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Owning Palette: Level VIs
Requires: Jitter Analysis Toolkit
Measures the times, locations, and amounts by which a waveform rises above and falls below a state level before or after a transition. The rise above a state level is known as overshoot, and the drop below a state level is known as undershoot. Wire data to the waveform input to determine the polymorphic instance to use or manually select the instance.
Note The terminology and measurement definitions for this VI comply with IEEE Standard 1812003, IEEE Standard on Transitions, Pulses, and Related Waveforms. 
Use the pulldown menu to select an instance of this VI.
This instance operates on the waveform data type when the Y data values are doubleprecision, floatingpoint numeric values. Use the I8 instance of this VI with integer data to reduce the size of the data and the memory usage.
waveform is the waveform to measure.
 
transitions contains information about the transitions in the waveform. Use the Find Transitions VI to generate this cluster.
 
transition select sets whether to identify overshoot and undershoot in the regions before or after each transition.


error in describes error conditions that occur before this node runs. This input provides standard error in functionality.  
slope specifies the direction of the transitions for which you want to return measurements.


overshoot sequence returns an array of the overshoot values for local maximums associated with the types of transitions you specify using slope and transition select. Overshoot measures the height as a fraction of the amplitude of the signal. Refer to the Details section of this topic for more information about how this VI calculates overshoot.  
overshoot timestamps returns timing information about the waveform that allows you to identify the times at which measurements in the corresponding sequence occur.
 
undershoot sequence returns an array of the undershoot values for local minimums associated with the types of transitions you specify using slope and transition select. Undershoot measures the height as a fraction of the amplitude of the signal. Refer to the Details section of this topic for more information about how this VI calculates undershoot.  
undershoot timestamps returns timing information about the waveform that allows you to identify the times at which measurements in the corresponding sequence occur.
 
error out contains error information. This output provides standard error out functionality. 
This instance operates on the waveform data type when the Y data values are 8bit signed integers.
waveform is the waveform to measure.
 
transitions contains information about the transitions in the waveform. Use the Find Transitions VI to generate this cluster.
 
transition select sets whether to identify overshoot and undershoot in the regions before or after each transition.


error in describes error conditions that occur before this node runs. This input provides standard error in functionality.  
slope specifies the direction of the transitions for which you want to return measurements.


overshoot sequence returns an array of the overshoot values for local maximums associated with the types of transitions you specify using slope and transition select. Overshoot measures the height as a fraction of the amplitude of the signal. Refer to the Details section of this topic for more information about how this VI calculates overshoot.  
overshoot timestamps returns timing information about the waveform that allows you to identify the times at which measurements in the corresponding sequence occur.
 
undershoot sequence returns an array of the undershoot values for local minimums associated with the types of transitions you specify using slope and transition select. Undershoot measures the height as a fraction of the amplitude of the signal. Refer to the Details section of this topic for more information about how this VI calculates undershoot.  
undershoot timestamps returns timing information about the waveform that allows you to identify the times at which measurements in the corresponding sequence occur.
 
error out contains error information. This output provides standard error out functionality. 
The following illustration shows the overshoot and undershoot in a single negative transition.
The following illustration shows the overshoot and undershoot in a single positive transition.
To calculate pretransition overshoot and undershoot for each transition, LabVIEW searches for a local minimum and maximum in the pretransition aberration region immediately preceding the beginning of the transition. The pretransition aberration region is defined as the minimum of 3*(end time – start time) and (current transition start time – previous transition end time) / 2. If the transition to measure is the first in the waveform, the interval is defined as the minimum of 3*(end time – start time) and (start time – beginning of the waveform).
If slope is falling, LabVIEW calculates the pretransition undershoot using the following equation:
If slope is rising, LabVIEW calculates the pretransition undershoot using the following equation:
If slope is falling, LabVIEW calculates the pretransition overshoot using the following equation:
If slope is rising, LabVIEW calculates the pretransition overshoot using the following equation:
where the state levels and amplitude are defined in the transitions input.
To calculate posttransition undershoot and overshoot for each transition, LabVIEW searches for a local minimum and maximum in the posttransition aberration region immediately following the end of the transition. The posttransition aberration region is defined as the minimum of 3*(end time – start time) and (next transition start time – current transition end time) / 2. If the transition to measure is the last in the waveform, the interval is defined as the minimum of 3*(end time – start time) and (end of the waveform – end time).
If slope is falling, LabVIEW calculates the posttransition undershoot using the following equation:
If slope is rising, LabVIEW calculates the posttransition undershoot using the following equation:
If slope is falling, LabVIEW calculates the posttransition overshoot using the following equation:
If slope is rising, LabVIEW calculates the posttransition overshoot using the following equation:
where the state levels and amplitude are defined in the transitions input.
Refer to the Overshoot Demo VI in the labview\examples\Jitter Analysis\Level Measurements directory for an example of using the Overshoot and Undershoot VI.
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