Agilent Technologies 8504B, User Manual, Page: 90 / 296

FINAL TRIM SIZE : 7.5 in x 9.0 in
P erforming Measurements
Using Markers
Markers are accessed from two front-panel keys:
Use 4
MRK
5 to display up to four markers , an additional xed marker , and
delta markers .
Use 4
MKR F CTN
5 to search for peak responses and to change the
measurement span based on marker positions .
The active marker can be moved to any point on the trace . When a
logarithmic amplitude scale is used, response values are displayed in dB;
when a linear amplitude scale is used, values are shown as the ratio of
reected power to the incident power . The displayed marker values are valid
even when the measured data is above or below the range displayed on the
screen.
1 markers display
relative values
When displaying delta markers , any of the four markers or a xed point can
be designated as the reference marker . The displayed markers show the
relative distance (or time) and amplitude from this reference marker . The
delta reference is displayed as a small 1 character . (This character is smaller
than the inactive marker triangles .) If one of the markers is the reference , the
delta character appears next to the marker number on the trace .
The xed marker is a
special delta marker
reference
Each of the four standard markers can only be positioned on the trace .
However , the xed marker can be position anywhere on the screen; it is not
limited to the trace . Use
NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN
FIXED MKR POSITION and
NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN
FIXED MKR VALUE to
position the xed marker . The xed marker can be set to the current active
marker position, by pressing
NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN
MARKER ! FIXED MARKER . Other markers can
then be activated and their values referenced to the xed marker .
What if a memory trace
is displayed?
If both data and memory are displayed, the marker values apply to the data
trace . If memory only is displayed, the marker values apply to the memory
trace .
Y ou can dene a peak Y ou can change the amplitude variation required for a peak to be identied.
The default value is 6 dB . The value species the amount that a trace must
increase and then decrease , relative to the surrounding responses or noise
oors , in order to be dened as a peak.
If peak excursion is dened as 20 dB , then the values of a and b , shown
in the following gure , must be at least 20 dB in order to be considered a
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