Instructions

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The Limit Action can be set to None, Beep, Pulse Out, Beep and Pulse Out together, or
Message. The action only takes places when the sweep has completed. The Pulse Out is
provided at the Trigger socket - see section 7.8.2.
Regardless of the setting of the Trigger Action, it is also possible to use the limit condition to
stop the sweep (see section 4.3.4.2) or to create an entry into a logging file (see section
7.11.5).
7.10.3 Creating and Loading Limit Patterns
Limit Patterns must be created outside of the instrument using PSA-Manager software - see
section 6.1.11.
Limit Patterns files have the extension .CSV and are located in the folder named TABLES.
Files can be transferred using either a USB Flash drive, or by direct connection to the USB port
of a PC. See section 5 for an explanation of copying and transferring files.
A limit pattern table file is loaded in a similar way to other types of file using a File Recall screen
- see section 5.4. Up to 999 pattern files can be held within the memory of the instrument.
Note that limit patterns and compensation tables are both placed in a folder called Tables and
can therefore appear within the same File Utilities screen. It is possible to toggle between the
two file types by pressing the key marked Tables (toggle).
7.10.4 Limit Offset
The Limit Offset function enables a limit to be offset
from its initial value. It is intended primarily for limit
patterns (which would otherwise have to be
regenerated) but can also be used with limit lines.
The Limit Offset control screen enables a limit to be
“nudged” up or down in steps of 1dB or 0.1dB.
Where a limit has had an offset applied to it, a **
symbol is displayed within the Set Limits control screen.
7.10.5 Limit Fix/Unfix
Limit patterns use absolute frequency points. Whenever the frequency range is changed, the
pattern on the screen is recalculated to be correct for the new frequency range.
In some circumstances, however, it is useful to avoid this recalculation taking place. If, for
example, a limit pattern had been created for the modulation around a specific centre
frequency, it may be useful to be able to apply that same pattern to a different centre frequency.
Pressing the Limit Fix/Unfix key fixes the pattern relative to the screen and displays a message
of “Lim Fix” on the top RH side of the graticule. Changes can now be made to centre frequency
without the pattern changing.
Note that the pattern is fixed on the screen and will become incorrect if the span or the
reference level is changed. Pressing the key again cancels the fix mode and recalculates the
limit pattern to be correct for the current centre frequency, span and reference level.
7.10.6 Creating and Loading Channel Markers
A special type of limit pattern file is available which consists only of vertical lines at frequency
points defined within the file. These can be displayed as an alternative to limit lines/patterns.
Up to two files can be displayed simultaneously in differing colours. Each file can contain up to
49 frequency points.
Channel Marker files are created using PSA Manager software. This is described further in
Appendix A (section 17).