User manual

26
Trigger System
6.3 Trigger type
The trigger type can be selected with the TYPE key
17
in
the TRIGGER section. A submenu will be opened.
6.3.1 Slope Trigger
The easiest and by far the most frequently used trigger
is the slope trigger. The oscilloscope triggers if slopes
that were set with the EDGE key occur within the signal
selected in the SOURCE menu. The signal slope has to
pass through the set trigger level. The trigger type EDGE
TRIGGER is selected in the Autosetup mode (AUTOSET
key). If, for instance, you select the pulse trigger and press
the AUTOSET key the setting will switch to Edge Trigger.
The TYPE key
31
in the TRIGGER section allows you to set
the trigger type. This opens a menu with corresponding
options. If the edge type is not active (highlighted in blue),
you can press the respective soft menu key to select this
type. The slope type (rising, falling or both) can be set
directly with the SLOPE
35
key. This will shift the setting
forward by one, i.e. from rising to falling slope, to both
slopes, and pressing the key yet one more time will trigger
another rising slope. The center of the status line on the
top of the display and the display above the SLOPE key
35
show which slope type has been selected.
The FILTER
36
key allows you to select how to couple the
signal for the trigger circuit:
❙ AUTO LEVEL:Automaticltersetting(default setting).
❙ AC: The triggersignaliscoupledviahighpasslterwitha
minimum cut-off frequency of 5 Hz which suppresses the
DC portion of the triggering signal. With a changing DC
portion, the trigger level remains at the set point in the AC
signal. The trigger type AUTO (AUTO/NORM key) includes
the Peak-Peak mode which sets limits for the trigger in the
AC signal. This setting means that the trigger condition
will be met for any applied signal without having to set the
level. For the trigger type NORM (AUTO/NORM key), the
Peak-Peak mode is deactivated, allowing the trigger level
to be moved past the peak values of the signal.
❙ DC: The trigger signal is coupled to the trigger circuit with
all signal portions (AC and DC voltage). This has no
impact on the triggering signal.
Fig. 6.2: Coupling modes with slope trigger
❙ HF: The triggersignaliscoupledviahighpasslterwitha
minimum cut-off frequency (-3 dB) of 30 kHz and is
automatically limited when triggering the level with
normal trigger. This coupling type should only be applied
to very high frequency signals.
❙ LP (low pass): The trigger signal is coupled via low pass
withamaximumcut-offfrequencyof5kHz.Thislter
removes high frequencies and is available with AC and
DC coupling.
❙ NR (noise reduction): A lowpasslterwithamaximum
cut-off frequency of 100 MHz will improve the noise
performanceforthetriggeramplier.Thislterremoves
high frequencies and is available with AC and DC
coupling.
The slope trigger can be coupled with a so called „B Trig-
ger“. This option is available via soft menu key SLOPE A/B.
Thisfunctionallowsyoutoadjustthetriggersuchthatrst
condition „A“ must be met and then another condition „B“
before the trigger will respond (refer to Fig. 6.3). E.g. it is
possibletodeneasource (channel) and a level of 120 mV
on the rising slope of that signal and for the second condi-
tion a level of 80 mV on the falling slope. Additionally, it is
possibletodenewhethertheBeventshouldoccuratime
(minimum 16 ns, maximum 8.59s) or a number of times
after the A event (minimum 1, maximum 65535) after the
A event. Both A and B trigger can have different sources. In
the SOURCE menu, you can use the soft menu key SOURCE
A / SOURCE B to select the respective source via universal
knob in the CURSOR/MENU section. You can select the ana-
log channels and an external trigger signal (Extern) which is
applied to the EXT-TRIG connector on the back panel of the
instrument.
The level, time or the number of events can be entered nu-
merically with the universal knob or in a submenu. In order
todothisrstselectthesetting,thenpushthesoftkey
next to NUMERIC INPUT. In the window which will open,
you can enter numbers and units with the universal knob
in the CURSOR/MENU section or numerical with KEYPAD
button.
6.3.2 Pulse Trigger
The pulsetriggerallowstriggeringforspecicpulsewidths
of positive or negative pulses or for pulse width ranges.
The oscilloscope triggers if a pulse occurs within the signal
selected in the SOURCE menu that matches the properties
setintheFILTERmenu.Ifapulsefulllsthetrigger con-
ditions, the oscilloscope triggers on the trailing slope, i.e.
for a positive pulse it triggers on the falling slope and for a
negative pulse on a rising slope. Activate the pulse trigger
by pressing the TYPE key
31
in the TRIGGER section. Press
the FILTER key
36
, then you can select additional settings
for the pulse trigger in the soft menu. There are six diffe-
rent settings:
The coupling types low pass and noise reduction may not be acti-
vated simultaneously.