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jitterDataDependent

Measure data-dependent jitter from waveform

Since R2024b

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Syntax

[DDJrms,DDJpkpk] = jitterDataDependent(x,y,SymbolTime = t)
[DDJrms,DDJpkpk] = jitterDataDependent(y,SampleInterval = s,SymbolTime = t)
[DDJrms,DDJpkpk] = jitterDataDependent(x,y,xr,yr)
[DDJrms,DDJpkpk] = jitterDataDependent(y,yr,SampleInterval = s)
[DDJrms,DDJpkpk] = jitterDataDependent(___,Name=Value)
[DDJrms,DDJpkpk,DDJpdf,binEdges,C] = jitterDataDependent(___)

Description

[DDJrms,DDJpkpk] = jitterDataDependent(x,y,SymbolTime = t) measures the data-dependent jitter from input jittery waveform by using the specified symbol time.

Data-dependent jitter combines the effect of the inter-symbol interference (ISI) and duty cycle distortion (DCD).

[DDJrms,DDJpkpk] = jitterDataDependent(y,SampleInterval = s,SymbolTime = t) measures the data-dependent jitter by using the specified sample interval and symbol time.

[DDJrms,DDJpkpk] = jitterDataDependent(x,y,xr,yr) measures the data-dependent jitter from input jittery waveform with respect to the reference waveform.

[DDJrms,DDJpkpk] = jitterDataDependent(y,yr,SampleInterval = s) measures the data-dependent jitter with respect to the reference waveform and specified sample interval.

[DDJrms,DDJpkpk] = jitterDataDependent(___,Name=Value) measures the data-dependent jitter using name-value arguments. Unspecified arguments take default values.

[DDJrms,DDJpkpk,DDJpdf,binEdges,C] = jitterDataDependent(___) measures the data-dependent rms and peak-to-peak jitter using the above arguments. It also estimates the probability density functions (PDFs) and bin edges for the data-dependent jitter and the correlation information for DCD and ISI.

Input Arguments

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Time coordinates of the jittery signal, specified as a monotonically increasing vector.

If you do not provide y, the function interprets x as edge times.

Data Types: double

Amplitude coordinates of the jittery signal, specified as a vector or as an eyeDiagramSI object.

If you do not provide x, the function assumes y is uniformly sampled at the rate specified by SampleInterval.

Data Types: double

Time coordinates of the reference signal, specified as a monotonically increasing vector.

Data Types: double

Amplitude coordinates of the reference signal, specified as a vector. If you do not provide x, yr must be sampled at the same points as y.

Data Types: double

Name-Value Arguments

Specify optional pairs of arguments as Name1=Value1,...,NameN=ValueN, where Name is the argument name and Value is the corresponding value. Name-value arguments must appear after other arguments, but the order of the pairs does not matter.

Example: J = jitterDataDependent(x,y,SampleInterval = s,Plot = on) calculates and plots the histogram of the data-dependent jitter from the input waveform defined by (x,y) and sample interval specified by s.

General

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Thresholds to separate symbol levels in the jittery waveform, specified as a vector. If you do not provide SymbolThresholds, the function calculates it from the histogram of y.

Data Types: double

Thresholds to separate symbol levels in the reference waveform, specified as a vector. If you do not provide ReferenceThresholds, the function calculates it from the histogram of yr.

Data Types: double

Sample time for uniformly sampled jittery and reference waveforms, specified as a scalar.

When you provide the time vectors of jittery and reference signals, the function ignores SampleInterval and uses time vectors instead.

Data Types: double

Symbol time for uniformly sampled jittery and reference waveforms, specified as a scalar. For clock waveforms, SymbolTime is half the of the period.

Data Types: double

Options to compare the data edge to the clock edge, specified as one of these:

  • time — Compares the closest edge times.

  • order — Compares the first edge on each set.

The function uses this argument in two scenarios only:

  • Both the measured and reference waveforms are clocks.

  • The measured waveform is a data waveform and the reference waveform is a clock waveform.

When both waveforms are data waveforms with the same pattern, the function matches the edges is based on the pattern.

Option to display histogram of data-dependent jitter, specified as true (1) or false or (0).

Data Types: logical

Metric Specific

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Maximum number of sinusoidal jitter frequencies to measure, specified as a scalar.

Data Types: double

Number of symbols prior to a given edge to correlate the jitter with, specified as a scalar.

Data Types: double

Number of symbols after a given edge to correlate the jitter with, specified as a scalar. If the signal uses PAM2 modulation, the default value for FutureSymbols is 0. For a modulation scheme of PAM3 or higher, the default value is 1.

Data Types: double

Reference for correlating duty cycle distortion, specified as oddeven or risefall.

Data Types: char

Bin edges for PDFs during correlation, specified as a vector.

By default, the function distributes BinEdges evenly with twice the resolution of Scott's rule.

Note

For best results, specify a bin centered at 0.

Data Types: double

Premeasured Jitter

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Timing error values due to inter-symbol interference (ISI), specified as a vector or a structure.

The structure contains the correlation information and is the output of the jitterIntersymbol function. The structure must contain these fields.

FieldDescription
Mean

[N×M] matrix, where N is the number of modulation levels and M is the sum of future symbols and past symbols.

Mean denotes the ISI values for each symbol level at each delay.

SymbolIndex

M long vector, where M is the sum of future symbols and past symbols. The vector cannot contain 0.

SymbolIndex specifies the delay each column of Mean corresponds to.

Delay is relative to the symbol edge at which the function applies the ISI. A delay of 1 corresponds to the symbol after the edge, and a delay of -1 corresponds to the symbol prior to the edge.

The elements of the vector denote the ISI values for each edge. The vector can also be:

  • A PDF estimate vector which has one less element than the binEdges vector.

  • A 2-element vector with rms and peak-to-peak values which specifies a truncated zero-mean Gaussian.

Data Types: double

Timing error values due to duty cycle distortion (DCD), specified as a vector or a structure.

The elements of the vector denote the DCD values for each edge.

The structure contains the correlation information and is the output of the jitterDutyCycle function. The structure must contain the Mean field, which is a 2-by-1 matrix. The first element is the odd or rising DCD value and the second is the even or falling DCD value.

Data Types: double

Output Arguments

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Observed rms data-dependent jitter, returned as a scalar.

Observed peak-to-peak data-dependent jitter, returned as a scalar.

PDF (probability distribution function) estimates of the data-dependent jitter, returned as a vector.

Bin edges for the PDFs for the data-dependent jitter, returned as a vector.

Correlation information for DCD and ISI, returned as a structure. C(1) denotes the DCD values and C(2) denotes the ISI values.

FOR both DCD and ISI, the structure contains these fields.

FieldDescription
Metric

Name of the metric.

Mean

Mean of each case.

Variance

Variance of each case.

PDF

PDFs for each case.

BinEdges

Bin edge vector for PDFs.

Version History

Introduced in R2024b

See Also

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