Decomposes the signal into a linear combination of Gaussian chirplet elementary functions and sums the Wigner-Ville Distribution (WVD) of all the Gaussian chirplet elementary functions to compute the quadratic time-frequency representation of signal. Use this VI if the signal contains Gaussian chirps. Wire data to the signal input to determine the polymorphic instance to use or manually select the instance.


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Inputs/Outputs

  • cnclst.png zoom settings —

    zoom settings specifies the frequency zoom factor and the zoom range.

  • ci32.png zoom factor —

    zoom factor specifies how much to zoom the spectrogram. zoom factor must be an integer greater than or equal to 1. The default is 1.

  • cdbl.png f0 —

    f0 specifies the lowest frequency in the resulting spectrogram in hertz. The default is NaN, which indicates that the lowest frequency equals 0 for real-valued input signals and that the lowest frequency equals -fs/2 for complex-valued input signals, where fs is the sampling rate of the signal.

  • ci32.png number of bins —

    number of bins specifies the total number of frequency bins in the resulting spectrogram. As the value of number of bins increases, the frequency range of spectrogram increases. The default value is -1, which specifies that the frequency range of spectrogram is from f0 to fs/2, where fs is the sampling rate of the signal. number of bins must not be greater than half of zoom factorxfrequency bins for real-valued input signals and must not be greater than zoom factorxfrequency bins for complex-valued input signals.

  • cu16.png extension —

    extension specifies the method to use to pad data at the borders of the input signal to lessen discontinuity. The extension length is half the window length.

  • c1dcdb.png signal —

    signal specifies the input signal.

  • cnclst.png time-frequency sampling info —

    time-frequency sampling info specifies the density to use to sample the signal in the joint time-frequency domain and defines the size of the resulting 2D time-frequency array.

  • ci32.png time steps —

    time steps specifies the sampling period, in samples, along the time axis in the joint time-frequency domain. The default is -1, which specifies that this VI adjusts time steps automatically so that no more than 512 rows exist in spectrogram.

  • ci32.png frequency bins —

    frequency bins specifies the number of bins along the frequency axis to sample the signal in the joint time-frequency domain. frequency bins must be a power of 2 and greater than 0. The scale info output contains the actual sampling period in hertz along the frequency axis.

  • ci32.png number of terms —

    number of terms specifies the maximum number of elementary functions to use in the adaptive 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.

  • cnclst.png elementary functions —

    elementary functions specifies the settings of the elementary functions.

  • cu16.png type —

    type specifies the type of elementary function to use to represent the signal.

  • ci32.png max window length —

    max window length specifies the maximum window length of the Gaussian envelopes of the elementary functions. The default is -1, which specifies that this VI sets the maximum window length as the power of 2 that is closest to but less than the signal length.

  • ci32.png reserved —

    reserved is reserved for future use.

  • cdbl.png sampling rate —

    sampling rate specifies the sampling rate of signal in hertz. sampling rate must be greater than 0, or this VI sets sampling rate to 1 automatically. The default is 1.

  • i2ddbl.png spectrogram —

    spectrogram returns the quadratic time-frequency representation of the signal. Each row corresponds to the instantaneous power spectrum at a certain time.

  • ifxdt.png scale info —

    scale info returns the time scale and the frequency scale information of the time-frequency representation, including the time offset, the time interval between every two contiguous rows, the frequency offset, and the frequency interval between every two contiguous columns of spectrogram. Use the TFA Get Time and Freq Scale Info VI to return detailed information about the time scale and the frequency scale.

  • i1dcdb.png reconstructed signal —

    reconstructed signal returns the signal reconstructed from the specified elementary functions.

  • ierrcodeclst.png error out —

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

    • TFA Adaptive Spectrogram Details

    You can combine a series of Gaussian chirplets to approximate a signal, s(t). The adaptive spectrogram is the summation of the weighted WVD of each Gaussian chirplet. The adaptive spectrogram does not contain cross-term interference. Because the WVD of the Gaussian function is nonnegative, the adaptive spectrogram is also nonnegative. Use the adaptive spectrogram if a set of Gaussian chirplets can represent the signal.