Instructions

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A compensation table file is loaded in a similar way to other types of file using a File Recall
screen - see section 5.4 .
Note that compensation tables and limit patterns 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 Limit Lines & the Limits Comparator | Creating Limit Patterns
These functions are only available when the upgrade option U02 is fitted - see section 6. A
description of the menu keys used to control the function is given in section 4.4.5 .
Two types of limits are available, Lines and Patterns. Up to two limits can be displayed, Limit 1
in red and Limit 2 in blue.
A Line is a simple horizontal line (single amplitude level) that can be set to any value.
A Pattern can have multiple levels and can include vertical steps and angled lines. Patterns are
contained within files that are lists of up to 49 frequency/amplitude points. When a file is used
by the instrument, linear interpolation is employed between the points.
Lines or patterns may be used as simple visual aids to determine whether a signal is within a
specific level range, or they may be used in conjunction with the Limits Comparator to create an
automatic action.
7.10.1 Setting Limits
Pressing the Set Limits key (Level/Limits > Limits >
Set Limits) brings up a control screen as shown.
The keys on the top line select which limit is to be
controlled by the bottom row keys. Where a limit line
or pattern has already been set, it can be turned on or
off using Limit On/Limit Off.
The status of the two limits is displayed within the
area directly above the keys.
Pressing Set Line defines the currently selected limit as a line (if it was previously a pattern)
and brings up a numeric entry keypad or tab/jog system by which the level of the line can be set
numerically in graticule units.
Pressing Select Pattern brings up a list of files from which a limit pattern can be loaded. Limit
pattern files have the default prefix PTN and are placed in the Tables folder. Pressing Recall
from the Recall Limits files screen will load the pattern as the selected limit.
7.10.2 The Limit Comparator
The limits comparator enables automated actions to be selected in response to specified limit
conditions. The actions include audible warning, pulse output from the trigger socket, stopping
of the sweep, or entry into a logging file.
The limit condition is created from the trace being either above or below the limit line/pattern. If
the measurement markers are turned off, or if only M1 is turned on, any part of the swept trace
being above or below the line will create the condition. If both M1 and M2 are turned on, the
limits comparison takes place only on the part of the trace between the markers.
The Limit Condition options are None, Above, Below, Outside or Inside. Where two limits are
being displayed, the limit conditions of Inside or Outside can be used. Note that there is no
concept of an upper or lower limit line. Above means above the higher point of the two limit
lines, Below means below the lower point of the two limit lines, Outside means either above the
higher point or below the lower point of the two limit lines, while Inside means between the
higher and lower points.