At/Norm.
Using the "At./Norm." button you can switch between
automatic trigger level selection (At) and normal, manual trigger level
selection (Norm.). The trigger level in automatic mode equals the level
during groundline crossing, in this simulation that is 0 V. The trigger
level in manual mode can be set using the "Level"
wheel located below the "At/Norm." button. Using that wheel, voltage values
larger than the amplitude of the signal can be set, too. However, as the
signal level will never reach that (higher) trigger level, the signal will
not be triggered in that case at all.
To make sure
that the simulation allows demonstration of this function even for high
input voltages, an algorithm has been implemented that does not use the
voltage of a signal: In the simulation a signal is always triggered as long
as the trigger wheel is rotated within a range of -90° and +90° from its
center position, outside this range it is not triggered. In reality the
maximum trigger level would equal 100 V, and the trigger range would be
based on the true voltage of the signal. After production of the simulation
this limitation has shown to be reasonable: For small input voltages on a
real oscilloscope minor moves of the wheel influence the trigger level
strongly. Such small movements cannot be executed by a simulation user with
his mouse exact enough to implement them in the simulation.
If a signal is triggered on ascending or descending flank
can be set using the "+/-"
button.
The following images show examples for different trigger
settings:
The "At/Norm."
button is off (=automatic level selection),
the
"+/-"
button is off (=trigger on ascending
flank)
The "At/Norm."
button is on (=manual trigger level
setting),
the "Level"
wheel is turned to about half of the signal amplitude,
the "+/-"
button is off (=trigger on ascending flank)
The "At/Norm."
button is on (=manual trigger level
setting),
the "Level"
wheel is turned to about half of the signal amplitude,
the "+/-"
button is on (=trigger on descending
flank)
The "At/Norm."
button is on (=manual trigger level
setting),
the "Level"
wheel is turned to a position lower than the lowest voltage of
the signal,
therefor the signal cannot be triggered, the screen remains
empty. |
