26
Subject to change without notice
H o r i z o n t a l S y s t e m
tion mode that match the manually specified search criteria.
Specific settings are available for each search type. Searches
can be performed on any analog channel or mathematical
signal. The searched time base section can be restricted by
defining a level.
Press the MENU key in the HORIZONTAL section of the control
panel to activate the search function in the soft menu. Use the
universal knob to select the menu item
SEARCH
. Once this mode
is activated, you can define events, e.g. a rise time with specific
attributes, such as
<
12ns. The search function will then look for
these events in STOP mode in the most current capture. Press
the menu item
SEARCH TYPE
and use the universal knob to
select the desired search criteria.
The following functions are available:
– Slope:
Comparable to the slope trigger; this function searches for
slopes in the signal. The point in time of a detected slope cor
-
responds to the point in time when the signal leaves the set
hysteresis. The soft key LEVEL selects a level for the slope
detection of the search function. The search function level
matches the trigger level of the
slope trigger, for instance.
Level and hysteresis will display in the signal window. The
hysteresis determines the area that the signal has to pass
until a valid slope is detected. This area also defines the
rise
time of the slope. It is recommended to select a sufficiently
large hysteresis to reduce noise on the signal slope.
– Pulse width:
Comparable to the pulse width trigger; this function
searches for pulses with a predetermined pulse width. A
pulse always consists of a rising and a falling slope. Leaving
the
hysteresis defines the start and end time of the pulse.
The level for the search function corresponds to the trigger
level of the
slope trigger, for instance. Level and
hysteresis
will display in the signal window. The adjustable comparison
type is a search criterium for the detected time event width.
The pulse width is the time period between start and stop
slope of the pulse.
– Peak:
The peak search function searches for pulses within the
signal. The time of the event is the maximum value of the
peak.
– Rise time / fall time:
This function searches for slopes with a specific rise /
fall
time within the signal. The point in time of a detected slope
corresponds to the point in time when the signal leaves the
set
hysteresis. The upper and lower level define the upper
/lower position of the hysteresis. The adjusted level will
display in the signal window. The adjustable comparison
type is a search criterium for the detected time event width.
– Runt:
A runt is an aborted pulse within a signal. This occurs when
the rise times of the system are greater than necessary for
the desired pulse width. A positive runt exceeds the lower
level of the
hysteresis, for instance, but does not reach the
upper level. The analyzing digital circuits of this signal fail
to detect the pulse which leads to transmission errors. The
pulse width of the
runt is defined by the entry and exit point
from the hysteresis (duration between start and stop slope
of the pulse). The adjustable comparison type is a search
criterium for the detected time event width. The difference
defines the maximum time range by which the specified
event width may vary.
Once you have selected the appropriate search type, you can
choose the desired
SOURCE
(choose from any of the activated
analog channels including mathematical channels). Use the
menu item
SETUP
to open a submenu where you can choose
the settings for the selected search criterium (e.g. greater than
a specific
pulse width). Some of the adjustable parameters may
be dependent on the time base (for a time base of 100µs/Div
the smallest time is 2µs, for 1µs/Div the corresponding time
value is 20ns). If events match the search criterium, they will be
highlighted. The soft menu
VIEW EVENT TABLE
allows you to
display the search results in a table format. Use the arrow keys
or the universal knob to navigate the events in STOP mode. The
Select option allows you to center the selected event. When the
zoom function is activated, the selected event will automatically
be centered in the zoom window.
Fig. 5.7: Search mode with event list
