User Manual
TDSCEM1
Communications Eye-Diagram Measurements
Application
071-0606-00
This document supports software version 1.0.0
and above.
Warning
The servicing instructions are for use by
qualified personnel only. To avoid personal
injury, do not perform any servicing unless you
are qualified to do so. Refer to all safety
summaries prior to performing service.
Copyright © T ektronix, Inc. All rights reserved. Licensed software products are owned by Tektronix or its suppliers and
are protected by United States copyright laws and international treaty provisions.
Use, duplication, or disclosure by the Government is subject to restrictions as set forth in subparagraph (c)(1)(ii) of the
Rights in T echnical Data and Computer Software clause at DFARS 252.227-7013, or subparagraphs (c)(1) and (2) of the
Commercial Computer Software – Restricted Rights clause at F AR 52.227-19, as applicable.
T ektronix products are covered by U.S. and foreign patents, issued and pending. Information in this publication supercedes
that in all previously published material. Specifications and price change privileges reserved.
Printed in the U.S.A.
T ektronix, Inc., P.O. Box 1000, Wilsonville, OR 97070–1000
TEKTRONIX and TEK are registered trademarks of T ektronix, Inc.
WARRANTY
T ektronix warrants that the media on which this software product is furnished and the encoding of the programs on the media
will be free from defects in materials and workmanship for a period of three (3) months from the date of shipment. If a
medium or encoding proves defective during the warranty period, T ektronix will provide a replacement in exchange for the
defective medium. Except as to the media on which this software product is furnished, this software product is provided “as
is” without warranty of any kind, either express or implied. T ektronix does not warrant that the functions contained in this
software product will meet Customer’s requirements or that the operation of the programs will be uninterrupted or error-free.
In order to obtain service under this warranty, Customer must notify Tektronix of the defect before the expiration of the
warranty period. If T ektronix is unable to provide a replacement that is free from defects in materials and workmanship
within a reasonable time thereafter, Customer may terminate the license for this software product and return this software
product and any associated materials for credit or refund.
THIS WARRANTY IS GIVEN BY TEKTRONIX IN LIEU OF ANY OTHER WARRANTIES, EXPRESS OR
IMPLIED. TEKTRONIX AND ITS VENDORS DISCLAIM ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. TEKTRONIX’ RESPONSIBILITY TO
REPLACE DEFECTIVE MEDIA OR REFUND CUSTOMER’S PAYMENT IS THE SOLE AND EXCLUSIVE
REMEDY PROVIDED TO THE CUSTOMER FOR BREACH OF THIS WARRANTY. TEKTRONIX AND ITS
VENDORS WILL NOT BE LIABLE FOR ANY INDIRECT , SPECIAL, INCIDENTAL, OR CONSEQUENTIAL
DAMAGES IRRESPECTIVE OF WHETHER TEKTRONIX OR THE VENDOR HAS ADVANCE NOTICE OF
THE POSSIBILITY OF SUCH DAMAGES.
Table of Contents
Getting Started
Operating Basics
Related Documentation vii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Conventions vii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Contacting T ektronix viii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Product Description 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Compatibility 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Requirements and Restrictions 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Updates Through a Web Browser 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Accessories 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installing the Application 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Connecting to a System Under T est 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating Basics 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Application Menu Structure 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Main and Side Menus 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Common Menu Items 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Utility Menus 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Using Basic Oscilloscope Functions 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Using Local Help 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Returning to the Application 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
W arning Messages 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuring the Display 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting Up the Application 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Standard Menu 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Measurement Setup 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Measurement Options 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Display Results Setup 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
T aking Measurements 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Saving the Results to a Data Log File 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Importing a Data Log File into a Personal Computer 12. . . . . . . . . . . . . . . . . . . . .
Viewing Data 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Saving and Recalling Setups 14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Saving a Setup 14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Recalling a Setup 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Exiting the Application 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tutorial 17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Connecting to a Communications Signal 17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting Up the Oscilloscope 17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Starting the Application 18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
T aking Measurements 19. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Saving the Results to a Data Log File 24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Viewing the Results.csv File (Data Log) 26. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
i
Table of Contents
Reference
Appendices
Stopping the Tutorial 26. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Returning to the Tutorial 26. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
GPIB Program Example 27. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Menu Structure 33. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Parameters Reference 35. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Standard Menu 35. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Measure Menu 35. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Measure Options Menu 36. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Logging Menu 36. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Control Menu 37. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Utility Menu 37. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Appendix A: Measurement Algorithms 39. . . . . . . . . . . . . . . . . . . . . . . .
Oscilloscope Setup Guidelines 39. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
T est Methodology 39. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Measurements 39. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Appendix B: GPIB Command Syntax 43. . . . . . . . . . . . . . . . . . . . . . . . . .
VARIABLE:VALUE TDS COMMAND 44. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Description 44. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Syntax 44. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Arguments and Returns 44. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Index
ii
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
List of Figures
Table of Contents
Figure 1: TDSCEM1 Communication Eye-Diagram Measurements
Application 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 2: Connecting to the SUT 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 3: Returning to the application 7. . . . . . . . . . . . . . . . . . . . . . . . .
Figure 4: Example of a mask pattern with an eye-diagram, the Results
readout and a .csv file (data log) 13. . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 5: Starting the application 18. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 6: TDSCEM1 application initial display 19. . . . . . . . . . . . . . . . . .
Figure 7: OC1/STM0 standard mask pattern selected 20. . . . . . . . . . . .
Figure 8: An OC1/STM0 eye-diagram, and Results readout 21. . . . . . .
Figure 9: Measure menu, page 1 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 10: Measure menu, page 2 22. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 11: Measure menu, page 3 22. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 12: Measure menu, page 4 23. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 13: Results readout for all measurements 23. . . . . . . . . . . . . . . . .
Figure 14: Logging setup menu 24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 15: Path to the RESULTS.CSV file 25. . . . . . . . . . . . . . . . . . . . . .
Figure 16: Copying the RESULTS.CSV file to a floppy disk 25. . . . . . .
Figure 17: Data in a Results.csv file viewed in a spreadsheet
program 26. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 18: Application-specific menu structure 33. . . . . . . . . . . . . . . . . .
Figure 19: Control and Utility menu structures 34. . . . . . . . . . . . . . . . . .
Figure 20: Eye-diagram and mask pattern values 40. . . . . . . . . . . . . . . .
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
iii
Table of Contents
List of Tables
Table 1: Common menu items 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 2: Utility menus 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 3: Display options 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 4: Mask pattern selections and communications standard
documents 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 5: Measurements 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 6: Measurement Options 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 7: Control menu items 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 8: Logging menu selections 12. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 9: Measure menu parameters 35. . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 10: Measure Options menu parameters 36. . . . . . . . . . . . . . . . . . .
Table 11: Logging menu parameters 36. . . . . . . . . . . . . . . . . . . . . . . . . .
Table 12: Control menu parameters 37. . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 13: Utility menus and parameters 37. . . . . . . . . . . . . . . . . . . . . . .
Table 14: Measurements and calculations 41. . . . . . . . . . . . . . . . . . . . . .
Table 15: VARIABLE:VALUE TDS COMMAND arguments and
queries 44. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 16: Measurement results queries 46. . . . . . . . . . . . . . . . . . . . . . . .
iv
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
General Safety Summary
Review the following safety precautions to avoid injury and prevent damage to
this product or any products connected to it. To avoid potential hazards, use this
product only as specified.
Only qualified personnel should perform service procedures.
While using this product, you may need to access other parts of the system. Read
the General Safety Summary in other system manuals for warnings and cautions
related to operating the system.
Connect and Disconnect Properly . Connect the probe output to the measurement
instrument before connecting the probe to the circuit under test. Disconnect the
probe input and the probe ground from the circuit under test before disconnecting
the probe from the measurement instrument.
Do not apply a potential to any terminal, including the common terminal, that
exceeds the maximum rating of that terminal.
Symbols and Terms
T erms in this Manual. This term may appear in this manual:
WARNING. Warning statements identify conditions or practices that could result
in injury or loss of life.
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
v
General Safety Summary
vi
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
Preface
This manual contains operating information for the TDSCEM1 Communication
Eye-Diagram Measurements Application. The manual consists of the following
chapters:
H The chapter Getting Started briefly describes the TDSCEM1 Communication
Eye-Diagram Measurements Application, lists oscilloscope compatibility,
and provides installation instructions.
H The chapter Operating Basics covers basic operating principles of the
application and includes a tutorial that teaches you how to set up the
application to acquire a waveform, take measurements, and view the results.
To show you how to operate the application using GPIB commands, this
chapter includes a simple GPIB program.
H The chapter Reference includes a diagram of the menu structure and
descriptions of parameters.
H The appendix Measurement Algorithms contains information on measure-
ment guidelines and on how the application takes the measurements.
Related Documentation
Conventions
H The appendix GPIB Command Syntax contains a list of arguments and values
that you can use with the GPIB commands and their associated parameters.
The user manual for your oscilloscope provides general information on how to
operate the oscilloscope.
This manual uses the following conventions:
H This manual refers to the TDSCEM1 Communication Eye-Diagram
Measurements Application as the TDSCEM1 application or as the application.
H When steps require that you make a sequence of selections using front-panel
controls and menu buttons, an arrow ( ➞
front panel button and a menu, or between menus. Names that are for a main
menu or side menu item are clearly indicated: Press VERTICAL MENU ➞
Coupling (main) ➞ DC (side) ➞ Bandwidth (main) ➞ 250 MHz (side).
) marks each transition between a
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
vii
Preface
Contacting Tektronix
Product
Support
Service
Support
For other
information
To write us Tektronix, Inc.
For application-oriented questions about a Tektronix measurement product, call toll free in North America:
1-800-TEK-WIDE (1-800-835-9433 ext. 2400)
6:00 a.m. – 5:00 p.m. Pacific time
Or contact us by e-mail:
tm_app_supp@tek.com
For product support outside of North America, contact your
local Tektronix distributor or sales office.
Contact your local Tektronix distributor or sales office. Or visit
our web site for a listing of worldwide service locations.
http://www.tektronix.com
In North America:
1-800-TEK-WIDE (1-800-835-9433)
An operator will direct your call.
P.O. Box 1000
Wilsonville, OR 97070-1000
viii
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
Getting Started
Product Description
The TDSCEM1 Communication Eye-Diagram Measurements Application is a
Java-based application that enhances basic capabilities of TDS oscilloscopes.
The application displays a mask pattern behind the eye-diagram of the communication signal being acquired. This allows you to visually analyze the eye-diagram against the mask pattern. In addition, the application can display other
measurements in a numeric format, as well as saving the information to a data
log file to view on a personal computer.
Figure 1 shows an example of a standard mask pattern, the eye-diagram of an
OC1/STM0 communications signal, and the Results readout.
Figure 1: TDSCEM1 Communication Eye-Diagram Measurements Application
Compatibility
The Communication Eye-Diagram Measurements Application is compatible with
the following Tektronix oscilloscopes:
H All TDS 500D and 700D Digital Phosphor Oscilloscopes with Option 2C
(Communications Signal Analyzer package) and Option HD (hard disk
drive) or Option 2M (hard disk drive plus 8 MB record length); the TDS
oscilloscope must also have firmware version 6.4e and up
H TDS 700C Color Digitizing Oscilloscopes with Option 2C (Communica-
tions Signal Analyzer package) and Option HD (hard disk drive) or Option
2M (hard disk drive plus 8 MB record length); the TDS oscilloscope must
also be serial number B020100 and up, with firmware version 6.4e and up
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
1
Product Description
You can also use this application with Tektronix TDS Option 3C (Short-wavelength Fibre Channel Optical Reference Receiver) or TDS Option 4C (Longwavelength SONET/SDH Optical Reference Receiver).
For a current list of compatible oscilloscopes, check the Tektronix, Inc. web site,
http://www.tektronix.com/Measurement/scopes/index.html in the Software and
Drivers category.
Requirements and Restrictions
The TDS Run-Time Environment V1.1.0 and above must be installed on the
oscilloscope to operate the TDSCEM1 application.
The TDS Run-Time Environment V1.2.0 and above must be installed on the
oscilloscope to use the GPIB commands.
Updates Through a Web Browser
You can find information about this and other applications at the Tektronix, Inc.
web site, http://www.tektronix.com/Measurement/scopes/index.html in the
Software and Drivers category. Check this site for application updates that you
can download and for free applications.
To install an application update, you will need to download it from the Tektronix
ftp site to a hard disk, copy it to a blank DOS-formatted floppy disk, and then
install it on your oscilloscope.
NOTE. More information about changes to the application or installation is in a
Readme.txt file on the ftp site. You should read it before you continue.
To copy the application from a web browser, follow these steps:
1. Access the ftp site at ftp://ftp.tek.com/mbd/support/00–index.html#1.
2. Scroll through the files to the TDSCEM1 application, select the file, and
download it to your hard disk drive. If necessary, unzip the file.
3. Copy the application from the hard disk to a blank, DOS-formatted floppy
disk.
4. Follow the Installing the Application procedure on page 3.
Accessories
2
There are no standard accessories for this product.
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
Installation
The TDSCEM1 floppy disk contains the Communication Eye-Diagram Measurements Application. You can download updates, if any, from the Tektronix ftp site
through a web browser.
NOTE. To operate the TDSCEM1 application, the TDS Run-Time Environment
V1.1.0 or above must be installed on your oscilloscope. To use GPIB commands,
the TDS Run-Time Environment V1.2.0 or above must be installed.
Installing the Application
To install the application from the floppy disk to your oscilloscope, follow these
steps:
1. Power off the oscilloscope.
NOTE. Additional information about the application or installation is located in a
Readme.txt file on the floppy disk. You should insert the floppy disk into a
DOS-based personal computer and read the Readme.txt file before you continue.
If you are updating the application, the Readme.txt file on the Tektronix ftp site
supercedes the Readme.txt file on the TDSCEM1 floppy disk.
2. Insert the disk in the floppy disk drive and power on the oscilloscope.
NOTE. To verify that the TDS Run-Time Environment V1.1 or above is installed,
watch for the name to appear at the top of the display when you power on the
oscilloscope. If it does not appear, contact your local Tektronix sales office.
After performing the power-up selftest, the oscilloscope automatically begins
the installation procedure.
As the application loads from the disk, the oscilloscope displays a clock icon
to indicate that it is busy. Also, the floppy disk drive LED is on, indicating
activity. If the clock icon continues to display after the floppy disk LED has
gone out, a problem has occurred with the installation. Repeat the above
procedure. If the problem persists, contact your Tektronix representative.
When the installation is complete, an Installation Complete message
displays.
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
3
Installation
3. Remove the floppy disk and cycle the power to the oscilloscope.
Connecting to a System Under Test
You can use a P6701B or P6703B optical receiver probe to connect between your
System Under Test (SUT) and the oscilloscope.
To connect the probe between the SUT and oscilloscope, refer to Figure 2 and
follow these steps:
WARNING. To avoid electric shock, you must ensure that power is removed from
the SUT before attaching a probe to it. Do not touch exposed conductors except
with the properly rated probe tips. Refer to the probe manual for proper use.
1. Power down the SUT.
2. Connect the optical receiver probe to CH 1 of the oscilloscope.
3. Press VERTICAL MENU ➞ Probe Functions (main) ➞ Cal Probe (side).
This removes the dark level (Pdark) from the signal which allows the cursors
to read the true signal power levels.
4. Connect the optical receiver probe to a communication signal in the SUT.
TDS Oscilloscope
SUT
Optical cable
CH1
P6701B or P6703B
O/E converter probe
Optical cable
Optical attenuator
Figure 2: Connecting to the SUT
4
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
Operating Basics
Operating Basics
This section contains information on the following topics and tasks:
H Application menu structure
H Using basic oscilloscope functions
H Warning messages
H Configuring the display
H Setting up the application
H Taking measurements
H Storing the results to a data log file
H Importing the data log file into a personal computer
H Viewing the results
H Saving and recalling setups
H Exiting the application
Application Menu Structure
There are two types of menus in the application menu structure: main menus and
side menus. Some side menus contain common menu items as shown in Table 1.
Main and Side Menus
The main menu names appear in the bottom of the display and the side menu
names appear on the right side of the display. To see the complete application
menu structure, refer to Figure 18 on page 33.
When you press the front-panel button associated with a main menu, the side
menu changes. In many cases, when you press a side menu, new side menu items
appear. As an example, the next figure shows you how to access the Help
selections through the main Utility menu and the Help side menu.
Main menu Side menu Side menu item
Utility
Help
First Page
Next page
Previous page
Last Page
Quit Help
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
5
Operating Basics
Common Menu Items
Utility Menus
Table 1 lists common side menu items.
T able 1: Common menu items
Menu item Description
Cancel Cancels the message being displayed
Done Indicates that you are through making changes to that set of side menus. The
application returns to the previous menu
OK Confirms the action
Table 2 lists the Utility menus.
T able 2: Utility menus
Utility name Description
Help Accesses the online help information and views various pages
Exit Exits the application
Save/Recall Setup Accesses the save and the recall menus for application setups
Display Options Accesses other menus where you can change display settings, such as
the message box location on the display
Using Basic Oscilloscope Functions
You can use the Utility menu to access help information about the application.
You can also use other oscilloscope functions and easily return to the application.
Using Local Help
The application includes local help information about the measurements modes,
with some explanation of the individual controls.
To display the local help, follow these steps:
1. Press Utility (main) ➞ Help (side).
2. Use the side menu buttons to navigate through the help.
6
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
Operating Basics
Returning to the
Application
Warning Messages
You can easily switch between the TDSCEM1 application and other oscilloscope
functions.
To access other oscilloscope functions, press the desired front panel control. To
return to the application, push the SHIFT and then the APPLICATION frontpanel menu buttons as shown in Figure 3.
Push the SHIFT and then the APPLICATION button to return to the application.
Figure 3: Returning to the application
All eye-diagram measurements provide a warning if the input conditions on
channel 1 do not support accurate measurements. For example, the OC12
standard mask selection warns you if the signal is outside the expected rate.
Configuring the Display
You can change how dialog boxes appear on your oscilloscope, as well as the
color of waveforms. The next figure shows how to access the Display Options
menu and Table 3 lists the options with a brief description of each.
Main menu Side menu Side menu item
Utility Display Options
T able 3: Display options
Option Description
Dialog box (visibility)
Box position Select where on the display to position dialog boxes: Left, Middle, or
Select Show or Hide to make dialog boxes visible or invisible
Right
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
Dialog Box
Box Position
Box Style
Color Theme
Done
7
Operating Basics
T able 3: Display options (Cont.)
Option Description
Box style Select the style of dialog boxes to be Opaque or Transparent
Color Theme Select a set of colors for waveforms and dialog boxes. The application
Setting Up the Application
You can set up the application to take eye-diagram measurements based on a
standard mask pattern, and to display the results or save them to a data log file.
offers seven color themes
Standard Menu
The next figure shows how to access the standard mask pattern selections.
Main menu
Standard
Side menu
None
OC1/STM0 51.84 Mb/s
OC3/STM1 155.52 Mb/s
OC12/STM4 622.08 Mb/s
FC133 Optical 132.8 Mb/s
FC266 Optical 265.6 Mb/s
FC531 Optical 531.2 Mb/s
FC1063 Optical 1.0625 Gb/s
Gigabit Ethernet Optical 1.25 Gb/s
Table 4 lists the mask pattern selections and the corresponding communication
standard document to which each measurement complies.
T able 4: Mask pattern selections and communications standard documents
Standard menu selection Communication standard document
OC1/STM0 51.84 Mb/s
OC3/STM1 155.52 Mb/s
OC12/STM4 622.08 Mb/s
FC133 Optical 132.8 Mb/s
GR-253-CORE ISSUE 1, December 1994, Synchronous Optical Network (SONET) Transport
Systems: Common Generic Criteria, Bellcore
ANSI X3.230-1994 Fibre Channel - Physical and Signaling Interface (FC–PH)
FC266 Optical 265.6 Mb/s
FC531 Optical 531.2 Mb/s
FC1063 Optical 1.0625 Gb/s
Gigabit Ethernet Optical 1.25 Gb/s ANSI/IEEE 802.3 Fifth Edition 1996 – Information T echnology – Telecommunications and
Information Exchange Standard
8
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
Operating Basics
Measurement Setup
The next figure shows how to access the measurement selections and Table 5
lists the TDSCEM1 measurements with a brief description of each.
Main menu Side menu
Jitter RMS
Jitter 6Sigma
Jitter PP
Crossing %
Eye Height
Eye Width
Measure
Quality Factor
P High
P Low
Ext Ratio
Ext Ratio %
Ext Ration dB
Duty Cycle Distortion sec
Duty Cycle Distortion %
Mask Hits
T able 5: Measurements
Measurement name Description
Jitter RMS The RMS value of the edge jitter of the communication sgnal in
seconds
Jitter 6Sigma The “6 sigma” value of the edge jitter of the communication signal in
seconds
Jitter PP The peak-to-peak value of the edge jitter of the communication
signal in seconds
Crossing % The crossing point of the communication signal as a percentage of
the height of the eye-diagram
Eye Height The height of the communication signal in watts
Eye Width The height of the communication signal in seconds
Quality Factor The ratio of the size of the communication signal to the “noise” on
the signal
P High The highest power level of the communication signal in watts
P Low The lowest power level of the communication signal in watts
Ext Ratio The ratio of the top of the communication signal to its base
Ext Ratio % The ratio of the top of the communication signal to its base as a
percentage
Ext Ratio dB The ratio of the top of the communication signal to its base in dBs
Duty Cycle Distortion sec Difference between the maximum and the minimum signal crossing
times at 50% of the level
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
9
Operating Basics
T able 5: Measurements (Cont.)
Measurement name Description
Duty Cycle Distortion % Difference between the maximum and the minimum signal crossing
times as a percentage of the bit period
Mask Hits The number of mask hits
Measurement Options
The next figure shows how to access the Measurement Options menu and
Table 6 lists the measurement options with a brief description of each.
Main menu Side menu
Measure Options
Sample Size
Filter
T able 6: Measurement Options
Option name Description
Sample Size The number of records needed in the eye-diagram to determine when the
results are stable; results are more accurate with more samples
Filter Enables or disables the Bessel Thompson filter and changes the settings of
the oscilloscope accordingly
To enable the Bessel Thompson filter, press the AUTOSET front-panel button.
NOTE. Once the Bessel-Thompson filter is enabled, changing some settings on
the oscilloscope will disable it. However, the display will not update and the
filter will appear to still be enabled, even though it is not.
10
To use the Bessel Thompson filter, the TDS oscilloscope must use the following
setups:
H Only use CH 1 to acquire the communications signal
H Set all other channels to Off
H In the VERTICAL MENU, set the Deskew to 0.0 on all channels
H In the ACQUIRE MENU, set the Acquisition mode to Sample
H In the MEASURE menu, enable the Filter through the Measure (main) ➞
Masks (main) ➞ Mask Options (main) menu.
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
Operating Basics
H In the ZOOM menu, set the Zoom Mode to Off and then use the VERTICAL
SCALE knob to set the Vert Attenuation to 20, 50, or 100 mW per division
or to a specific value between 20 mW and 100 mW.
Display Results Setup
Taking Measurements
The measurement results (see Table 5 on page 9) display in a Results readout
dialog box. To view the mask pattern, eye-diagram, and the results, change the
configuration of the Results readout through the Display Options side menu.
When the measurement parameters are set up, you can acquire data from the
communications signal. To do so, follow these steps:
1. Press Control (main). Table 7 lists menu items in the Control menu.
T able 7: Control menu items
Menu item Description
Mode
Single
Free Run
Start The application starts to take measurements from the signal
Pause The application stops taking measurements and waits for a Continue
Continue When paused, the application continues taking measurements
Performs measurements on a single acquisition and stops
Repeatedly acquires the signal, and takes measurements
Stop The application stops taking measurements
2. Press Mode (side) to select Single or Free Run acquisition mode.
3. Press Start (side).
NOTE. Do not change oscilloscope settings while a measurement is being taken.
Doing so can invalidate the measurement.
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
11
Operating Basics
Saving the Results to a Data Log File
You can save the measurement results in a data log file. The next figure shows
the Logging setup menu and Table 8 lists the TDSCEM1 data log file selections
with a brief description of each.
Main menu Side menu
Logging
On/Off
Store Results In:
Clear Log File
T able 8: Logging menu selections
Data log file Description
On/Off Stores the measurement results in a .csv file that you can view later on a
personal computer
Store Results In: Allows you to name the .csv file; the extension must be .csv
Clear Log File Resets all result values to zero. You must disable the log file before you can
clear its contents
Importing a Data Log File into a Personal Computer
You can import the data log file (.csv file) into into a spreadsheet, database, or
data analysis program on your personal computer for further analysis. To do so,
follow these steps:
1. Insert a blank DOS-formatted floppy disk into the floppy disk drive of the
oscilloscope.
12
2. Copy the .csv file from the hd0: to the fd0:. Refer to the Tutorial section.
3. Insert the floppy disk into the floppy disk drive on your personal computer.
4. Copy the .csv file.
5. Open the file using a spreadsheet, database, or data analysis program.
The rows represent successful measurements. The columns represent each type
of measurement taken. Figure 4 on the next page shows an example of the .csv
file viewed in a spreadsheet program on a personal computer.
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
Viewing Data
y
Operating Basics
The application displays the selected mask pattern with the eye-diagram of the
communications signal for visual analysis, and can display the results from
selected measurements as numeric values in a Results readout. (You can also log
the data to a .csv file for viewing on a personal computer.)
Figure 4 shows an example of the various ways to view the measurement data.
Mask pattern with e
Jitter
RMS
ABCDEFGHIJKLMNO
1.95E-10 1.17E-09 1.05E-09 48.67925 2.23E-04 1.81E-08 18.92857 2.75E-04 1.00E-05 27.5 3.636364 14.3933 1.00E-09 5.184 0
1
2 2.12E-10 1.27E-09 1.10E-09 48.85496 2.23E-04 1.81E-08 20.15385 2.73E-04 1.10E-05 24.8182 4.029304 13.9476 1.10E-09 5.7024 0
3 2.04E-10 1.22E-09 1.15E-09 49.61538 2.24E-04 1.80E-08 21.66667 2.71E-04 1.10E-05 24.6364 4.059041 13.9157 1.05E-09 5.4432 0
4 1.95E-10 1.17E-09 1.05E-09 49.23664 2.23E-04 1.82E-08 20.15385 2.72E-04 1.00E-05 27.2 3.676471 14.3456 1.00E-09 5.184 0
A .csv file viewed in a spreadsheet program on a personal computer
Jitter
6Sig
Jitter
PP
Crossing
Eye
Height
Eye
Width
e-diagram
Qual
Fact
P High P Low
Ext
Ratio
Results readout
Ext
Ratio %
Ext
Ratio dB
D Cycle
Dist sec
D Cycle
Dist %
Mask
Hits
Figure 4: Example of a mask pattern with an eye-diagram, the Results readout and a .csv file (data log)
To view parts of the mask pattern and eye-diagram that are obscured by the
Results readout, push the CLEAR MENU button. To return to the application,
push the SHIFT then the APPLICATION front-panel menu buttons.
NOTE. To view the mask pattern, eye-diagram, and the results, you can change
the configuration of the display through Utility (main) ➞ Display Options (side).
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
13
Operating Basics
The next figure shows how to make the Results readout visible or invisible.
Main menu Side menu Side menu item
Utility
NOTE. The Results readout does not have to be visible to save measurements to a
data log file. The application can save the measurement results to a data log file
while the oscilloscope displays the mask pattern and eye-diagram, and takes
measurements.
Saving and Recalling Setups
You can use the Save/Recall Setup menu to save and recall application setups.
The TDSCEM1 application Save/Recall function is totally independent of the
primary oscilloscope Save/Recall function stored in nonvolatile RAM.
Display Options
Dialog Box: On/Off
Saving a Setup
The next figure shows how to access the Save/Recall Setup menu.
Main menu Side menu Side menu item
Utility Save/Recall Setup
Recall Setup
Recall from File:
Save Setup
Save to File:
Done
NOTE. Press Utility (main) ➞ Save/Recall Setup (side) to access the menu items
that you can use to save and to recall setup files.
To save the application setup to the file displayed in the Save to File: menu item,
press Save Setup (side).
To create a new file in which to save the application setup, follow these steps:
1. Press Save to File: (side).
2. Use the direction arrows and Delete Char (side) to clear the existing file
name or part of the file name.
14
3. Use the General Purpose (GP) knob to select each character in the file name.
Press Enter Char (side) after selecting each character.
The file name can be up to eight characters long.
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
Operating Basics
4. Press OK Accept (side) to save the file name.
5. Press Save Setup (side) to store the application setup in the file just created.
6. Press Done (side).
Application setups are always saved in the APPS/TDSCEM1/TEMP directory
(accessed through the File Utilities menu) on the oscilloscope. Once you have
saved a setup, you must recall it to use it again.
Recalling a Setup
Exiting the Application
To recall the application settings from the Default setup file or from a saved
setup file, follow these steps:
1. Press Recall from File: (side) until Default or the desired setup file name
displays.
NOTE. The application always starts with the settings in the Default setup file.
2. Press Recall Setup (side).
3. Press Done (side).
To exit the application, press Utility (main) ➞ Exit (side). To confirm, press
OK (side).
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
15
Operating Basics
16
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
Tutorial
This tutorial teaches you how to setup and take measurements, and view the
results on the display or from a log file. In addition, it teaches you how to exit
the application and how to save and recall setups. Further operating information
is located in the Operating Basics section.
Before you begin the tutorial, you need to do the following tasks:
H Connect to a communication signal
H Set up the oscilloscope
H Start the application
NOTE. This tutorial uses a standard communication signal from the Tektronix
Quick Start 7 board. Your results will match those shown in this section if you
connect your TDS oscilloscope to the same signal.
Connecting to a Communications Signal
Connect an optical receiver probe between the OC1/STM0 communications
signal on the Quick Start 7 board and CH 1 on your TDS oscilloscope as
described in Connecting to a System Under Test on page 4.
Be sure to calibrate the probe and power up the Quick Start 7 board.
Setting Up the Oscilloscope
To set up the oscilloscope, follow these steps:
1. Press SETUP ➞ Recall Factory Setup (main) ➞ OK Confirm Factory Init
(side) to set the oscilloscope to the default factory settings.
2. Press the VERTICAL MENU ➞ Ch 1 Coupling Impedance (main) ➞ DC
(side) ➞ W and select 50.
3. Press WAVEFORM OFF as often as necessary to remove all waveforms
from the display.
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
17
Tutorial
Starting the Application
To perform these lessons, the TDSCEM1 application must be installed on the
oscilloscope. See Installation on page 3.
To start the application, follow these steps:
1. Press SETUP ➞ Select Application (main).
2. Use the general purpose (GP) knob to select hd0:, and press SELECT.
See Figure 5.
18
Figure 5: Starting the application
3. Use the GP knob to select the TDSCEM1.APP file and press Activate
Application (side).
The application starts up and displays as shown in Figure 6.
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
Tutorial
Taking Measurements
Figure 6: TDSCEM1 application initial display
In this lesson, you will learn how to use the TDSCEM1 application to take
measurements from an eye-diagram and its corresponding standard mask pattern.
To become familiar with communication eye-diagram measurements, follow
these steps:
1. Press Standard (main) ➞ OC1/STM0 51.84 Mb/s (side).
Figure 7 shows the Standard setup menu with the OC1/STM0 mask pattern
selected.
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
19
Tutorial
Figure 7: OC1/STM0 standard mask pattern selected
2. Press CH 1 to display the OC1/STM0 waveform.
3. To take the measurement, press Control (main) ➞ Start (side).
The Control menu (main) displays Control Sequencing while the application
is executing. When the Control menu displays Control Ready, the application has completed the calculations.
NOTE. The TDSCEM1 application properly aligns the eye-diagram of the
communications signal over the selected mask pattern.
4. Wait for the calculations to complete. Figure 8 shows the mask pattern, the
OC1/STM0 eye-diagram, and the measurement Results readout.
NOTE. By default, the Jitter 6 Sigma and Crossing measurements display.
20
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
Tutorial
Figure 8: An OC1/STM0 eye-diagram, and Results readout
5. Press Measure (main) and set all the measurements to “On.” Figures 9, 10,
11, and 12 show all the measurements selected.
Figure 9: Measure menu, page 1
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
21
Tutorial
Figure 10: Measure menu, page 2
Figure 11: Measure menu, page 3
22
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
Tutorial
Figure 12: Measure menu, page 4
6. To take the measurement, press Control (main) ➞ Start (side). Figure 13
shows the Results readout for all the measurements.
Figure 13: Results readout for all measurements
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
23
Tutorial
Saving the Results to a Data Log File
To save the measurement results to a data log file, follow these steps:
1. Press Logging (main) ➞ On (side). Figure 14 shows the Logging setup
menu.
24
Figure 14: Logging setup menu
2. To log the results to a .csv file, press Control (main) ➞ Start (side).
The “comma separated variable” file format (.csv) is compatible with many
spreadsheet, database, or data analysis programs on a personal computer.
3. After the measurement completes, press Control (main) ➞ Start (side) to log
more data to the results.csv file. Repeat this step two more times. There are
now four rows of data in the results.csv file.
4. To copy the results.csv file to a floppy disk to view on a personal computer,
follow these steps:
a. Insert a blank DOS-formatted floppy disk into the floppy disk drive on
the oscilloscope.
b. Press SAVE/RECALL SETUP ➞ File Utilities (main).
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
Path to the .csv file
Tutorial
c. Use the GP knob to highlight APP and press SELECT.
d. Use the GP knob to highlight TDSCEM1 and press SELECT.
e. Use the GP knob to highlight TEMP and press SELECT.
Figure 15 shows the RESULTS.CSV file and the path to it.
Figure 15: Path to the RESULTS.CSV file
f. Use the GP knob to highlight RESULTS.CSV and press Copy (side).
g. Use the GP knob to highlight fd0: and press Copy RESULTS.CSV to
selected directory (side). Figure 16 shows this side menu item.
Figure 16: Copying the RESULTS.CSV file to a floppy disk
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
25
Tutorial
5. Eject and remove the floppy disk from the floppy disk drive.
Viewing the Results.csv File (Data Log)
You can import the RESULTS.CSV file to a DOS-based personal computer and
then view the data log file with a spreadsheet, database, or data analysis
program. Figure 17 shows an example of how the RESULTS.CSV file might
look in a spreadsheet program on a personal computer.
Jitter
RMS
ABCDEFGHIJKLMNO
1
1.95E-10 1.17E-09 1.05E-09 48.67925 2.23E-04 1.81E-08 18.92857 2.75E-04 1.00E-05 27.5 3.636364 14.3933 1.00E-09 5.184 0
2 2.12E-10 1.27E-09 1.10E-09 48.85496 2.23E-04 1.81E-08 20.15385 2.73E-04 1.10E-05 24.8182 4.029304 13.9476 1.10E-09 5.7024 0
3 2.04E-10 1.22E-09 1.15E-09 49.61538 2.24E-04 1.80E-08 21.66667 2.71E-04 1.10E-05 24.6364 4.059041 13.9157 1.05E-09 5.4432 0
4 1.95E-10 1.17E-09 1.05E-09 49.23664 2.23E-04 1.82E-08 20.15385 2.72E-04 1.00E-05 27.2 3.676471 14.3456 1.00E-09 5.184 0
Jitter
6Sig
Jitter
PP
Crossing
Eye
Height
Eye
Width
Qual
Fact
P High P Low
Ext
Ratio
Ext
Ratio %
Ext
Ratio dB
D Cycle
Dist sec
D Cycle
Dist %
Figure 17: Data in a Results.csv file viewed in a spreadsheet program
Stopping the Tutorial
If you need more than one session to complete the tutorial lessons, you can stop
the tutorial and return to it another time. To do so, you will need to save the
oscilloscope setup and then the application setup.
To save the oscilloscope setup, refer to the user manual for your oscilloscope.
The procedure varies between models.
To save the application setup and stop your session, refer to Saving a Setup on
page 14 and to Exiting the Application on page 15.
Mask
Hits
Returning to the Tutorial
26
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
To return to the tutorial setup, you can recall the saved oscilloscope setup from
the hard disk, and then restart the application.
To recall the oscilloscope setup, refer to the user manual for your oscilloscope.
The procedure varies between models.
To recall the application setup, refer to Recalling a Setup on page 15.
GPIB Program Example
This section contains an example of a GPIB program that can execute the
TDSCEM1 application.
To execute the TDSCEM1 application with a GPIB program, the program should
comply with the following guidelines:
H Turn on the GPIB response leaders with the “HEADER OFF” command;
refer to the programmer manual for your TDS oscilloscope
H The application startup must complete before sending additional GPIB
commands to the application (see example)
H The measurements cycle must complete before data is queried (see example)
H The error variable should be checked to ensure that an error has not occurred
because of a measurement command problem
This example shows how a GPIB program might execute the application to do
the following tasks:
H Start the application
H Select a mask pattern
H Enable a measurement
H Set the sample size
H Enable the logger
H Take a measurement
H Check for an error
H Exit the application
Refer to Appendix B: GPIB Command Syntax for a complete list of the GPIB
command syntax with the arguments, variables and variable values.
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
27
GPIB Program Example
/* C Example Program: TDSCEM1 GPIB control */
/* ===========================================================
* This sample program is for the Tektronix Java–based TDSCEM1
* Communication Eye–Diagram Measurements Application
*/
#include <string.h>
#include <stdio.h>
#include <sys/timeb.h>
#include <windows.h>
#include ”C:\Program Files\NationalInstruments\GPIB\NI488\LangInt\C\decl–32.h”
int start_application(/* in */ int scope);
int do_single_measurement(/* in */ int scope);
void main (void)
{
char read_buffer [100] = ””;
char write_buffer [100] = ””;
int scope;
int status;
/*
* Open session with for IBIC
*/
scope = ibfind (”DEV2”);
status = ibpad (scope, 1);
status = ibtmo (scope, T10s);
/*
* Start Application
*/
if (start_application(scope)){
printf (”Application is started up!\n”);
/*
* Select a mask standard
*/
sprintf (write_buffer, ”%s”, ”Variable:value \”maskStandard\”,\”OC1\””);
status = ibwrt (scope, write_buffer, strlen (write_buffer));
/*
* Turn on Jitter RMS measurement
*/
sprintf (write_buffer, ”%s”, ”Variable:value \”jitterRmsState\”,\”On\””);
status = ibwrt (scope, write_buffer, strlen (write_buffer));
28
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
GPIB Program Example
/*
* Set sample size to 32
*/
sprintf (write_buffer, ”%s”, ”Variable:value \”sampleSize\”,\”32\””);
status = ibwrt (scope, write_buffer, strlen (write_buffer));
/*
* Turn on the logger
*/
sprintf (write_buffer, ”%s”, ”Variable:value \”loggerState\”,\”On\””);
status = ibwrt (scope, write_buffer, strlen (write_buffer));
/*
* Do a single measurement
*/
if (do_single_measurement(scope)){
/*
* Query measurement result
*/
sprintf (write_buffer, ”%s”, ”Variable:value? \”jitterRMS\””);
status = ibwrt (scope, write_buffer, strlen (write_buffer));
status = ibrd (scope, read_buffer, sizeof (read_buffer));
if (ibcnt != 3) { /* It’s not an empty string */
read_buffer [ibcnt] = 0; /* Get rid of extra characters */
printf (”jitterRMS? %s\n”, read_buffer);
}
else{
printf (”*** Computation Error ***\n”);
}
}
else{
printf (”*** Measurement fails ***\n”);
}
}
else{
printf (”*** Fails to start Application ***\n”);
return;
}
/*
* Exit application
*/
printf (”Exit application!\n”);
sprintf (write_buffer, ”%s”, ”Variable:value \”application\”,\”exit\””);
status = ibwrt (scope, write_buffer, strlen (write_buffer));
/*
* Program Ending
*/
printf (”Program Terminating Normally\n\n”);
}
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
29
GPIB Program Example
/*–––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––
* Function: start_application
* Argument: scope
* Return: 1 if success, 0 otherwise
*
* This function starts the application and comfirms the complition of startup
*/
int start_application(/* in */ int scope)
{
char read_buffer [100];
char write_buffer [100];
char app_name[30] = ”\”TDSCEM1\”\n”;
int status;
int timer = 0;
int i = 0;
/*
* Start Application
*/
sprintf (write_buffer, ”%s”, ”Application:activate \”hd0:/tdscem1.app\””);
status = ibwrt (scope, write_buffer, strlen (write_buffer));
printf (”Starting application, please wait...\n”);
do{ /* Wait for application to completely start up */
timer = timer + 2;
if (timer > 30) { /* The application normally take 24 seconds to start up */
printf (”***Application start up time out***\n”);
return 0; /* Something is wrong if application does start up*/
}
sprintf (write_buffer, ”%s”, ”Variable:value? \”application\””);
status = ibwrt (scope, write_buffer, strlen (write_buffer));
status = ibrd (scope, read_buffer, sizeof (read_buffer));
read_buffer [ibcnt] = 0; /* Get rid of extra characters */
Sleep(2000);
}while (strcmp(app_name, read_buffer) != 0);
/* Application start up! */
return 1;
}
30
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
GPIB Program Example
/*–––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––
* Function: do_single_measurement
* Argument: scope
* Return: 1 if success, 0 otherwise
*
* This function does a single measurement and checks error status
*/
int do_single_measurement(/* in */ int scope)
{
char read_buffer [100];
char write_buffer [100];
char state[10] = ”\”Ready\”\n”;
int status;
int timer = 0;
int i = 0;
/*
* Start measurement
*/
printf (”Do a single measurement...\n”);
sprintf (write_buffer, ”%s”, ”Variable:value\”sequencerState\”,\”Sequencing\””);
status = ibwrt (scope, write_buffer, strlen (write_buffer));
do{
timer = timer + 2;
if (timer > 60) { /* Assumes single measurement is done in 60 seconds */
printf (”***Measurement time out***\n”);
return 0; /* Something is wrong if sequencerState does not come back
* to Ready */
}
sprintf (write_buffer, ”%s”, ”Variable:value? \”sequencerState\””);
status = ibwrt (scope, write_buffer, strlen (write_buffer));
status = ibrd (scope, read_buffer, sizeof (read_buffer));
read_buffer [ibcnt] = 0; /* Get rid of extra characters */
Sleep(2000);
}while (strcmp(state, read_buffer) != 0);
/*
* Though sequencerState Back to Ready, need to check the error variable
* to make no error occur during measurement
*/
sprintf (write_buffer, ”%s”, ”Variable:value? \”error\””);
status = ibwrt (scope, write_buffer, strlen (write_buffer));
status = ibrd (scope, read_buffer, sizeof (read_buffer));
if (ibcnt != 3){ /* error string is not empty */
read_buffer [ibcnt] = 0; /* Get rid of extra characters */
printf (”*** Error: %s ***\n”, read_buffer);
return 0;
}
return 1;
}
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
31
GPIB Program Example
32
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
Reference
Menu Structure
Figure 18 shows the relationship of the application-specific menus.
Main menu
Standard
Measure
Side menus
None
OC1/STM0 51.84 Mb/s
OC3/STM1 155.52 Mb/s
OC12/STM4 622.08 Mb/s
FC133 Optical 132.8 Mb/s
FC266 Optical 265.6 Mb/s
FC531 Optical 531.2 Mb/s
FC1063 Optical 1.0625 Gb/s
Gigabit Ethernet Optical 1.25 Gb/s
Jitter RMS
Jitter 6Sigma
Jitter PP
Crossing %
Eye Height
Eye Width
Quality Factor
P High
P Low
Ext Ratio
Ext Ratio %
Ext Ration dB
Duty Cycle Distortion sec
Duty Cycle Distortion %
Mask Hits
Measure Options
Logging
Sample Size
Filter
On/Off
Store Results In:
Clear Log File
Figure 18: Application-specific menu structure
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
33
Menu Structure
Figure 19 shows the structure of the Control and Utility menus.
Main menus Side menus, level 1
Mode Single/Free Run
Control
Utility
Start
Pause
Continue
Stop
Help
Exit
Save/Recall Setup
Display Options
Side menus, level 2
First Page
Next page
Previous page
Last Page
Quit Help
OK
Cancel
Recall Setup
Recall from File:
Save Setup
Save to File:
Done
Dialog Box
Box Position
Box Style
Color Theme
Done
Figure 19: Control and Utility menu structures
34
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
Parameters Reference
This section describes the TDSCEM1 application parameters. You should refer
to the user manual for your oscilloscope for operating details associated with
each front-panel menu button.
Refer to Appendix B: GPIB Command Syntax for a complete list of the GPIB
command syntax with the arguments, variables and variable values that
correspond to the TDSCEM1 parameters.
Standard Menu
The selections for the Standard menu are as follows:
H None, the default selection
H OC1/STM0 51.84 Mb/s
H OC3/STM1 155.52 Mb/s
H OC12/STM4 622.08 Mb/s
Measure Menu
H FC133 Optical 132.8 Mb/s
H FC266 Optical 265.6 Mb/s
H FC531 Optical 531.2 Mb/s
H FC1063 Optical 1.0625 Gb/s
H Gigabit Ethernet Optical 1.25 Gb/s
Table 9 lists the parameters for the Measure menu, the selections available, and
the default settings.
T able 9: Measure menu parameters
Parameter Selections Default setting
Jitter RMS On, Off Off
Jitter 6Sigma On, Off On
Jitter PP On, Of f Off
Crossing % On, Off On
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
35
Parameters Reference
T able 9: Measure menu parameters (Cont.)
Parameter Default settingSelections
Eye Height On, Off Off
Eye Width On, Off Off
Quality Factor On, Off Off
P high On, Off Off
P low On, Off Off
Ext Ratio On, Off Off
Ext Ratio % On, Off Off
Ext Ratio dB On, Off Off
Duty Cycle Distortion sec On, Off Off
Duty Cycle Distortion % On, Off Off
Mask Hits On, Off Off
Measure Options Menu
Logging Menu
Table 10 lists the parameters for the Measure Options menu, the selections
available, and the default settings.
T able 10: Measure Options menu parameters
Parameter Selections Default setting
Sample Size 32 to 32767 in increments of 1 256
Filter On, Off On
Table 11 lists the parameters for the Logging menu, the selections available, and
the default settings.
T able 11: Logging menu parameters
Parameter Selections Default setting
On/Off On, Off Off
36
Store Results In: results.csv or new file name results.csv
Clear Log File None
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
Control Menu
Utility Menu
Parameters Reference
Table 12 lists the parameters for the Control menu and the selections available.
T able 12: Control menu parameters
Parameters Selections Default setting
Mode Single, Freerun Single
Start None
Pause None
Continue None
Stop None
Table 13 lists each utility menu, the parameters, the selections available and
default settings.
T able 13: Utility menus and parameters
Utility menu Paramters Selections Default setting Comments
Help Refer to Figure 19
on page 34.
Exit Refer to Figure 19
on page 34.
Save/Recall
Setup
Display Options Dialog Box
Recall Setup
Recall from File:
Save Setup
Save to File:
Box Position
Box Style
None Help returns to the last page viewed
None
None
Saved setup files
None
setup1.ini, or new file name
On, Off
Left, Middle, Right
Opaque, Transparent
Default
setup1.ini
On
Right
Opaque
Recalls the setup file displayed in
the Recall from File: menu item
Selects the setup file to recall
Saves the setup to the file displayed
in the Save to File: menu item
Selects or creates the setup file to
save
Color Theme
Based on the TDS oscilloscope
choices.
TDS Default Colors affect dialog boxes and
waveforms
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
37
Parameters Reference
38
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
Appendices
Appendix A: Measurement Algorithms
The TDSCEM1 application displays a standard mask pattern behind the
eye-diagram of the communications signal being acquired. The application can
also take measurements from the eye-diagram of a communication signal.
Oscilloscope Setup Guidelines
For all measurements, use the following guidelines to set up the oscilloscope:
1. Always connect the communication signal to CH 1.
2. The vertical scale for the communication signal must be set so that the
eye-diagram does not exceed the vertical range of the TDS oscilloscope.
3. The input power level must be kept under 250 mW.
Test Methodology
The application performs the measurement according to the following algorithm:
Measurements
1. Imports the eye-diagram.
2. Performs the measurement.
3. Uses the results in the Results readout, or saves the results to a data log file.
All eye-diagram measurements are based on the power level, the voltage level, or
the time locations of edges within each acquisition. Mask patterns are defined in
the Standard menu.
Figure 20 shows a mask pattern with an eye-diagram and the areas from which
values are taken that are used to calculate measurments.
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
39
Appendix A: Measurement Algorithms
T
cross1
P
top
T
cross2
P Values
P
cross1
P
base
P
cross2
Figure 20: Eye-diagram and mask pattern values
The P values include the mean and standard deviation of the vertical location of
Ptop and Pbase. These areas are used with a specified sample size to statistically
measure the following values:
H pTopMean, the mean value of Ptop
H pTopSigma, the standard deviation of Ptop
H pBaseMean, the mean value of Pbase
40
T1 Values
H pBaseSigma, the standard deviation of Pbase
The T1 values are vertical and horizontal values associated with the leftmost
crossing point. These areas are used to establish the following directions:
H tCross1Mean, the horizontal mean of the left crossing point at T
cross1
H tCross1Sigma, the horizontal standard deviation of the left crossing point
at T
cross1
H tCross1PP, the horizontal peak-to-peak deviation of the left crossing point
at T
cross1
H pCross1Mean, the vertical mean of the left crossing point at P
cross1
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
Appendix A: Measurement Algorithms
T2 Values
The T2 values are vertical and horizontal values associated with the rightmost
crossing point. These areas are used to establish the following directions:
H tCross2Mean, the horizontal mean of the right crossing point at T
H tCross2Sigma, the horizontal standard deviation of the right crossing point
at T
H tCross2PP, the horizontal peak-to-peak deviation of the right crossing point
at T
DCD Values
The DCD values are horizontal values associated with the rightmost crossing
point at 50% of the eye height. These areas are used to establish the dcdPP, the
horizontal peak-to-peak deviation of the left crossing point at half the height of
the eye.
MaskHit Values
The MaskHit values are the number of hits in the mask.
Table 14 lists the measurements and how the application calculates them.
T able 14: Measurements and calculations
cross2
cross2
cross2
Measurement Calculated using Definition
Jitter RMS tCross1Sigma The RMS value of the edge jitter of the
eye-diagram in seconds
Jitter 6Sigma 6*tCross1Sigma The “6 sigma” value of the edge jitter of the
eye-diagram in seconds
Jitter PP tCrossPP The peak-to-peak value of the edge jitter of
the eye-diagram in seconds
Crossing % 100*[(pCross1Mean–pBaseMean)(pTopMean–pBaseMean)] The crossing point of the eye-diagram as a
percentage of the height of the eye
diagram
Eye Height (pTopMean–3*pTopSigma)–(pBaseMean+3*PBaseSigma) The height of the eye-diagram in watts
Eye Width (tCross2Mean–3*tCross2Sigma)–(tCross1Mean+3*tCross1Sigma) The width of the eye-diagram in seconds
Quality Factor (pTopMean–pTopBase)/(pT opSigma+pBaseSigma) The ratio of the size of the eye-diagram to
the “noise” on the eye-diagram
P High pT opMean The highest power level of the eye-diagram
in watts
P Low pBaseMean The lowest power level of the eye-diagram
in watts
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
41
Appendix A: Measurement Algorithms
T able 14: Measurements and calculations (Cont.)
Measurement DefinitionCalculated using
Ext Ratio pTopMean/pBaseMean The ratio of the top of the eye-diagram to
its base
Ext Ratio % 100*(pBaseMean/pTopMean) The ratio of the base of the eye-diagram to
its top as a percentage
Ext Ratio dB 10*log (pT opMean/pBaseMean) The ratio of the top of the eye-diagram to
its base in dBs
Duty Cycle Distortion sec dcdPP Difference between the maximum and the
minimum signal crossing times at 50% of
the level
Duty Cycle Distortion % 100*dcdPP/(Eye Width) Difference between the maximum and the
minimum signal crossing times as a
percentage of the bit period
Mask Hits maskHits The number of hits in the mask
42
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
Appendix B: GPIB Command Syntax
This appendix describes the GPIB command syntax that you can use in your
GPIB program to do the following tasks:
H Start the TDSCEM1 application
H Recognize an active application with GPIB protocol
H Program and read application setup parameters
H Sequence measurements
H Synchronously read measurement results
Description. Gives the function of the command, conditions of its use, and its
interactions with other commands.
Syntax. Gives the valid select and query command forms. The required arguments are listed in their proper order.
For example, in the syntax definition
Arguments. The arguments to a command are defined along with their range of
values.
Returns. Defines the data returned in response to a command query.
Refer to the GPIB Program Example section for an example of a GPIB program
that can execute the TDSCEM1 application.
NOTE. Refer to the GPIB Program Example section for guidelines to use while
designing your GPIB program.
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
43
Appendix B: GPIB Command Syntax
VARIABLE:VALUE TDS COMMAND
Description
VARIABLE:VALUE TDS COMMAND accepts string arguments for a control or
data variable and a value to which to set the argument.
Syntax
VARIABLE:VALUE
VARIABLE:VALUE <variable name>",<variable value>"
the arguments <variable name> and <variable value> are required
in the order indicated.
Arguments and Returns
Table 15 lists the arguments, their function, and the query returns.
T able 15: VARIABLE:VALUE TDS COMMAND arguments and queries
Variable name Variable value Function Query form
application Exit Terminates the active application Returns a string that corresponds to
the name of the active application
boxBackground {Transparent, Opaque} Sets the message box background Returns the message box background
boxPosition {Left, Middle, Right} Sets the message box position Returns the message box position
boxVisibility {On, Off} Sets box visible or invisible Returnsbox visible or invisible
colorTheme {TDSDefault, Black, Green,
Mild, Purple, Steel, Tek Blue}
crossingState {On, Off} Sets the state of the crossing measure-
dcdState {On, Off} Sets the state of the dcd measurement Returns the state of the dcd measure-
dcdPercentState {On, Off} Sets the state of the dcdPercent
extRatioState {On, Off} Sets the state of the extRatio measure-
extRatioPState {On, Off} Sets the state of the extRatio %
extRatioDState {On, Off} Sets the state of the extRatio dB
eyeHeightState {On, Off} Sets the state of the eye height
eyeWidthState {On, Off} Sets the state of the eye width mea-
Sets the TDS oscilloscope color
scheme
ment
measurement
ment
measurement
measurement
measurement
surement
Returns the TDS oscilloscope color
scheme
Returns the state of the crossing
measurement
ment
Returns the state of the dcdPercent
measurement
Returns the state of the extRatio
measurement
Returns the state of the extRatio %
measurement
Returns the state of the extRatio dB
measurement
Returns the state of the eye height
measurement
Returns the state of the eye width
measurement
44
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
Appendix B: GPIB Command Syntax
T able 15: VARIABLE:VALUE TDS COMMAND arguments and queries (Cont.)
Variable name Query formFunctionVariable value
filterState {On, Of f} Sets the state of the digital filter Returns the state of the digital filter
jitter6SigmaState {On, Off} Sets the state of the jitter 6 Sigma
measurement
jitterPPState {On, Off} Sets the state of the jitter peak-to-peak
measurement
jitterRmsState {On, Off} Sets the state of the jitter RMS mea-
surement
loggerDestination Sets the data log file name Returns the data log file name
loggerState {On, Of f} Sets the state of the data log Returns the state of the data log
maskStandard {None, OC1, OC3, OC12,
FC133, FC266, FC531,
FC1063, ENET1250}
maskState {On, Off} Sets the state of the eye-diagram
pTopState {On, Off} Sets the state of the pTop measure-
pBaseState {On, Off} Sets the state of the pBase measure-
qualityFactorState {On, Off} Sets the state of the quality Factor
recallName Any string that uses one to
eight characters from A to Z
and/or zero to nine
sampleSize Any number from 32 to 32767 Sets the statistical sample size used to
Sets the communications mask
standard
measurement
ment
ment
measurement
Sets the recalled setup file name Returns the saved setup file name
take measurements
Returns the state of the jitter 6 Sigma
measurement
Set the state of the jitter peak-to-peak
measurement
Returns the state of the jitter RMS
measurement
Returns the communications mask
standard
Returns the state of the eye-diagram
measurement
Returns the state of the pTop measurement
Returns the state of the pBase measurement
Returns the state of the quality Factor
measurement
Returns the statistical sample size
used to take measurements
saveName Any string from one to eight
characters from A to Z and/or
zero to nine
setup {Default, Recall, Save} Sets the setup file name Returns the setup file name
sequencerMode {FreeRun, Single} Sets the sequencer mode Returns the sequencer mode
sequencerState {Ready, Paused, Sequencing} Sets the state of the sequencer Returns the state of the sequencer
Sets setup file name Returns the setup file name
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
45
Appendix B: GPIB Command Syntax
Table 16 lists the measurement results queries.
T able 16: Measurement results queries
Variable name Function
crossing Returns the crossing measurement
dcd Returns the dcd measurement
dcdPercent Returns the dcd % measurement
error Returns an error message or returns “” if no error is detected
extRatio Returns the extinction ratio measurement
extRatioP Returns the extinction ratio % measurement
extRatioD Returns the extinction ratio dB measurement
eyeHeight Returns the eye height measurement
eyeWidth Returns the eye width measurement
jitter6Sigma Returns the jitter 6 Sigma measurement
jitterPP Returns the jitter peak-to-peak measurement
jitterRMS Returns the jitter RMS measurement
mask Returns the mask measurement
pHigh Returns the pHigh measurement
pLow Returns the pLow measurement
qualityFactor Returns the quality factor measurement
46
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
Index
Index
Symbols
.csv file
definition, 24
example of viewing, 13
importing, 12
saving, 12
A
accessories, 2
ANSI documents, 8
application
basic functions with an oscilloscope, 6
description, 1
exiting, 15
GPIB program example, 27
menu structure, 5, 33
returning, 7
setting up
standard eye-diagram masks, 8
to display results, 11
to save results to a data log file, 12
to take measurments, 9
starting, 18
test algorithms, 39
tutorial, 17
updates, 2
D
data log file
example of viewing, 13
importing, 12
saving, 12
saving the results tutorial lesson, 24
Default Setup, 15
dialog boxes, changing the appearance, 7
Display Options, 7
Done, 6
E
exiting the application, 15
eye-diagram, 8
viewing obscured parts, 13
F
Free Run acquisition mode, 11
G
GPIB protocol
command syntax, 43
guidelines, 27
program example, 28
C
Cancel, 6
CH 1 only channel used, 4
changing settings during a measurement, 11
CLEAR MENU button, 13
command syntax, 43
common menu items, 6
communication standards documents, 8
configuring the display, 7
connection to CH 1, 4
contacting T ektronix, viii
Control menu, 11
parameters, 35, 36, 37
conventions, vii
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
H
Help, online, 6
I
installation
application, 3
downloading updates, 2
L
leaving the application, 15
47
Index
lessons. See tutorial lessons
log file, example, 13
Logging menu, 12
M
main menus, 5
Measure menu, 9
Measure Options menu, 10
measurements
algorithms, 41
application test method, 39
descriptions, 9
display results, 11
example of viewing the results, 13
GPIB program example, 27
oscilloscope changes, 11
parameters, 35
selections, 9
setting up, 8
turning off display, 14
tutorial lessons, 17
menu
Control, 11
overview , 33
menu structure
description, 5
detailed illustration, 33
messages, W arning, 7
O
Okay , 6
online help, 6
oscilloscope
basic functions with the application, 6
compatibility, 1
setup guidelines, 39
P
R
readout, turning off, 14
Recall from File:, 15
Recall Setup, 15
recalling a setup, 14
requirements and restrictions, 2
Results readout, turning off, 14
S
Save Setup, 14
Save to File:, 14
Save/Recall Setup menu, 14
setup
default, 15
recalling, 15
saving, 14
setup menus, descriptions, 10
side menus, 5
Single acquisition mode, 11
SONET document, 8
Standard menu, 8
starting, application, 18
T
technical support, viii
T ektronix, contacting, viii
terms, vii
tutorial lessons, 17
saving the results to a data log file, 24
Statistics readout, 21
taking a measurement, 19
U
Utility menu, parameters, 37
Utility menus, 6
parameters, reference section, 35
product
compatibility, 1
description, 1
requirements and restrictions, 2
updates, 2
Q
quitting the application, 15
48
V
viewing, obscured parts of an eye-diagram, 13
W
Warning messages, 7
waveforms, display color, 8
web site, 2
TDSCEM1 Communication Eye-Diagram Measurements Application User Manual
Loading...