Operators Manual Owner manual

HDO6000 High Definition Oscilloscope
Type - see Trigger Types for details. This selection drives the remainder of the trigger setup. The default
selection is Edge.
Source - the channel signal upon which to base the trigger. If a trigger is designed to work with multiple
inputs, like a Pattern trigger, you do not have to choose a single source, but will be given controls for
setting the conditions on each source.
Coupling - the type of signal coupling at the input. Choices are:
l DC - All the signal’s frequency components are coupled to the trigger circuit for high frequency
bursts or where the use of AC coupling would shift the effective trigger level.
l AC - The signal is capacitively coupled. DC levels are rejected, and frequencies below 50 Hz are
attenuated.
l LFREJ - The signal is coupled through a capacitive high-pass filter network, DC is rejected and sig-
nal frequencies below 50 kHz are attenuated. For stable triggering on medium to high frequency sig-
nals.
l HFREJ - Signals are DC coupled to the trigger circuit, and a low-pass filter network attenuates
frequencies above 50 kHz (used for triggering on low frequencies).
Level - the source Voltage level or levels that mark the threshold for the trigger to fire. Trigger levels
specified in Volts normally remain unchanged when the vertical gain or offset is modified.
Find Level - where available, this button sets the Level to the signal mean.
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.
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