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


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Inputs/Outputs

  • cnclst.png trimmed percent —

    trimmed percent specifies how this VI trims the spectrogram at high frequencies and at low frequencies before computing the MIF. If obvious noise exists at high frequencies or at low frequencies, use trimmed percent to improve the accuracy of the MIF estimation.

  • cdbl.png upper —

    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.

  • cdbl.png lower —

    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.

  • c2ddbl.png spectrogram —

    spectrogram specifies the quadratic time-frequency representation of a signal.

    Use the Time Frequency Spectrogram VIs to compute the spectrogram of the signal.

  • cfxdt.png scale info —

    scale info specifies the time scale information and the frequency scale information of the time-frequency representation.

  • cerrcodeclst.png error in (no error) —

    error in describes error conditions that occur before this node runs. This input provides standard error in functionality.

  • icclst.png MIF —

    MIF returns the mean instantaneous frequency of the signal at each time bin.

  • idbl.png t0 —

    t0 returns the lowest value of the time bins in seconds.

  • idbl.png dt —

    dt returns the interval between the time bins in seconds.

  • i1ddbl.png frequency —

    frequency returns the resulting mean instantaneous frequencies at each time bin in hertz.

  • ierrcodeclst.png error out —

    error out contains error information. This output provides standard error out functionality.

    • TFA Mean Instantaneous Frequency Details

    The following equation defines the MIF of a signal:

    where is the spectrogram 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 Frequency VI:

    • Blood Flow Measurement VI: labview\examples\Time Frequency Analysis\TFAApplications
    • Liquefaction Detection VI: labview\examples\Time Frequency Analysis\TFAApplications
    • Mean Instantaneous Frequency or Bandwidth (MIF or MIB) VI: labview\examples\Time Frequency Analysis\TFAFunctions
    • Quadratic JTFA Method VI: labview\examples\Time Frequency Analysis\TFAGettingStarted