User`s guide

LIMIT
LINES
LIMITS
FIX REL
When accessed by ISAVE), pressing LIMIT LINES stores the current limit-line
tables in spectrum analyzer memory or on the memory card. When accessed
by (m), pressing LIMIT LINES recalls limit-line tables from spectrum
analyzer memory or the memory card. See “To Save a Limit-Line Table or
Amplitude Correction Factors” or “To Recall Limit-Line Tables or Amplitude
Correction Factors” in Chapter 5 for more information.
Front-Panel Key Access: [mj or m
allows you to choose fixed or relative type of limit lines. The fixed (FIX) type
uses the current limit line as a reference with fixed frequency and amplitude
values. The relative (REL) setting causes 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.
As an example, assume you have a frequency limit line. If the limit line is
specified as 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, it is displayed relative to the spectrum analyzer
center frequency and reference level. If the center frequency is at 1.2 GHz, a
relative limit-line segment with a frequency coordinate of 300 MHz will display
the limit-line segment at 1.5 GHz. If the amplitude component of the relative
limit-line segment is -10 dB, then -10 dB is added to the reference level
value to obtain the amplitude of the given component (reference level offset
included).
RELATIVE is displayed in the limit-line table when the limit-line type is
relative; FIXED is displayed when limit-line type is fixed.
A limit line entered as fixed may be changed to relative, and one entered as
relative 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 spectrum analyzer. If a time and amplitude limit line
is used, the amplitude values change but the time values remain the same.
Front-Panel Key Access: (jjj
LIMITS
FRQ TIME
selects whether limit lines will be entered using frequency or sweep time
to define the segments. Limit lines can be created by the user to test trace
data. They can be specified as a table of limit-line segments of amplitude
versus frequency, or of amplitude versus time. Time values are evaluated with
respect to the spectrum analyzer sweep time. A time value of zero corresponds
to the start of the sweep, which is the left edge of the graticule.
Switching the limit line definition between frequency and time will erase the
current limit line table. The message If you are sure, press key again to
purge data will appear. Press LIMITS FRQ TIME again to purge the limit line
table and switch between frequency and time.
Front-Panel Key Access: [DISPLAY_)
7-50 Key Descriptions