Triggering
CSA8000B & TDS8000B User Manual 3-41
Positive-going edge Negative-going edge
Trigger slope can be positive or negative, with
trigger point occurring on the slope specified.
Trigger level
can be adjusted
vertically.
Figure 3- 11: Slope and level define the trigger event
Trigger Modes. The trigger modes control the behavior of the instrument when
not triggered:
HNormal mode sets the instrument to acquire a waveform only when
triggered. Normal mode does not acquire data if triggering stops, rather the
last waveform records acquired remains “frozen”on the display (if the
channels containing them are displayed). If no last waveform exists, none is
displayed. See Figure 3--12, Normal trigger mode.
HAuto mode sets the instrument to acquire a waveform even if a trigger event
does not occur. Auto mode uses a timer that starts after trigger rearm. If the
trigger circuit does not detect a trigger after this timeout (about 100 ms), it
auto triggers, forcing enough trigger events to acquire all active channels. In
the case of repetitive acquisitions in automatic trigger mode, waveform
samples are acquired, but at different places in the data stream (synchroniza-
tion is lost). See Figure 3--12, Automatic trigger mode. If you do not apply a
signal to any channel displayed, a baseline is displayed for that channel.
Triggered waveform Untriggered waveforms
Normal trigger mode Automatic trigger mode
Figure 3- 12: Triggered versus untriggered displays