Hardware Settings:Recommended Settings:Spectrum:FFT Window Type Property

No window is applied.

Applies a Hanning window to the waveform using the following equation:

y[i] = 0.5 * x[i] * [1 - cos(w)]

where	w = (2)i/n
	n = the waveform size

The Hanning window is useful for analyzing transients that are longer than the time duration of the window, as well as for general-purpose applications.

Applies a Hamming window to the waveform using the following equation:

y[i] = x[i] * [0.54 - 0.46cos(w)]

where	w = (2)i/n
	n = the waveform size

Note  Hanning and Hamming windows are similar. However, in the time domain, the Hamming window does not approach zero at the edge of the window as fast as does the Hanning window.

Applies a Blackman-Harris window according to the following equation:

y[i] = x[i] * [0.42323 - 0.49755cos(w) + 0.07922cos(2w)]

where	w = (2)i/n
	n = the waveform size

Applies an Exact Blackman window according to the following equation:

y[i] = x[i] * [a ₀ - a ₁cos(w) + a₂cos(2w)]

where	w = (2)i/n
	n = waveform size
	a 0 = 7938/18608
	a 1 = 9240/18608
	a 2 = 1430/18608

Applies a Blackman window according to the following equation:

y _i = x _i[0.42 - 0.50cos(w) + 0.08cos(2w)]

where	w = (2)i/n
	n = the waveform size

A Blackman window is useful for analyzing transient signals, and provides similar windowing to Hanning and Hamming windows but adds one additional cosine term to reduce ripple.

Applies a Flat Top window according to the following equation:

y[i] = x[i] * [a ₀ - a ₁cos(w) + a ₂cos(2w) - a ₃cos(3w) + a ₄cos(4w)]

where	w = (2)i/n
	n = waveform size
	a 0 = 0.215578948
	a 1 = 0.41663158
	a 2 = 0.277263158
	a 3 = 0.083578947
	a 4 = 0.006947368.

The fifth-order Flat Top window has the best amplitude accuracy of all the window types. The increased amplitude accuracy (_0.02 dB for signals exactly between integral cycles) is at the expense of frequency selectivity. The Flat Top window is most useful in accurately measuring the amplitude of single frequency components that have little nearby spectral energy in the signal.

Applies a 4-Term Blackman-Harris window according to the following equation:

y[i] = x[i] * [0.422323 - 0.49755cos(w) + 0.07922cos(2w)]

where	w = (2)i/n
	n = the waveform size

The 4-term Blackman-Harris window has a side-lobe rejection in the upper 90 dB, with a moderately wide side lobe.

Applies a 7-Term Blackman-Harris window according to the following equation:

y[i] = x[i] * [a ₀ - a ₁cos(w) + a ₂cos(2w) - a ₃cos(3w) + a ₄cos(4w) - a ₅cos(5w) + a ₆cos(6w)]

where	w = (2)i/n
	n = waveform size
	a 0 = 0.27105140069342
	a 1 = 0.43329793923448
	a 2 = 0.21812299954311
	a 3 = 0.06592544638803
	a 4 = 0.01084209837
	a 5 = 0.00077658482522
	a 6 = 0.00001388721735.

The 7-term Blackman-Harris window has the highest dynamic range of the available windowing types and is ideal for signal-to-noise ratio applications.

The Low Side Lobe window further reduces the size of the main lobe. The following equation defines the Low Side Lobe window.

where	N = length of the window
	w = (2 n/N)
	a0 = 0.323215218
	a1 = 0.471492057
	a1 = 0.17553428
	a3 = 0.028497078
	a4 = 0.001261367