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80SJNB Jitter, Noise, BER, and Serial Data Link Analysis (SDLA)

ZZZ

Software

Printable Application Help

*P077064105*

077-0641-05

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80SJNB Jitter, Noise, BER, and Serial Data Link Analysis (SDLA) Software

ZZZ

Printable Application Help

w.tek.com

077-0641-05

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Copyright © Tektronix. All rights reserved. Licensed software products are owned by Tektronix or its subsidiaries or suppliers, and are protected by national copyright laws and international treaty provisions.

Tektronix products are covered by U.S. and foreign patents, issued and pending. Information in this publication supersedes that in all previously published material. Speciﬁcations and price change privileges reserved.

TEKTRONIX and TEK are registered trademarks of Tektronix, Inc.

TEKPROBE, and FrameScan are registered trademarks of Tektronix, Inc.

This document supports 80SJNB software version 4.3.X and greater, for the DSA8300 only.

Contacting Tektronix

Tekt roni 14150 SW Karl Braun Drive P. O . B o x 5 0 0 Beaverton, OR 97077 USA

x, Inc.

For pro

duct information, sales, service, and technical support: In North America, call 1-800-833-9200. Worldwide, visit www.tek.com to ﬁnd contacts in your area.

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Table of Contents

Welcome

Welcome to the 80SJNB jitter, noise, BER, serial data link, PAM4, and TDECQ analysis software ..... 1

Preface

Relateddocumentation............................................................................................. 3

GPIB info

Relevant Web sites ................................................................................................. 3

Conventions ......................................................................................................... 4

Types of application help information............................................................................ 4

Application help use................................................................................................ 5

Feedback............................................................................................................. 6

Getting started

Product description................................................................................................. 7

Requirements and restrictions..................................................................................... 7

Accessories.......................................................................................................... 8

Connecting to a device under test (DUT)........................................................................ 8

Deskewing probes and channels .................................................................................. 9

The importance of jitter and noise separation . . . . . . . . . . . . . . . . . . . . . . . . ........................................... 9

Jitter and noise separation methods.............................................................................. 10

rmation................................................................................................... 3

Table of Contents

Operating basics

About operating basics............................................................................................ 13

General information

Starting the 80SJNB application............................................................................ 13

Returning to the oscilloscope application.................................................................. 14

Returning to the 80SJNB application....................................................................... 15

Minimizing and maximizing the application window .................................................... 15

Exiting the application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................. 16

Software and ﬁle installation directory..................................................................... 16

File name extensions ......................................................................................... 17

File menu ...................................................................................................... 18

Viewmenu..................................................................................................... 19

Setup menus ................................................................................................... 20

Oscilloscope settings ............... .. .. . . . . . . . . . . . . . . . . . . . . . . . . .............................................. 21

About the results.............................................................................................. 21

Clearing results................................................................................................ 22

About plotting ................................................................................................. 22

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Table of Contents

Navigating the user interface

Windows user interface

80SJNB user interface information

Setting up the application for analysis

About conﬁguring the application foranalysis ............................................................ 28

Conﬁguring sources

Signal Path Conditioning

About analysis settings . . . .. . . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . ............................................. 52

About mask test settings ..................................................................................... 56

About PAM4 signal analysis ................................................................................ 59

About TDECQ Measurements .............................................................................. 60

About measurements

About the user interface................................................................................. 22

User interface items deﬁnitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..................................... 23

About navigation......................................................................................... 24

About the80SJNB tool bar ............................................................................. 25

About measurement results tabs........................................................................ 27

MATLAB user interface................................................................................. 28

About acquiring data .................................................................................... 29

Selecting a Stop on Condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. ...................................... 31

Selecting scope setuprecall on exit.................................................................... 32

Selecting clock recovery ................................................................................ 33

Selecting phase reference ............................................................................... 34

Selecting the datapattern ............................................................................... 35

Selecting the signal conditioning....................................................................... 36

Selecting the patternclock.............................................................................. 37

Selecting thesource...................................................................................... 37

About spread spectrum clocking (SSC) ............................................................... 39

About Serial Data Link Analysis (SDLA) Signal Path Settings.................................... 40

Setting Filter Conditions ................................................................................ 41

Channel

Setting Channel Conditions ........................................................................ 42

Frequency Domain.................................................................................. 42

Time Domain ........................................................................................ 45

Equalizer

About the Equalizer................................................................................. 45

Continuous Time Linear Equalizer (CTLE)...................................................... 46

Equalizer Taps....................................................................................... 48

Saving and loading taps ............................................................................ 51

Taking measurements.................................................................................... 61

Displaying measurements............................................................................... 61

Jitter measurement deﬁnitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...................................... 62

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Table of Contents

Noise measurement deﬁnitions......................................................................... 63

SSCModulation MeasurementDeﬁnitions........................................................... 63

80SJNB PAM4 measurements.......................................................................... 64

Fast TDECQ test measurements deﬁnitions ...... . . . . . . . . . . .. . . .. . .. . .. .............................. 65

Mask test measurementdeﬁnitions .................................................................... 65

Rise, Fall measurements ................................................................................ 66

Sample Count............................................................................................. 66

Steps to Acquire Data ........................................................................................ 67

Save and Recall Setup Files

Saving and Recalling Setup Files ........................................................................... 68

Savinga Setup File ........................................................................................... 68

Recalling a Saved Setup File ................................................................................ 68

Save and Recall Data Files

Saving and Recalling Data Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . ........................................ 69

Saving a Data File ............................................................................................ 69

Recalling a Saved Data File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ......................................... 69

Working with Plots

About Working with Plots ................................................................................... 70

Plot type deﬁnitions ...................... . . . . . . . . . . . . . . . . . . . . . . . ............................................. 70

Selecting andviewing plots.................................................................................. 71

Examining plots............................................................................................... 72

Exporting plot data

About exporting plot ﬁles ............................................................................... 72

Copying plot images..................................................................................... 73

Exporting raw data....................................................................................... 74

Export Waveform data................................................................................... 74

Export results............................................................................................. 75

Export graph (plot) data................................................................................. 75

Plot types

Jitter plots ............................... .. .. . . . . . . . . . . . . . . . . . ............................................. 76

Eye plots .................................................................................................. 77

Noise plots ................................................................................................ 79

Pattern plots .............................................................................................. 80

SSCplot................................................................................................... 80

Working with numeric results.................................................................................... 81

An application example........................................................................................... 86

Parameters

About application parameters .................................................................................... 93

Analysis settings ................................................................................................... 93

Acquisition settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ................................................... 95

Signal path settings ................................................................................................ 96

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Table of Contents

Mask test settings . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . ................................................... 97

Mask ﬁle structure................................................................................................. 97

Remote control

Remotecontrol introduction.................................................................................... 101

GPIB reference materials....................................................................................... 101

Programming tips................................................................................................ 102

Variable:Value Commands

Syntax........................................................................................................ 104

Variable name arguments and queries.................................................................... 105

Valid graph name strings for GraphSelection<n> command. . . . . . . . . . . . . . ............................. 115

Variable:Value results queries ............................................................................. 116

GPIB commands error codes .............................................................................. 122

Programming examples

Program

Program example: conﬁgure and operate 80SJNB...................................................... 123

Program example: measuring jitter in presence of SSC.......... . . . . . . . . .............................. 125

Program example: compensating for signal path impairments with equalization ................... 127

ming examples introduction..................................................................... 122

Algorithms

t measurement algorithms................................................................................ 131

Abou

Test methodology................................................................................................ 131

Correlations

Correlation to real-time oscilloscope jitter measurements . . . . . . . . . . . ....................................... 133

ird Party Licenses

InterX.m license ................................................................................................. 135

PDFSharp license................................................................................................ 135

Index

iv 80SJNB Printable Application Help

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Welcome Welcome to the 80SJNB jitter, noise, BER, serial data link, PAM4, and TDECQ analysis software

Welcome to the 80SJNB jitter, noise, BER, serial data link, PAM4, and TDECQ analysis software

The 80SJNB analysis software enhances the capabilities of the DSA8300 Digital Serial Analyzer. Several versions are available: 80SJNB Essentials, 80SJNB Advanced with Serial Data Link Analysis, 80SJNB-PAM4 Dispersion Eye Closure Quaternary for PAM4) measurement that is now part of the PAM4 package..

80SJNB Essentials provides the following features:

Perform advanced jitter and noise analysis (RJ, DDJ, PJ, DCD, BUJ, TJ@BER, and RN, DDN(high) and DDN(low), BUN, TN@BER, vertical and horizontal eye opening at BER)

Perform mask testing on PDF eyes and BER contours

Acquire complete pattern waveform at 100, 40, 20, or 10 Samples/UI

with advanced PAM4 signaling analysis, and 80SJNB with TDECQ (Transmitterand

Perform random and deterministic jitte

Isolate and measure crosstalk in form of bounded uncorrelated jitter (BUJ)

Display results graphically including histograms, spectra, and bathtub curves

Display 2-D eye diagrams (correlated eye, probability density function (PDF) eye, and bit error ratio (BER) eye)

Save complete acquisition results to a data ﬁle

Analyze jitter, noise, and BER in the presence of spread spectrum clocking (SSC)

80SJNB Advanced includes everything in Essentials and adds:

Signal path emulation, allowing you to emulate the environment your signal encounters from the transmitter to the receiver. Feature include:

Supports CTLE, FFE, and DFE equalization

Allows user-deﬁned arbitrary ﬁlters (use for de-embedding, CTLE Transmitter equalization, and other applications)

Supports channel emulation (TDR/TDT and S-parameter based channel descriptions)

Other features commonly known as SDLA (Serial Data Link Analysis)

80SJNB PAM4 includes everything in Advanced and adds:

r analysis including BER estimation

Comprehensive jitter, noise and BER analysis for each eye

Global PAM4 signal characterization measurements

Full signal path emulation support

Rise/Fall measurements

80SJNB Printable Application Help 1

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Welcome Welcome to the 80SJNB jitter, noise, BER, serial data link, PAM4, and TDECQ analysis software

80SJNB TDECQ (Transmitter and Dispersion Eye Closure for PAM4) includes everything in PAM4 and adds:

Standard IEEE TDECQ measurements

A number of control parameters for the TDECQ measurement

Plots with annotations for the results

What do you want to do?

Read the pro

Go to Operating Basics

duct description

(see page 7).

(see page 13).

2 80SJNB Printable Application Help

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Preface Related documentation

See also:

Using Online Help (see page 5)

4 80SJNB Printable Application Help

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Preface Application help use

Application help use

Application help has many advantages over a printed manual because of advanced search capabilities. The main (opening) Help screen shows a series of book icons and three tabs along the top menu, each of which offers

Contents tab - organizes the Help into book-like sections. Select a book icon to open a section; select any o

Index tab - enables you to scroll a list of alphabetical keywords. Select the topic of interest to display the corres

Search tab - enables you to search the entire help contents for keywords. Select the topic of interest to display t or screen shots.

NOTE. Blue-underlined text indicates a hyperlink to another topic. For example, select the blue text to jump to the topic on Feedback to Tektronix.

a unique mode of assistance:

f the topics listed under the book.

ponding help page.

he corresponding help page. Search results do not include text contained within illustrations

(see page 6)

TIP. When you use a mouse, the normal cursor changes to a link cursor when over an active hyperlink.

80SJNB Printable Application Help 5

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Preface Feedback

Feedback

Tektronix values your feedback on our products. To help us serve you better, please send us suggestions, ideas, or other comments you may have about your application or oscilloscope. Send your feedback to techsupport

Please be as speciﬁc as possible and include the following information:

General information

@tektronix.

Oscillosc

Module and probe conﬁguration. Include model numbers and the channel/slot location.

Serial data standard.

Signaling rate.

Pattern type and length.

Your name, company, mailing address, phone number, FAX number.

NOTE. Please indicate if you would like Tektronix to contact you regarding your suggestion or comments.

ope model number, ﬁrmware version number, and hardware/software options,ifany.

Application-speciﬁc information

80SJNB Software version number.

Description of the problem such that technical support can duplicate the problem.

If possible, save the oscilloscope waveform ﬁle as a .wfm ﬁle.

ossible, save the 80SJNB data to a .mat ﬁle (File > Save Data).

If p

If possible, save the 80SJNB and oscilloscope settings to a .stp ﬁle (File > Save Settings).

Once you have gathered this information, contact technical support by phone or through email. If using email, be sure to enter “80SJNB Problem” in the subject line, and attach the .stp and .wfm ﬁles.

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Getting started Product description

Product description

The 80SJNB software application enhances the capabilities of the DSA8300 Digital Serial Analyzer by providing Jitter, Noise, and BER analysis (Essentials) and features for de-embedding the ﬁxture, channel emulation, a of PAM4 signals to 80SJNB Advanced including the TDECQ measurements.

nd FFE/DFE equalizer support (Advanced). The PAM4 option adds comprehensive analysis

You ca n u s e t

Jitter and noise analysis from DC to 400 Gb/s and beyond

Jitter and noise separation (see the Importance of Jitter and Noise Separation (see page 9))

Perform random and deterministic jitter and noise analysis, and TJ@BER, TN@BER and BER estimation

Isolate jitter and noise due to crosstalk, and make random and deterministic estimations in the presence of crosstalk

Show results as numeric and graphical displays

Display 2-D eye diagrams (Correlated Eye, Probability Density Function (PDF) Eye, and Bit Error Rate (BER) Eye) for both NRZ and PAM4 signals

Perform mask testing on PDF eyes and BER contours

Support for CTLE, FFE and DFE equalization

Perf

Allow user-deﬁned linear arbitrary ﬁlters

Support for Channel Emulation (from TDR/TDT and S-parameter based channel descriptions)

Analyze jitter, noise, and BER in the presence of Spread Spectrum Clocking (SSC)

his application to do the following tasks:

orm TDECQ (Transmitter and Dispersion Eye Closure for PAM4)

Save results to a PDF ﬁle

Save and recall instrument setups

See also:

Review Requirements and Restrictions (see page 7)

Requirements and restrictions

Operating system. Microsoft Windows 7 Ultimate (32 bit) operating system operating on the DSA8300

Digital Serial Analyzer oscilloscope.

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Getting started Accessories

ADVTRIG option. 80SJNB requires the Advanced Trigger option (ADVTRIG). Contact Tektronix about

purchasing this option.

82A04/82A04B Phase Reference m odule. For acquisition in the presence of Spread Spectrum Clocking

(SSC), this application requires that the sampling oscilloscope be equipped with a Tektronix 82A04 or 82A04B Phase Reference module. The 82A04/4B also lowers the jitter ﬂoor to 100 fs. Contact Tektronix about purchasing the module for your sampling oscilloscope.

Keyboard an

mouse is not required but simpliﬁes screen selections.

Accessor

There ar Tektronix Web site for information on optional accessories relevant to your application.

Asecon screen and the 80SJNB application screen.

Refer t application.

Conn

ecting to a device under test (DUT)

You c

d mouse. You must use a keyboard to enter names for some save and export operations. A

ies

e no standard accessories for this product. Refer to the product data sheet available on the

d monitor connected to the TekScope is recommended for simultaneous viewing of the oscilloscope

o Requirements and Restrictions

an use any compatible probe or cable interface to connect your DUT and the instrument.

(see page 7) for additional items required to use the 80SJNB

WAR NING. To avoid electric shock, remove power from the DUT before attaching probes. Do not touch exposed conductors except with the properly rated probe tips. Refer to the probe manual for proper use.

Refer to the General Safety Summary in your oscilloscope manual.

See also:

Deskewing Probes and Channels (see page 9)

An Application Example (see page 86)

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Getting started Deskewing probes and channels

Deskewing probes and channels

To be sure of accurate results for two-channel measurements, it is important to ﬁrst deskew the probes or cables and oscilloscope channels before you take measurements.

NOTE. Deskew the DSA8300 Quick Start User Manual and the DSA8300 Online Help for information and procedures for deskewing probes and channels.

ing is performed from the TekScope application, not from the 80SJNB application. Refer to

The importance of jitter and noise separation

Jitter is an important characteristic to analyze for serial data links, but the analysis should not stop at just jitter. To properly evaluate a data link, it is necessary to analyze both jitter and noise.

Two components need to be added to the traditional jitter analysis:

The nois

Jitter measurements based on the threshold crossing of a ﬁnite-speed transition should include vertical noise i

Noise measurements and jitter and noise separation and reconciliation is performed on all 4 levels of aPAM4

Depending on the magnitude of the vertical noise and the transient response of the transmitter and

smission channel, the magnitude of this inﬂuence can vary widely. Ultimately the jitter and noise

tran analysis allows for accurate BER projections for the targeted communication link.

e/vertical eye closure should be considered similar to that of jitter/horizontal eye closure.

nﬂuence.

signal.

o www.tek.com/jitter for additional jitter and timing analysis information.

Go t

80SJNB Printable Application Help 9

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Getting started Jitter and noise separation methods

Jitter and noise separation methods

Bit error rates (BER) of a serial data stream are impacted by both jitter and noise. An accurate decomposition of jitter and noise in the sources of impairments is critical to correctly estimate the signal path behavior at larger BER. The jitter and noise maps are critical to help debugging the devices under test.

Since jitter and noise analysis follows a similar path, this discussion covers just the jitter decomposition.

The basic separation of jitter in data-dependent and uncorrelated elements is accomplished by two targeted acquisition steps:

Correlated Acquisition Step: the application ﬁlters a high resolution acquisition of the full pattern to eliminate the uncorrelated elements. The analysis of the ﬁltered pattern yields the data dependent characteristics, such as Data Dependent Jitter (DDJ) and Duty Cycle Distortion (DCD).

Uncorrelated Acquisition Step: the uncorrelated elements of jitter are isolated by acquiring on well deﬁned single spots in the pattern, thus eliminating the dependency on the pattern itself. The data

uired in the uncorrelated acquisition step is then further analyzed to isolate random unbounded

acq components from the bounded deterministic components. This extended analysis is critical to help predict long term behavior of the DUT.

Historically only spectral separation was used for separation (availablestillastheSpectral (Legacy) analysis method). This method improperly qualiﬁes certain complex bounded uncorrelated components as unbounded, which inﬂates the random jitter (RJ) measurement result.

Spectral separation with isolation of bounded uncorrelated jitter (Spectral + BUJ) works by also analyzing the cumulative distribution function (CDF) of the uncorrelated non periodic jitter data. In the spectral separation of Periodic Jitter from the Random Jitter, the distinct spectral lines are removed from the frequency domain representation of the global uncorrelated jitter data to quantify the periodic jitter components, PJ. In the legacy method, the spectral method evaluated the remaining spectral data as Random Jitter (RJ).

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Getting started Jitter and noise separation methods

The presence of complex bounded uncorrelated impairments (for example, originating from crosstalk) requires signiﬁcant additional steps to isolate the bounded, uncorrelated jitter (BUJ) from the periodic jitter (PJ), nonperi

The CDF analysis is performed in two steps: before and after the spectral separation that identiﬁes the periodic spe second analysis step yields the nonperiodic elements, and ﬁnally the random jitter components.

odic jitter (NPJ), and random jitter (RJ) components.

ctral components. The ﬁrst analysis step yields the total bounded uncorrelated jitter, while the

A parallel a the behavior of the link in terms of bit error ratio (BER).

nalysis track develops the noise map, and a combination of the two analysis tracks characterizes

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Getting started Jitter and noise separation methods

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Operating basics About operating basics

About operating basics

These topics cover the following tasks:

Navigating the user interface (see page 24)

User interface information (see page 22)

Using oscilloscope functions (see page 21)

Setting up the application (see page 28)

Viewing the measurement results as plots (see page 22)

Exporting Plot Files (see page 72)

Saving (see page 68) and recalling (see page 68) setup ﬁles

Saving (see page 69) and recalling (see page 69) data ﬁles

What do you want to do?

Start the 80SJNB Application (see page 13)

See also:

File Name Extensions (see page 17)

File Menus (see page 18)

Starting the 80SJNB application

There are several ways to start the 80SJNB application.

If the TekScope application is minimized, double-click the 80SJNB application icon on the Windows desktop to start the 80SJNB application.

If the TekScope application is running and open, select Applications > 80SJNB or 80SJNB Advanced.

In Windows, select Start > All Programs > Tektronix Applications > 80SJNB > 80SJNB.exe.

80SJNB Printable Application Help 13

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Operating basics Returning to the oscilloscope application

TIP. With a second monitor connected to the TekScope, you can move the 80SJNB application display to the second monitor, allowing you to view both screens at the same time.

See also:

Returning to

Returning to the Oscilloscope Application (see page 14)

the 80SJNB Application

(see page 15)

Returning to the oscilloscope application

The 80SJNB application ﬁlls the entire screen and hides the TekScope application. To return to the

TekScope display, click the Back to Scope button

You can also minimize the 80SJNB application or exit the 80SJNB application entirely.

See also:

Minimizing and Maximizing the Application (see page 15)

Exiting the Application (see page 16)

in the toolbar.

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Operating basics Returning to the 80SJNB application

Returning to the 80SJNB application

The TekScope application ﬁlls the entire screen. If the 80SJNB application is already running but the TekScope application is displayed on top, bring the 80SJNB application to the front using one of the following me

Click the App button on the TekScope toolbar.

Select Applications > Switch to 80SJNB.

thods.

TIP. If you have a keyboard attached, you can switch between running applications by pressing the Alt + Tab keys.

Minimizing and maximizing the application window

To minimize the application to the Windows task bar, select the command button in the application

bar.

To maximize the application, select the minimized application from the Windows task bar. Alternately, if

have a keyboard attached, switch between displayed applications by pressing Alt + Tab keys.

you

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Operating basics Exiting the application

Exiting the application

To exit the application, select File > Exit or the command button in the application menu bar.

Software and ﬁle installation directory

The 80SJNB software is installed in the following directory:

C:\Progra

m Files\TekApplications\80SJNB

Save and recall directory

The directory structure for saving and recalling setup and data ﬁles and exporting data is:

C:\User

The default user name is:

Tek_Local_Admin

Standard masks are installed at:

C:\Users\Public\Documents\Tektronix\Masks

s\<user name>\Documents

See also:

File Name Extensions (see page 17)

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Operating basics File name extensions

File name extensions

Extension Description

.bmp .csv

.ﬂt 80SJNB application ﬁlter ﬁle

.jpg

.mat

.msk .png

.s1p

.s2p

.s4p

.stp

.tap

.txt

.wfm File that deﬁnes time domain waveforms or a frequency domain 1-port S-parameter (created

xxx

File that uses a bitmap format

File that uses a comma separated value format

File that uses a joint photographic experts group format

File that uses native MATLAB binary format to store data acquired by 80SJNB

Tektronix mask ﬁle (Mask ﬁle structure

File that uses a portable network graphics format

Files that deﬁne 1-port, 2-port, and 4-port frequency domain S-parameters

80SJNB application setup ﬁle

80SJNB application equalization tap ﬁle

File that uses an ASCII format

onnect) for channel emulation

by IC

80SJNB accepts both DSA8300 and IConnect .wfm ﬁles

(see page 97))

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Operating basics File menu

File menu

The File menu lets you save and recall application setups, data ﬁles, and recently accessed ﬁles.

CAUTION. Do not edit a setup ﬁle or recall a ﬁle that was not generated by the application.

Menu item Description

Save Settings Saves the current application settings in a .stp ﬁle

Recall Settings Browse to select an application setup (.stp) ﬁle to recall; restores the application and oscilloscope

to the values saved

Save Data Saves the current

Saving is disabled if there is no acquired data to save or an acquisition is now in process

Recall Data

Export Results

Export Waveform Acquired exports the raw acquired pattern before processing of the data

Print Prints the displayed plots and all numeric results

Print to File

Exit Exits the application

xxx

Recall a saved data ﬁle for analysis

All plots and results are based on the recalled data

Recalling is dis

Exports jitter

Signal attributes and analysis conﬁ guration parameters are added to the report to qualify the measurement results.

Correlated ex

Print the displayed plots and all numeric results to a .pdf ﬁle

See also:

in the setup ﬁle

acquired data in a .mat ﬁle for later analysis

abled if an acquisition is now in process

and noise analysis results to a csv format user speciﬁed ﬁle.

ports the acquired w aveform after ﬁltering out the uncorrelated components

About the 8

0SJNB Tool Bar

(see page 25)

Saving a Setup File (see page 68)

Recalling a Saved Setup File (see page 68)

SavingaDataFile(see page 69)

Recalling a Saved Data File (see page 69)

About Exporting Plot Files (see page 72)

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Operating basics Vi ew menu

View menu

The View menu lets you conﬁgure the display of plots and/or numerical data. The menu contents depend on the current acquisition mode (NRZ or PAM4).

NRZ acquisition mode View menu

Menu item Description

1-up Displays a single plot on the screen

2-up Displays two plots on the screen

4-up

Plots Only Hides all numeric data, expands the displayed plot(s) to ﬁll the screen

Numeric Summary Displays the plots and a summary of the analysis results

Full Numeric Results

Global Results Displays a summary of Jitter and Noise measurements, Rise/Fall, and level measurements

JNB Results Displays the JNB Results tab, which contains the JNB results table

Mask Results Displays the Mask Results tab, which contains the Mask test results table

xxx

PAM4 acquisition mode View menu

Displays the maximum of four plots on the screen

Displays the plots and the full results table (JNB or Mask)

Menu i

tem

Descr

iption

1-up Displays a single plot on the screen

2-up Displays two plots on the screen

4-up

Displays the maximum of four plots on the screen

Plots Only Hides all numeric data, expands the displayed plot(s) to ﬁll the s creen

Numeric Summary Displays the plots and a summary of the analysis results

ll Numeric Results

Displays the plots and the full results table (JNB or Mask)

Global Results Displays the global PAM4 results tab containing global and summary information

NB Results: Eye0

NB Results: Eye1

JNB Results: Eye2

Displays the JNB Results tab for eye 0, which contains the eye 0 results table

Displays the JNB Results tab for eye 1, which contains the eye 1 results table

Displays the JNB Results tab for eye 2, which contains the eye 2 results table

Mask Results Displays the Mask Results tab, which c ontains the Mask test results table

Rise/Fall

Displays the R ise/Fall measurements and their statistical analysis

Measurements

xxx

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Operating basics Setup menus

Table 1: Fast TDECQ acquisition mode View menu

Menu item Description

1-up

Displays a single plot on the screen – TDECQ

No other conﬁguration is relevant except

Global Results Displays 4 measurements: TDECQ, OMA Outer, ER, and AOP

xxx

See also:

About the 80SJNB Tool Bar (see page 25)

Setup menus

The Setup menus provide access to the various conﬁguration menus.

Menu item Description

Acquisition

Signal Path Displays the Signal Path dialog screen to deﬁne the signal path characteristics to simulate the

Analysis

Mask Test

Default Setup Returns the Acquisition, Signal Path, and Analysis settings to their default values

xxx

About the 80SJNB Tool Bar (see page 25)

Displays the Acquisition setup dialog screen to select and conﬁgure the source for measurements and control key oscilloscope setups

actual conditions your signal may encounter

Displays the Analysis dialog screen to change settings that affect how measurements are made and displayed

Displays the Mask Test Setup dialog screen to load a mask and deﬁne the mask test parameters

See About Application Parameters

(see page 93) to view the default settings for each conﬁguration

20 80SJNB Printable Application Help

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Operating basics Oscilloscope settings

Oscilloscope settings

All relevant oscilloscope settings are accessible using the Acquisition dialog box of the 80SJNB application.

To bring the TekScope application to the front of the display, click the Back to Scope button or minimize the 80SJNB application. Alternately, you can use the Alt + Tab keystoswitchbetween applications if you have a keyboard attached.

See also:

About Con

Returning to the Application (see page 14)

Minimizing and Maximizing the Application (see page 15)

ﬁguring the Application for Analysis

About the results

There are two ways to view analysis results: as numeric data and as graphical plots.

You can log the results data to .csv ﬁles for viewing in a spreadsheet, database, text editor or data analysis program.

There are several results tables: Global measurements, Jitter and Noise and BER analysis for each of the eyes (3 for PAM4), Mask analysis results, and statistical analysis for the Rise and Fall measurements.

See also:

Working with Results (see page 81)

Clearing Results (see page 22)

(see page 28)

Exporting Plot Files (see page 72)

Exporting Results from the File Menu (see page 18)

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Operating basics Clearing results

Clearing results

Click the Clear Data button to remove the existing plot displays and results. You may want to clear the data before acquiring new data or between cycles when the sequence mode is set to Free run.

NOTE. The numeric results and plot ﬁles are erased each time a new acquisition cycle is started.

About plotting

The application displays the results as plots for more comprehensive analysis. Before or after you take measurements, you can select to display a single plot, two plots or four plots. You can select the type of data you want to view in each plot window.

See also:

Starting the Application (see page 13)

Deﬁnitions of the application user interface items (see page 23)

Minimizing and Maximizing the Application (see page 15)

Exiting the Application (see page 16)

User interface items deﬁnitions

Item Description

Area

Box

Browse

Check box

Command button Initiates an immediate action, such as the Start command button in the Control panel

Keypad

Menu bar

Status bar Line located at the bottom of the application display that shows the acquisition status and the

Virtual keyboard

Visual frame that encloses a set of related options

Use to deﬁne an option; enter a value with the Keypad or a Multipurpose knob

Displays a window where you can look through a list of directories and ﬁles

Use to select or clear an option

On-screen keypad that you can use to enter numeric values

All options in the application window (except the Control panel) that display when you s elect a menu bar item

Located along the top of the application display and contains application menus

latest Warning or Error message

On-screen keyboard that you can use to enter alphanumeric strings, such as for ﬁle names

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Operating basics About navigation

Item Description

Scroll bar Vertical or horizontal bar at the side or bottom of a display area that you use to move around in

that area

Tool bar

xxx

Located along

the top of the application display and contains application quick launch buttons

About navigation

The application provides you with several ways to display the results:

The drop-down menus available in the menu bar allows for screen conﬁguration (one, two, or four plots, summary or full numeric results table)

The buttons in the tool bar allow for screen conﬁguration

The drop-down menus available in the plot display windows allow you to choose from the available plots, and Copy, Examine, and Export plots

The status bar at the bottom of the screen contains progress information and displays error conditions detected

Double clicking on a displayed graph opens the plot in a MATLAB window. MATLAB provides additional display capabilities such as panning, zooming, data cursors, and 3D rotation. The Examine button from the drop-down menu of the plot also opens the MATLAB window.

See also:

Windows User Interface (see page 22)

24 80SJNB Printable Application Help

Page 33

Operating basics About the 80SJNB tool bar

About the 80SJNB Toolbar (see page 25)

About Conﬁguring the Application for Analysis (see page 28)

About the 80SJNB tool bar

The toolbar provides quick access to the most common functions you need to conﬁgure the settings, start the acquisition, and control the numerical and plot displays. Most tasks are also available using the drop-down lists from the File menu bar.

Acquisition button. Use the Acquisition button to select and conﬁgure the source for measurements and control key oscilloscope setups. Any change in the Acquisition settings clears all the data. The Acquisition button is disabled during the acquisition and processing cycle.

Signal Path button. Use the Signal Path button to deﬁne the signal path characteristicsto simulate the actual conditions your signal may encounter. Changes made in the signal path settings does not clear the data, only the results. The Signal Path button is disabled during the acquisition and processing cycle.

Analysis Setup button. Use the Analysis Setup button to change settings that affect how measurements are made and displayed. Changes made in the analysis settings does not clear the data, only the results are updated. The Analysis Setup button is disabled during the acquisition and processing cycle.

Mask test button. Use the Mask Test button to select a mask and conﬁgure the mask test.

Free Run On/Off button. Use the Free Run button to select the sequence mode (free run on

or off).

When OFF, the button remains blue and the acquisition and processing cycle completes one pass over the entire pattern. Off is the default mode.

When Free Run is ON, the button turns green cycle repeats until stopped. The correlated components are averaged with previous data while the uncorrelated components are accumulated for increased statistical content. At the acquisition cycle, the plots and measurements are updated.

indicating that the acquisition and processing

completion of each

Free Run mode is recommended when:

There is a doubt that one acquisition cycle is enough. A change in the results indicate that additional acquisition cycles was needed.

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Operating basics About the 80SJNB tool bar

The correlated waveform shows irregular disturbances. It is possible that uncorrelated information can leak into the single-pass correlated ﬁltering. Acquiring a larger statistical sample improves analysis in th

Several Standards specify the size of the data samples to be used for measurements. See the Stop on Conditions s

e presence of crosstalk.

etup in Acquisition dialog.

To ha lt a Fr e Sequence mode, so that the acquisition stops when the cycle is complete.

button is pressed, do not change any instrument settings. When the Run button is pressed, all current measurement data and plot displays are cleared. During the acquisition and processing cycle, the Signal Path, Analysis, Acquisition, and Run buttons are disabled.

During the acquisition and processing cycle, the Run button is replaced with the Pause button Click Pause to interrupt the current acquisition and processing cycle. Click the button again to resume the cycl and processing cycle so you can view and save the measurement data between cycles.

Sequence mode, stopping the cycle produces no results and you must click the Start button to start a new cycle.

is set to ON (cumulating previous data with new), you can clear the existing results and plots during the processing cycle, thus starting a new acquisition and processing cycle.

e Run cleanly, deselect the

Run button. Use the Run button to start the acquisition and processing cycle. Once the run

e. This is useful when the acquisition is set to Free Run, allowing you to halt the acquisition

Stop button. Use the Stop button to end the acquisition and processing cycle. While in Single

Clear Data button. Use the Clear Data button to clear all results and plot displays. If Free Run

Plot Display buttons. Use the window pane buttons to display between 1, 2, or 4 plots.

u can change the number of plot displays at any time.

button. This converts the Free Run mode back to Single

meric Results Display button. The results button changes the display to a complete list of

statistics. If the application is displayed on a larger screen, the numeric results display shows all the results at once.

Back to Scope button. Use this button to bring the TekScope display to the front of the screen.

See also:

About Conﬁguring the Application for Analysis (see page 28)

About Analysis Settings (see page 52)

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Operating basics About measurement results tabs

About measurement results tabs

The application shows several measurement results tabs depending on the coding of the signal (NRZ or PAM4) being measured.

The three NRZ tabs are labeled Global, JNB Results and Mask. These tabs show thesamegraphsbut display different numeric results. Global results display a summary of Jitter and Noise measurements, Rise/Fall, and level measurements. Tab JNB Results displays all jitter, noise, and BER results. The Mask

plays all mask results such as hit ratio, margins, and BER limit.

tab dis

For PAM4 signals, six tabs are available. The Global tab displays both global PAM4 results and summary

s across all eyes. The JNB Results tab is replaced by three tabs, one per eye, labeled Eye0, Eye1 and

result Eye2. Eye0 is the lowest eye. These tabs display all jitter, noise and BER results for their respective eyes. The Rise/Fall tab displays the Rise/Fall measurements and their statistical analysis. When Fast TDECQ mode is selected, measurements are limited to 4: TDECQ, OMA Outer, ER, and AOP.

The currently selected tab is labeled with a larger font. In addition, the three Eye tab labels are color coded to match the ﬁgures having one graph per eye. In such ﬁgures, the yellow, green and red graphs represent the data for eyes 0, 1 and 2, respectively.

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Operating basics MATLAB user interface

MATLAB user interface

The 80SJNB application includes MATLAB®plots to provide further data analysis and visualization of the plot displays.

MATLAB provides multiple capabilities to display and annotate the plot diagrams, including:

Pan and Zoom

2D and 3D visualization

Rotation

Data Curso

Color enhancements

MATLAB is a product distributed by MathWorks. You can view the MATLAB documentation and tutorials on their Web site: http://www.mathworks.com

About conﬁguring the application for analysis

The tool bar provides an Acquisition (see page 29) button to conﬁgure the application to acquire data,

Signal Path

to change settings that affect how measurements are made and displayed, andaMask test (see

page 97) button to set the mask test parameters.

NOTE. The Acquisition settings must be set before starting an acquisition cycle. You can modify the Signal Path and Analysis settings without the need to reacquire data. You can also change the Mask Test without the need to reacquire data.

28 80SJNB Printable Application Help

(see page 40) button to set signal path conditions, an Analysis (see page 52) button

Page 37

Operating basics About acquiring data

Use the Sequenc run) or stop after one cycle is complete.

After setting up the application, you can select the Run button cycle.

After the acquisition and processing cycle has completed, you can view the results as numerical

page 81) statistics or graphically (see page 22).

A typical scenario to setup the 80SJNB application and acquire data involves the following steps:

1. Set the Source, Data Rate, and Pattern Length.

2. Select Coding: NRZ or PAM4.

3. Set the number of Samples per UI.

4. Select a Stop on Condition.

5. Set the required Count.

6. From the tool bar, select Free Run mode.

7. Issue a Run command.

8. Wait until the 80SJNB application ﬁnishes running and then stops

e button

to have the acquisition and processing of data run continuously (free

to start the acquisition and processing

(see

See also:

About Acquiring Data (see page 29)

About acquiring data

Before making jitter and noise measurements, you need to select and conﬁgure the signal source.

Use the Acquisition button

In the Acquisition dialog box, select the signal source and signal coding (NRZ or PAM4), and deﬁne the acquisition parameters. Some parameters (such as the Clock Recovery, Phase Reference Sources, and the optical signal conditioning) are copied from the oscilloscope state.

One of the key acquisition parameters is the number of samples per unit interval. The default is 100 samples per unit interval. For higher throughput and support of longer record lengths than PRBS13, you can optionally select 40 samples per unit interval.

The Fast TDECQ acquisition mode is optimized to return TDECQ measurements in minimum time. The Number of Samples per UI defaults to 5, and can be set to 10, or for pattern length shorter than PRBS13Q, to 20, 40, or 100.

Click the AutoSync to Selected Source button to have the 80SJNB application automatically obtain and enter the following information from the signal applied to the channel deﬁned as the Signal Source:

to display the Acquisition dialog box.

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Operating basics About acquiring data

Data Pattern Rate

Data Pattern Length

Recommended Data:Clock Ratio (when Spread Spectrum Clocking (SSC) signaling is used)

NOTE. Acquisition in the presence of SSC requires certain cabling propagation delays to be preserved. Please contact Tektronix for an up-to-date diagram of cabling lengths.

NOTE. Tektronix recommends running this functionality in the oscilloscope (the equivalent menu exists in Setup > Mode/Trigger > Pattern Sync/FrameScan Setup). The important difference is that the oscilloscope UI/PI allows manual entry of some of the parameters of the AutoSync, which dramatically improves the success r the pattern length item from the AutoSync search, makes the data pattern length much more likely to succeed. Refer to the DSA8300 TekScope application online help for details about the Pattern Sync settings.

ate of AutoSync. For example, manually entering the Data Pattern Length, and then unchecking

See also:

Selecting a Stop on Condition (see page 31)

Selecting Scope Setup Recall On Exit (see page 32)

Selecting Clock Recovery (see page 33)

Selecting Phase Reference (see page 34)

Selecting the Data Pattern (see page 35)

Selecting the Signal Conditioning (see page 36)

Selecting the Pattern Clock (see page 37)

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Operating basics Selecting a Stop on Condition

Selecting the Source (see page 37)

Analysis Settings (see page 52)

Selecting a Stop on Condition

The Stop on Condition selections allow you to control the amount of data to be acquired and processed before stopping.

NOTE. The F ree Run mode has to be selected for the Stop on Conditions to be active. Use the Sequence

button

There are four options to control the stop condition:

Never. This is the default condition. The acquisition and processing of data runs continuously until

explicitly stopped by user by clicking on the Stop button.

Acquisition cycles. Acquisition Cycles instructs the 80SJNB application to continue acquiring and

processing data until the deﬁned number of cycles have completed. Note that changing the number of

sition Cycles coerces the numbers associated with the other two options. Each acquisition cycle

Acqui includes a number of uncorrelated samples, selected by design, and a number of samples correlated with the data pattern, which depends on the pattern length and the number of samples per data bit – which is also selected by design.

The following equation describes the relationship between these parameters:

Total Population Limit = Acquisition Cycles * (Uncorrelated_Samples_Per_Cycle + Samples_Per_Bit * Pattern_Length)

Uncorrelated samples. Uncorrelated Samples instructs the 80SJNB application to continue acquiring and

processing data until the data required for jitter and noise processing exceeds the speciﬁed number. The

efault count is a number that represents 2 acquisition cycles.

elect the continuous acquisition and processing mode.

to s

Total population limit. Total Population Limit instructs the 80SJNB application to continue acquiring and

processing data until the total number of samples exceeds the speciﬁed number. The default count is a number that represents 2 acquisition cycles, and reﬂects the selected Pattern Length.

The actual number of acquired and processed samples is displayed in Sample Count (see below), and corresponds to the nearest integer number of acquisition and processing cycles.

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Operating basics Selecting scope setup recall on exit

Select

ing scope setup recall on exit

Acquir oscilloscope state. When this control is checked, exiting the 80SJNB application (File > Exit) restores the oscilloscope to the state which was stored when 80SJNB application was launched.

ing data for jitter and noise analysis requires the 80SJNB application to fully control the

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Operating basics Selecting clock recovery

Selecting clock recovery

The Advanced Trigger option (ADVTRIG) that generates the pattern synchronous triggers requires a clock source synchronous with the signal. When using a clock derived from a clock-recovery module installed in source module, the conﬁguration and its frequency.

All native clock recovery modules support two different conﬁgurations: one that connects the recovered clock from the back of the module to the internal pattern synchronous trigger generator; and, for optimal jitter p Input.

the oscilloscope (such as optical sampling modules), use the Pattern Clock ﬁelds to select the

erformance, the module full rate clock output can be connected to the front panel Clock/Prescale

These s

The Rate setting is limited to the capabilities of the selected module. The numeric keypad is unavailable for use

ettings are grayed out if no modules with clock recovery are detected at application startup.

unless the module can accept USER deﬁned rates.

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Operating basics Selecting phase reference

Selecting phase reference

You can use a Phase Reference module (such as the Tektronix 82A04B) to reduce the trigger jitter of the signal source, thus increasing the jitter measurement accuracy. If analyzing a signal using Spread Spectrum Clocking (SS

If using a Phase Reference module, set the channel source and the frequency of the applied clock.

These settings are grayed out if a Phase Reference module is not detected at application startup. If a Phase Reference module is detected, you have the option to not use the module by selecting None as the Source.

C), a Phase Reference module is required.

TIP. Selec Jitter) and the correlated waveforms. However, the throughput is lowered in this mode.

NOTE. W frequency when the data was acquired. The Source ﬁeld remains unchanged regardless if phase reference was used when the recalled data ﬁle was created.

ting a Phase Reference module dramatically improves the accuracy of DDJ (Data Dependent

henusingarecalleddataﬁle, the Phase Reference Frequency ﬁeld is updated to indicate the

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Page 43

Operating basics Selecting the data pattern

Selecting the data pattern

Deﬁning the Data Pattern requires that you deﬁne both the data rate of the signal source and the pattern length in bits. You can choose the data rate from a predeﬁned set of lengths or enter a value with the numeric keyp

NOTE. Selecting a data rate that does not match the communication standard that is set in the instrument’s Horizontal Communication Standard setting dialog box causes the oscilloscope setting to change to User.

When selecting the pattern length, only the length is important. The precise bit sequence is unimportant if it is repetitive.

To analyze a clock pattern, select a 2 bits pattern (or a multiple). The analysis is performed on both edges.

ad.

NOTE. Whenusingarecalleddataﬁle, the Data Pattern ﬁelds are updated to indicate the state of the settings when the data was acquired.

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Operating basics Selecting the signal conditioning

Selecting the signal conditioning

Use this control to select what type of ﬁltering, if any, you want performed on the selected channel. The available ﬁlters depend on the capabilities of the module.

If the Filter is set to None, you can use the Bandwidth box to select the bandwidth of the channel. The available bandwidth selections depend on the capabilities of the module. Refer to the documentation for the module about its ﬁlter or bandwidth settings.

The list of hardware ﬁlters are speciﬁc to the selected module as data source. A comprehensive list of the hardware ﬁlters, the standards they support, and the data rates, are listedintheDSA8300Programmer Manual. The manual speciﬁes the token names that are used by the programmatic interface to select a particular ﬁlter.

The range and resolution of scale values for a selected channel is dependent on multiple factors: module type, probe type if attached, and an external attenuation factor. Use the DSA8300 programmatic interface comma for details.

Scope Noise is a relevant parameter for the TDECQ measurement. For optical modules enter measured scope noise in μW. For electrical modules, scope noise is entered in μV. Default is 0.

nds when an external attenuation factor is required. See the DSA8300 product documentation

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Operating basics Selecting the pattern clock

Selecting the pattern clock

The Pattern Sync built-in capability provides user pattern synchronous triggers. The feature, enabled by theAdvancedTriggerOption(ADVTRIG),isdrivenbythePatternClock.

The available Pattern Clock sources depend on the instrument conﬁguration. The default selection is Clock/Prescale Input, and this selection is available for all conﬁgurations. Connect the clock source to the CLOCK INPUT/PRESCALE TRIGGER front-panel connector.

When the oscilloscope is equipped with one or more clock recovery capable modules, the CR units are also available as sources for the Pattern Clock.

Each native clock recovery source appears on the Pattern Clock source list twice to allow for two different conﬁgurations:

Selecting Cx Clock Recovery sets the instrument to pick up the recovered clock from the back of the module using and internal signal path.

Selecting Cx CR to Clock/Prescale Input sets the instrument clock recovery signal source to the CLOCK INPUT/PRESCALE TRIGGER connector on the front panel. Connect the output of the clock recovery module to the front panel CLOCK INPUT/PRESCALE TRIGGER input.

Depending on the data rate, choosing one conﬁguration over the other could result in different intrinsic jitter performance. See Selecting Clock Recovery particular cabling setup is necessary; only external Clock Recovery (such as with a Tektronix CR286A) can be used. If the Tektronix 82A04/82A04B Phase Reference module is used intheab the 82A04/82A04B setup determines the jitter performance. The intrinsic jitter of the pattern trigger circuit becomes invisible.

When the clock source is a dedicated Clock Recovery Unit, like the Tektronix CR125A, CR175A, or CR286A, the instruments are controlled by a USB-link to the oscilloscope. The syntax of the programmatic interface is speciﬁed in the DSA8300 Programmer Manual. The header of the commands are TRIGger:CLCRec:CRC.

Selecting the source

The application takes measurements on waveforms speciﬁed as sources (also called signal sources). The source can be a channel (CH1 through CH8) or a deﬁned math waveform. You can useanydeﬁnedmath waveform, whether it is deﬁned in the 80SJNB conﬁguration as a differential setup or in the TekScope application.

(see page 33). In general, if there is SSC then a

sence of SSC,

Specify whether the source waveform is NRZ or PAM4.

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Operating basics Selecting the source

NOTE. Selecting PAM4 disables SSC.

If your signal source uses Spread Spectrum Clocking (SSC), select the SSC check box so that the application can make accurate measurements that account for clock rate modulation

NOTE. If a saved data ﬁle is recalled, the signal source selection remains unchanged but all result panels will indicate the recalled data ﬁle as the source. The “SSC is present” ﬁeld is updated to match the setting from the recalled data ﬁle.

See also:

About Spread Spectrum Clocking (SSC) (see page 39)

Clicking the Diff button displays the dialog box to create a differential Math waveform by deﬁning a positive and negative waveform source (the negative waveform source is subtracted from the positive waveform source). This generates a single mathematical waveform that the 80SJNB application can use as the w

aveform measurement source.

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Operating basics About spread spectrum clocking (SSC)

About spread spectrum clocking (SSC)

Spread Spectrum Clocking (SSC) is the technique of modulating the clock frequency to minimize EMI effects. SSC affects the analysis process and the results of jitter, noise and BER measurements. If SSC is not correc reﬂected in the total jitter and noise, and ultimately in the BER estimates.

When SSC is present, 80SJNB measures the attributes of SSC and corrects the results.

SSC conﬁguration requirements

NOTE. SSC is a vailable only for NRZ coding measurements.

If using clock recovery, the clock recovery unit must be able to handle SSC. Use one of the Tektronix BERTScope clock recovery instruments if SSC is present in the signal.

The TekScope must have an 82A04 or 82A04B Phase Reference Module installed. The module minimizes the effect of the SSC on the data by sampling synchronously the data and clock. Also, by acquiring the clock in the 82A04/4B module, 80SJNB characterizes the SSC present in the clock and uses that information to correct the jitter, noise, and BER measurements performed on the data.

ted for its effects, the results show as a large amount of periodic jitter components that are

TIP. The “SSC is present” check box is disabled if the Phase Reference module is not installed in the instrument.

Use the following settings to optimize the SSC phase correction for the signal you are measuring:

Clock recovery

Data rate range

500 Mbps – 1 Gbps Data Rate * 4 Standard

1 Gbps – 2 Gbps Data Rate * 2 Standard

2 Gbps – 4 Gbps

4 Gbps – 8 Gbps

8 Gbps – 12.5 G bps

xxx

The Clock Recovery unit clock output is either Standard or Subrate Clock.

Clock recovery is typically provided from a CR125A, CR175A, or CR286A BERTScope Clock Recovery Instrument.

frequency

Data Rate

Clock recovery output rate

Standard

Subrate (1/2)

Subrate (1/4)

1,2

Data:Clock ratio (JNB)

1:4

1:2

1:1 Data Rate

2:1

4:1

Phase reference frequency (JNB)

Data Rate * 4

Data Rate * 2

Data Rate/2

Data Rate/4

When you instruct 80SJNB that the data has SSC (by checking the “SSC is present” check box), the following constraints are enforced based on the current Data Rate:

Phase Reference source is selected.

Phase Reference frequency is set to the recommended value in the table Conﬁguration Settings for SSC.

A recommended Data:Clock Ratio is displayed to suggest the recommended subrate clock.

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Page 48

Operating basics About Serial Data Link Analysis (SDLA) Signal Path Settings

NOTE. Changes to the Data Rate are reﬂected in the Phase Reference Frequency and Data:Clock Ratio. You must make the appropriate changes to the Clock Recovery unit parameters.

The Full Numeric Results page shows the status (on or off) of the SSC setting. The results of the SSC analysis are presented in two forms, numeric results and a plot. When viewing the full numeric results table, the SS depth of the SSC clock modulation in parts-per-million (ppm) and Frequency reﬂects the SSC modulation frequency.

To view the plot of the SSC modulation proﬁle, select the Plot>SSC>SSC Proﬁle.

C Modulation section has two ﬁelds: Magnitude and Frequency. Magnitude represents the

TIP. The conﬁguration settings are also available through the GPIB programming interface of the oscilloscope. Refer to the information provided with the oscilloscope.

About Serial Data Link Analysis (SDLA) Signal P ath Settings

The Signal Path Settings are available for use with the 80SJNB Advanced and PAM4 versions. If you are using the 80SJNB Essentials version, you're allowed to use the dialog boxes but are not allowed to place any of the functions into the signal path.

The Signal Path settings allow you to emulate the environment your signal encounters, all the way from the transmitter to the receiver. With the Signal Path dialog box, your signal path is represented by a line from the transmitter (Tx) to the Receiver (Rx). Along this line, you have the ability to emulate an arbitrary ﬁlter and/or a channel. You can then deﬁne an equalizer to compensate for the effects the ﬁlter and channel introduce. Also, ﬁxture de-embed is supported.

Selecting a signal path arrow (Filter, Channel, or Equalizer) inserts or removes the function from the signal path. When inserting a function into the signal path, its dialog box automatically displays.

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Operating basics Setting Filter Conditions

Selecting a signal path button (Filter, Channel, or Equalizer) displays the dialog box for that function without inserting or removing the function from the signal path.

By simulating the signal environment, you can effectively emulate probing the signal at the receiver rather than the output of the transmitter. With the use of the Equalizer, you can improve the signal quality at the receiver.

Full signal path functionality supports PAM4 signals.

then design compensations to

TIP. You can move a function in and out of the signal path without affecting any settings.

To learn more about each of the signal path settings, select the following:

(see page 41)

Filter

Channel (see page 42)

Equalizer (see page 45)

Setting Filter Conditions

The Signal Path Filter allows you to specify an arbitrary linear FIR ﬁlter to be applied to the acquired data pattern. For instance, the transmitter may artiﬁcially enhance the signal at certain frequencies to overcome known problems in the channel. You can use a ﬁlter to emulate this action or compensate for transmitter signal pre-emphasis. Use the ﬁlter to insert a continuous-time linear equalizer (CTLE) in the signal path, which standards typically specify for PAM4 signaling.

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Page 50

Operating basics Setting Channel Conditions

You can deﬁne or load a CTLE from the Equalizer. Inserting a de-embed ﬁlter is the most common use of the Filter. Use the SDLA (Serial Data Link Analysis) tool to generate the de-embed ﬁlters. See details below

To use the ﬁlter, move the Filter function into the signal path and use the Filter ﬁle box or browse button to specify the ﬁ ﬁlter ﬁles are provided as examples, but you are responsible for providing the ﬁlter ﬁles.

lter ﬁle. The default location for the ﬁlter ﬁles is in the Windows/Documents folder. A few

To use th e F i de-embedding ﬁlter from the S-parameters of the ﬁxture. Please visit the www.tektronix.com/sdla site, or contact Tektronix Support for details.

See Uncorrelated Scaling (see page 51) for information about this setting.

The following is an example of the ﬁlter ﬁle format:

@ 5.7e-005, 2.4e-005, 5.4e-005, 2.1e-005, 5.1e-005

The '@' means that it is valid for all frequencies.

Up to

lter block for de-embedding, you will need an additional software tool to create a

20,000 coefﬁcients may be speciﬁed.

Setting Channel Conditions

Web

The Signal Path Channel allows you to emulate the channel (interconnect or lane) carrying the signal. There are two ways to deﬁne the channel, with Time Domain

Domain (see page 42) S-parameters.

See Uncorrelated Scaling

(see page 51) for information about this setting.

(see page 45) waveforms and Frequency

Frequency Domain

With Frequency Domain selected, the channel is deﬁned with an S-parameters ﬁle. Use the ﬁle selection boxorBrowsebuttontoselecttheﬁle.The default location for the ﬁles are in the Windows/Documents folder. You are responsible for providing the S-parameters ﬁle.

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Operating basics Frequency Domain

The S-param

eters ﬁle can contain data for 1-port, 2-port, or 4-port devices. Once a ﬁle is selected, the application reads its contents and generates the appropriate dialog for you to select the particular S-parameter in the ﬁle to use.

1-Port. Files with 1 port of data contain only 1 S-parameter so they do not require any further input. These

ﬁles may be IConnect 1-port ﬁles or Touchstone 1-port ﬁles.

2-Port. Files with data for 2 ports contain 4 S-parameters as a 2x2 matrix. These are Touchstone 2-port

ﬁles. When the application recognizes such an S-parameter ﬁle, a dialog is created for you to select the S-parameter representing channel transmission. The typical selection isS

, and is the default selection,

but this may need to be changed if the ﬁle contains a 2x2 subset of the 4x4 matrix of S parameters deﬁning a4-portsystem.

4-Port. Files with data for 4 ports may contain single-ended or mixed-mode data. These are Touchstone

4-port ﬁles.

If the data is single ended, you must map the port numbers as used in the ﬁle to physical locations in your link. A default mapping is assumed. The application will use this mapping to compute the S

parameter

dd21

(for transmission of a differential signal) from the appropriate four S-parameters measured using single ended data.

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Operating basics Frequency Domain

If the data is mixed mode, you must select the data layout in the ﬁle. The most common layout is DC12 and is the d

efault selection. The application always uses the S

parameter for computing the transmitted

dd21

waveform no matter which mapping is selected.

NOTE. 80SJNB Advanced uses the 'insertion loss' information only.

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Operating basics Time Domain

Time Domain

With Time Domain selected, the Reference waveform and Transmitted waveform generate the channel behavior. Use the ﬁle boxes or browse buttons to select the ﬁles you want to use. The default location for the ﬁles i waveform ﬁles.

NOTE. We recommend that the waveform ﬁle be a measurement of the channel from a Tektronix TDR/TDT system. Required raw oscilloscope waveforms are:

a. A reference throughput (no DUT is inserted, just a throughput connection between the TDR step source and the acquisition c hannel on the TDT end).

b. A DUT throughput measurement (the TDR step source and the TDT acquisition channel are connected through the DUT).

s in the Windows/Documents folder. You are responsible for providing the time domain

About the Equalizer

The equalizer compensates for transmission channel impairments in the form of frequency-dependent amplitude and phase distortions resulting in intersymbol interference (ISI) in the communication data stream.

80SJNB provides tools to support three types of equalizers: CTLE (Continuous Time Linear Equalizer), FFE (Feed Forward Equalizer), and DFE (Decision Feedback Equalizer). The linear feed-forward equalizer (FFE) is deﬁned by a user speciﬁed number of taps, taps per symbol (or unit interval), and the weight of each tap. The equalizer becomes a decision-feedback equalizer (DFE) when the number of DFE

aps is set to a number larger than 0.

NOTE. Tap values and weights are used interchangeably.

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Operating basics Continuous Time Linear Equalizer (CTLE)

To learn about setting up the Equalizer, see:

Continuous Time Linear Equalizer CTLE

Equalizer Taps (see page 48)

Uncorrelated Scaling (see page 51)

(see page 46)

Continuous Time Linear Equalizer (CTLE)

The equalizer includes an optional ﬁlter that is intended to be a Continuous Time Linear Equalizer. However, when loading the equalizer from a ﬁlter ﬁle (extension .ﬂt) any ﬁlter may be used. If the radio button Deﬁne CTLE is selected the user can deﬁne a 1- or 2-stage CTLE.

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Operating basics Continuous Time Linear Equalizer (CTLE)

The schematic in the CTLE Deﬁnition dialog portrays each stage (assuming 2 poles per stage) of the CTLE ﬁlter. The plotted function schematically shows the frequency response of the ﬁlter.

You can select a standard with a speciﬁed peaking in dB, which automatically ﬁlls in the remaining parameters of the dialog, or manually deﬁne the remaining parameters of the dialog.

ADCis the gain at DC.

fZis the frequency of the zero of the ﬁlter.

fP1is the frequency of the ﬁrst pole.

a 2-pole stage, f

For

is the frequency of the second pole. For a 1-pole stage, fP2is not deﬁned.

When 2 stages are deﬁned, the ﬁlters deﬁned by the separate stages are convolved to produce the ﬁlter.

TE. Clicking Apply or OK causes the ﬁlter to be included in the updated deﬁnition of the Equalizer, but

when you exit this dialog and return to the Signal Path – Equalizer dialog, you must click Apply or OK there, too, in order for the updated deﬁnition to now deﬁne the Equalizer. In addition, the Equalizer must be made active for its deﬁnitiontobeusedatall.

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Operating basics Equalizer Taps

Equalizer Taps

The behavior of the equalizer is controlled by the number of taps and the tap values. Using the equalizer requires that you specify the number of FFE and DFE taps, and the FFE spacing of the taps. You can also incorporate effects.

an equalizer ﬁlter delay by specifying a reference tap to compensate for precursor channel

You c a n ma nu application calculate the tap values.

Go to FF

Go to DFE Taps description (see page 49)

ally set the FFE and DFE tap values, or you can use the Autoset Taps button to let the

E Taps description

(see page 48)

FFE Taps

FE Taps are weights applied to a set of samples taken from the data stream to compensate for

The F channel impairments manifested in the form of ISI. The number of FFE Taps represent the length of history in data samples that contribute to the computation of a current bit. Data stream samples could be distanced at unit intervals, in which case the number of FFE taps represents the number of preceding bits that contribute to the correction of the current bit. Alternatively, the data stream could be sampled at a higher rate per bit, yielding a fractionally-spaced FFE tap set.

The number of FFE taps defaults to 1, with the capability to specify up to 100 taps. The default FFE tap spacing is at unit intervals. You can conﬁgure up to 10 taps per symbol.

The FFE Tap values could be speciﬁed by you using the FFE Taps dialog, or computed by the application with the Autoset Taps button.

Go to Autoset Taps description

Go to Saving and Loading Taps (see page 51)

48 80SJNB Printable Application Help

(see page 50)

Page 57

Operating basics Equalizer Taps

Pressing the FFE Taps button displays a dialog showing the current FFE tap values. You can specify each FFE tap coefﬁcient individually. Pressing the Defaults button sets the ﬁrst FFE tap to 1 and the rest to 0.

You can use the Save Taps button to save a set of coefﬁcients to a ﬁle. Use the Load Taps button to load saved Tap ﬁles.

aps

DFE T

DFE taps are weights applied to the previous digital decisions made by the slicer (comparator + latch). The

ber of DFE Taps speciﬁes the number of bits contributing to the current input to the slicer. The default

num number of DFE Taps is 0, in which case the equalizer is a linear FFE one. The maximum number of DFE Taps is 40. Weights are scalars speciﬁed by you or computed by the Autoset Taps function.

See Autoset Taps

ressing the DFE Taps button displays a dialog showing the current DFE tap values. You can specify each

P DFE tap coefﬁcient individually. Pressing the Defaults button sets all DFE tap values to 0.

80SJNB Printable Application Help 49

(see page 50) for a description about using the autoset taps function.

Page 58

Operating basics Autoset Taps

You can use the Save Taps button to save a set of coefﬁcients to a ﬁle. Use the Load Taps button to recall saved Tap ﬁles.

TIP. When u

Filter Settings

FFE Reference Tap. The FFE Reference Tap is a ﬁlter delay in unit intervals that should be set to

compensate for the delay between the transmitter output and the equalizer input. The value of the Referen

DFE Rise Time Selector. The Rise Time Selector speciﬁes the Gaussian ﬁlter used to emulate the DFE

feedback path band-limited behavior. The rise time defaults to Track Data Rate, in which the conﬁguration is set to 1/5 of the unit interval equivalent with the data rate. Track tap interval designs a Gaussian ﬁlter with a rise equal to 1/5 of the spacing between taps. Selecting User allows you to specify the rise time from 1

Uncorrelated Scaling. See Uncorrelated Scaling

ce Tap is constrained by the number of FFE Taps and the number of taps per symbol.

ps to 4 ns.

Autoset Taps

sing the Equalizer, you are required to always have at least 1 FFE tap. DFE taps are optional.

(see page 51) for a description.

The tap autoset function computes a set of tap values that optimize the eye opening for the data pattern applied to the input of the equalizer. If the DFE tap number is 0, the algorithm yields an optimal set of FFE taps, while if the equalizer is speciﬁed as a DFE by a positive DFE tap number, the Autoset Taps algorithm jointly optimizes the forward and feedback loop tap coefﬁcients. The optimization algorithm is the least-mean-square error (LMS) and the optimization targets the signal to noise ratio at the sampling phase.

The Autoset Taps will account for the FFE Taps/Symbol and Reference Tap speciﬁcations.

The tap autoset algorithms computes a set of FFE and DFE taps using a least-mean-square optimization algorithm. The optimization algorithm is the least-mean-square error (LMS) and the optimization targets the signal to noise ratio at the sampling phase. If TDECQ computation is enabled, the Autoset Taps performs a MMSE (minimum mean square error) optimization according to the IEEE standard.

NOTE. You can autoset tap values even if the Equalizer is not inserted in the signal path.

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Operating basics Saving and loading taps

Saving and loading taps

Use these controls to save or load a set of taps from a ﬁle. The browse directory defaults to Windows/My Documents and the ﬁle extension is .tap.

The ﬁle format is the following:

<FFE>

<TapsPerS <ReferenceTap>value<\ReferenceTap> <Tap1>value<\Tap1> <Tap2>value<\Tap2>

...

<Tapn>value<\Tapn> </FFE> <DFE>

<Tap1>value<\Tap1>

<Tap2>value<\Tap2>

...

<Tapn>value<\Tapn> </DFE

</TapFile>

</Tektronix>

ymbol>value<\TapsPerSymbol>

Uncorrelated scaling

The signal path settings (Filter, Channel, Equalizer) each have an uncorrelated scaling setting. The Uncorrelated Scaling value multiplies the uncorrelated random noise RMS and uncorrelated periodic noise values. Uncorrelated noise scaling affects the uncorrelated jitter as projected through the average slew rate. The 80SJNB Signal Path does not process uncorrelated noise in any other way.

If you insert a default equalizer (an FFE Tap 1 value equal to 1, and zero DFE taps) in the Signal Path and set the Uncorrelated Scaling factor to its minimal value (0.01), the conﬁguration will isolate the effects of noise on jitter measurements. This conﬁguration produces results that correlate with “jitter only” type analysis tools.

NOTE. The overall Signal Path uncorrelated scaling factor is the product of all signal path uncorrelated scalar values of the active functions.

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Operating basics About analysis settings

About analysis settings

The Analysis settings affect how measurements are made and displayed. The settings are saved with the 80SJNB application whenever it is closed so that restarting the application results in using the same settings.

NRZ Analysis dialog box

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Operating basics About analysis settings

PAM4 Analysis dialog box

TIP. Changes to Analysis settings are reﬂected in the current plots and results.

Setting the analysis method

The Method selection sets which analysis methodology to use for the Jitter and Noise breakdown:

The Spectral + BUJ (Bounded Uncorrelated Jitter) is using a combination of spectral isolation of the periodic components and the anal uncorrelated jitter and noise data, before and after spectral separation. The presence of crosstalk dictates the selection of this method.

The Spectral (Legacy) mode relies on spectral separation of the periodic and random components.

The default setting is Spectral + BUJ. When switching the analysis method between the two options, the acquisition data is preserved, and new results are recomputed, displayed, and plots made available. W the selected coding scheme is PAM4, the Spectral+BUJ is the only analysis method available.

ysis of the cumulative distribution function (CDF) of the

hen

Setting the Rx optimizer

You can deﬁne the receiver slicers of the eye(s) or have the slicers determined automatically by the Rx Optimizer.

The Rx optimizer is a set of eye analysis algorithms that select the optimum point within each eye (both threshold and phase) for placing the receiver slicer. Values entered in the text boxes for decision thresholds and sampling phases are ignored save in extreme cases that the optimizer cannot analyze, e.g., a completely closed eye.

For NRZ the user selects one of the two radio buttons “User Speciﬁed” and “Optimize Receiver.”

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Operating basics About analysis settings

For PAM4 the “User Speciﬁed” control is still present but now there are three radio buttons for the optimizer, one for each of the optimizer’s two modes. In the ﬁrst mode, labeled Optimize to Center Eye OIF (Common Ph phase. The algorithm JNB uses in this mode is deﬁned by the standards OIF CIE 2014.230 and IEEE

802.3bj. The second Common Phase option for optimized receiver is according to the IEEE speciﬁcation.

The third option has the three receiver slicers that are separately optimized for each eye. This algorithm decides the relative importance of horizontal and vertical spacing around the receiver slicer. In cases where one is substantially more important than the other the optimum receiver slicer may be placed closer to an edge of an eye than might be expected. This is correct behavior.

The IEEE standard for optical receivers sets the reference decision threshold to the average optical power, and adds and subtracts 1/3 of the optical modulation amplitude. The sampling phase is common for all three eyes, and it is the middle of the unit interval.

The receiver slicers are denoted by white crosses in the SP Receiver PDF Eye ﬁgure (Matlab version of the ﬁgure only). The following ﬁgure shows receiver slicers with independent phases computed by the Rx Op

timizer.

ase), the receiver slicers of the three eyes are constrained to have the same sampling

Setting the decision thresholds

TheDecisionThresholds,onepereye(oneforNRZandthreeforPAM4),specify the boundary between two adjacent signal levels.

When Optimize Receiver is selected, the decision threshold text boxes are disabled and the Rx Optimizer computes the optimum decision points (both decision thresholds and sampling phases).

When Optimize Receiver is not selected, the decision threshold text boxes are enabled.

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Operating basics About analysis settings

When Optimize Receiver is not selected and Absolute is selected, the decision thresholds use the absolute value provided in volts (electrical) or watts (optical).

When Optimize Receiver is not selected and Normalized is selected, the decision thresholds are calculated based on waveform data according to the percent value of the signal amplitude.

Setting the time unit

TheTimeUni

t sets the units (Seconds or Unit Intervals) used when displaying the measurement results.

Setting the sampling phases

The Sampling Phases determine the times of the sampling points and of all noise and vertical eye opening measurements within the unit interval.

When a PAM4 signal is analyzed, either each eye can have its own Sampling Phase or all three phases can be set to the same time.

When Optimize Receiver is selected, the sampling phase text boxes are disabled and the Rx Optimizer calculates the optimum decision points (both decision thresholds and sampling phases).

For PAM4 there are two options to optimize using a common phase:

selected, the optimization is unconstrained and the software calculates the optimum sampling

If not point for each eye independently of the other eyes.

lected the optimization is constrained so that all sampling points are the same. When Optimize

If se Receiver is not selected the sampling phase text boxes are enabled according to OIF and IEEE standards.

When Optimize Receiver is not selected, and Seconds is selected, the sampling points use the absolute value entered. Zero seconds is the center of the unit interval.

When Optimize Receiver is not selected, and Unit Intervals is selected, the sampling point is calculated based on the fraction of a unit interval. Zero UI is the center of the unit interval.

Setting the measurement bit error rates (BER)

There are three BER values to set: Global, JxBER and JyBER. The Global BER is used for all measurements qualiﬁed by a BER value. Total jitter is also calculated for JxBER and JyBER.

All three total jitter values are displayed on the eye tabs. The JxBER and JyBER total jitter values are labeled Jx and Jy unless the speciﬁed BER has the values 2.5e

-3

or 2.5e

-10

, in which case they are labeled

J2 or J9, respectively.

ER Correction Factor

Extinction Ratio Correction Factor is a compensation for offsets and drifts in photodiodes, which can generate nonzero voltage when no light is present at the input. This can occur due to lack of dark level compensation, photodiode dark currents, or can be generated by electrical ampliﬁers following the diode.

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Operating basics About mask test settings

The Correction Factor values run from -99% to 100% of signal amplitude. Default is 0%.

TDECQ Measure

The computation of the TDECQ (Transmitter and Dispersion Eye Closure Quaternary for PAM4) needs to be enabled by

The histogram width on which the TDECQ computation is enabled is speciﬁed in % of UI. The default is 4%, and the r

TDECQ Extended Analysis selection will instruct the algorithm to optimize the measurement parameters across the parameters are limited to 4000 symbols for optimal throughput performance.

full pattern. If the selection is unchecked – the default, the optimization of measurement

ment

the user.

ange is 0% – 10%.

Computing rise/fall times

The transition times between signal levels are optionally computed by selecting the check box labeled ComputeRise/FallTimes.Thedeﬁnitionofthereferencelevelscanbesetin percent using the Low and High text boxes.

For NRZ the rise/fall times are displayed on the Global tab. For PAM4 they are displayed on the Rise/Fall tab.

About mask test settings

The Mask Test setup dialog deﬁnes the target and parameters of mask testing.

There are two 80SJNB statistical analysis products on which mask testing can be performed, the SP Receiver PDF Eye and the BER Contours. Both of these are deﬁned at the receiver side of the Signal Path emulator.

The mask deﬁnitions are loaded from Tektronix standard format mask ﬁles. These ﬁles include parameters that deﬁne the signal, the mask polygons, and the mask testing qualiﬁers.

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Operating basics About mask test settings

NOTE. Changes to mask test settings are reﬂected in the current plots and results.

Selecting the mask test

he Load button and browse to select a mask ﬁle, which has the extension .msk. Parsing the ﬁle

Click t ﬁlls in the Mask Test Deﬁnition ﬁelds of the setup dialog. These values can be edited and, by using the Save button, saved in another mask ﬁle.

A mask ﬁle contains the following information:

ame of the standard for which the mask was deﬁned

The n

Signal type is limited to NRZ

Standard data rate. This rate can be edited, and if the acquired signal rate andmaskﬁledataratedo not match, a message “Mask is scaled to signal rate” is displayed

The polygons that deﬁne the mask testing area, which are visible on the target plots

Target Hit Ratio, deﬁned as the sum of probabilities that the modeled signal is within the mask

Target Mask Margin, deﬁned as a positive or negative percentage of the speciﬁed mask size

Target BER value that deﬁnes the curve of constant BER that will be used for the BER Contour mask testing

Checking Horizontal Autoﬁt causes the mask test to be evaluated at all horizontal positions to obtain the best test result in terms of maximum mask margins or minimum hit ratios.

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Operating basics About mask test settings

Selecting the runtime options

Check Enable Mask Testing button to perform mask testing.

The Test Target pull down list speciﬁes the JNB analysis products to which the mask can be applied: SP Receiver PDF Eye or the BER Contour.

When changing the Mask Test Target the relevant plot with the Mask will be displayed. If the target plot is displayed already, the mask will be added to the plot. If the plot is not displayed, the test target plot will replace the upper left corner plot.

Consider the use cases for mask testing on the PDF Eye:

Given a target Hit Ratio, ﬁnd the largest mask margin that does not exceed that hit ratio.

Given a target Mask Margin, ﬁnd the actual hit ratio.

Given a Ta

The use cases for mask testing on BER Contours are:

Given a target BER, ﬁnd the largest mask margin that does not exceed that BER.

Given a target Mask Margin, ﬁnd the BER Limit, which is the lowest BER contour that contains the mask.

Given a target BER and Mask Margin, determine the Pass or Fail status.

For PDF Eye mask testing, there are three polygon areas to consider: overshoot, center and undershoot. You can choose to test against all regions or only the center polygon.

The settings are saved with the 80SJNB application whenever it is closed so that restarting the application results in using the same settings. Using the File > SaveSettings control saves the settings for later use.

rget Hit Ratio and Mask Margin, determine the Pass or Fail status.

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Operating basics About PAM4 signal analysis

About PAM4 signal analysis

The 80SJNB PAM4 option performs the full jitter, noise and BER analysis on the PAM4 modulated signals, to support measurement and analysis of 100-400 Gbps electrical and optical communication links.

Signal impairment sources for PAM4 are categorized in similar ways as for NRZ systems: uncorrelated jitter and noise sources, crosstalk, bounded and unbounded types. JNB will perform the full analysis on each PAM4 ey

The PAM4 signal analysis process is as follows:

1. The signal Coding is selected from the Analysis panel. Default is NRZ, and the user has the option to select PAM4.

2. If PAM4 is selected, the JNB Results tab changes to a set of 3 Results tabs (Eye0 lowest eye, Eye1 middle eye, and Eye2 upper eye). The content of each result tab is the same as for NRZ, and includes a compreh

3. An additional Global tab speciﬁc to PAM4 displays a result panel containing a set of transmitter side and rec

e, and also performs a set of global PAM4 speciﬁc measurements.

ensive jitter and noise analysis with the BER estimations of total jitter and noise.

eiver side PAM4 speciﬁc measurements.

4. Each Plot will reﬂect the signal and processing characteristics of a PAM4 signal. Eye plots contain

ee stacked eyes for PAM4. Horizontal and vertical Bathtub curves are composite plots of each

all thr individual eye.

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Operating basics About TDECQ Measurements

About TDECQ Measurements

TDECQ is a measure of an optical transmitter’s vertical eye closure when transmitted through a worst case optical channel, as measured with a bandwidth equivalent to a reference receiver. The signal path includes an e implemented in the 80SJNB software.

qualizer, as speciﬁed by IEEE standards. The reference receiver and the equalizer are

The acquire ideal reference receiver when optimally equalized by a reference equalizer. The optimization is an iterative process until a target SER is met. The attributes and targets of optimization are deﬁned by Standards.

Low TDECQ values are qualiﬁers of high quality optical links. The threshold of pass/fail for TDECQ measurements are speciﬁed by Standards.

There are two major operation modes for TDECQ, one for optimal throughput and one for a comprehensive jitter, noise and BER analysis, which includes the TDECQ measurement.

The Fast TDECQ Acquisition Mode (see Acquisition dialog) will acquire the full pattern, typically an SSPRQ one as required by IEEE Standard. Focus is on maximum acquisition and processing speed. This mode yields the fastest response for TDECQ measurement, along with OMA Outer (Optical Modulation Amplitude), ER (Extinction Ratio), and AOP (Average Optical Power). An additional control in the Analysis panel allows an extensive optimization cycle, called TDECQ Extended Analysis. This requires extra

If the Fast TDECQ Acquisition Mode is unchecked, the full acquisition and analysis cycle is performed. This TDECQ. You have a choice to add the computation of TDECQ to this cycle by checking the Compute TDECQ button available in the Analysis panel. The TDECQ Extended Analysis is available for this acquisition mode as well.

Scope noise is a key parameter for the TDECQ measurement. It has to be removed from the measured signal noise to allow the optical link to account only for the added noise measure. Use the DSA8300 measurement system to determine the scope noise for the particular module conﬁguration. The Acquisition control panel requires the you to enter the scope noise value.

d waveform is processed to ﬁnd the largest noise that could be convolved with the signal by an

processing time.

mode of operation analyzes all three PAM4 eyes and performs global measurements that include

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Operating basics Taking measurements

Taking measurements

The most relevant oscilloscope measurement settings are accessible using the Analysis dialog box of the 80SJNB application.

Displaying measurements

You can use the tool bar to select how the results are displayed: numeric results, plots (up to four), or a combination.

What do you want to do?

Display the deﬁnitions of Jitter measurements

Display the deﬁnitions of Noise measurements (see page 63)

Measurement Algorithms (see page 131)

Go to Wor

Go to Working with Plots (see page 70)

king with Numeric Results

(see page 81)

(see page 62)

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Operating basics Jitter measurement deﬁnitions

Jitter measurement deﬁnitions

Jitter measurements Description

Random Jitter

RJ (RMS)

RJ(h) (RMS) Horizontal c

RJ(v) (RMS) Vertical co

Determini

DJ Measured Deterministic Jitter

DDJ Data Dependent Jitter

DCD Duty Cycle Distortion

DDPWS Data Dependent Pulse Width Shrinkage

BUJ(d-d)

PJ(h) Horizontal component of periodic jitter (peak-to-peak)

PJ(v) Vertical component of periodic jitter (peak-to-peak) induced by noise converted to jitter

NPJ(d-d)

Total Jitter @ BER

TJ (1E-12) Total Jitter at user-speciﬁed BER

Eye Opening (1E-12) Horizontal Eye Opening at user speciﬁed BER

Other Jitter measurements

Jx (JxBER) Total Jitter at second user-speciﬁed BER

Jy (JyBER) Total Jitter at third user-speciﬁed BER

Rj(d-d)

Dj(d-d)

xxx

stic Jitter

Measured Random Jitter

omponent of random jitter

mponent of random jitter induced by noise converted to jitter through an

average slew rate

Measure

Measured Periodic Jitter (peak-to-peak)

through an average slew rate

Measured NonPeriodic Jitter, Dual Dirac model

Random jitter based on the dual Dirac model

Deterministic jitter based on the dual Dirac model

d Bounded Uncorrelated Jitter, Dual Dirac model

NOTE. J2 Jitter: For a BER speciﬁed as 2.5E-3, the Total Jitter becomes J2 Jitter. J2 Jitter measures all but 1% of the statistical total jitter distribution.

J9 Jitter: For a BER speciﬁed as 2.5E-10, the Total Jitter becomes J9 Jitter. J9 Jitter represents an estimation of all but 10E-9 of the statistical total jitter distribution.

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Operating basics Noise measurement deﬁnitions

Noise measurement deﬁ nitions

Noise measurements Description

Random Noise

RN (RMS)

RN(v) (RMS) Vertical com

RN(h) (RMS) H orizontal

Determini

stic Noise

DN Measured Deterministic Noise

DDN Data Dependent Noise

DDN(level 1)

DDN(level 0)

BUN(d-d)

PN(v) Vertic

PN(h) Horiz

NPN(d-d)

Total Noise @ BER

TN (1E-12) Total Noise at user-speciﬁed BER

Eye Opening (1E-12) Eye Opening at user-speciﬁed BER

e Amplitude

xxx

Uncorrelated random noise (RN) and periodic noise (PN) measurements are performed on both logical levels 1 and 0 to account for signiﬁcant differences, which may be the case when the measurements are performed on optical signals.

Measured Random Noise

ponent of random noise

component of random noise induced by jitter converted to noise through an

average slew rate

Data Depe

Measure

Measur

ndent Noise on logical level 1

ndent Noise on logical level 0

d Bounded Uncorrelated Noise, Dual Dirac model

ed Periodic Noise

al component of periodic noise (peak-to-peak)

ontal component of periodic noise (peak-to-peak) induced by jitter converted to

noise through an average slew rate

red NonPeriodic Noise, Dual Dirac model

Measu

The amplitude of the eye computed as the m ean-to-mean of logical 1 and logical 0 bit levels sampled at the user deﬁned Sampling Phase.

SSC Modulation Measurement Deﬁnitions

SSC modulation measurements Description

Magnitude

Frequency

xxx

80SJNB Printable Application Help 63

Spread spectrum clock modulation magnitude of the clock in parts-per-million (ppm) units.

Spread spectrum clock modulation frequency.

Page 72

Operating basics 80SJNB PAM4 measurements

80SJNB PAM4 measurements

Eye and Level measurements for PAM4 and NRZ

Measurement Description

Eye measurements

RJ RMS Standard deviation of the random (Gaussian) jitter

TJ Total jitter at target BER

Width Eye width at target BER

Decision Threshold

RN RMS Standard deviation of the random (Gaussian) noise

TN Total noise at target BER

Height Eye height at target BER

Sampling Phase Phase of the sampling point

Center Deviation Sampling phase skew relative to middle eye

OMA or VMA Optical or Voltage modulation amplitude

Level measurements

Mean

RMS Standard deviation of the measurements

PkPk

xxx

Decision thresholds for horizontal analysis

Mean value (volts or watts) of the measurements deﬁning this signal level

Range of the measurements

NOTE. Width and Height: For a BER speciﬁed as 1E-6, the Width and Height become EW6 and EH6, as deﬁned by OIF CIE 2014.230.

PAM4 global measurements

Measurement Description Ideal value

Minimum Signal Level Half the smallest of the level separations 1/6 of peak–peak

Effective Symbol Level 1 Level linearity measure from Level0 and Level1 1/3

Effective Symbol Level 2 Level linearity measure from Level2 and Level3 1/3

Level Mismatch Ratio (RLM) Minimum Signal Level relative to ideal Minimum Signal Level (if

levels were evenly spaced)

Level Deviation

Level Thickness Averaged, normalized level standard deviation at minimum

Level Time Deviation Time deviations between levels measured at minimum inter-symbol

Average deviation of level spacing from ideal spacing 0%

inter-symbol interference

interference positions

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Operating basics Fast TDECQ test measurements deﬁnitions

PAM4 global measurements (cont.)

Measurement Description Ideal value

Vertical Eye Closure

OMA Outer or VMA Outer

Minimum eye amplitude loss 5 dB

Amplitude between Level0 and Level3

TDECQ Transmitter and dispersion eye closure for PAM4

ER Extinction Ratio 3 dB- 10 dB range

AOP Average Optical Power N/A

xxx

Fast TDECQ test measurements deﬁnitions

Measurement Description Ideal value

TDECQ Transmitter and Dispersion Eye Closure Quaternary

OMA Outer Optical Modulation Amplitude between PAM4 Level 0 and Level 3

ER Extinction Ratio

AOP Average Optical Power

xxx

Mask test measurement deﬁnitions

Mask test measurements Description

N/A

< 2.4 dB typical

<2.4dB

PDF Hit Ratio Per Region

Overshoot

Center

Measured hit ratio in the overshoot polygon

Measured hit ratio in the center polygons

Undershoot Measured hit ratio in the undershoot polygon

Results Over All Regions

PDF Mask Margin Measured mask margin given a target hit ratio

PDF Hit Ratio Measured hit ratio over all tested polygons given a target mask margin

BER Mask Margin Measured mask margin given a target BER

BER Limit Measured BER Limit given a target mask margin

Pass/Fail

Status

Pass or Fail given a target mask margin and either hit ratio or BER

Horizontal Shift Amount the mask was shifted in time

xxx

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Page 74

Operating basics Rise, Fall measurements

Rise, Fall measurements

Measurement Description

Mean Mean transiti

Standard Deviation Standard deviation of the transition times

Coefﬁcient of Variation Standard Deviation divided by the Mean

Minimum

Maximun

Count Number of transitions

xxx

NOTE. The Rise/Fall measurements for NRZ are on the Global tab.

Sample Count

Both results tables, Summary and Full Results are displaying the Sample Count of the data used for the derivation of the measurements.

The Sample Count ﬁeld represents the amount of statistical data acquired and analyzed, and contains the full pattern acquisition, the jitter and noise characterizing data.

on time

Minimum of t

Maximum of the transition times

he transition times

When in Free Run, the count is continuously incremented with the newly acquired and processed data.

66 80SJNB Printable Application Help

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Operating basics Steps to Acquire Data

Steps to Acquire Data

To acquire data from acquisition channels and take measurements, follow these steps:

1. Select setup and signal type.

2. Select processing cycles. When in Free Run mode, the following acquisition and processing continues until you stop it:

acquisition and averaging of data-correlated patterns

acquisition, accumulation and statistical analysis of uncorrelated data

3. Select

To st op t

he acquisition, do one of the following:

If you w be useful if you have started a sequence on a long waveform and then realize you would like to change the conﬁguration.

If you wish to interrupt the acquisition and processing cycle, select . Select a second time to resume the acquisition.

If you wish to halt a Free Run mode cleanly, toggle the Sequence button. This will convert the Free Run mode (indicated by the green button) to Single cycle mode (indicated by the blue button) so that the acquisition stops when the cycle is complete. Single cycle is the default mode.

ish to stop the acquisition and processing cycle before it completes, select

play the Acquisition dialog box and conﬁgure the application according to your

to dis

to toggle the acquisition mode between free run (continuous) and single acquisitions and

to start the acquisition and processing cycle.

.Thismay

P. Use the Clear Data

80SJNB Printable Application Help 67

button to delete all measurement results and plots.

Page 76

Operating basics Saving and Recalling Setup Files

Saving and Recalling Setup Files

You can use the File menus to save and recall different oscilloscope and application setups. Setup ﬁles store the oscilloscope and application settings.

CAUTION. Do n

ot edit a setup ﬁle or recall a ﬁle that was not generated by the application.

See also:

Saving a Setup File

Recalling a Saved Setup File (see page 68)

(see page 68)

Saving a Setup File

To save the 80SJNB application and oscilloscope settings to a setup ﬁle, follow these steps:

1. Select File > Save Settings to open the Save dialog box.

2. In the ﬁle browser, select the directory in which to save the setup ﬁle.

3. Use the keyboard to enter a new ﬁle name. The application appends a .stp extension to the ﬁle name.

4. Save the setup ﬁle. If the selected ﬁle name already exists, a conﬁrmation dialog appears that allows

you to cancel the operation.

NOTE. The application saves the oscilloscope setup.

Recalling a Saved Setup File

To recall the application and oscilloscope settings from saved setup ﬁles, follow these steps:

1. Select File > Recall Settings to open the Recall dialog box.

2. In the Recall dialog box, select the directory from which to recall the setupﬁle.

3. Select a setup ﬁle name, and then select Open.

CAUTION. Do not manually edit setup ﬁles. If you try to recall a setup ﬁle that was manually edited, the recall operation fails.

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Operating basics Saving and Recalling Data Files

Saving and Recalling Data Files

You can use the File menus to save acquired data and then recall it later for analysis.

CAUTION. Do not edit a data ﬁle or recall a data ﬁle that was not generated by the application.

See also:

SavingaDataFile(see page 69)

Recalling a Saved Data File (see page 69)

Saving a Data File

To save the data acquired by the 80SJNB application, follow these steps:

1. Select File > Save Data to open the Save dialog box.

2. In the ﬁle browser, select the directory in which to save the data ﬁle.

3. Use the keyboa

4. Savethedataﬁle. Iftheselectedﬁlenamealreadyexists,aconﬁrmationdialog appears that allows

youtocancelt

rd to enter a new ﬁle name. The application appends a .mat extension to the ﬁle name.

he operation.

Recalling a Saved Data File

To recall the acquisition data from saved data ﬁles, follow these steps:

1. Select File > Recall Data to open the Recall dialog box.

2. In the Recall dialog box, select the directory from which to recall the data ﬁle.

3. Select a data ﬁle name, and then select Open.

CAUTION. Do not manually edit setup ﬁles. If you try to recall a setup ﬁle that was manuallyedited, the recall operation fails.

80SJNB Printable Application Help 69

Page 78

Operating basics About Working with Plots

About Working with Plots

You can display plots in a variety of layouts using the tool bar. One, two, or four plots can be displayed

Plot t

using the plo changes to a summary table of data. To remove the plots entirely from the display, select the Show

Numeric Results button

If the plots have been removed from the display, redisplay the plots by either selecting one of the plot display buttons or click the tab of the data table.

t display buttons

on the tool bar.

in the toolbar. When displaying plots, the results data table

See also:

Plot Type Deﬁnitions (see page 70)

Functions in Plot Windows (see page 72)

About Exporting Plot Files (see page 72)

Selecting and Viewing Plots (see page 71)

ype deﬁnitions

ypes are divided into the following categories:

Plot t

Jitter: See Jitter Plots (see page 76) for a list of the types of jitter plots and their descriptions.

Noise: See Noise Plots (see page 79) for a list of plot types and descriptions.

Eyes: See Eye Plots (see page 77) for a list of plot types and descriptions.

Patterns: See Pattern Plots (see page 80) for a list of plot types and descriptions.

SSC: See SSC Plot (see page 80) for a description.

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Operating basics Selecting and viewing plots

Selecting and viewing plots

To select and view a plot, follow these steps:

1. Select one of the plot views

2. For each plot window, select a type of plot to display. Each plot display is based on the current analysis

results. Plots are updated as new results are acquired.

To sel ect a p you can right-click anywhere on the existing plot display.) From the drop-down menu, use the Plot menu to select a plot from the plot categories (Jitter, Noise, Eyes, Patterns, SSC).

lot type for display in the plot window, click

, (single plot, two plots, or four plots).

on the tab of the plot window. (Alternatively,

When the target signal has a PAM4 coding scheme, plots will include the relevant information for each of the three stacked eyes. The plots are color coded: yellow for eye0, green for eye1, and red for eye2.

lso:

See a

About Exporting Plot Files (see page 72)

80SJNB Printable Application Help 71

Page 80

Operating basics Examining plots

Examining plots

You can examine plots in greater detail by either double-clicking in the plot window or selecting Examine from the drop-down list in the plot window. Either of these actions launches a MATLAB plot window which provid

See also:

MATLAB User Interface (see page 28)

es advanced tools to examine graphical displays of data.

About exporting plot ﬁles

There are two ways to export plot information from the 80SJNB application for use in other applications:

You can export the numerical data that is represented in the plot ﬁgure. This may be useful for performing additional data pr

You can create an image ﬁle that captures the current plot view. This is a useful way to document your results.

The application offers the following choices from the drop-down list (right-mouse click over the selected plot).

Plot lets you select a different plot to display in the window. The window displays the new plot based on the acquired data.

ocessing.

Examine opens a MATLAB plot window which provides additional tools to more closely examine plot characteristics.

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Operating basics Copying plot images

Copy Image saves the contents of the plot window as an image ﬁle.

Export saves the numerical values from the plot window in text or MATLAB format.

NOTE. Export plot functions are disabled whenever the application is actively sequencing.

See also:

Exporting Raw Plot Data (see page 74)

Exporting Plot Images (see page 73)

File Name Extensions (see page 17)

Copying plot images

You can copy the plot image displayed in any one of the plot windows. The copy is placed in the Windows clipboard so you can paste the image into other Windows programs. This is convenient for creating reports and engineering records to share with others.

To create an image ﬁle of a plot, follow these steps:

1. Tap the the instrument, right-click anywhere within the plot window of the plot youintendtocopy.)

2. Select Copy Image from the drop-down list. This copies the image to the Windows clipboard.

3. Open your destination program (such as WordPad or Paint) and paste the image into the application.

ee also:

Exporting Raw Plot Data (see page 74)

area of the plot window of the plot that you want to copy. (If using a mouse attached to

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Page 82

Operating basics Exporting raw data

Exporting raw data

The 80SJNB provides the following methods to export raw data:

Export Waveform. Accessed from the File menu, exports the underlying acquired waveform and correlated pattern data used for processing.

Export Results. Accessed from the File menu, exports the measurement results to a .csv text ﬁle that canbeopenedinaspreadsheettool.

Export. Accessed from the plot window, exports the data used to create the plot image. This method allows access to any node along the signal path.

Export Wa

To export the waveform data used for processing, follow these steps:

1. Select File > Export Waveform > Correlated or File > Export Waveform > Acquired:

The Correlated waveform is the result of ﬁltering the Acquired Waveform to eliminate uncorrelated components (such as random and periodic jitter and noise).

The Acquired waveform contains the raw acquired pattern before any processing is done on it. (The only processing on the raw data is interpolation for NULL points.)

2. Use the Export Waveform dialog box to specify the ﬁle name and path. The ﬁle name default is “Correlated” or “Acquired” (depending on the selection), with the default ﬁle location at Wi

veform data

ndows/Documents. Enter a new ﬁle name and/or directory location as needed.

3. Use the drop-down Save as type list to select the ﬁle type. The choices are:

Comma Separated Values (.csv): ASCII text that can be loaded into a spreadsheet. Thisisthe default selection.

MATLAB (.mat): Binary data in the native MATLAB 7.0 format.

4. Click Save.

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Operating basics Exporting raw data

TIP. Binary ﬁles typically use about 40% more d isk space than .csv ﬁles.

Export result

1. To export the measur

2. Select File > Export Resu

3. Use the Export Results dialog b

ement results to a .csv format text ﬁle, follow these steps:

lts.

ox to set the ﬁle name and path. The ﬁle name default is “Results,”

with the default ﬁle location at Documents. Enter a new ﬁle name and/or directory location as needed.

4. Click Save.

All numeric results are exported. The following table shows some PAM4 numeric results as shown in a spreadsheet.

.. .

Decision Threshold 0.1297174 –0.006247496 0.1474331 V

RJ(RMS)

RJ(h)(RMS)

RJ(v)(RMS)

DJ 2.83E-11 3.17E-11 3.78E-11

DDJ 1.83E-11 2.78E-11 2.18E-11

DCD .. .

xxx

3.71E-13 3.72E-13 3.71E-13

3.64E-13 3.63E-13 3.65E-13

7.24E-14 7.44E-14 6.92E-14

9.50E-12 9.94E-13 1.53E-11

Export graph (plot) data

To export the numeric data used to create a speciﬁc plot, follow these steps:

1. Touc h the

area of the plot window of the plot you want to export. (If using a mouse attached to

the instrument, right-click anywhere within the plot window that you want to export.)

2. Select Export from the drop-down menu.

3. Use the Export Graph dialog box to specify the ﬁle name and path. The ﬁle name default is “Graph,”

with the default ﬁle location at Windows/Documents. Enter a new ﬁle name and/or storage location as needed.

4. Select the ﬁle type from the Save as type. The choices are:

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Page 84

Operating basics Jitter plots

Comma Separated Values (.csv): ASCII text that can be loaded into a spreadsheet. This is the default format.

MATLAB (.mat): Binary data in the native MATLAB 7.0 format.

Change in exp

orted plot data with release 4.X. When exporting a .CSV ﬁle from the context menu of a

noise graph depicting RN PDF or RN*PN PDF, 80SJNB V4.X writes the columns in a different order than was don in prior versions.

For all NRZ noise graphs, the data is exported in two columns:

Column 1: v

oltage at which the noise was measured

Column 2: probability of noise at the given voltage in the eye

Prior versions of 80SJNB (V3.X and earlier) swap these two columns when exporte the plot data.

For PAM4 plots, noise graphs are exported in four columns:

Column 1: voltage at which the noise was measured

Column 2: probability of noise at the given voltage in eye 0

Column

3: probability of noise at the given voltage in eye 1

Column 4: probability of noise at the given voltage in eye 2

See also:

ing Plot Images

Copy

(see page 73)

Jitter plots

Jitter plots Description

vs Bit

DDJ

DDPWS vs Bit

DDJ PDF

DDJ Spectrum

RJ PDF

Data Dependent Jitter versus Bit displays the deviation of edge crossings at the user-speciﬁed Decision Threshold for each bit of the entire pattern. The pattern itself

shown in the background for cross reference. If the pattern is very long, the bits

is are visible only when opening the graph with Examine.

Data Dependent Pulse Width Shrinkage versus Bit displays the pulse width shrinkage for each isolated one and zero in the pattern.

Data Dependent Jitter Probability Density Function is the histogram of the data pattern correlated jitter, including Duty Cycle Distortion. The PDF is composed of the crossing deviations at the user speciﬁed Decision Threshold of all edges of the data pattern.

The Data Dependent Jitter Spectrum is the result of the time domain to frequency domain transformation of the series of crossing deviations of data pattern edges at the user speciﬁed Decision Threshold.

Random Jitter Probability Density Function shows the Gaussian distribution of the random, unbounded, uncorrelated jitter component. It is computed from data acquired on a single edge of the bit stream.

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Operating basics Eye plots

Jitter plots Description

PJ PDF

RJ*PJ Spectrum

RJ*PJ PDF Random Jitter and Periodic Jitter Probability Density Function is the histogram of the

DJ PDF

TJ PDF Total Jit

BER Bathtub

Q Bathtub The Q-scaled curve is a linearized scale version of the BER Bathtub curve. It

xxx

The zoom feature defaults to horizontal zoom only.

Periodic Jitter Probability Density Function represents the histogram of the uncorrelated

, bounded, periodic jitter component. It is computed by spectral

separation of the jitter data acquired on a single edge of the bit stream.

Random and Periodic Jitter Spectrum represents the spectral distribution of the uncorrelated jitter acquired on a single edge. The spurs represent the periodic jitter spectral lin

es, and the rest of the evenly distributed spectral lines compose the

random jitter spectrum.

uncorrelated jitter data acquired on a single edge of the pattern.

Deterministic Jitter Probability Density Function shows the distribution of the bounded jitter com

ponent. The histogram is computed by convolving the DDJ PDF with the

PJ PDF.

ter Probability Density Function represents the computed histogram derived from all jitter components, correlated and uncorrelated, bounded and unbounded. The convolution of DJ PDF and RJ PDF yields the Total Jitter histogram.

The BER Bathtub curve is computed as a horizontal slice of the 3-dimensional BER Eye at th

e Decision Threshold. It represents the extrapolated total jitter and horizontal

eye opening limits at projected bit error rates.

represents the extrapolated total jitter and horizontal eye opening limits at projected

or rates.

bit err

Eye plots

Eye plots Description

Correlated Eye

PDF Eyes

The Correlated Eye is a color graded eye pattern built by folding the correlated pattern at clock rates. The correlated pattern is computed from the acquired full length data pattern by ﬁltering out the uncorrelated components.

PDF Eye plots can be computed at various stages of the signal path emulator when using the 80SJNB Advanced version. When using the Essentials version of the 80SJNB, all PDF Eye plots are identical.

If a signal path component is not inserted into the signal path, the PDF Eye plot for the output of the component is identical to the upstream PDF Eye plot. For example, if computing the PDF Eye plot for the output of the Channel function, but the Channel function is not inserted into the signal path, the PDF Eye plot will be identical to the PDF Eye plot of the output of the Filter function.

80SJNB Printable Application Help 77

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Operating basics Eye plots

Eye plots Description

SP In The SP In PDF Eye is a color graded Probability Density Function representing the eye pattern at

the transmiss Eye with uncorrelated jitter and noise probability distributions.

SP Filter

The SP Filter PDF Eye is a color graded Probability Density Function representing the eye pattern at the output of the ﬁlter if the ﬁlter function is inserted in the signal path. It is constructed from the convolution

SP Channel

The SP Chann pattern at the output of the channel emulator if the Channel function is inserted in the signal path. It is constructed from the convolution of the Correlated Eye with uncorrelated jitter and noise proba

The PDF Eye is a color graded Probability Density Function representing the eye pattern at the

SP Receive PDF Eye

output of t of the link. It is constructed from the convolution of the Correlated Eye with uncorrelated jitter and noise probability distributions.

This sele

BER Eye

The BER Eye is a three-dimensional color graded map representing the predicted bit error rates at all decis

QEye

The Q Eye all decision thresholds and sampling phases in the unit bit interval with a linearized Q-scale, rather than the BER logarithmic scale.

BER Contour

The BER Contours show the boundaries of the eye opening at the projected bit error levels.

TDECQ Eye The plot is a three-dimensional color graded map of the equalized eye diagram used for the

compu slices on which the histograms are assessed.

xxx

ot is computed at the end of the signal path, regardless of using the 80SJNB Advanced or Essentials version.

Eye pl Tthe 80SJNB Advanced version (with Signal Path emulator) provides PDF Eye plots at the various stages (functions) of the emulator. If the function

is not inserted, the PDF Eye plot is identical to the upstream plot.

ion side of the signal path. It is constructed from the convolution of the Correlated

of the Correlated Eye with uncorrelated jitter and noise probability distributions.

el PDF Eye is a color graded Probability Density Function representing the eye

bility distributions.

he Equalizer if the Equalizer function is inserted in the signal path at the receiver side

ction was displayed as PDF Eye in 80SJNB application versions before version 2.1.

ion thresholds and sampling phases in the unit bit interval.

is a three-dimensional color graded map representing the predicted bit error rates at

tation of TDECQ . When opened in Matlab (double click on the plot), it shows the vertical

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Operating basics Noise plots

Noise plots

Noise plots Description

DDN vs Bit

Data Dependen speciﬁed Sampling Phase through the entire pattern. The pattern itself is shown in the background for cross reference. If the pattern is very long, the pattern bits are visible only

RN*PN PDF Random and Pe

uncorrelated noise distributionondataacquiredonasingleﬂat spot of logic level 1 of the bit stream.

RN PDF

Random Noise Probability Density Function shows the Gaussian distribution of the random acquired on a single ﬂat spot of logic level 1 of the bit stream.

PN PDF

Periodic Noise Probability Density Func tion represents the histogram of the uncorrelated, bounded, periodic noise component. It is computed by spectral separati data stream.

DN PDF

Deterministic Noise Probability Density Function shows the distribution of the bounded noise component. The histogram is computed by convolving the DDN PDF with the

DDN PDF

Data De pattern correlated noise distribution on both logic levels 1 and 0. It includes the data levels at all user speciﬁed unit bit interval Sampling Phase.

TN PDF Total Noise P robability Density Function represents the computed histogram derived

from all noise components, correlated and uncorrelated, bounded and unbounded.

nvolution of DN PDF and RN PDF yields the Total Noise histogram.

The co

RN*PN

Spectrum

m and Periodic Noise Spectrum represents the spectral distribution of the

Rando uncorrelated noise acquired on a single ﬂat spot of logic level 1. The spurs represent the periodic noise spectral lines, and the rest of the evenly distributed spectral lines

ose the random noise spectrum.

comp

DDN

Spectrum

Data Dependent Noise Spectrum is the result of the time domain to frequency

The domain transformation of the series of level samples taken on all bits at the user speciﬁed Sampling Phase of the unit bit interval.

BER Bathtub

The BER Bathtub curve is computed as a vertical slice of the 3-dimensional BER Eye

the user speciﬁed unit bit interval Sampling Phase. It represents the extrapolated

at total noise and vertical eye opening limits at projected bit error rates.

Q Bathtub The Q-scaled curve is a linearized scale version of the BER Bathtub curves. It

represents the extrapolated total noise and vertical eye opening limits at projected

it error rates.

xxx

The zoom feature defaults to horizontal zoom only.

t Noise versus Bit displays the data levels sampled at the user

when opening the graph with Examine.

riodic Noise Probability Density Function is the histogram of the

, unbounded, uncorrelated noise component. It is computed from data

on of the noise data acquired on a single ﬂat spot of logic level 1 of the

PN PDF.

pendent Noise Probability Density Function is the histogram of the data

80SJNB Printable Application Help 79

Page 88

Operating basics Pattern plots

Pattern plots

Pattern plots can be computed at various stages of the signal path emulator when using the 80SJNB Advanced version. When using the Essentials version of the 80SJNB, all Pattern plots are identical.

If a signal path component is not inserted into the signal path, the plot for the output of the component is identical to the upstream plot. For example, if computing the pattern plot for the output of the Channel function, b the pattern plot of the output of the Filter function.

Pattern plots Description

SP_In

SP_Filter

SP_Channel

SP_Equalizer

xxx

The zoom feature defaults to horizontal zoom only.

ut the Channel function is not inserted into the signal path, the pattern plot will be identical to

The Signal Path Input signal plots the correlated pattern at the transmission side of the Signal Path, the input to the simulated serial link. The correlated pattern results when the a cquired pattern is ﬁltered for the removal of the uncorrelated jitter and noise components. For closer examination of the pattern, use Examine which provides pan and zoom capabilities, and data cursors.

The Signal Path Filter output plots the correlated pattern at the output of Filter, if the Filter function is inserted in the signal path. The selected Filter ﬁle determines the effects of the Filter function on the waveform. If the Filter function is not inserted in the signal path, The SP_Filter displays the upstream waveform, in this case SP_In.

The Signal Path Channel output plots the correlated pattern at the output of the Channel emulator if the Channel function is inserted in the signal path. The selected S-parameter or time domain waveform set determines the attributes of the signal at the output of Channel. If the Channel function is not inserted in the signal path, SP_Channel displays the upstream waveform which could be the SP_Filter or SP_In function of signal path conﬁguration.

The Signal Path Equalizer output plots the correlated pattern at the output of the Equalizer if the Equalizer function is inserted in the signal path at the receiver side of the data link. The conﬁguration of tap numbers and tap values determines the attributes of the equalizer and shapes the signal at the output. If the Equalizer function is not inserted, SP_Equalizer plot displays the upstream signal which could be any of the previous patterns, depending on the signal path conﬁguration.

SSC

plot

Cplot

CProﬁle

scription

e Spread Spectrum Clocking proﬁle displays the function used for modulating

Th the serial link clock frequency. If the “SSC is present” check box is checked in the Acquisition setup dialog, the proﬁle plot is displayed.

xxx

The zoom feature defaults to horizontal zoom only.

80 80SJNB Printable Application Help

Page 89

Operating basics Working with numeric results

Working with numeric results

After an analysis is complete, you can display the results as numeric data in either a summary or detailed (full) table. Use the View menu in the ﬁle menu bar to select how to display the data. A summary of data allows room t

In both the summary and detailed views, the numeric panel has three or six tabs depending on the Coding (NRZ or PAM4

o display the plots while the full results replaces the plot display entirely.

The summary selections list the noise and jitter measurements but not the breakdown of the measurements. The results tabs display relevant jitter or mask test results.

Selected eye tab detail tables show more detail, as shown in the following:

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Operating basics Working with numeric results

Eye tabs (both NRZ and PAM4)

Mask tabs (both NRZ and PAM4)

Global tab for NRZ

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Operating basics Working with numeric results

Global tab for PAM4

Rise/Fall tab (PAM4 only)

NOTE. If it happens that the speciﬁed reference levels are not crossed for at least one transition, the only statistic reported is the minimum of the measurements for that transition.

You can easily switch between summary and detailed numeric displays by clicking the numeric results

button

Click on a results tab to display the results. The active tab is indicated by magniﬁed label text.

NRZ results tabs

and the plot window buttons .

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Operating basics Working with numeric results

PAM 4 results tabs

To hide the summary table and provide more room for the plot displays, click the displayed tab. Click the tab again to show the summary data table.

Here you can see that the plot windows ﬁll the entire screen and the numeric result tabs are at the bottom of the screen.

lots and results tabs

NRZ p

84 80SJNB Printable Application Help

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Operating basics Working with numeric results

PAM4 plots and results tabs

TDECQ Eye plot

See also:

Working with Plots (see page 70)

Noise Measurement Deﬁnitions (see page 63)

80SJNB Printable Application Help 85

Page 94

Operating basics An application example

Jitter Measurement Deﬁnitions (see page 62)

SSC Modulation Measurement Deﬁnitions (see page 63)

An application example

Thefollowingexampleusesthe80SJNBapplication on an optical signal for fast analysis of BER, Jitter, and Noise. This simpliﬁed application example shows how to conﬁgure and use the application. This may help you when setting up your own test situation.

Requirements:

DSA8300 oscilloscope

80SJNB software

ADVTRIG

Optical module with clock recovery. The following example uses the 80C11-CR4 Optical Sampling Module

SMA cables

Advanced Trigger Option installed

Set up the oscilloscope

1. Insta

2. Turn

3. Push the Default Setup front panel button.

4. Select Channel 1.

5. Push the SETUP DIALOGS button.

6. Click the Horz tab.

7. Set the Horizontal scale to 5ns.

8.C

ll the modules and make the signal connections (the example assumes using channel 1 as the

signal source).

on the instrument and wait for instrument and application startup to complete.

lick the Mode/Trigger tab.

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9. Verify that Trigger Source is set to Clock and select C1 Clock Recovery as the clock source.

10. Click th

11. Click the Pattern Sync/FrameScan Setup button.

12. Enter the Data Rate parameter (for example, 9.8 Gbps).

13. Set the Pattern Length parameter (for example, 127 bits).

e Pattern button in the Scope Mode (Clock Trigger Source) area.

14. Click Close.

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NOTE. You should now have a stable signal display on the DSA8300. If not, recheck all settings, signal source, and connections. The 80SJNB application requires a stable signal to acquire data for accurate measurements

Set up the 80SJNB application

1. Click Applications > 80SJNB in the DSA8300 menu to start the 80SJNB application.

You can also use the Windows 80SJNB desktop shortcut or the Windows Start menu Start > Programs >

Tektronix Applications > 80SJNB > 80SJNB to start the 80SJNB application.

1. Wait for the 80SJNB application to ﬁnish loading.

2. Click the Acquisition button (

3. Most of the conﬁguration settings are already ﬁlled in, as the 80SJNB application acquired the values

from the oscilloscope conﬁguration. If not, click the AutoSync to Selected Waveform button to sync the Source, Data Pattern, and Pattern Sync settings to the oscilloscope.

Since this is an optical signal and we’re using the clock recovery signal, you’ll need to select the optical signal ﬁlter and select the clock recovery settings.

The setup in this example does not include a Phase Reference module, so this ﬁeld is grayed out.

) to open the acquisition dialog box.

Click OK to apply the settings and close the dialog box.

4. Click

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to start the acquisition and processing cycle.

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While the cycle is running, you’ll see the sequence of events displayed at the bottom of the application display. When the cycle is complete, the application displays the message “Analysis Complete.”

5. Once the cycle is complete, you’ll see the displayed results. The example below shows a four plot display with the summary table of the numerical results.

Working with the results

1. Click to minimize the plot displays and show the detailed results table.

2. Redisplay the plot (or plots) by selecting one of the plot display buttons .

Click the JNB Results tab to minimize the detailed list to a summary list.

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3. With the plots now redisplayed, click the Conﬁgure Plot icon ( ) on the plot tab to display a drop-down menu for that plot. The menu provides several functions, one of which is to select a different typ

You can select any plot type. The plot is displayed based on the data based on the results of the last processing cycle.

e of plot to display in that window.

4. To further examine a plot, you can display any plot in a MATLAB window, providing you with more

tools to work with the data. Click the Conﬁgure Plot (

The plo

MATLAB provides multiple capabilities to display and annotate the plot diagrams, including:

Thefollowingﬁgureshowsa3DBEREyeplotusingtherotatefunction.

t opens in a new window to provide further data analysis and visualization of the plot displays.

Pan and Zoom

2D and 3D visualization

Rotation

Data Cursors

or enhancements

Col

) icon and choose Examine.

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Close the window to return to the 80SJNB display.

This is the end of the example. You can continue on by acquiring new data, displaying various types of plots, and examine the plots with the various tools available.

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92 80SJNB Printable Application Help

Tektronix 80SJNB Primary User

Specifications and Main Features

Frequently Asked Questions

User Manual