Accepts an input signal of a single waveform or an array of waveforms and measures the transition duration (rise or fall time), slew rate, undershoot, and overshoot of a selected positive or negative transition in each waveform. Wire data to the signal in 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 181-2003, IEEE Standard on Transitions, Pulses, and Related Waveforms.


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The following information applies to the pre-transition and post-transition outputs of both instances of this VI.

pre-transition

To calculate the pre-transition undershoot and overshoot, LabVIEW searches for a local minimum and maximum in the pre-transition aberration region immediately preceding the beginning of the transition specified by edge number and polarity. The pre-transition 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 polarity is falling, LabVIEW calculates the pre-transition undershoot using the following equation:

If polarity is rising, LabVIEW calculates the pre-transition undershoot using the following equation:

If polarity is falling, LabVIEW calculates the pre-transition overshoot using the following equation:

If polarity is rising, LabVIEW calculates the pre-transition overshoot using the following equation:

Note LabVIEW uses the Histogram method to calculate the state levels and amplitude, regardless of the method specified by percent level settings.

post-transition

To calculate the post-transition undershoot and overshoot, LabVIEW searches for a local minimum and maximum in the post-transition aberration region immediately following the end of the transition specified by edge number and polarity. The post-transition 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 polarity is falling, LabVIEW calculates the post-transition undershoot using the following equation:

If polarity is rising, LabVIEW calculates the post-transition undershoot using the following equation:

If polarity is falling, LabVIEW calculates the post-transition overshoot using the following equation:

If polarity is rising, LabVIEW calculates the post-transition overshoot using the following equation:

Note LabVIEW uses the Histogram method to calculate the state levels and amplitude, regardless of the method specified by percent level settings.

Example Illustrations

The following illustration shows the undershoot and overshoot in a negative single transition.

The following illustration shows the undershoot and overshoot in a positive single transition.

Examples

Refer to the following example files included with LabVIEW.

  • labview\examples\Signal Processing\Waveform Measurements\Pulse and Transition Measurements.vi
  • labview\examples\Signal Processing\Waveform Measurements\N channel Pulse and Transition Measurements.vi