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Chapter 2 121
Instrument Functions: A - L
Display
Instrument Functions: A - L
2.4.5.3 Limits (Fixed Rel)
Specifies whether the current limit lines are fixed or relative.
Pressing Limits to choose fixed (Fixed)orrelative(Rel) limit lines. The fixed (Fixed)typeuses
the current limit lines as a reference with fixed frequency and amplitude values. The
relative (Rel) setting results in the current limit-line value to be relative to the displayed
center frequency and reference level amplitude values. When limit lines are specified with
time, rather than frequency, the
Rel setting only affects the amplitude values. The current
amplitude values will be relative to the displayed reference level amplitude, but the time
values will always start at the left edge of the graticule.
For example, assume you have a frequency limit line. If the limit line is specified as fixed
(
Fixed) entering a limit line segment with a frequency coordinate of 300 MHz displays the
limit line segment at 300 MHz. If the same limit line table is specified as relative (
Rel), it is
displayed relative to the analyzer center frequency and reference level. If the center
frequency is at 1.0 GHz, a relative limit line segment with a frequency coordinate of 300
MHz will display the limit line segment at 1.3 GHz. If the amplitude component of the
relativelimitlinesegmentis-10dB,the-10dBisaddedtothereferencelevelvalueto
obtain the amplitude of the given segment (reference level offset included).
A limit line entered as
Fixed may be changed to Rel, and one entered as Rel may be changed
to Fixed. When changing between fixed and relative limit lines, the frequency and
amplitude values in the limit line table change so that the limit line remains in the same
position for the current frequency and amplitude settings of the analyzer. If a time and
amplitude limit line is used, the amplitude values change but the time values remain the
same.
Key Path:
Display, Limits
Factory
Default: Fixed for a new limit.
History: Added with firmware revision A.03.00
Remote Command:
NOTE If you need to change the domain with:CALCulate:LLINe:CONTrol:DOMain,
do it before this command. Changing the domain deletes all the existing limit
line values.
:CALCulate:LLINe:CMODe FIXed|RELative
:CALCulate:LLINe:CMODe?
Example: :CALC:LLIN:CMOD FIX sets limit lines 1 and 2 limits to fixed.