bands, in milliseconds squared. VLF power returns the absolute value of power in VLF bands, in milliseconds squared. LF power returns the absolute value of power in LF bands, in milliseconds squared. HF power returns the absolute value of power in HF bands, in milliseconds squared. LF norm returns the normalized unit of power in LF bands, which represents the relative value of LF power in proportion to the total power minus the VLF power. HF norm returns the normalized unit of power in HF bands, which represents the relative value of HF power in proportion to the total power minus the VLF power. LF/HF returns the ratio of LF power to HF power. VLF returns the distribution of power in VLF bands. LF returns the distribution of power in LF bands. HF returns the distribution of power in HF bands.
	error out contains error information. This output provides standard error out functionality.

Example

Refer to the HRV Analyzer VI in the labview\examples\Biomedical\Biosignal directory for an example of using the HRV FFT Spectrum VI.