Instructions

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4.4.5 Amplitude Limits (when fitted)
sets one or two horizontal lines or complex patterns that can be compared with the
sweep. This function is only available when the upgrade option U02 is fitted - see
section 6. Creates a set of bottom-row function keys as follows:
creates a control screen that enables the selection of lines and patterns, or allows
existing ones to be turned on or off. When Set Line is pressed, the value can be
entered numerically in dBm or dBuV. When Select Pattern is pressed, a Recall File
screen is opened enabling a pattern to be loaded from a file. See section 7.10.1.
creates a pop-up menu that selects the criteria upon which a limit condition is
created. The options are None, Above, Below, Outside or Inside.
creates a pop-up menu that selects an action that will be performed when the limit
condition occurs. The options are None, Beep, Pulse Out, or Beep + Pulse Out.
Note that other actions (sweep triggering or log file entry) can also be created from the limits
condition. Further information on the Limits function is given in section 7.10.
creates a control screen from which a limit can be offset from its initial values. This
is particularly useful for limit patterns which would otherwise have to be recreated.
See section 7.10.4 for more information.
enables a pattern that was created for a particular centre frequency (e.g. a
modulation channel width limit pattern) to be applied to a different centre frequency.
Pressing the key fixes the pattern relative to the screen and displays a message of
“Lim Fix” on the top RH side of the graticule. See section 7.10.5 for more information.
4.4.5.1 Channel Marker Files
A Channel Marker file is a special case of a Limit Pattern file which produces only vertical lines
at frequencies defined within the file. See section 7.10.6
4.4.6 Overload Indication
Signal levels that are greater than the reference level can not be displayed and may cause
errors in the measurement.
Two types of overload indication are provided. Signals that cause the trace to rise above the
reference level are indicated by a red arrow at the top of the graticule. Overload of the ADC is
indicated by a red background warning message below the graticule area. More information
about signal overload and measurement error is provided in section 7.1.
Limits
Limit
Conditio
Limit
Action
Set
Limits
Limit
Condition
Limit
Action
Limit
Offset
Limit
Fix/Unfix