To select a window, press ($GG) ~~~~~~;~~E~; .%HMW. A menu is presented that allows the selection of three window types (see ‘lhble 6-12).

able 6-12. Impulse Width, Sidelobe Level, and Windowing Values

 

Window

ImpnlSe

Low Pass

SkP

SbP

 

Type

Sidelobe

llUpUlSC3

Sidelobe

mseThe

 

 

Level

Width (50%)

Level

(10 - 90%)

 

 

 

 

 

 

 

 

 

Minimum

-13dB

O.bO/Freq Span

-21 dJ3

0.45IFreqSpan

 

Normal

-44dB

0.9WFreq Span

-60 dB

OXWFreq Span

 

Maximmn

-75 dB

139/Freq Span

-70 dB

1AS/Freq Span

 

 

 

 

 

 

 

 

 

 

 

 

 

 

NOTE: The bandpass mode simulates an impulse stimuli. Bandpass impulse width is twice that of low pass impulse width. The bendpass impulse sidelobe levels are the same as low pass impulse sidelobe levels.

Choose one of the three window shapes listed in Table 6-12. Or you can use the knob to select any windowing pulse width (or rise time for a step stimulus) between the softkey values. The time domain stimulus sidelobe levels depend only on the window selected.

,;.... /:,.;.,,*,...,..,....:::.:...., _

_

~~~~~

is essentially no window. Consequently, it gives the highest

 

sidelobes.

~~~

 

 

.‘“...:.:.:...:

/..:.:.:.:.:...;~..:

_

,.,.......: /

,,.

 

;fJqjgfmi

 

 

..,,..,.,,.....,.,.,.,,

:..::

....“

...:,::::::::::.:::::::::...:.:.,::::::..,..::::.

.”:::,:,‘::::::...:,~,.:...~,.: ,,;.. :. ,,

(the preset mode) gives reduced sidelobes and is the mode most often used.

window gives the minimum sidelobes, providing the greatest dynamic range.

~~~~~~~~~~~~~~~~~~~~~~~ remembers a user-specified WindoW pulse Width (or step

.:... .:::........: u;;.....A.....v;.......w;.A.....;:.w;:.A..ciii>;;:.. .A...w;;.i..: :... rise time) different from the standard window values.

A window is activated only for viewing a time domain response, and does not affect a displayed frequency domain response. Figure 6-72 shows the typical effects of windowing on the time domain response of a short circuit reflection measurement.

Application and Operation Concepts 6-137

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Image 418
HP 8753E manual Sidelobes, 10 90%