Scaled Window VI
- Updated2025-07-30
- 4 minute(s) read
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.
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 = xi | enbw = 1 |
| 6dB BW = 1.21 | |
| Hanning | |
| a0 = 0.5 | cg = 0.5 |
| a1 = 0.5 | enbw = 1.5 |
| 6dB BW = 2.0 | |
| Blackman-Harris | |
| a0 = 0.42323 | cg = 0.42323 |
| a1 = 0.49755 | enbw = 1.708538 |
| a2 = 0.07922 | 6dB BW = 2.27 |
| Exact Blackman | |
| a0 = 0.42659071367153911200 | cg = 0.42659071367 |
| a1 = 0.49656061908856408100 | enbw = 1.693699 |
| a2 = 0.07684866723989682010 | 6dB BW = 2.25 |
| Blackman | |
| a0 = 0.42 | cg = 0.42 |
| a1 = 0.5 | enbw = 1.726757 |
| a2 = 0.08 | 6dB BW = 2.3 |
| Flat Top | |
| a0 = 0.215578948 | cg = 0.215578948 |
| a1 = 0.41663158 | enbw = 3.770246506303 |
| a2 = 0.277263158 | 6dB BW = 4.58 |
| a3 = 0.083578947 | |
| a4 = 0.006947368 | |
| 4 Term B-Harris | |
| a0 = 0.35875 | cg = 0.35875 |
| a1 = 0.48829 | enbw = 2.004353 |
| a2 = 0.14128 | 6dB BW = 2.67 |
| a3 = 0.01168 | |
| 7 Term B-Harris | |
| a0 = 0.27105140069342415 | cg = 0.27105140069342415 |
| a1 = 0.43329793923448606 | enbw = 2.631905 |
| a2 = 0.21812299954311062 | 6dB BW = 3.5 |
| a3 = 0.065925446388030898 | |
| a4 = 0.010811742098372268 | |
| a5 = 7.7658482522509342E-4 | |
| a6 = 1.3887217350903198E-5 | |
| Low Sidelobe | |
| a0 = 0.323215218 | cg = 0.323215218 |
| a1 = 0.471492057 | enbw = 2.215350782519 |
| a2 = 0.17553428 | 6dB BW = 2.95 |
| a3 = 0.028497078 | |
| a4 = 0.001261367 | |