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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).
7.6.4 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.
7.6.5 Limit Fix/Unfix
This allows a limit pattern, once loaded, to be fixed relative to the screen enabling it to be used
for any centre frequency rather than just the one for which it was created.
7.7 The Logging Function
The Logging function is only available when the upgrade option U01 is fitted (see section 6).
A description of the menu keys used to control the function is given in section 4.8.1.
The logging function saves results into log files within the memory of the instrument. The type
of result saved can be selected as Centre Level (logs only the amplitude at the centre
frequency), Peak Level (logs the frequency and amplitude of the highest peak in every sweep),
Full Trace (logs the whole trace) or Screen Image (logs the whole screen as a bit-map image).
The saving of an entry into the file can be after every sweep (continuous) or in response to a
Timer, a key press (manual trigger), the external trigger input, or the Limits function.
Each entry within the file includes the time of the entry as read from the instrument’s real time
clock. Up to 25,000 entries can be saved within a single file with the exception of Screen Image
logging where the entries are limited to 2,500. The saving of an entry takes a finite length of
time varying from 0.1 seconds (centre amplitude or peak value) up to 1.5 seconds (screen
image). Entries are only saved after the sweep has been completed, and the sweep cannot re-
start until the entry has been saved.
Note that, when a logging file is “enabled”, the sweep mode is automatically set to Repeat and
the sweep trigger is set to Free Run. No changes can be made to the set-up of the analyser
while logging is in progress.
7.7.1 The Logging Control Menu
Selecting Logging Control from the Logging sub-
group menu (see section 4.8.1) opens a new control
screen as shown opposite.
The type of data to be logged, the trigger type, and
the timer interval (if used) must be set prior to
entering Logging Control. This information is shown
within the area above the keys.
Similarly the spectrum analyzer state (frequency span, level etc). must also have been set-up in
advance.