Company Events Academic Community Support Solutions Products & Services Contact NI MyNI

Time Varying Filter Dialog Box

LabVIEW 2013 Advanced Signal Processing Toolkit Help

Edition Date: June 2013

Part Number: 372656B-01

»View Product Info

Requires: Advanced Signal Processing Toolkit

In the TFA Time Varying Filter VI, ensure the open front panel? control is set to TRUE and run this VI to display this dialog box.

Use this dialog box to configure a time varying filter for filtering a signal.

This dialog box includes the following components:

  • Gabor Transform Settings—Contains the following options:
    • N (frequency bins)—Specifies the number of carrier frequencies of Gabor elementary functions. N (frequency bins) must be a power of two. For stable reconstruction, N (frequency bins) must be greater than or equal to dM (time steps). The ratio between N (frequency bins) and dM (time steps) is also called oversampling rate.
    • dM (time steps)—Specifies the step size to move the window. This VI sets dM (time steps) to a power of 2 automatically.
    • Gaussian window length—Specifies the window length of Gabor elementary functions. This VI sets Gaussian window length to a power of 2 automatically. Gaussian window length must be greater than or equal to N (frequency bins).
    • Analysis and synthesis window—Displays the analysis window and the synthesis window. This VI uses the analysis window and the synthesis window for the Gabor transform and the Gabor expansion, respectively. To accurately characterize the local properties of the signal in the join time-frequency domain, the analysis window and the synthesis window must match as closely as possible.
  • Mask Settings—Contains the following options:
    • Mask source—Specifies whether to design a mask manually or load a previously saved mask.
    • Mask method—Specifies the masking method to use. This option is available only if you select Design in the Mask source pull-down menu. Contains the following options:
      • Threshold—Specifies to set the amplitude of Gabor coefficients with a value less than Threshold to zero. Contains the following options:
        • NI Vision installed—Indicates if NI Vision is installed. The de-noise operation for the mask is available only when NI Vision is installed.
        • Threshold—Specifies the amplitude of the threshold for the Gabor coefficients.
        • Noise Level—Removes the small particles in the joint time-frequency representation plot. The functionality to remove small particles requires NI Vision.
      • Morphologic—Allows you to manually select Gabor coefficients on the Gabor Coefficients intensity graph. The amplitude of Gabor coefficients that you do not select is set to zero. Contains the following options:
        Tip  Right-click in the Gabor Coefficients graph to perform dilation for the morphologic mask. You can press the <Ctrl-Z> keys to undo the last action.
        • Apply Mask—Specifies to accept the morphologic mask.
        • Clear Mask—Specifies to clear the morphologic mask.
      • Arbitrary—Allows you specify cursor groups on the Gabor Coefficients intensity graph to select Gabor coefficients. The amplitude of Gabor coefficients that you do not select is set to zero. Contains the following options:
        Tip  Right-click in the Gabor Coefficients graph to set cursors for the arbitrary mask. To set a new group of cursors, increment the Group Index. You can press the <Ctrl-Z> keys to undo the last action.
        • Group Index—Specifies the index of cursor groups. To set a new group of cursors, increment the Group Index.
        • Apply Mask—Specifies to accept the arbitrary mask.
        • Clear Mask—Specifies to clear the arbitrary mask.
  • Preview—Displays the filtered signal. The filtered signal displayed in the Signals graph is in green.
  • Save Mask—Saves the mask information that you specify in this VI.
  • Load Mask—Specifies the file from which this VI reads the mask information. This option is available only if you select From File in the Mask source pull-down menu.
  • Gabor Coefficients and Waveform—Displays the magnitude of the Gabor coefficients in the upper graph and the time-domain input signal and filtered signal in the lower graph.
    • dB?—Specifies whether to display the magnitude of the Gabor coefficients in decibels or in a linear scale.
    • Gabor Coefficients—Displays the magnitude of the Gabor coefficients on an intensity graph.
    • Display Mode—Specifies the display mode of complex-valued signals. This option is available only if you run the Complex instance of the TFA Time Varying Filter VI.
    • Signals—Displays the input signal and the filtered signal.

 

Your Feedback! poor Poor  |  Excellent excellent   Yes No
 Document Quality? 
 Answered Your Question? 
Add Comments 1 2 3 4 5 submit