R&S FSQ Signal Analyzer - Rohde & Schwarz

R&S FSQ Instrument Functions
4.6 Basic Settings
Basic Settings
In this section, the general settings, printout, and instrument settings are described
in detail.
4.6.1 Setup of Limit Lines and Display Lines – LINES Key
Limit lines are used to define amplitude curves or spectral distribution boundaries on
the display screen which are not to be exceeded. They indicate, for example, the
upper limits for interference radiation or spurious waves which are allowed from a
unit under test (UUT). For transmission of information in TDMA (e.g. GSM), the
amplitude of the bursts in a timeslot must adhere to a curve which must fall within a
specified tolerance band. The lower and upper limits may each be specified by a
limit line. Then, the amplitude curve can be controlled either visually or automatically
for any violations of the upper or lower limits (GO/NOGO test).
The instrument supports limit lines with a maximum of 50 data points. 8 of the limit
lines stored in the instrument can be used simultaneously and activated in the splitscreen
mode either in Screen A, Screen B or in the two windows. The number of
limit lines stored in the instrument is only limited by the capacity of the flash disk
used.
For each limit line, the following characteristics must be defined:
• The name of the limit line. The limit line data are stored under this name and can
be examined in the table LIMIT LINES.
• The domain in which the limit line is to be used. Here, a distinction is made
between the time domain (span = 0 Hz) and the frequency domain (span > 0 Hz).
• The reference of the interpolation points to the x-axis. The limit line may be
specified either for absolute frequencies or times or for frequencies which are
related to the set center frequency and times related to the time on the left edge
of the diagram.
• The reference of the interpolation points to the y-axis. The limit line can be
selected either for absolute levels or voltages or referred to the set maximum level
(Ref Lvl). The position on the display depends on the REF LEVEL POSITION.
• With relative reference values for the y-axis, it is possible to enter an absolute
threshold (THRESHOLD) which lowers the relative limit values (see below).
• The type of limit line (upper or lower limit). With this information and the active limit
checking function (Table LIMIT LINES, LIMIT CHECK ON, the R&S FSQ checks
for compliance with each limit.
• The limit line units to be used. The units of the limit line must be compatible with
the level axis in the active measurement window.
• The measurement curve (trace) to which the limit line is assigned. For the
R&S FSQ, this defines the curve to which the limit is to be applied when several
traces are simultaneously displayed.
• For each limit line, a margin can be defined which serves as a threshold for
automatic evaluation.
• In addition, commentary can be written for each limit line, e.g. a description of the
application.
Operating Manual 1313.9681.12 - 01 4.153