Applies a scaled window to the time-domain signal and outputs window constants for further analysis. Wire data to the signal in input to determine the polymorphic instance to use or manually select the instance.


icon

Inputs/Outputs

  • c1dmsdt.png signals in —

    signals in is the array of signals to window.

  • cu32.png window —

    window specifies the time-domain window used.

  • cdbl.png window parameter —

    window parameter is the beta parameter for a Kaiser window, the standard deviation for a Gaussian window, and the ratio, s, of the main lobe to the side lobe for a Dolph-Chebyshev window. If window is any other window, this VI ignores this input.

    The default value of window parameter is NaN, which sets beta to 0 for a Kaiser window, the standard deviation to 0.2 for a Gaussian window, and s to 60 for a Dolph-Chebyshev window.

  • cerrcodeclst.png error in (no error) —

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

  • i1dmsdt.png signals out —

    signals out returns the array of windowed signals.

  • inclst.png window constants —

    window constants contains important constants for the selected window.

  • idbl.png eq noise BW —

    eq noise BW is the equivalent noise bandwidth of the selected window.

    To compute the power in a given frequency span, divide a sum of individual FFT lines by eq noise BW.

  • idbl.png coherent gain —

    coherent gain is the inverse of the scaling factor applied due to the window.

  • ierrcodeclst.png error out —

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

    • The windowed time-domain signal is scaled so that when the power or amplitude spectrum of the windowed waveform is computed, all windows provide the same level within the accuracy constraints of the window. This VI also returns important window constants for the selected window. These constants are useful when you use VIs that perform computations on the power spectrum, such as the Power & Frequency Estimate VI.

    Defining Equations

    All cosine windows without scaling are defined by the following equation.

    where , n is the number of elements in X, and m is the number of elements in the window coefficient array a[].

    For this VI, the preceding equation is modified to include division by the coherent gain (cg), as shown in the following equation.

    Coefficients and Window Parameters for the Different Window Types

    This section provides information about the a coefficients and window parameters for each window type available in this VI. Each window type has the following window parameters:

    • coherent gain (cg)
    • equivalent noise bandwidth (enbw)
    • 6dB bandwidth (6dB BW)
    Rectangle
    a[] is empty because no window is applied.cg = 1
    The window equation is yi = xienbw = 1
    6dB BW = 1.21
    Hanning
    a0 = 0.5cg = 0.5
    a1 = 0.5enbw = 1.5
    6dB BW = 2.0
    Blackman-Harris
    a0 = 0.42323cg = 0.42323
    a1 = 0.49755enbw = 1.708538
    a2 = 0.079226dB BW = 2.27
    Exact Blackman
    a0 = 0.42659071367153911200cg = 0.42659071367
    a1 = 0.49656061908856408100enbw = 1.693699
    a2 = 0.076848667239896820106dB BW = 2.25
    Blackman
    a0 = 0.42cg = 0.42
    a1 = 0.5enbw = 1.726757
    a2 = 0.086dB BW = 2.3
    Flat Top
    a0 = 0.215578948cg = 0.215578948
    a1 = 0.41663158enbw = 3.770246506303
    a2 = 0.2772631586dB BW = 4.58
    a3 = 0.083578947
    a4 = 0.006947368
    4 Term B-Harris
    a0 = 0.35875cg = 0.35875
    a1 = 0.48829enbw = 2.004353
    a2 = 0.141286dB BW = 2.67
    a3 = 0.01168
    7 Term B-Harris
    a0 = 0.27105140069342415cg = 0.27105140069342415
    a1 = 0.43329793923448606enbw = 2.631905
    a2 = 0.218122999543110626dB BW = 3.5
    a3 = 0.065925446388030898
    a4 = 0.010811742098372268
    a5 = 7.7658482522509342E-4
    a6 = 1.3887217350903198E-5
    Low Sidelobe
    a0 = 0.323215218cg = 0.323215218
    a1 = 0.471492057enbw = 2.215350782519
    a2 = 0.175534286dB BW = 2.95
    a3 = 0.028497078
    a4 = 0.001261367