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Quality Factor VI

LabVIEW 2012 Jitter Analysis Toolkit Help

Edition Date: June 2012

Part Number: 373270B-01

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Owning Palette: Eye Diagram Measurements VIs

Requires: Jitter Analysis Toolkit

Measures the quality of a waveform based on the histograms at the base and top of an eye diagram formed from the waveform. Wire data to the waveform input to determine the polymorphic instance to use or manually select the instance.

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

Quality Factor (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.
level crossings contains information about the locations of level crossings in the original waveform. You can use the Level Crossing VI to generate this cluster.
t0 specifies the time at which the first sample occurs in the original waveform.
dt specifies the time interval in seconds between the individual samples in the original waveform.
indexes contains the index numbers of the samples in the waveform with values that fall at the crossing level.
slope identifies the direction of the first transition in the waveform.

-1Falling Edge—Specifies the transition is a falling edge, or one with a negative slope.
1Rising Edge (default)—Specifies the transition is a rising edge, or one with a positive slope.
crossing level specifies the value of the waveform at each of the samples in indexes.
error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
quality factor returns the quality measure for the waveform using the mean and standard deviation values of the histograms formed at the base and top of an eye diagram. LabVIEW uses the following equation to calculate the quality factor.



When random jitter causes the standard deviations of the histograms at the base and top to increase, the quality factor decreases and indicates a lower quality signal.
decision voltage returns the computed best decision voltage, or the lowest bit error rate.
estimated BER returns an estimate of the bit error rate, given the quality factor.
error out contains error information. This output provides standard error out functionality.

Quality Factor (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.
level crossings contains information about the locations of level crossings in the original waveform. You can use the Level Crossing VI to generate this cluster.
t0 specifies the time at which the first sample occurs in the original waveform.
dt specifies the time interval in seconds between the individual samples in the original waveform.
indexes contains the index numbers of the samples in the waveform with values that fall at the crossing level.
slope identifies the direction of the first transition in the waveform.

-1Falling Edge—Specifies the transition is a falling edge, or one with a negative slope.
1Rising Edge (default)—Specifies the transition is a rising edge, or one with a positive slope.
crossing level specifies the value of the waveform at each of the samples in indexes.
error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
quality factor returns the quality measure for the waveform using the mean and standard deviation values of the histograms formed at the base and top of an eye diagram. LabVIEW uses the following equation to calculate the quality factor.



When random jitter causes the standard deviations of the histograms at the base and top to increase, the quality factor decreases and indicates a lower quality signal.
decision voltage returns the computed best decision voltage, or the lowest bit error rate.
estimated BER returns an estimate of the bit error rate, given the quality factor.
error out contains error information. This output provides standard error out functionality.

 

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