TFA Mean Instantaneous Bandwidth VI

LabVIEW 2014 Advanced Signal Processing Toolkit Help

Edition Date: June 2014

Part Number: 372656C-01

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Owning Palette: Feature Extraction VIs

Requires: Advanced Signal Processing Toolkit

Computes the mean instantaneous bandwidth (MIB) of a signal from its spectrogram. The mean instantaneous bandwidth reveals how the frequency bandwidth of the signal changes over time.

Details  Examples

	trimmed percent specifies how this VI trims the spectrogram at high frequencies and at low frequencies before computing the instantaneous bandwidth. If obvious noise exists at high frequencies or at low frequencies, use trimmed percent to improve the accuracy of the instantaneous bandwidth estimation. upper specifies the percent of noise power at high frequencies to the total power of the spectrogram. upper must be less than 100–lower. The larger the percentage, the more bins at high frequencies this VI trims. lower specifies the percent of noise power at low frequencies to the total power of the spectrogram. lower must be less than 100–upper. The larger the percentage, the more bins at low frequencies this VI trims.
	spectrogram specifies the quadratic time-frequency representation of a signal. Use the Time Frequency Spectrogram VIs to compute the spectrogram of the signal.
	scale info specifies the time scale information and the frequency scale information of the time-frequency representation.
	error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
	MIB returns the mean instantaneous bandwidth of the signal at each time bin. t0 returns the lowest value of the time bins in seconds. dt returns the interval between the time bins in seconds. bandwidth returns the resulting mean instantaneous bandwidth at each time bin in hertz.
	error out contains error information. This output provides standard error out functionality.

TFA Mean Instantaneous Bandwidth Details

The following equation defines the instantaneous bandwidth of a signal:

where is the spectrogram of the signal, and is the mean instantaneous frequency of the signal. The spectrogram can result from any Time Frequency Spectrogram VI.

Examples

Refer to the following VIs for examples of using the TFA Mean Instantaneous Bandwidth VI:

• Blood Flow Measurement VI: labview\examples\Time Frequency Analysis\TFAApplications
• Mean Instantaneous Frequency or Bandwidth (MIF or MIB) VI: labview\examples\Time Frequency Analysis\TFAFunctions