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State Levels VI

LabVIEW 2012 Jitter Analysis Toolkit Help

Edition Date: June 2012

Part Number: 373270B-01

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Owning Palette: Level VIs

Requires: Jitter Analysis Toolkit

Computes the high and low state levels of a waveform and the corresponding amplitude. You can use state levels to identify the position in time of a waveform feature to be measured. Wire data to the waveform input to determine the polymorphic instance to use or manually select the instance.

You also can use the Reference Levels (waveform in) instances of the Reference Levels VI to measure the state levels of a waveform.

The terminology and measurement definitions for this VI comply with IEEE Standard 181-2003, IEEE Standard on Transitions, Pulses, and Related Waveforms.

Use the pull-down menu to select an instance of this VI.

State Levels (DBL)

This instance operates on the waveform data type when the Y data values are double-precision, floating-point 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.
t0 specifies the start time of the waveform.
dt specifies the time interval in seconds between data points in the waveform.
Y specifies the data values of the waveform.
state levels settings sets the method this VI uses to determine the high and low state levels of a waveform.
Note  With any method you use to calculate state levels, very irregular waveforms might result in inaccurate state level measurements. In this case, manually specify state levels that are appropriate for the specific waveform.
method specifies how LabVIEW computes the high and low state levels of the waveform.

0histogram (default)—Returns the levels of the histogram bins with the maximum number of hits in the upper and lower regions of the waveform. The upper and lower regions of the waveform include the upper and lower 40%, respectively, of the peak-to-peak range of the waveform.
1peak—Searches the entire waveform for its maximum and minimum levels.
2auto select—Determines whether the histogram bins that correspond to the high and low state levels each have over 5% of the total hits. If so, LabVIEW returns those results. Otherwise, LabVIEW uses the peak method. This ensures a reasonable answer for either a square wave (ignoring the overshoot and undershoot) or a triangle wave (where a histogram fails).
3auto select independent—Determines whether the histogram bins that correspond to the high and low state levels each have over 5% of the hits within their respective regions. If so, LabVIEW returns those results. Otherwise, LabVIEW uses the peak method. This ensures a reasonable answer when positive pulses in the waveform are much longer than negative pulses, and vice versa, such as when the waveform contains duty cycle distortion.
histogram size specifies the number of bins in the histogram LabVIEW uses to determine the high and low state levels of the waveform. If you select the peak method, LabVIEW ignores this input.
histogram method specifies how LabVIEW computes the high and low state levels of the waveform. Currently, mode is the only available histogram method.

0mode
search width/total bins specifies the percent level of the waveform at which to set the upper boundary of the region that corresponds to the low state of the waveform and the lower boundary of the region that corresponds to the high state. LabVIEW uses the lesser of this value and 0.5. The default is 0.45.

If you select the peak method, LabVIEW ignores this input.
error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
waveform dup returns waveform unchanged.
state levels returns the state level information from the waveform.
amplitude is the difference between high state level and low state level.
high state level returns the level at which a pulse or transition waveform is defined to be in its highest state.
low state level returns the level at which a pulse or transition waveform is defined to be in its lowest state
error out contains error information. This output provides standard error out functionality.

State Levels (I8)

This instance operates on the waveform data type when the Y data values are 8-bit signed integers.

waveform is the waveform to measure.
t0 specifies the start time of the waveform.
dt specifies the time interval in seconds between data points in the waveform.
Y specifies the data values of the waveform.
state levels settings sets the method this VI uses to determine the high and low state levels of a waveform.
Note  With any method you use to calculate state levels, very irregular waveforms might result in inaccurate state level measurements. In this case, manually specify state levels that are appropriate for the specific waveform.
method specifies how LabVIEW computes the high and low state levels of the waveform.

0histogram (default)—Returns the levels of the histogram bins with the maximum number of hits in the upper and lower regions of the waveform. The upper and lower regions of the waveform include the upper and lower 40%, respectively, of the peak-to-peak range of the waveform.
1peak—Searches the entire waveform for its maximum and minimum levels.
2auto select—Determines whether the histogram bins that correspond to the high and low state levels each have over 5% of the total hits. If so, LabVIEW returns those results. Otherwise, LabVIEW uses the peak method. This ensures a reasonable answer for either a square wave (ignoring the overshoot and undershoot) or a triangle wave (where a histogram fails).
3auto select independent—Determines whether the histogram bins that correspond to the high and low state levels each have over 5% of the hits within their respective regions. If so, LabVIEW returns those results. Otherwise, LabVIEW uses the peak method. This ensures a reasonable answer when positive pulses in the waveform are much longer than negative pulses, and vice versa, such as when the waveform contains duty cycle distortion.
histogram size specifies the number of bins in the histogram LabVIEW uses to determine the high and low state levels of the waveform. If you select the peak method, LabVIEW ignores this input.
histogram method specifies how LabVIEW computes the high and low state levels of the waveform. Currently, mode is the only available histogram method.

0mode
search width/total bins specifies the percent level of the waveform at which to set the upper boundary of the region that corresponds to the low state of the waveform and the lower boundary of the region that corresponds to the high state. LabVIEW uses the lesser of this value and 0.5. The default is 0.45.

If you select the peak method, LabVIEW ignores this input.
error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
waveform dup returns waveform unchanged.
state levels returns the state level information from the waveform.
amplitude is the difference between high state level and low state level.
high state level returns the level at which a pulse or transition waveform is defined to be in its highest state.
low state level returns the level at which a pulse or transition waveform is defined to be in its lowest state
error out contains error information. This output provides standard error out functionality.

 

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