Theory of Operation
Windowing of Data

After the data is acquired for the time record, but before the Fourier transform occurs, the time data is windowed.

Click the blocks of the illustration below to help understand how windowing works.

Because the windowing process reduces the time domain information, resolution in the frequency domain will be reduced. The effective resolution bandwidth (ResBW) is determined by the windowing function used.

ResBW = Normalized ENBW / T
Where: T =	time record length in seconds
ResBW =	the Resolution Bandwidth
Normalized ENBW =	equivalent noise bandwidth of window, normalized to window length

For more ResBW information, see the following topics:

• About Resolution Bandwidth

• How ResBW Interacts with Other Parameters

• Window Shapefactor and Equivalent Noise BW

• Understanding Time and Frequency Parameters