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ET User’s Guide 4-39
Using Instrument Functions
Using Limit Testing
Additional Notes on Limit Testing
Stimulus and
Amplitude Values In frequency sweep mode, the stimulus values are interpreted as
frequencies; in power sweep mode, the stimulus values are interpreted
as output power levels.
CAUTION
The values entered for stimulus and amplitude are unitless. If the
measurement format is changed after limit lines are set, the amplitude
values do not automatically change. Therefore, you should select the
format you want to use before entering your limits.
Calculating the
Frequency of a
Data Point The frequency of each data point is calculated using the following
formula:
where pt number ranges from 1 (for the leftmost display point) to
number of points (the rightmost display point).
Limit Testing and
Measurement
Points Limit testing is only performed on actual data points, not interpolated
values between them. The limit lines or points that you enter are
converted to values at each measurement point. Most of the time this has
little or no effect on the validity of the limit testing. However, note the
following examples of problems that could arise when using limit lines:
Freq pt number
( )
pt number
1 –
( )
stop freq
start freq
–
 
 
×
number of points
1 –
-----------------------------------------------------------------------------------------------------------------------------
start freq
+ =