DFFT Options 
FFT Options Window Selection
SignalScope provides a selection of different data windows that may be applied to the time domain data, before the application of the FFT.
Select from the available data window types by tapping or clicking on the desired window name.
The available data windows include:
- Uniform (rectangular)
- Bartlett
- Blackman
- Flat Top
- Hamming
- Hann (Hanning)
- Rife-Vincent 2
- Exponential (decay only, for impulse testing)
- Force (for impulse reference input)
- Force Exponential (combined Force and Exponential windows, for impulse reference input)
Exponential Window
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Time Constant
This defines the time constant of the exponential decay. Updating this value will automatically adjust the final value (defined below). -
Final Value (%)
This value defines how much decay occurs over the length of the window. For example, if the value is 1%, the window function will exponentially decay from 1 to 0.01 across the length of the window. Updating this value will automatically adjust the time constant. -
Auto Update
The relationship between the time constant and the final value will change whenever the FFT length or the sample rate changes. When this happens one of the values can remain as it is, but the other must be automatically updated. This option allows you to choose which one will be updated.
Force Window
-
Window Length (s)
The force window has a value of 1 for a certain length of time, after which it quickly decays to 0 using a half-cosine function. This value specifies the length of the first portion of the window in seconds. Updating this value will automatically adjust the length as a percentage. -
Window Length (%)
The force window has a value of 1 for a certain length of time, after which it quickly decays to 0 using a half-cosine function. This value specifies the length of the first portion of the window as a percentage of the total window length (the FFT length). Updating this value will automatically adjust the length in seconds. -
Auto Update
The relationship between the window length in seconds and length as a percentage of the total window length (FFT length) will change whenever the FFT length or the sample rate changes. When this happens one of the values can remain as it is, but the other must be automatically updated. This option allows you to choose which one will be updated.
Window Preview
Here, you will see a graph of the selected window function over the total window length (FFT length).