Eyeheight PM-2E User's Guide

SAgilent J-BERT N4903B High-Performance SerialBERTUser GuidesAgilent Technologies

10 Agilent J-BERT N4903B High-Performance Serial BERT

– Decide on Trigger On or Off. This setting becomes effective if the Trigger/Ref Clock Out port is set to Sequence Trigger (trigger at block begin). S

User-Defined Sequences - ReferenceThe elements of the Sequence Editor and the dialog boxes that can be opened fromthe Sequence Editor are described be

In this example, the number of blocks has been set to three. A "None" blockgenerates no pattern and is completely ignored (indicated by a st

a browser and search for the file that contains the pattern. You can search forfiles with the extentions .ptrn, .txt, or .dat.If the pattern file cont

Every loop has a delete button [×] and a loop condition button.Clicking the delete button [×] removes the loop from the sequence.The initial (default)

Table 14Icon Name DescriptionNew Click this icon to create anew sequence. This opensthe Properties dialog. See“Creating a NewSequence” on page 99 ford

Table 14Icon Name DescriptionFrom PG Click this icon to uploadthe present sequence fromthe pattern generator tothe Sequence Editor. Thisallows you to

Table 14Icon Name DescriptionCrossTalk Click this icon to open theCrossTalk dialog. Use thisdialog to fill everysequencer block of thesecond channel

N O T EIf you edit the SequenceExpression manually, take care to adhere to the syntax andorder of the keywords.Remember that you must download the upd

By default, the Sequence Editor shows one block that is automatically repeated.It has a length of 512 bits and generates Pause 0 data (pure zeros).2Cl

1 Planning the TestPlanning the Test - ConceptsThe following topics provide some information that can help you in planning testswith the Serial BERT:•

7In the toolbar, click Discard to reject all the new changes.Exporting Patterns in Sequencer-Pattern EditorTo export the current pattern under a new n

Table 15Icon Name DescriptionApply Click this icon to apply thepattern to the hardware (incase the sequence isalready active), or simplyupdate the cor

Table 15Icon Name DescriptionFind Click this icon to open theFind Pattern Segmentdialog box and perform thesearch and replaceoperation for a specified

Table 15Icon Name DescriptionINS/OVRClick this icon to toggleamong the insert, dynamicinsert and overwriteediting mode:With Insert mode youinsert bits

Table 15Icon Name DescriptionSymbol Codings Click this icon to openSymbol Settings dialog.See “Symbol Settings” onpage 116 for details.Pattern View Cl

It uses a different set of background color to distinguish between the two channels.The RED background denotes the pattern for Data Out chanel while t

Using this dialog, you can:• Choose Select Trace as Data Out/Aux Data Out to create a Standard patternor as Both to create an Alternate pattern.• Ente

This dialog contains a drop-down list which provides the following options.• Off Mode: Displays the pattern editor without any symbol coding.• OOB Mod

Export TraceThe Export Trace dialog saves a copy of the currently edited pattern.The Export Trace dialog is shown in the figure below:N O T EThe Expor

Pattern PropertiesThe Pattern Properties dialog is used to view/change the properties of the currentpattern(s).This dialog provides the following opti

• Clock Out• Aux Data Out• Aux Data Out• Trigger/Ref Clock Out• Trigger/Ref Clock OutTermination of output ports improves the test performance.Importa

3 Setting up Patterns120 Agilent J-BERT N4903B High-Performance Serial BERT

4 Setting up the Pattern GeneratorSetting up the Pattern Generator - ConceptsThe Serial BERT's pattern generator generates an output signal based

Input and Output PortsInput and Output Ports - ConceptsThe pattern generator's input ports are used to set the pattern generator's clockfreq

• Delay Control InAllows you to connect a signal for generating jitter in the data outputs.• Aux InThe signal at the Aux In port can be used to switch

Understanding the Output Protection CircuitThe generator module offers a huge flexibility for external termination schemesand external termination vol

The parameters can be changed to configure the output according to the DUT’stermination requirements. Be aware that the changes are not applied immedi

Incorrect Termination Detection on M8061A Output(s)The incorrect termination detection state on M8061A output(s) occurs when theamplifier detects an o

As shown in this figure, the signal output levels have the following components:• Vhi is the upper voltage level of the signal.• Vlo is the lower volt

N O T ENote that the delay is on Data and Aux Data.Crossover is the voltage level where the overlapped rising and falling edges of thelogic levels int

The following table lists the characteristics generally associated with some logicfamilies. All values are nominal.Table 18Logic Family Vhigh[V] Vlow[

Table 1Fraction Exponent Instrument Display1/10,0001 x 10-41E-41/100,0001 x 10-51E-51/1,000,0001 x 10-61E-61/10,000,0001 x 10-71E-7Understanding SERSy

Note that an internal protection circuit becomes active if the termination voltageis wrongly adjusted. The protection circuit sets the output voltages

Input and Output Ports - ProceduresYou have to do the following to set up the pattern generator's output ports:Setting Logic Levels and Terminati

Adjust Output Levels (optional)Data, Aux Data, Clock and Trigger/Ref Clock offset and voltage levels can beadjusted. This is typically done when you w

To change the de-emphasis amplitude ratio value (for details see “Understandingthe N4916A/B De-Emphasis Signal Converter” on page 37), click inside th

N O T EOnce you have connected the pattern generator to the N4916A/B De-EmphasisSignal Converter, the Output Levels and Termination shown on the scree

Input and Output Ports - ReferenceThe pattern generator produces clock and data outputs that serve as frequencyreference and device stimulus for the d

VloThis text field allows manual entry of the logic low voltage level and displays thecurrent value.To modify the value, click inside the text field a

Half Rate Clocking and Clock Duty CycleA checkbox allows to enable half rate clocking: the clock at the clock output runsat half the bit rate. In half

0V (Disable)C A U T I O NBefore clicking this button, ensure that your device's inputs tolerate groundpotential.Use this button to clamp the patt

De-EmphasisUse this text box to enter the pre-cursor value. The value is interpreted as dB or %depending of the specified mode.N O T EThis is applicab

Understanding the Serial BERTThe Serial BERT, also referred to as a Bit Error Ratio Tester (BERT), is a powerfulinstrument that enables you to analyze

The Serial BERT can be connected to an external clock to allow it to run as partof a larger external system.• Use of a modulated clockA frequency- or

For the pattern generator the following rules apply:• Below 620 Mbit/s, the pattern generator can only be operated with an externalclock source, becau

To set the bit rate:1If the external clock source has a frequency of 10 MHz, connect the clock sourceto the pattern generator's 10 MHz Ref In por

Bit Rate - ReferenceThe Bit Rate Setup window contains the following elements:Clock SourceClock source can be one of the following:• Internal: The clo

External PLL Clock Divider and MultiplierThe internal clock (i.e. the bitrate) is the external PLL divided by the value specifiedin the divider field

Clock Rate IndicatorsThe PG (Pattern Generator) and ED (Error Detector) bit rate indicators shown inthe lower pane display their current bit rate.The

3Select the trigger pattern that you want to be generated.See “ Trigger/Ref Clock Output - Reference” on page 146“ Aux Data Output -Reference” on page

Alternate Pattern Trigger LevelN O T EThis option applies for alternating patterns only.Select this option to set the trigger level high whenever alte

Pattern Trigger PositionN O T EThis option is not available for alternate patterns.Select this option to send a trigger signal that is synchronized to

Data OutTrigger Out10 1 . . . .1 1000100 10 11 1000100 . . . .•Shift Trigger PositionClicking the left and right buttons will move the bit trigger pos

Option/Upgrade for jitter injection. Total jitter can be composed from random,periodic, sinusoidal, and bounded uncorrelated sources.• J11, U11Spread

• Clock Divider• Second Channel• Multiplexer mode• De-EmphasisN O T EThe options on the Aux Data Output dialog are disabled when the N4876AMultiplexer

• Create the pattern then save it.1Click "Properties" icon to set up the properties of the current pattern,including parameters and length.2

• From the Pattern menu, click Sequence Editor.• You will be now able to select edit and drop in the data you want on both theRegular Channel and the

• Send the patterns to the outputs by pressing “To PG”.You should be now able to send the data.Setting up the Pattern Generator 4Agilent J-BERT N4903B

Aux Data Output - ReferenceIf you wish to use the pattern generator's Aux Data Out port, set the mode fromthe following options:• Set the Aux Dat

having to care for the correct setup of the required data streams. The PG patternis considered to be the serialized output of the connected multiplexe

You can enable the input after reducing the voltage to a safe level.Delay Control Input - ProceduresN O T EThe following procedure does not apply to S

N O T EThis checkbox is not available on instruments on which the calibrated and integratedjitter injection option J10 is installed. On such instrumen

Using an External Signal for Inserting ErrorsTo configure the Serial BERT to insert a single error into the output streamaccording to an external sign

T I PTo find out how your DUT reacts on very small bit error rates, set up the patterngenerator to enter errors once every 10-12 bits and run a longer

Express®, SATA 3 Gb/s, USB3, fully buffered DIMM, Hypertransport, CEI, or 10GbE.The following De-Emphasis Signal Converter can be used:N4916A De-Empha

Error Add Setup Dialog BoxThe Error Add Setup dialog box provides the following configuration options:Channel SelectWith this option, you can apply th

InternalSelect this option to use internal error insertion functions:•Error RateAllows to select from a preset bit error ratio from 1.000E-02 to 1.000

further configuration possibilities. This pattern is sent as long as the outputport is enabled.See “Setting up Patterns - Concepts” on page 61 for mor

–Continuous AOnly pattern A is output repeatedly.–Continuous BOnly pattern B is output repeatedly.–Alternate ABThe output stream switches between patt

3In the Aux In section, define whether the Serial BERT should insert pattern Bin Level Sensitive or Edge Sensitive mode.See “Aux In” on page 165 for m

Continuous BSelect this option to send out only pattern B repeatedly.B0 B1 B2B B B B B B B B B B B BData OutAlternate ABSelect this option to alternat

Aux InData Out A A B A B B B•Edge SensitivePattern A is sent out until a rising edge at Aux In is detected. Then, at the nextcomplete repetition of pa

5 Setting up the Error DetectorSetting up the Error Detector - ConceptsThe error detector analyzes an incoming bit stream, compares it to the expected

• BER location modeYou can specify whether all errors are counted or only the errors that occurredon a particular bit position or range of positions.•

Understanding Error Detector Input PortsThe error detector has the following input ports:• Clock InThis port needs to be connected to a clock signal u

• Programmable via J-BERT N4903B or stand-alone• USB and LAN connectivityOnce the N4916A/B is connected, it can be conveniently controlled via the Ser

single trigger pulse is sent. If continuous errors are detected, the error out signalwould be a clock signal.Error OutErrordetectedData INAn Errors wi

Why Can Wrong Terminations Damage Your Device?Choosing wrong terminations may cause your device to output voltage levels thatare not as expected. It m

Data Input Setup - ReferenceThe ED Input Setup dialog is accessed from the Sampling Point Setup window. Itis used to set up the error detector's

TerminationIn this field, enter the termination voltage that is appropriate for the incoming datasignal. This selection should be made before the devi

clock from the pattern generator), or extract the clock signal from the incomingdata (CDR mode).CDR mode does not work for all kinds of data patterns.

N O T EThe “frequency” is the modulation frequency, and “amplitude” is the tracking ofthe PLL.Data rate and loop parametersThe data stream contains mu

The threshold voltage can be derived from the input signal via a low-pass filter.This will work fine for most applications. But applications that do n

The following figure clarifies the behavior in the range between 615Mbit/s and620 Mbit/s:615 Bitrate [Mbit/s]620Limitations do not applyin this rangeL

With this method you can still place the sampling point anywhere in the clockcycle to find the optimum sampling point, even at low frequencies.Clock 3

8Either enter the transition density manually, or run a measurement to updatethis value.Clock Setup - ReferenceThe Clock Setup window contains the fol

• 2-slot AXIe module that can be controlled from J-BERT N4903B user interfacevia USB• Expands data rate of J-BERT N4903B pattern generator up to 28.4

Preset ListThe Preset list contains clock rate values that are commonly used by the errordetector.These presets also modify the loop parameters of the

transition density. In such a case enter the value given in the specification, so thatthe CDR behaves according to the standard. If a standard from th

• press the Measure button to measure the voltage level of the incoming signalwhile a burst signal is applied.Once the level is defined, it remains fi

N O T EAll measurements (except Jitter Measurement) in "8B/10B Symbol Comparison","Bit Comparison without PCIe3 SKPOS" and "B

Understanding the Error Free Receiving in PCI® Express 3.0 128B/130B Encoded Data ComparisonWhen RX detects incoming data correctly, the pattern loope

N O T EThe "Bit Comparison without USB3.1 SKPOS" error ratio mode supports the bit rateup to 10.35 Gbit/s. However, if you want to use bit r

4Choose the error ratio mode from the following options:aBit Comparisonb8B/10B Symbol ComparisoncBit Comparison without PCIe3 SKPOSdBit Comparison wit

However, if you select error ratio based on "8B/10B Symbol Comparison",follow the below steps.5Click cBER Setup.It opens a cBER Setup dialog

9You can view the details of the selected presets. To do so, either click View/Edit Preset button or double-click the preset. Remember, the details of

N O T EThe "Automatic" mode is selected by default for symbol alignment.The "ReAlign" button is disabled in "Automatic"

For understanding, the Serial BERT GUI can be divided into three panes; namelythe upper, middle and the lower pane.The following picture illustrates t

Error Ratio - Reference8B/10B Presets DialogThe 8B/10B Presets dialog allows you to enter a short description, values for FillerPrimitives definition

Table 19Standard Filler SymbolsUSB3.0 Skip: K28.1, K28.110B Symbol alignment: K28.5SATA Align: K28.5, D10.2, D10.2, D27.310B Symbol alignment: K28.5MI

10B Alignment SymbolThe 10B Alignment Symbol contains the K28.1, K28.5 and K28.7 symbol for 10Balignment. You can use the drop-down list to specify sy

Sampling Point SetupSampling Point Setup - ConceptsThis section provides basic information on the sampling point setup and eyediagrams.How Does the Sa

observed. The eye is bounded by overlaid logic 1 and 0 voltages (top and bottom)and multiple 0 to 1 and 1 to 0 transitions (left and right).Different

Understanding Bit Recovery ModeIn bit recovery mode (BRM), the error detector does not expect any particularpattern. Nevertheless, it detects bit erro

• Error Location Capture cannot be used.• The function Error Detector Pattern tracks the Pattern Generator Pattern isdisabled. This function is not re

The Sample Point in the eye diagram moves horizontally as you change thevalue.T I PWhile adjusting the data input delay, you can monitor the BER bar o

2Click the Bit Recovery Mode button.The Sync Now button is no longer available.Note that you can also enable the bit recovery mode from the Pattern wi

Data DelayThe data input delay defines the point in time (in reference to the clock signal) atwhich the incoming data signal is measured. Specifically

© Agilent Technologies, Inc. 2014No part of this manual may be reproduced inany form or by any means (includingelectronic storage and retrieval or tra

• Control’s Title: Displays the title of the control window.The following picture illustrates the middle pane of the Serial BERT.The middle pane allow

Sync NowClick this button to manually start a pattern synchronization. See “What Type ofSynchronization Should You Use?” on page 208 for information o

CancelClick this button to cancel the Auto Align, 0/1 Threshold Center, or Data Centerfunctions while they are in progress. The following parameters w

This function is useful for providing a "starting point" for sampling somewherewithin the data eye on the vertical voltage axis. It is recom

Trigger and Aux OutputTrigger and Aux Output - ConceptsThe error detector has a Trigger Out and an Aux Out port that you can use to sendsignals to oth

threshold is set below or above the data eye, the output at Aux Out will beconstant high or low, respectively.4Click OK to finish the Trigger and Aux

The usage of the enhanced error detector trigger is based on the PCIe3 SKPOS(Skip Ordered Set). The 130 bit SKPOS is used as detect word and is notcon

Introduction to Pattern SynchronizationPattern synchronization (sync) refers to aligning the incoming data pattern withthe internal reference pattern.

Detect Word48 bitsDetect Word48 bitsDetect Word48 bitsDetect Word48 bitsDetect Word48 bitsReferencePointCorrect SyncExpectedPatternIncomingBit stream•

The detect word on which the error detector attempts to resync is chosen strictlyby chance. So if there are two instances of the detect word in the pa

N O T EAdjusting the data input delay may cause momentary clock loss. If you selectManual Sync mode, this may also result in sync loss.• Burst sync mo

How to use the Navigation MenuThe navigation Menu comes with a pull down menu which provides a centrallaunching point for the various controls of the

How Can You Tell if Your Synchronization is False?You may suspect false synchronization under the following conditions:• You are using a pattern other

Introduction to Burst Sync ModeThe burst sync mode is a special operating mode for measuring data in bursts ofbits, rather than one continuous stream

How Burst Sync Mode WorksThe following figure presents the basic order of events that make up a burst modemeasurement. It also illustrates how the ins

3The error detector can then synchronize to the incoming signal. For PRBS, thefirst received bits are used to seed the synchronization. If there is an

The Bit Count Time is the part of the burst from which the bits can actually becounted. The remainder of the burst is covered by the Begin Margin and

Table 21Parameter ValuesBegin Margin CDR Settling Time + SynchronizationTimeEnd Margin Valid after GateBit Count Time Burst Length - Begin Margin - En

Starting too late: If the Gate In signal is applied too late, the Bit Count Time willbe shortened, and thus the burst sync ratio will be low (which fo

2Select the synchronization mode (Normal or Burst sync mode).N O T EThe burst sync mode is disabled in "8B/10B Comparison", "Bit Compar

7Press OK to confirm your settings.Pattern Synchronization - ReferenceThe error detector can synchronize the data patterns in the following ways:• In

anymore. Also test results would not correlate with other error counters such asprotocol testers anymore.The high error ratio also serves as a trigger

Each pull down menu and its option are described in the following section:The File menu allows you to perform the following tasks:• Generate a new pat

Error AccumulationError Accumulation - ConceptsThe Serial BERT instantly starts measuring the BER when the error detectorreceives data. However, to pe

Error Accumulation - ReferenceThe Accumulation Setup window contains the following elements:Activation Mode•ManualActivate this option to configure th

PeriodThe accumulation period cannot be specified for Manual tests.•TimeSelect this option to configure the error detector to accumulate bit errors fo

BER LocationBER Location - ConceptsThe Serial BERT can be run in BER location mode. In this mode, the errors are notcounted on all bits of the data si

With this option, all errors are counted.With this option, only errors occuring in the block between the specified StartBit and Block Length are count

Audio Signals - ProceduresTo set up the warning sounds, do the following:1Click Audio menu item from the ED Setup submenu.2Check the Audio on checkbox

Main VolumeClick any point on the slider or drag it to change the main volume level. You willhear a test tone at the new volume level.Audio on BER Ala

6 Advanced AnalysisAdvanced Analysis - ConceptsThe Serial BERT offers several different kinds of advanced measurements forvarious purposes:This type o

The Fast Eye Mask measurement is first of all meant for production and screeningtests. It allows to determine very quickly whether the eye opening see

changing the measurement settings after the measurement has been run, pleasenote:• Parameters that affect the data capture.Changes on the Parameters p

• Sampling Point Setup• Trigger and Aux Setup• Pattern Sync• Accumulation Setup• Start Accumulation• Stop Accumulation• BER Location• AudioFor more in

How to Export MeasurementsTo export the measurement data into a .txt file for later use in external spreadsheetapplications:1After your measurement ha

4Repeat the measurement with modified parameters and observe the newresults.5To distinguish the two graphs, change the color of one graph by tipping t

How to Change Measurement Properties and the Graphical DisplayThe various tabs in the Properties dialog box allow you to specify the parametersfor the

Depending on the current measurement type, you can change:– BackColor: The background color of the graphs (default is white)– BERMarkerColor: The colo

Advanced Analysis - ReferenceThis section covers reference information such as definitions of importantparameters and the descriptions of supplementar

Timing Unit DefinitionsThe timing unit specifies the timebase for the measurements. It is possible toswitch between the unit interval (UI) or seconds

At 100MHz, the pulse period is 1/100 × 10-6s = 10-8s = 10ns; this is the unit interval(UI). For example, a value - in fact, any parameter that is spec

The following values are displayed for the current marker positions:Table 23Value DescriptionUpper Right Time and BER of the upper rightintersection o

This formula describes a bell-shaped Gauss curve. If μ is zero and σ varied, youwould get the curves illustrated in the figure below:The height and po

Table 24Parameter Symbol MeaningMuμMean.DUT Output Timing/Jittermeasurement:The position of the markercenter on the time scale.Output Levelsmeasuremen

The Results menu provides the following:• BER Results• Accumulated Results• Eye ResultsFor more information on Results, refer to the section “Evaluati

As the bathtub borders are not uniform (both have two edges), the linear derivative(the jitter) will show two peaks:If you switch to linear scale and

But your dBER distribution may also look like this:The measurement will calculate the Level and Standard Deviation results from alldata points. The ma

Output Timing CharacteristicsThe sampling point is swept automatically within a 1.5 clock period to generate a"bathtub" curve. The resulting

Example ResultsThe following illustration shows the resulting graph of a typical DUT Output Timingmeasurement:The following figure shows a typical jit

2All measurement points that have BER between the BER Threshold andMinimum BER for RJ/DJ Separation are transformed into Q-space.The Q-factor describe

The Estimated Total Jitter (TJ) allows you to predict the jitter expected for verylow bit error rates that would take a long time to measure. It is ob

Explanation of the Fast Total Jitter MeasurementThe Fast Total Jitter measurement is an optimized method to determine the totaljitter for devices that

operates with a BER better than let us say 10-12; whether the true BER is 1.1 ×10-13 or 2.7 × 10-15 is irrelevant.To abort the measurement for a singl

Note that there is a gap where the BER is so close to 10-12 that we cannot decide.For example, if we compared 3 × 1012 bits and got two errors (a meas

We do not need to know the exact BER values at x+ and x-. It is sufficient to assurethat BER(x-) is greater than 10-12 and BER(x+) is lower than 10-12

In addition, the About button on the Help displays the license information of theSerial BERT.Which Test is Appropriate?Which Test is Appropriate? - Co

DUT Output Timing/Jitter - ProceduresThis section shows how to set up and use the DUT Output Timing/Jittermeasurement. As an example, we measure the o

9Press Sync Now and then Auto Align to find the optimum sampling point. Checkthat the synchronization and the alignment were successful. None of the e

These settings are used for data collection. Changes here require the testto be run again. See “Parameters Tab” on page 252 for details.– Pass/Fail ta

• Number of ErrorsAfter this number of errors, the measurement stops for the current sample pointand moves to the next one. This allows you to speed u

– Fast Total Jitter at BERThis enables the Fast Total Jitter measurement. Before enabling thismeasurement, you need to know the BER floor of the devic

N O T EIf the results of a Fast Total Jitter measurement are displayed, only the appropriateparameters are compared and flagged:•Phase Margin•Optimal

View TabThe graph shows either the bathtub curve or the jitter distribution vs. time.The BER graph (the bathtub) shows the BER vs. sample delay.The BE

N O T EBecause the right-hand slope of the tub does not provide additional information onthe jitter, the measurement's jitter display shows only

If this is selected, RJ/DJ separation is not available.• BER ThresholdTo calculate the parameters for the given BER threshold. This is the BER levelfo

To analyze the graphs at a particular point, you can use the markers. Additionally,you can display all related values for the markers in the marker re

The following references may also be helpful in determining how to test yourdevice.• For a list of recommended patterns for your device and applicatio

Table 26Parameter Description DefinitionOptimal Sample PointDelayThe average of the left (A)and right (B) bathtub/BERthreshold intersections.(A+B)/2Ph

• Jitter MeanMean value for total jitter. Calculated as the weighted average of the left edgejitter histogram.• Random Jitter RMSThe total jitter comp

RJ/DJ values can be calculated in this case, they are not shown becauseconfidence in the results is too low.Explanation of the Fast Total Jitter Measu

Peak-to-peak value of the total jitter. Calculated as the pulse period (unitinterval) minus the Phase Margin at the Total Jitter BER Threshold.• Total

Three Available ViewsThe Output Levels measurement provides three different graphical views tovisualize the calculated results:•BER versus ThresholdTh

Changes on the Pass/Fail, View, Graph, and Color tabs only affect the displayof the results. There is no need to repeat the measurement.Variable Decis

4Use a shielded cable to connect the pattern generator's Data Out port and theerror detector's Data In port.5Switch to the Pattern panel and

In this example, we expect the signal voltages to be between -1.75V and -0.95V.The Sample Threshold values proposed above cover this range well.The Re

How to Improve the Output Levels DisplayYou can change the display of an existing measurement, for example, if you wishto see more details to investig

How to Change the Output Levels PropertiesIn the example measurement, we have set the focus on speed: 100 threshold levelsand 1,000,000 compared bits

The Serial BERT allows you to run tests from 150 Mb/s up to 12.5Gb/s(depending on the options with which you bought the instrument). See “ErrorDetecto

This graph shows the absolute values of the derivative of the bit error rates overthe thresholds (dBER/dTh). It visualizes the data that forms the bas

After this number of errors, the measurement stops for the current sample pointand moves to the next one. This allows you to speed up the measurement.

As you can see from the figures above, Edge Resolution Optimization does notsacrifice the precision of the measurement. But it can reduce the measurem

In the following figure, you can see how errors are flagged.Advanced Analysis 6Agilent J-BERT N4903B High-Performance Serial BERT 273

If you compare the Low Level result with the limit we have set on the Pass/Failtab, you will find that the measured result fails the upper pass/fail l

This graph shows the extrapolation of the optimum Q-factor and the optimumthreshold level from a limited number of measured points.The measured data p

This is the bit error rate threshold at which the Threshold Margin is determined.It is also the upper threshold for the Q-factor calculations.The BER

N O T EIf you have a mouse connected to your Serial BERT, you can access manyparameters and display options conveniently from the context menu. This l

• Low LevelThe Low Level is the mean of the lower dBER/dTh distribution. It is calculatedas:• Mean LevelThe Mean Level is the middle between the High

where Mean is the High Level of the terminal.• Low Level Std. Dev.The Low Level Standard Deviation is calculated as:where Mean is the Low Level of the

Table 3BER STM-64/OC-192(9.95328 Gb/s)STM-16c/OC-48c(2.48832 Gb/s)STM-4c/OC-12c(622.08 Mb/s)STM-1/OC-3(155.52 Mb/s)1E-12 ~ 5 minutes ~ 20 minutes ~ 80

Table 29Parameter Name Pass/FailQ High Level Nr. PointsQ High Level R^2Q Low LevelQ Low Level Std.DevQ Low Level Nr. PointsQ Low Level R^2For some of

The Q High Level is the mean, calculated from the linear regression curve forthe high level data:m =-AB• Q High Level Std.DevThe Q High Level Standard

• Q Low Level Std.DevThe Q Low Level Standard Deviation is the σ (Sigma), calculated from the linearregression curve for the low level data:s = -1B•

Mathematical BackgroundBit errors are caused by noise, and the Q-factor describes the signal-to-noise ratioat the decision circuit.It is possible to c

This function, applied to the high level and low level data points, yields newthreshold vs. value combinations.In the area of low BER (typically below

This graph shows two straight lines. The intersection of these lines marks the Q-factor and the Q optimum Threshold.Mathematically, the standard devia

•The R2 values are excellent (greater than 0.95).• The mean levels and standard deviations returned by the Q-factor calculationsdiffer from the measur

Eye OpeningEye Opening - ConceptsThe Eye Opening measurement generates a three-dimensional bit error rate (BER)diagram as a function of the sample del

The contour plot shows discrete lines of equal bit error rate - just like thecontour lines on a map. The color of a line indicates the respective BER

Example ResultsThe following figure shows the graphical result of a typical Eye Openingmeasurement:Eye Opening - ProceduresThis section shows how to s

Connecting the DUTConnecting the DUT - ConceptsThis section provides information on how to connect your DUT for several commontest scenarios.N O T ETh

• Optimizing the view of the results (see “How to Optimize the View of theResults” on page 291)• Using the color bar (see “How to Use the Color Bar” o

How to Execute the Eye Opening MeasurementTo run the Eye Opening measurement:1Switch to the Analysis panel and then press the Eye Opening icon.2Press

– View tab, Graph tab, and Color tabAll settings on these tabs only affect the way the data is displayed. You donot need to run the measurement again.

Table 30Option DescriptionAdd color... To add an additional color to thecolor gradient at the cursorposition. The BER range for thisnew color will be

How to Change the BER Range of a ColorThe bit error ranges are set automatically, but you can change these areas. To doso:• Move the handles of a colo

Parameters TabN O T EIf you modify the parameters on this page, you have to rerun the measurement toupdate the results.Set the criteria for moving to

• Low LevelSpecifies the lower limit of the measurement voltage range. Enter the value inmV. This value should be slightly lower than the lowest expec

In the tabular view, each of the calculated values will be marked with anicon if it failed the test.The following illustration shows an Eye Opening me

View TabThe graph shows either a Contour Plot, a Pseudo Color Plot, or only one curve forthe selected bit error rate threshold.The contour plot shows

It shows the contour line at the BER threshold.Furthermore, the following parameters can be set on the View tab of theProperties dialog box:You can an

Contents1 Planning the TestPlanning the Test - Concepts 11Introduction to the Serial BERT 11Introduction to the Serial BERT - Concepts 11Navigating

Diagram 1. Connections for Different In/Out Data RatesOften used for multiplexers, or when the data rate received by the device is notequal to the dat

and drop the horizontal BER threshold in the graphical display to change thisvalue.You can select the number of Decimal Places to be displayed in the

Explanation of the Numerical ResultsAdditionally to the graphical results, the measurement provides numerical results:Measurement ParametersThe measur

Understanding the Result ParametersAll result parameters are calculated from the BER threshold contour line and itsbounding box. So, all parameters ch

N O T EThe Error Location Capture measurement is disabled in "8B/10B Comparison","Bit Comparison without PCIe3 SKPOS" and "Bi

• No other advanced measurement (Output Timing, Output Levels, etc.) can berunning.• Error Location Capture can only run when the BER Location Mode is

How to Demonstrate the Error Location Capture MeasurementTo demonstrate the Error Location Capture measurement:1Switch to the Pattern panel and press

Choose between a binary or hexadecimal display of the pattern. The currentsetting is shown in the status bar below the pattern window.Note that in hex

• Length: This field indicates the length of the captured data. Note that the valuehere does not equal the length of the pattern.Compare Pattern FileT

This is achieved by measuring the bit error rate at a limited number of test points.Up to 32 measurement points can be specified, each defined by a sa

Instead of UI (one Unit Interval is equal to one system clock period), the relativetime can also be specified in seconds.• The Voltage is the decision

Diagram 3. Connections for an AmplifierOften used for amplifiers.Diagram 4. Connections for a Flip-FlopOften used for flip-flops.Planning the Test 1Ag

• Optimizing the View of the Results. (See “How to Optimize the View of theResults” on page 311 ).How to Prepare the Fast Eye Mask MeasurementTo prepa

The measurement is run and the result window shows the bit error rates measuredat six measurement points.The Relative Time refers to the current sampl

Parameters TabNote that if you modify the parameters on this page, you have to rerun themeasurement to update the results.Set the criteria for moving

Depending on the quality and characteristics of the eye opening, theresulting 50% threshold may deviate from the decision threshold defined inthe load

N O T EThe BER Threshold will usually be 0, since you want the measurement to fail if asingle bit was received in error.The pass/fail threshold applie

You can select the number of Decimal Places to be displayed in the table.Eye DiagramEye Diagram - ConceptsThe Serial BERT provides quick design analys

Methods of RepresentationsThere are two methods of representing the eye diagram:• Waveform• ContourWaveformWaveform is the shape, and form of a signal

The BER Threshold is configurable. The BER Threshold is the level up to which thesignal is represented as waveform, and BER values below this threshol

italics. A BER value for which a Contour does not exist is struck across. You canselect multiple BER values. The lower BER values are in red and pink,

N O T EThe mask test is enabled when "center" is set to "middle of eye", and "persistence"is set to "infinite"

Diagram 5. Connections for a MUX/DEMUX PairUsed to test multiplexer/demultiplexer (MUX/DEMUX) pairs. For accuratemeasurement results, the timing of da

N O T EThe scroll bar at the bottom of the table shows the entire table and its contents.For more details refer to “Eye Diagram - Reference” on page 3

7Set up the error detector to match the input range and the termination with thepattern generator’s levels:– Select an Input Range from –2 V to 0 V– S

How to Change the Default Settings of an Eye Diagram?To achieve desired results, you can change the measurement parameters:1Click the Properties butto

The view tab options set the parameters to measure, and choose units forthe displayed results in the numerical table. (Refer to “View” on page333 for

– Eye Measurements tabThe Eye Measurements tab lists out all the measurements. The user canselect specific results.6 Advanced Analysis324 Agilent J-BE

How to Set Markers?Markers help in tracking the BER at specific points, so to set the markers:1Click on the Graph tab2Select Show Maker Lines3 Apply S

The Marker reading is shown on the left side of the graph.4Click the marker readout button on the top left corner to see the detailed markerreadout.Ho

5 StartThis starts the Mask Measurement.You also have options for setting MaskMargins, and Mask Scaling.6Click the mask readout button on the bottom l

/* Region Number */ 2Region TypeYou can define three types of regions for each region number you have specified:• STD defines the actual mask region.•

:MTES:INP:MODE DIFFIn the above example, the Y1 and Y2 values define the mask with an absolutevoltage value. In some mask files, Y1 and Y2 values are

Diagram 7. Connections for a SONET/SDH Receiver (PGonly)Often used with network equipment, such as SONET/SDH receivers. The deviceshown may or may not

• Property Page• Legend States• Left Panel Values• Automated Eye Parameter Measurement1Click on the Analysis Menu2Click on ‘Save Measurement’To Recall

When you click on ‘Export Data’ the following screen appears:The Clipboard option saves the data on a clipboard.The ‘Format Options’ takes you to the

The ‘Error’ option gives the user the choice of saving, the BER, the Compared Bits,and the Errors, for different combinations of expected 1s, 0s, and

With ‘middle of eye’, the center of the eye coincides with the center of the screen.• TransitionWith ‘transition’, the transition of the eye coincides

Marks the lower edge of the eye window boundary• Right BoundaryMarks the higher edge of the eye window boundarySet the criteria for eye width and eye

Ratio of two optical power levels, low level and high level• dBUnit for measuring the extinction ratio.ratio[dB]=10*log(ratio)• %Extinction Ratio in p

Set criteria for the markers:• Show Marker LinesThis option enables the markers on the screen.• Reset markerThis brings the marker back to its default

The Mask Run Control aligns the mask, switches it on, starts displaying the numberof waveforms, and the number of mask violations per mask region, and

Table 31S.No Parameter Description4 0-Level Zero level is themeasurement of the meanvalue of the logical 0 of aneye diagram.Note: This measurement ism

Table 31S.No Parameter Description7 Eye Width The horizontalmeasurement of the eyeopening at a specified BERThreshold.Note: The Eye Width iscalculated

Diagram 9. Connections of the De-Emphasis Signal ConverterThe Data Output of the Pattern Generator is connected to the Input of the N4916A/B. The unus

Table 31S.No Parameter Description10 Jitter RMS A standard deviation of thecrossing point histogramwith respect to BERthreshold.Note: The Jitter RMS i

Table 31S.No Parameter Description14 OMA The Optical ModulationAmplitude (OMA) is thedifference between the 1-level power and 0-levelpower.Note: The O

Eye Diagram ScreenThis graph gives the picture of the Eye Diagram Screen.Spectral JitterSpectral Jitter - ConceptsThe Spectral Jitter measurement allo

The Spectral Jitter measurement detects even small periodic components that maybe hidden in a high level of random noise. It informs you about the fre

These records are automatically processed. The error information is subject to afast Fourier transform (FFT). FFT reveals the spectral components and

Jitter caused by a triangle signal shows an even distribution:Last, but not least, the histogram of jitter modulated by a sinusoid exhibits twosignifi

• You can switch between linear and logarithmic scales.• Graphical markers and the zoom function assist you when you are analyzingthe graph visually.•

100 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1101 0 1 0 1 0 1 0 1 1 0 1 0 1 0 1 0 1increasing right shift decreasing right shift increasing left shift decreasi

N O T EThe Spectral Jitter measurement should only be used in conjunction with data thathas an equal distribution of ones and zeros over time. Otherwi

The fundamental frequency and its harmonics appear.Such spectra have been measured with the Spectral Jitter measurement.A logarithmic power scale show

Diagram 11. Connections of the M8061A with J-BERT N4903BThe Data In 1, Data In 2 and Aux Clk In of M8061A have to be connected to AuxData Out, Data Ou

Leakage makes it impossible to detect minor adjacent spectral components. Thefollowing two figures refer to a slightly disturbed sine wave.When you pe

• Every window reduces the spectral power.• Results obtained from different devices can only be compared if the samewindow is used.Spectral Jitter - P

9Press Sync Now and then Auto Align to find the optimum sampling point. Checkthat the synchronization and the alignment were successful. None of the e

These settings are used for data collection. Changes require to run the testagain. See “Parameters Tab” on page 252 for details.– Pass/Fail tabThese s

data rate / Acquisition DepthFor example: If you have a data rate of 2.5 GHz and an Acquisition Depth of128 Kbit, the frequency resolution is 19.0735

The other windows have the shapes illustrated in the figure below:You can see from the figure that the Blackman window is the strongest filter.The win

N O T EThe pass/fail criteria do not control measurement execution. The measurement runwill be completed even if the measurement fails for one or more

View TabThe graph shows the noise versus frequency. The View tab provides you withvarious options for analyzing the data and setting frequency ranges

The figure above shows the absolute power scale and values as calculated by theFFT. You can also calculate relative values.Relative values can be norm

Choose between logarithmic and linear scale for displaying the frequencies.Display the power either in a logarithmic (dB) or linear scale.Show the ent

1 Planning the Test36 Agilent J-BERT N4903B High-Performance Serial BERT

6 Advanced Analysis360 Agilent J-BERT N4903B High-Performance Serial BERT

7 Evaluating ResultsEvaluating Results - ConceptsThe Serial BERT offers several different kinds of tests that can be run:• Instantaneous MeasurementsT

• Frame Error Ratio (FER)• Calculated Bit Error Ratio (cBER)• Filler Symbol Ratio (FSR)• Disparity Error Ratio (DER)• Illegal Symbol Ratio (ISR)In ord

This can be used to see how changes to your device affect the "BER" / "8B/10B Comparison" / "Bit Comparison without PCIe3 SKP

How to Monitor BER ResultsThere are different ways, how you can monitor instantaneous BER values:1Listen to the BER warning tones. See “Audio Signals

3View the Bit Comparison without USB3.1 SKPOS bar and errors indicator. See“Status Indicators” on page 372 for details.How to Analyze Instantaneous Me

Instantaneous Measurements - ReferenceThis section describes all elements of the BER Results window and 8B/10BComparison Results windows and their var

8B/10B Comparison Results WindowThis window displays the actual or cumulative results of the followingmeasurements:• Symbol Error Ratio (SER). See “SE

Click this button to toggle between SER or AccumSER results.This area displays the actual symbol frame error count or cumulative error count.FER Resul

You can click Accumulated/Actual button to toggle between cBER orAccumcBER results.The Error Count/Accum Error Count area displays the actual error co

2 Setting up External Instrument(s)Setting up External Instrument(s) - ConceptsThe External Instrument(s) menu allows you to enable external instrumen

• The FSR is the current FSR, calculated upon a period of 200ms.• The AccumFSR shows either the accumulated FSR of the current accumulation,or if no a

• The DER is the current DER, calculated upon a period of 200ms.• The AccumDER shows either the accumulated DER of the currentaccumulation, or if no a

• The ISR is the current ISR, calculated upon a period of 200ms.• The AccumISR shows either the accumulated ISR of the current accumulation,or if no a

You can drag the yellow alarm threshold mark to change the SER Alarm Threshold.The FER bar displays the FER calculated upon a period of 200 ms.You can

N O T EThe two additional error indicators "Symb Lock" and "8b10b Error"will only appearif you select the error ratio as 8B/10B Sy

• No new errors: The triangle icon on the button will remain yellow.If an error occurs, the detailed error message is displayed for a few seconds on t

The PG and ED measured bit rates are displayed here for your reference.Accumulated MeasurementsAccumulated Measurements - ConceptsAccumulation refers

N O T EDuring measurement logging, the Serial BERT logs data in ten-second intervals.Your log file may be missing up to the last ten seconds of data.

How to View the ResultsYou can view data from accumulated measurements in several ways:1Click the Accumulated Results menu item from the Results subme

Ratios GraphThis graph displays the delta errored 1's ratio, delta errored 0's ratio, and total deltaerror ratio at data points over the ent

N O T EN4916B De-emphasis box is supported for Aux Data Out channel of the patterngenerator as well in second channel mode.The figure below shows the

N O T EThe zooming function cannot be used before the accumulation period has ended.N O T ETo view precise BER data for every point in time, view the

•Errored 0's RatioThe ratio of the errored 0's count to the bit count is displayed here to 4significant digits.•Errored 0's CountThe nu

Interval Results•Error Free SecondsThe number of seconds in which no errors were measured is displayed here.•Error Free DecisecondsThe number of decis

•Accumulation PeriodFor single and repeat accumulation modes, the accumulation period isdisplayed here. The period will be displayed in elapsed second

The status is unknown. This can occur if accumulation has not been started,or if Burst Sync mode has not been activated.•Burst Sync RatioPercentage of

Ratio GraphThis graph displays the delta symbol errored 1's ratio, delta symbol errored 0'sratio, and total delta symbol error ratio at data

•Compared Symbol Count (Symbol counter)The number of compared symbols considered for the accumulation period isdisplayed here. This may not be equal t

•Illegal Symbol Count (Illegal symbol counter)The total number of illegal symbol count received in a time interval is displayedhere.•Disparity Error R

The raw number of received symbols by the error detector equals the sum offiller primitives (which are being dropped before comparison) and the actual

one single frame error. In contrast to this, the Serial BERT loses patternsynchronization and must re-synch before the test can be continued. Currentl

De-emphasis is a method that reduces the voltage of a digital signal if the generatedlevel is high or low for more than one clock period. The principl

Ratio GraphThis graph displays the delta symbol errored 1's ratio, delta symbol errored 0'sratio, and total delta symbol error ratio at data

Accumulated Measurements for Bit Comparison without USB 3.1SKPOSThe Accumulated Results window for Bit Comparison without USB 3.1 SKPOScontains a grap

Accumulation Parameters for Bit Comparison without USB 3.1SKPOSFor detailed information on "Bit Comparison without USB3.1 SKPOS" accumulatio

Eye Measurements - ReferenceEye results are displayed for the Current Align and Previous Align process. Theyare also graphically displayed on a repres

N O T EMost oscilloscopes measure eyes differently, using statistical data. Therefore, theeye results of a Serial BERT and an oscilloscope may be diff

8 Jitter Tolerance TestsJitter Tolerance Tests - ConceptsN O T EThis chapter refers only to Serial BERT instruments on which the calibrated andintegra

• Intersymbol interference• Level noiseThis refers particularly to the performance of phase-locked loops (PLLs) or clockdata recovery circuits (CDR).J

The Serial BERT provides the Interference Channel option J20 to simulate levelvariations by adding sinusoidal interference.For more information see• “

Bounded Uncorrelated JitterSimilar to random jitter, bounded uncorrelated jitter (BUJ) has also a Gaussiandistribution, but this distribution is cut (

The jitter amplitude is usually specified in UI. One UI (Unit Interval) is always thereciprocal of the present data rate. For example, if the data rat

User-Defined Sequences 96User-Defined Sequences - Concepts 96User-Defined Sequences - Procedures 99User-Defined Sequences - Reference 101Sequencer-Pa

the roles of the two branches. The delayed signal has now a larger amplitude thanthe direct signal. A waveform example is illustrated in the following

Intersymbol interference can be simulated by inserting a defined transmission pathbetween the pattern generator and the DUT.CrosstalkCrosstalk between

Edge, level, and shape variations impact width, height, and symmetry of the eyeopening. An example is shown below:How the N4903 Generates JitterAn Ser

and the RJ sources, i.e. BUJ and RJ are mutually exclusive with sRJ. In addition,an external jitter signal can be applied at the Delay Ctrl Input.Note

The Interference Channel provides a switchable signal path with Nelco 4000-6 FR4characteristics. This path can be connected between the pattern genera

If P1 is used as input, sinusoidal interference is (or can be) added after the signalhas passed the chosen trace. Seen from the DUT, this is called &q

The delay lines show markers which indicate the used and the remaining jitteramplitude in UI. Colored bars allow you to judge the impact of each jitte

• Random Jitter• Spectrally Distributed Random Jitter• External Jitter Source (Connected to the Delay Ctrl input)It depends on the jitter configuratio

• Specify which delay line (220ps or 610ps) is used for the generation of PJ andBUJ.N O T EIf the 610ps delay line is selected and has any jitter sour

Set Jitter ConfigurationUse Jitter Configuration area to specify whether you want to use:• SSC or rSSC• RJ and BUJ or sRJSet Jitter Distribution1Speci

Select the Delay LineTo select the delay line for (sinusoidal) periodic jitter 1 and 2 and BUJ, press610ps button. The LED will turn green if the 610p

Understanding the N4916B Clock MultiplierThe clock multiplier option enables error counting and error analysis of devicesusing half-rate clocking. The

A parameter that must be set for any jitter type is Amplitude. This defines thetimely width of the jitter component.4Observe the consumption of delay

To specify the jitter components:1Activate a jitter source (press the corresponding button).2Press Edit button to access all parameters of the corresp

This opens a window which allows you to set all parameters available for thegiven jitter type.6Specify the following parameters:– Standard– Sweep Time

Jitter Setup - ReferenceThe Jitter Setup function is used for composing the total jitter in a defined andcalibrated way.Jitter EnableThe Jitter On/Off

Defining Jitter Delay on Clock and DataUse this entry to define the delay between 220ps jitter on clock and data.Delay Line SwitchThis switch can be p

Delay Line DisplayThe delay line display shows red markers that indicate the consumption of delayline capacity by the present jitter setup.Colored bar

The Jitter Setup area allows you to enable a jitter source, to change its mostcommonly used jitter parameters directly or to go into advanced edit mod

• Change the ‘centerspread’value: the bitrate remains unchanged, while theupper and lower frequency changes according to the selected deviation. Thede

The selected deviation type is also indicated in the jitter composition shown in theJiter Setup area. The following are the deviation type indication

Residual Spread Spectrum ClockThe Residual Spread Spectrum Clock (rSSC) is generated by modulating the clockthat is used for data generation. It can t

The Data In 1, Data In 2 and Aux Clk In of M8061A have to be connected to AuxData Out, Data Out and Aux Clk Out ports of the J-BERT N4903B, respective

The maximum peak-to-peak Amplitude is limited by the chosen frequency.The maximum Frequency of the rSSC jitter source depends on the amplitude.Sinusoi

Periodic Jitter 1 ParametersThe Periodic Jitter is characterized by:• Amplitude• Frequency• WaveformA graph indicates whether the chosen setting of fr

You can click on the corrosponding button to choose among the different modesof Periodic Jitter 2. The green LED on the button indicates the currently

The maximum peak-to-peak Amplitude is limited by the free capacity of the chosendelay line.The maximum Frequency of the periodic jitter source depends

The maximum peak-to-peak Amplitude is limited by the free capacity of the chosendelay line.The stop frequency has to be higher than start frequency an

You can use this drop-down list to specify whether you want to select a pre-definedstandard or a user-defined standard. All the available pre-defined

• Amplitude• PRBS polynomial• Low pass filterA graph indicates whether the chosen setting of frequency and amplitude istolerable.You can specify your

The bounded uncorrelated jitter source is equipped with three low-pass filters withcut-off frequencies at 50, 100, and 200 MHz. One of these filters i

The random jitter source is equipped with a 10 MHz high pass and a 100 MHz and500 MHz low pass filter to limit the spectral range. All these filters c

This is the low frequency jitter amplitude as rms valueThis is the high frequency jitter amplitude as rms valueThe Spectrally Distributed Random Jitte

Now since the physical connections are OK, you can enable the externalinstruments through the Serial BERT's Config window.1Click Config menu item

N O T EEven if the External jitter source is enabled, you can still add or change internaljitter components. The range of the external jitter source i

Interference Channel SetupInterference Channel Setup - ConceptsThe optional Interference Channel module can be plugged into the instrument. Foran intr

If you have enabled sinusoidal interference, enter appropriate values forFrequency, Amplitude, and Mode.Interference Channel Setup - ReferenceThe Inte

The frequency range of sinusoidal interference is limited (see the technicalspecifications).One of four modes can be chosen for sinusoidal interferenc

Green points (BER below limit) and red crosses (BER above limit) are used todisplay the results.After a measurement has exceeded the target BER or whe

When the measurement has finished, the jitter composition shown in the JitterSetup window is restored.Target BERThe target bit error ratio must be spe

Vertical Search MethodsYou can specify that the jitter amplitude changes in linear steps from maximum tominimum or vice versa. The step size is adjust

When you search in upward direction (from minimum to maximum), the test forone frequency stops as soon as the measured BER exceeds the target bit erro

Jitter Tolerance Characterization - ProceduresTo access the Jitter Tolerance Characterization measurement, press thecorresponding menu item from the J

3Set the Number of Steps between start and stop.The Number of Steps yields a set of logarithmically equidistant frequencies.In Manual mode, the automa

Example - 3The following image shows the Config window when the M8061A 28Gb/sMultiplexer with De-emphasis is connected to the J-BERT N4903B.2Choose th

3If desired, set a Relax Time.For details see “Relax time” on page 435.Setting the Search Mode1Choose one of six search modes:– Downwards linear– Down

This opens a dialog box which allows you to load a file. By default, the browsersearches for files with the suffix .jcs, but you can load any file.N O

You can also abort the test at any time by pressing the Abort button.Once the measurement has finished, the jitter composition shown in the JitterSetu

2Select 'Generate HTML report'.3Select the folder where you want to save the report, name the file, and save it.Jitter Tolerance Characteriz

In Manual mode, you can edit the automatically calculated frequencies. You canalso enter your own list of frequencies, with a minimum of two frequenci

next. The chosen method impacts the measurement duration. The specifiedparameters influence both measurement duration and precision.You can choose one

This defines the minimum jitter amplitude step size. The test for one frequencystops when this step size is reached.For a description of this method r

N O T EThe Jitter Tolerance Compliance measurement is a software option that requires alicense. For details on how to obtain and install such licenses

During a jitter tolerance compliance test, jitter with the specified jitter amplitudeis sequentially applied at a number of frequency points in the fr

The standards demand and the measurement generates jitter with sinusoidaldistribution.In terms of the Serial BERT, sinusoidal jitter (SJ) and periodic

N O T EUse Refresh button to reload the external instruments list, in case, if you are notable to see them in the instrument list. However, if the Con

• numbers of received bits and errors• a confidence levelAdditionally, a relax time can be specified.Number of Received Bits or ErrorsWhen numbers of

Predefined StandardsThe Jitter Tolerance Compliance option provides a number of predefined standards.Predefined standards specify:• Jitter frequency r

User-Defined StandardsYou can create your own standard in a text file.A user-defined standard consists of a paired list of numbers.Each pair specifies

Jitter Frequency Test PointsYou can specify the jitter frequency range to be used for the test, from 1 kHz up tosome hundred MHz. You can hence measur

Jitter Tolerance Compliance - ProceduresTo access the Jitter Tolerance Compliance measurement, click JitterCompliance from the Jitter submenu.To set u

The list contains all predefined standards, including user-defined standards.User-defined standards are preceded by an asterisk (*).3Select one of the

T I PWith the Auto Frequencies checkbox, you can adjust the test frequenciesautomatically to the selected standard. This is described belowin “Setting

2If desired, change the default values. For example, if only a certain frequencyrange has to be tested:Enter the Start Frequency and the Stop Frequenc

2Choose the Verification Method.Setting a Confidence Level is generally recommended. See also “Target BER”on page 449.If you enable Absolute Bits/Erro

This opens the Jitter Setup window.2Enable jitter generation. Press the respective checkbox.3Activate Sinusoidal jitter.4Activate Periodic jitter5Set

How to Enable/Disable N4916B De-Emphasis FunctionTo enable/disable the de-emphasis function:1From the Config window, select the De-Emphasis function c

Selecting a point, and clicking on 'Set', updates the Sinusoidal and Periodic jitterof that point on the Jitter Setup page.Generate HTML Rep

Managing User-Defined StandardsUser-defined standards are saved in the folder C:\<instrument model>\JTolStandards.The extension is .jcs.To add a

Exporting Measurement ResultsTo export the measurement results into a .txt file for later use in externalspreadsheet applications:1After your measurem

frequency range and the jitter amplitude range of the standard is given in thepreview. A description is displayed at the bottom of the Standard tab.Th

Consider these recommendations when setting up the pattern generator (see“Setting up the Pattern Generator - Concepts ” on page 121).• Additional Jitt

In Manual mode, you can edit the automatically calculated frequencies. You canalso enter your own list of frequencies, with a minimum of two frequenci

This displays the list of measured points. The list classifies the points with theirfrequency, amplitude, and status. The status indicates whether the

Jitter Tolerance Measurement 4/10/2006 12:12:37 PMStandard: XAUIMargin: 0 %Condition: 2^23-1 [email protected] Gb/s; Comment: Passed Points: (frequency; ampl

8 Jitter Tolerance Tests468 Agilent J-BERT N4903B High-Performance Serial BERT

9 Solving ProblemsSolving Problems - ConceptsThis section provides information that can help you to troubleshoot the SerialBERT in case any problems o

How to Enable/Disable N4916B Clock Multiplier FunctionTo enable/disable the Clock Multiplier function:1Select the Clock Multiplier function from the g

If the input signal is still out of range for any of these parameters, the error detectorwill be immediately disconnected again.Error Detector Does no

BERT connected to your device:• There is no clock signal from your device.• Your device is faulty.DATA LOSSThis indicator turns red when no data signa

ErrorThis indicator turns red when errors are detected. View the BER bar or BER Resultsto see the nature of the errors.BERT connected looped back or t

Some phenomenon you might observe with the possible causes are listed below:Constant Errors (More Errored 0's than 1's)A hardware failure ma

The error ratio during periods of constant errors was 0.00195313. This correspondsto 1.953E-3.Random ErrorsRandom errors may have been caused by a noi

Sync Loss SecondsThe sync loss seconds in this example may have been caused by high bursts oferrors or momentary clock loss. The clock signal from a c

Using the Measurement Log to Identify ProblemsMeasurement Logs are saved as CSV (comma separated variable) files. Follow thesteps below to view result

Table 32Instantaneous CumulativeBIT COUNT BIT COUNT CumulativeERROR COUNT ERROR COUNT CumulativeERROR RATIO ERROR RATIO CumulativeERRORED 0 COUNT ERRO

Other MessagesOther Messages - ConceptsThis section covers additional error messages that may occure when working withthe Serial BERT.Overheat Protect

The Serial BERT will be shut down, your instrument settings will not be saved.If the Serial BERT has indicated overheating, do the following:• Shut do

1Select the Multiplexer function from the given list. It opens the MultiplexerConnection dialog.The following image shows the an example of N4876A.2Cl

N4916B System Setup CalibrationN4916B System Setup CalibrationThe input timing of the N4916B has to be calibrated to ensure error free operationfor al

W A R N I N GThe instrument settings will be lost once you start the calibration process. It isrecommended to save the instrument settings before you

– Press the Auto Align key on the front panel– Switch to the Accumulated Results Screen– Press the Start Accum key on the front panel to start the BER

Table 33InputTimingErrors Forwarddistanceto ‘bad’settingBackwarddistanceto ‘bad’setting1 0 3 12 0 2 23 0 1 34 50 0 05 1000 0 06 100 0 0Case-2 (Calibra

How to Create the Calibration SettingsUse the following calibration settings:• Preset Instrument State• Enable De-Emphasis• Set all cursors to 0dB• Se

• Connect the N4903B’s Trigger Output with the oscilloscope’s Front panelTrigger input• Connect the N4916B’s Data Output with channel 1 of the oscillo

• Input Timing Setup = 2• Input Timing Setup = 39 Solving Problems486 Agilent J-BERT N4903B High-Performance Serial BERT

• Input Timing Setup = 4• Input Timing Setup = 5Solving Problems 9Agilent J-BERT N4903B High-Performance Serial BERT 487

• Input Timing Setup = 6Input Timing Setup #1 shows timing violations at the input of the N4916B. All othermeasurements do not show any violations dur

The example above was done for a target BER measurement of 10-3 and aconfidence level of 95%. As a rule of thumb, this requires to measure approximate

N O T EEnsure that the timing adjustment has to be run at least once when either theN4903B, N4876A or the cables connecting both are being exchanged i

When using lower target BER values, the required measurement time per InputTiming Setting is getting longer very quickly.The required measurement time

4Click Yes to continue if you have already saved the settings. Once the autoadjustment starts, you will see the adjustment progress in the following s

M8061A System Setup AdjustmentM8061A System Setup AdjustmentThe input timing of M8061A has to be adjusted to ensure error free operation forall data r

N O T EThe adjustment process may take several minutes for completion.The following message will pop up after the successful completion ofadjustment p

If this happens, ensure that the N4916A has been correctly installed (see “Installingthe N4916A/B - Procedure” on page 539).Check the Power SupplyEnsu

correctly, the VISA Assistant should indicate an instrument named "D4916".Click UsbDevice1 or D4916.5Click the Formatted I/O tab.6In the Ins

4From the Navigation Menu, select External Instrument(s) and then clickConfig sub-menu. The Config window shows a list of all instruments connectedto

Then the oscilloscope should show an output eye like the following:If you see a display like above everything is ok.If you see merely one fixed level,

4Connect the Output of the N4916A to the Data Input of the error detector.5Ensure that the error detector follows the generated pattern.– Press the Au

Note that a de-emphasis value of 6 dB causes a 50 percent amplitude reduction.Check the Output of the Pattern Generator with a ScopeIf the N4916A does

5 Setting up the Error DetectorSetting up the Error Detector - Concepts 167Inputs and Outputs 168Inputs and Outputs - Concepts 168Inputs and Outputs

Once the multiplexer function is enabled, a M8061A menu entry is added tothe External Instrument(s) sub-menu.3To disable the multiplexer function, cle

3Connect the Data Output of the Serial BERT to the Data Input of the errordetector.4Ensure that the error detector follows the generated pattern.– Pre

Cannot-Connect ProblemsAn error message may appear when you now press Enable.If this happens, ensure that the N4916B has been correctly installed (see

3From the Agilent IO Control menu, open the VISA Assistant.4If no VISA alias name has been assigned so far, the VISA Assistant shouldindicate an instr

7Click the *IDN? button. This generates the identification query in SCPI format.The instrument should return "Agilent Technologies, N4916B,,"

Once the de-emphasis function is enabled you can see the de-emphasisparameters in the PG Output screen.7Again, from the Config window, corrosponding t

Then the oscilloscope should show an output eye like the following:If you see a display like above everything is ok.If you see merely one fixed level,

The eye diagram should look like this after some seconds:Check the Output of the Pattern Generator with a ScopeIf the N4916B does not produce a signal

The oscilloscope should show the following picture:If you see only a straight line, ensure that the pattern generator is not disabled andthat it is se

1Connect PG Clock Out to Clock Multiplier Clock In2Terminate PG Clock Out with 50 Ohm3Termiate PG Trigger Out with 50 Ohm4Terminate Clock Multiplier C

Check the Output of the N4916B (Clock Multiplier Part) Using aScope ( Clock Multiplier 2)Following are the steps to test clock multiplier 2 using a sc

Controlling N4876A MultiplexerAfter the multiplxer function has been enabled through the Config window, thefollowing parameter are visible in Multiple

N4916B Status LEDsThis following section explains about the different LEDs that are available on thefront panel of the N4916B De-Emphasis Signal Conve

Problems with the N4876AProblems with the N4876A - ConceptsWhen you have opened the External Instrument(s) - Config window and haveselected N4876A fro

3From the Agilent IO Control menu, open the VISA Assistant.4If no VISA alias name has been assigned so far, the VISA Assistant shouldindicate an instr

7Click the *IDN? button. This generates the identification query in SCPI format.The instrument should return "Agilent Technologies, N4876A,"

6Click Enable button. It enables N4876A 28 Gb/s Multiplexer 2:1 that isconnected between data out of Serial BERT and the DUT.Once the output levels of

Then the oscilloscope should show an output eye like the following:If you see a display like above everything is OK.If you cannot see a clear eye diag

3Terminate PG Data /Out with 50Ohm4Terminate PG Clock /Out with 50Ohm5Ensure that the error detector follows the generated pattern.– Press the Auto Al

If you see only a straight line, ensure that the pattern generator is not disabled andthat it is set up to generate a pattern (e.g. PRBS).N4876A Statu

Table 35LED Name DescriptionLAN Constantly green when LAN is operableConstantly red when LAN is not operableFlashing green when deviceidentification i

on the front panel of M8061A. For more information on the functionality of theseLEDs, refer to the section “M8061A Status LEDs” on page 522.Check the

The Config window contains the following elements:The Refresh button allows you to reload the external instruments list, in case, ifyou are not able t

5Corresponding to the M8061A entry, select the Mux with Deemphasis functioncheck box from the given options under Enable Function column. It opens the

7Again, from the Config window, corresponding to M8061A, clear the Mux withDeemphasis function check box. It will disable the multiplexer function, an

If you cannot see a clear eye diagram, then check if the M8061A is connectedproperly to the J-BERT N4903B. The M8061A must be connected to Aux Data Ou

• After the M8061A is ready, the red "FAIL" LED goes off and the green "ACCESS"LED stays on.• When the green "ACCESS" LE

9 Solving Problems524 Agilent J-BERT N4903B High-Performance Serial BERT

10 Customizing the InstrumentCustomizing the Instrument - ConceptsThe Serial BERT provides various utilities for adjusting the instrument to yourperso

How to Create the Agilent Recovery PartitionWhen booting the instrument for the first time, the Agilent Recovery System willautomatically set up the r

Table 36Options DescriptionRun CHKDSK to resolve Disk Issues If you encounter any malfunctions youshould always try this option first.CHKDSK won’t del

Configuring the InstrumentConfiguring the Instrument - ConceptsThis section covers information on the configuration of the Serial BERT.Updating the So

Configuring the Instrument - ProceduresFollow the instructions below to configure the instrument according to yourpersonal needs:Setting Date and Time

provides the De-Emphasis function while the N4916B provides De-Emphasis andoptional Clock Multiplier functions.The Update button allows you to update

For more details refer to “Using an External Monitor ” on page 533 and “Usingthe On-Screen Keyboard” on page 532.N O T EIf the touchscreen is disabled

Configuring the Instrument - ReferenceThe Serial BERT has the following utilities for configuring the instrument:Set Date/Time Dialog BoxThis function

1On the Utilities menu, click Touchscreen Off. The Enable Touchscreen icon isplaced in the upper right hand corner of the instrument display.2Click th

2Press the On-Screen Keyboard button to open the on-screen keyboard.3Click letters or numbers as desired. For numbers, you must add the unit bypressin

T I PYou can always move the On-Screen Keyboard window by clicking its title bar anddragging it.Additionally, you can switch between different views o

Installing Software LicensesInstalling Software Licenses - ProceduresThe Serial BERT has optional features that require a license. The followingproced

Licenses DialogThe Licenses dialog informs you about the options that require a license.The HOST ID / MAC Addr shown in the window is the MAC Address

At the present time, the J20 Interference Channel is available. This module can beused for adding intersymbol interference and sinusoidal interference

If you connect P2 to the Data Out of the Pattern Generator, P1 provides the output.C A U T I O NThe module has golden 2.4 mm connectors. Be sure to us

Installing the N4916A/B - ProcedureThe N4916A/B De-Emphasis Signal Converter is an optional instrument that canbe connected to the Serial BERT. For ge

For more information on input timing adjustment of N4876A, refer to the section“N4876A System Setup Adjustment” on page 490.Clock Multiplier WindowThe

3Click the About item to check the details.If you wish to update the Agilent IO Libraries Suite, you can download the softwarefromhttp://www.agilent.c

5Click Next and let the Wizard locate the appropriate driver. The USB driver ispart of the Agilent IO Libraries Suite.6Step through the Wizard by clic

Assigning a VISA Alias NameAssigning a unique VISA alias name to the N4916A/B simplifies remoteprogramming and helps to make programs portable. The Se

4Click OK.The Agilent Connection Expert for N4916A shows a window like the following:The Agilent Connection Expert for N4916B shows a window like the

1Use the N4915A-004 cable or a 2.4 mm cable (m-m) longer than 350 mm andconnect the pattern generator's Data Out port to the Input port of the N4

entering the required information. You can remove keyboard and mouse when youare done.Checking the Serial BERT Software RevisionThe Serial BERT softwa

If you wish to update the Agilent IO Libraries Suite, you can download the softwarefromhttp://www.agilent.com/find/iolib.Installation instructions are

Assigning a VISA Alias NameAssigning a unique VISA alias name to the N4876A simplifies remote programmingand helps to make programs portable. The Seri

"N4876A" is the alias used by the software.4Click OK.The Agilent Connection Expert for N4876A shows a window like the following:For detailed

connect the pattern generator to the N4876A. Make sure to connect Data Outto Data In, Aux Data Out to Aux Data In and Aux Clk Out to Aux Clk In.2Mount

• If the Half Rate Clock check box is selected, the multiplier of the clock multiplierwill be set automatically to 2 and the frequency sent to the clo

1Connect the USB cable between the USB ports available on the front side ofthe ESM of chassis with the USB port available on the rear side of J-BERTN4

4Connect the differential outputs of the M8061A to the DUT. If only one outputof the M8061A is needed, connect a 2.4 mm 50 Ohm termination to the unus

2The instrument web server responds with the instrument’s “Welcome Page”,as shown in the screen below.3Click on the left-side link to control/monitor

The WebControl dialog provides the user with the current IP address of theinstrument. The IP address can be used on the internet explorer to address t

4On the web control dialogue shown above you can request for help by pressingthe 'Help' button on the lower right hand corner.5The instrumen

PrintingPrinting - ProceduresThis section provides information on setting up and using a printer:Connecting a Printer to the InstrumentThe instrument

Removing a PrinterWhen you disconnect a printer from the instrument and no longer intend to use it,you can remove the printer driver and increase the

Configuring Printer PropertiesYou can change the properties of a selected printer:1On the File menu, click Print Setup2Click Configure Printer...This

File ManagementFile Management - ProceduresThis section provides information on saving and recalling instrument states, logfiles, patterns, and screen

N O T EEnsure your instrument state files have the extension, *.btz. If you do not specifyan extension or use a different extension, the instrument ma

M8061A WindowThe M8061A is a 2:1 multiplexer to characterize serial interfaces of up to 28.4 Gb/s with optional de-emphasis to extend the rate of J-BE

2Open a spreadsheet application on your PC.3Import the measurement log file. If your application has an import wizard, youmay need to indicate that da

Table 38Instantaneous CumulativeED CLOCK LOSS ERROR DECISECONDS CumulativeDATA LOSS ERROR FREE DECISECONDS CumulativeSYNC LOSS SECONDS CumulativeBURST

To save an image of the display screen, do the following:1In the File menu, select Save.2Select Save Screen Capture...This opens a dialog box, which

Self TestSelf Test - ConceptsThe self test checks specific hardware components for basic functionality. Atinitialization, the following self tests are

This opens the Self Test Options dialog box.2Select the desired tests and click the Run Test button.3After the self test has finished, the results are

Select All/Unselect AllUse the Select All button to select all tests in the Self Test Options dialog box.After clicking the button, it becomes the Uns

10 Customizing the Instrument566 Agilent J-BERT N4903B High-Performance Serial BERT

Index0/1 Decision Threshold, 1970/1 Threshold, 1980/1 THReshold Center button, 2000V (Disable) button, 13810 MHz Ref Input, 1228B/10B Comparison

Constant Errors, 473Contour, 320Contour plot, 288Creating New Pattern, 71Criteria for Moving to the NextMeasurement Point, 312Crossover, 127Cros

Grid , 320HHardware-generated patterns, 61High Level, 277High Level Std. Dev., 278IIllegal Symbol Ratio, 182Input and Output PortsError Detector,

• Amplitude: Used to set the amplitude of the signal. This parameter is enabledif the amplifier coupling is set to AC.• High: Used to set the upper vo

Number of Valid Points, 313Numerical ResultsEye Opening, 301Output Levels, 277Output Timing, 259Spectral Jitter, 359OOffset threshold, 312On-Scr

Q High Level Std.Dev, 281Q Low Level, 281Q Low Level Nr. Points, 282Q Low Level R^2, 282Q Low Level Std.Dev, 282Q Optimum Threshold, 280Q Residu

View tabFast Eye Mask, 314Vlo, 136Vof, 135Voltageof measurement point, 313WWaveform, 320Web Server, 551XXover, 137ZZero SubstitutionPatternzero

The ClkGen tab allows you to select clock source. It provides the followingparameters:• Clock Source: Used to select the clock source to either CLK IN

Table 4M8061A Parameters and RangeParameters RangePostCursor3 -12.04 dB to 12.04 dBPostCursor4 -6.02 dB to 6.02 dBPostCursor5 -6.02 dB to 6.02 dBThres

6 Advanced AnalysisAdvanced Analysis - Concepts 227Advanced Analysis - Procedures 229Advanced Analysis - Reference 234DUT Output Timing/Jitter 241DUT

2 Setting up External Instrument(s)60 Agilent J-BERT N4903B High-Performance Serial BERT

3 Setting up PatternsSetting up Patterns - ConceptsThe purpose of data patterns is to simulate the type of data that your device mightreceive in the r

User patterns are file-based, editable patterns. These may be patterns that you setup using the Serial BERT's Pattern Editor, or any of the patte

They are referred to by their pattern lengths, which are powers of 2. Longer patternlengths give a better approximation of random data and provide a m

designed to lock onto a single frequency may have a tendency to lock ontoharmonics. A long PRBS may uncover such undesirable behavior.When to Use Whic

User PatternsUser Patterns - ConceptsUser patterns are user-editable patterns that are written to the Serial BERT'smemory for pattern generation

N O T EIf you save a modified text format pattern to the same file name, it is always savedin binary format. If you wish to preserve the original text

• In hex or text format, each character represents four bits-only the characters'0' to '9' and 'A' to 'F' are

is an odd number of bits long, it is loaded into the RAM 512 times. Because of therestricted memory space, there are also restrictions to the pattern

How the Serial BERT Generates Memory-Based PatternsThe basic concept of how the Serial BERT generates memory-based patterns isrelatively simple: The S

Accumulated Measurements 376Accumulated Measurements - Concepts 376Accumulated Measurements - Procedures 377Accumulated Measurements - Reference 378E

A0 A1 A2 B0 B1 B2 A0 A1 A2A A A A A A A A B B B B B B B B A A A A A A A AImplications of Using Memory-Based PatternsThere are several implications to

User Patterns - ProceduresYou can do the following tasks in the Edit Pattern window:• “Creating New Patterns” on page 71• “Opening Existing Patterns”

2In the toolbar, click the Open icon.The Select User Pattern dialog box opens.3Use this dialog box to locate and open the desired pattern. You can sel

If the pattern has already been saved earlier, the saved file is updated.Otherwise, the Windows standard Save As dialog box opens, where you candefine

Table 6Pattern Type Next Required ActionSequence Enable this checkbox if you intendto download a user-definedsequence. Patterns generatedwithin a sequ

Loading Patterns Directly from the Pattern EditorAfter you have finished editing a pattern in the pattern editor, you can load thispattern directly to

N O T EOnce the pattern of a specific length is captured from the error detector , it can besent back to the error detector and the pattern generator.

Table 9Icon Name DescriptionExport Click this icon to to openExport Trace dialog. See“Export Trace” on page118 for details.To PG Click this icon to se

Table 9Icon Name DescriptionINS/OVRClick this icon to toggleamong the insert, dynamicinsert and overwriteediting mode:With Insert mode youinsert bits

Table 9Icon Name DescriptionProperties Click this icon to changethe properties of thecurrent pattern. See“Pattern Properties DialogBox” on page 82 for

N4876A System Setup Adjustment 490N4876A System Setup Adjustment 490M8061A System Setup Adjustment 492M8061A System Setup Adjustment 492Problems with

Table 9Icon Name DescriptionPatSelClick this icon to open thePattern Select Formdialog box. For moreinformation, see “LoadingPatterns to the PatternGe

Pattern Editor Canvas and Status BarThe pattern editor canvas displays the pattern and offers you to edit it.In case of symbols, the pattern editor ca

Disparity Error (D): This indicator turns red if there is any disparity error in thepattern. In case of alternate patterns, the indicator will indicat

To find out more about appropriate pattern lengths, see “Pattern Resolutions andLengths” on page 67.Select Standard if you want to use this pattern as

Description for the captured Pattern.Pattern capture length in bits.Captures the entire pattern length of currently loaded pattern in the error detect

In addition, The Find Pattern Segment dialog box also allows you to replace thesearched pattern segment with the desired pattern segment.Looks for the

With the Block Edit Configuration dialog box, you define the Range that is to bemodified. The available options for the Range are:• Select AllChoose t

• Fill with Ones• Invert. The Invert does the following functions:Symbol Mode off: Invert the bits.Symbol Mode OOB: 0 becomes 1, 1 becomes 0, Z remain

N O T EThe Recode tab is not accessible if Symbol Mode is set to OFF.3TracesThis tab provides the following options:– CopyChoose this option to copy d

– Rotate RightTreats the pattern data in the specified range as a circular buffer and rotatesthe bits to the right by the specified amount. No data wi

File Management 558File Management - Procedures 558Preset Instrument State 562Preset Instrument State - Procedures 562Self Test 563Self Test - Concept

With this checkbox you can determine whether both pattern generator and errordetector use the same data pattern.If you clear this checkbox, the Error

Only available on the Error Detector Pattern page. Enables the error detector's bitrecovery mode. For details see “Understanding Bit Recovery Mod

Table 10n Sequence Length Longest Run of 1's Longest Run of 0's7 128 7 710 1,024 10 1011 2,048 11 1113 8,192 13 1315 32,768 15 1523 8,388,60

The ones (mark) density can be varied to put the pattern out of balance in arandomly distributed way. This may be useful for systems that are AC-coupl

How the Hardware Generates PRBS2^n -1 PRBS is an inverted, hardware-generated pattern that is created by a seriesof shift registers with adjustable fe

Range of Hardware-Generated PRBS PatternsThe following table lists the hardware-generated 2^n -1 PRBS pattern lengths thatcorrespond to different n va

User-Defined SequencesUser-Defined Sequences - ConceptsThis section describes the basics of user-defined sequences.A sequence is created and maintaine

Description=optionalStart=optionalBlock #=repeated for each block, numberedLoop=repeated for every loop, not numberedExample of a SequenceExpression:(

N O T ELength is related to master channel (Data Out) while the other channel (Aux Data)will always follow this length.• Trigger: Refers to the patter

• Every sequence can be stored in a file and recalled from that file. However, theSequenceExpression does not include user patterns. Recalling a seque