Teledyne Lecroy WaveSurfer 3000, Руководство оператора, Страница: 43 / 97

Operator's Manual
Trigger Holdoff
Holdoff is an additional condition that may be set for Edge and Pattern triggers. It can be expressed either as a period of
time or an event count. Holdoff disables the trigger temporarily, even if the trigger conditions are met, until the holdoff
conditions are also met. The trigger fires when the holdoff has elapsed.
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
This is a period of time to wait to fire the trigger, either since the beginning of the acquisition or since the trigger
conditions were met.
Sometimes you can achieve a stable display of complex, repetitive waveforms by placing a holdoff condition on the time
between each successive Edge 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.
In the figure below, 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.
Edge trigger with holdoff by time.
Hold Off by Events
For purposes of Hold Off, Events refers to the number of times the trigger conditions have been met, counted either from
the beginning of the acquisition or since the last trigger. For example, if the hold-off number of Events is 2 counted from
the beginning of the acquisition, the trigger fires on the third event.
In the figure below, the bold edges on the trigger source indicate that a positive slope has been selected. The broken,
upward-pointing arrows indicate potential triggers, while the bold ones show where triggers actually occur after the
holdoff expires.
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