Measurement Computing WaveBook rev.3.0 - Manual (Page 147)

WaveBook User’s Manual. 6-24-99 Theory of Operation 8-13
Above-Level Trigger
Rising slope
Instantaneous duration
Level initialization
Trigger Level
Hysteresis
Trigger Trigger
No
Trigger
This trigger is valid whenever the signal level is above the trigger level and stays valid until the signal level
goes below the hysteresis range. In the figure, the channel trigger is valid during the 2 shaded intervals.
Whether this condition triggers WaveBook or not, depends on the type of multi-channel triggering ("AND"
or "OR") and on the state of other trigger channels. With "OR" multi-channel triggering, WaveBook will
trigger when the signal first rises above the trigger level—if ready for a new trigger, WaveBook will also
trigger the second time the signal rises above the trigger level. With "AND" multi-level triggering,
WaveBook will not trigger until every specified trigger channel is valid. If all other trigger channels are
valid, WaveBook will trigger when the signal reaches the shaded region; but if some channels are not valid,
this channel will have no effect.
Below-Level Trigger
Falling slope
Instantaneous duration
Level initialization
Trigger Level
Hysteresis
No Trigger No Trigger
Trigger Trigger
This trigger is valid whenever the signal level is below the trigger level and stays valid until the signal level
goes above the hysteresis range (the reverse of above-level triggering). As with all multi-channel trigger
types, WaveBook's actual trigger depends on the combination of this trigger with the other channels' trigger
states.
Above-Level-With-Latch Trigger
Rising slope
Latched duration
Level initialization
Trigger
Trigger Level
In this trigger type, the channel becomes valid when the signal level rises above the trigger level and stays
valid until the acquisition is complete and WaveBook is re-armed.
Below-Level-With-Latch Trigger
Falling slope
Latched duration
Level initialization Trigger
Trigger Level
The channel becomes valid when the signal level rises above the trigger level and stays valid until the
acquisition is complete and WaveBook is re-armed (the reverse of above-level-with-latch triggering).
Latched triggers are often used in multi-channel "AND" triggering, where WaveBook will not trigger until
all trigger channels are valid. After a latched trigger becomes valid, it stays valid (waiting for the other
triggers to become valid) until WaveBook is triggered and the acquisition completes. If the trigger is non-
latched instead of latched, the channel may not stay valid and WaveBook will not trigger until the channel
becomes valid again and all channels simultaneously reach their trigger levels. In other words, latched
triggering is used to trigger after something has occurred, but non-latched triggering is used only during
the simultaneous occurrence of desired signal levels. It is possible to combine different trigger types in a
single multi-channel trigger. For example, WaveBook could trigger when channel 3 is below 0.9 volts after
channel 2 has gone above -1.3 volts (by configuring channel 3 for below-level triggering and channel 2 for
above-level-with-latch triggering).