Agilent Technologies 5000 Series manual FUNCtionWINDow

3Commands by Subsystem

:FUNCtion:WINDow

(see page 530)

Command Syntax :FUNCtion:WINDow <window>

<window> ::= {RECTangular HANNing FLATtop}

•The RECTangular window is useful for transient signals, and signals where there are an integral number of cycles in the time record.

•The HANNing window is useful for frequency resolution and general purpose use. It is good for resolving two frequencies that are close together, or for making frequency measurements. This is the default window.

•The FLATtop window is best for making accurate amplitude measurements of frequency peaks.

	The :FUNCtion:WINDow command allows the selection of three different
	windowing transforms or operations for the FFT (Fast Fourier Transform)
	function.
	The FFT operation assumes that the time record repeats. Unless an
	integral number of sampled waveform cycles exist in the record, a
	discontinuity is created between the end of one record and the beginning
	of the next. This discontinuity introduces additional frequency components
	about the peaks into the spectrum. This is referred to as leakage. To
	minimize leakage, windows that approach zero smoothly at the start and
	end of the record are employed as filters to the FFTs. Each window is
	useful for certain classes of input signals.
Query Syntax	:FUNCtion:WINDow?
	The :FUNCtion:WINDow? query returns the value of the window selected
	for the FFT function.
Return Format	<window><NL>
	<window> ::= {RECT HANN FLAT}
See Also	• "Introduction to :FUNCtion Commands" on page 182

192 Agilent InfiniiVision 5000 Series Oscilloscopes Programmer's Reference