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Level
Level defines the source voltage at which the trigger circuit will generate an event (a change in the input signal
that satisfies the trigger conditions). The selected trigger level is associated with the chosen trigger source. Note
that the trigger level is specified in volts and normally remains unchanged when the vertical gain or offset is
modified.
The Amplitude and Range of the trigger level are limited as follows:
•
±5 screen divisions with a channel as the trigger source
•
±400 mV with EXT as the trigger source
•
±4 V with EXT/10 as the trigger source
•
none with LINE as the trigger source (zero crossing is used)
Note: Once specified, Trigger Level and Coupling are the only parameters that pass unchanged from trigger
mode to trigger mode for each trigger source.
Holdoff by Time or Events
Holdoff is an additional condition of Edge trigger. It can be expressed either as a period of time or an event count.
Holdoff disables the trigger circuit for a given period of time or number of events after the last trigger occurred.
Events are the number of occasions on which the trigger condition is met. The trigger will again occur when the
holdoff has elapsed and the trigger's other conditions are met.
Use holdoff to obtain a stable trigger for repetitive, composite waveforms. For example, if the number or duration
of sub-signals is known you can disable them by choosing an appropriate holdoff value. Qualified triggers operate
using conditions similar to holdoff.
Hold Off by Time
Sometimes you can achieve a stable display of complex, repetitive waveforms by placing a condition on the time
between each successive trigger event. This time would otherwise be limited only by the input signal, the
coupling, and the instrument's bandwidth. Select a positive or negative slope, and a minimum time between
triggers. The trigger is generated when the condition is met after the selected holdoff time, counted from the last
trigger. Any time between 1 ns and 20 s can be selected. The delay is initialized and started on each trigger.
Edge Trigger with Holdoff by Time. The bold edges on the trigger source indicate that a positive slope has been selected. The
broken upward-pointing arrows indicate potential triggers, which would occur if other conditions are met. The bold arrows indicate
where the triggers actually occur when the holdoff time has been exceeded.
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