Trigger Source; Trigger Position - Tektronix 222 Operator's Manual

More On How It Works-222 DSO Operators
selected, the previous waveform is displayed only until the display is
updated (about 30 ms). If a trigger has not occurred in that time, a trig-
ger is forced and whatever data is captured is displayed. At the
slower SECIDIV settings, blanking of the trace between the forced
trigger and the display update will be visible to the user.
SSEQ: In SSEQ (single-sequence) MODE, one triggered acquisition
is made. The display is then held, and no further SSEQ acquisitions
occur until the trigger system is rearmed. Press the button to
rearm for another acquisition. Changing a control that affects the
acquisition parameter also resets the SSEQ trigger mode, and a new
acquisition is started at the changed setting.
6.7 TRIGGER SOURCE
Trigger SOURCE selects the signal source of the trigger events
(VERT, CH 1, CH 2, or
EXT).
With VERT selected, the lowest num-
bered channel displayed is the source of the trigger signal. Select
CHI or CH2 if a specific channel signal is wanted as the trigger signal
source. The channel selected need not be displayed to supply the
trigger signal. Trigger coupling follows the coupling of the channel
signals for VERT, CHI, and CH2 Trigger SOURCE. Trigger input
coupling for EXT Trigger is always "dc".
6.8
TRIGGER POSITION
For STORE display mode waveforms, the trigger position in the
acquired waveform is selectable. The three choices permit the userto
examine a different time window around a trigger event.
POST: Post-trigger means that most of the waveform data is
displayed after the trigger position. There are only
64
data points
displayed before the trigger position.
MID: Mid-trigger places the trigger position in the middle of the
display with 256 data points displayed before the trigger position.
PRE: Pretrigger means that most of the waveform data is displayed
before the trigger position. There are
448
data points displayed
before the trigger position.
The trigger point for a waveform displayed in NONSTORE mode
occurs at the sixth data point.
REV JUN 1989