Tektronix TDSDVD User manual

TDSDVD Optical Storage Analysis Application

2 TDSDVD Optical Storage Analysis Application

Copyright © Tektronix, 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 Technical 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 FAR 52.227-19, as applicable.

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

Tektronix, Inc. P.O. Box 500, Beaverton, OR 97077

TEKTRONIX, TEK, and TEKPROBE are registered trademarks of Tektronix, Inc.

TDSDVD Optical Storage Analysis Online Help, OLH0200, Version 01.00

TDSDVD Optical Storage Analysis Application

General Safety

WARNING: To avoid injury to eyes, wear eye protection if the

possibility of exposure to high-intensity rays or laser radiation exists.

WARNING: To avoid electric shock, remove power from the system under test (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.

4 TDSDVD Optical Storage Analysis Application

Table of Contents

Welcome tothe TDSDVD Optical Storage Analysis Application ............... 7

Using Online Help......................................................................................7

Related Documentation.............................................................................. 8

Accessing Online Documents....................................................................9

Contacting Tektronix..................................................................................9

Product Feedback......................................................................................9

Color Printing ........................................................................................... 10

Getting Started 11

Product Description..................................................................................11

Accessories.............................................................................................. 11

Compatibility.............................................................................................12

Requirements and Restrictions................................................................12

Installation................................................................................................13

Connecting to a System Under Test........................................................16

Operating Basics 19

Running the Application........................................................................... 19

The Application Interface.........................................................................20

Command Buttons ................................................................................... 22

Application Menu Bar...............................................................................24

Minimizing and Maximizing the Application.............................................. 24

Accessing Oscillo scope Functions...........................................................24

Exiting the Application.............................................................................. 25

Application Directories ............................................................................. 25

File Name Extensions.............................................................................. 25

Taking Measurements 27

About Taking Measurements................................................................... 27

Taking Measurements Guidelines............................................................27

Acquiring the Data Signal......................................................................... 30

Displaying an Eye Waveform................................................................... 30

Selecting a Standard................................................................................ 31

Setting Up the Input Options....................................................................32

Selecting and Configuring Measurements...............................................39

Taking Measurements.............................................................................. 40

Viewing Results........................................................................................ 40

Saving and Recalling Setups...................................................................42

Saving Results to a File...........................................................................43

Using Custom Plug-In Processes ............................................................ 46

Tutorial 49

Introduction to the Tutorial ....................................................................... 49

Setting up the Oscilloscope...................................................................... 49

TDSDVD Optical Storage Analysis Application

Recalling a Waveform..............................................................................49

Starting the Application............................................................................ 50

Setting Up the Signal Source...................................................................50

Selecting the Measurement.....................................................................51

Configuring the Measurement.................................................................. 51

Taking the Measurement.........................................................................52

Viewing the Results..................................................................................53

Displaying a Measurement Histogram.....................................................54

Displaying a Time Interval Analysis (TIA) plot.......................................... 55

Saving the Measurement Data................................................................. 55

Stopping the Tutorial................................................................................55

Returning to the Tutorial........................................................................... 56

Reference 57

Menus......................................................................................................57

Parameters...............................................................................................87

Algorithms................................................................................................ 91

GPIB Programming................................................................................ 101

6 TDSDVD Optical Storage Analysis Application

Introduction

Welcome to the TDSDVD Optical Storage Analysis Application

The TDSDVD Optical Storage Analysis & Measurement Application is a Java– based application that lets you quickly and easily measure and analyze CD/DVD/MO optical storage device signals.

What do you want to do?

Read the Product Description on page 11 Learn About Online Help on page 7 Go to Installation on page 13

Using Online Help

Select Help on the right side of the application's Menu bar to open the Help window. The main (opening) Help window has three tabs:

• Table of Contents (TOC) tab: Displays the help information organized into book-like sections. Click a book icon to open a section; select any of the topics listed under the book.

• Index tab: Displays a list of alphabetical keywords. Click the topic of interest to bring up the appropriate help page.

• Find tab: Displays a box in which you can enter a word or words for which to search. a text-based search.

To print a topic, select the Print button from the help topics menu bar. If you are printing to a monochrome printer, see Color Printing on page 10.

Select the Back button to return to the previous help window. Sometimes you can jump from one topic to another through a hyperlink. If the Back button is "grayed out" or a jump is not available, choose the "Help Topics" button to select the originating help topic.

Browse buttons (Next >> and Previous <<) allow you to move forward and backward through topics in the order of the Table of Contents.

A Green text (with dotted underline) indicates a Popup window. Click the green text to display a brief help message. Click to return to the topic.

Green-underlined text indicates a Jump (link) to another topic. Select the green text to jump to the related topic.

TDSDVD Optical Storage Analysis Application

Introduction

To return to the Online Help Table of Contents, select Help Topics from the Help Top Menu.

See Also

Using Online Help on page 7

8 TDSDVD Optical Storage Analysis Application

Introduction

Accessing Online Documents

To view a PDF file of the TDSDVD online help from a PC with the application installed, select Start > Programs > TekApplications > TDSDVD, and select the PDF file from the list. The corresponding PDF file displays.

To run the TDSDVD online help without starting the application, select Start > Programs > TekApplications > Help. The TDSDVD help program displays.

Contacting Tektronix

Phone 1-800-833-9200*

Address Tektronix, Inc.

Web site www.tektronix.com

Sales support 1–800–833–9200, select option 1*

Service support 1–800–833–9200, select option 2*

Technical support Email: techsupport@tektronix.com

Department or name (if known) 14200 SW Karl Braun Drive P.O. Box 500 Beaverton, OR 97077 USA

1–800–833–9200, select option 3* 1–503–627–2400

* This Telephone number is toll free in North America. After office hours, please leave a voice mail message. Outside North America, contact a Tektronix sales office or distributor; See the Tektronix web site for a list of offices.

Product Feedback

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

Send your feedback to us by email to techsupport@tektronix.com or FAX us at (503) 627-5695. Please provide as much of the following information as possible:

• Your name, company, mailing address, phone number, and FAX number

• Oscilloscope model number and hardware options, if any

• Probes used

• Software version number

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

problem

TDSDVD Optical Storage Analysis Application

Introduction

• If possible, save the oscilloscope and application setup and information .set and .ini files

• If possible, save the waveform on which you are performing the measurement as a .wfm file

Once you have gathered this information, you can contact technical support by phone or through e-mail. If using e-mail, be sure to enter in the subject line "TDSDVD Problem," and attach the .set, .ini, and .wfm files. Please indicate if you would like to be contacted by Tektronix regarding your suggestion or comments.

To create oscilloscope screen shots to include with your email or FAX, follow these steps:

1. In the oscilloscope menu bar, select File > Export to display the Export dialog box.

2. Enter a file name. The default file type is bitmap (.bmp).

3. Select Save. The file is saved in the C:\TekScope\Images directory. You can then attach the file to your email (depending on the capabilities of your email editor).

Color Printing

Many of the online help topics include color examples of application screens. Printing these color topics on a monochrome printer can result in loss of image information due to how different monochrome printers interpret and print color information.

If you do not have access to a color printer, you should print the topic from the application Online Help PDF (portable document format) file. You can find the file in the Documents directory on the Optional Applications Software on a Windows-Based Oscilloscope CD.

10 TDSDVD Optical Storage Analysis Application

Getting Started

Product Description

The TDSDVD Optical Storage Analysis and Measurement Application is a Javabased application for measuring and analyzing the amplitude, modulation, and timing characteristics of CD/DVD/MO optical storage device encoded signals. The application features include:

• Supports, but is not restricted to, common CD/DVD/MO optical storage standards

• Displays measurement results as numeric values, linear plots, or histogram plots

• Supports adding external MATLAB (version 6.1 or later) and .DLL signal analysis/processing software.

Accessories

• Supports Time Interval Analysis (TIA) display

• Displays a count of Track Error pulses

• Ability to install and run TDSDVD on a PC to take advantage of greater

processing power; the PC must be connected to the oscilloscope on which the TDSDVD applicationis installed and enabled

• Saves measurement setups and results to a file

What do you want to do?

Check Compatibility, see page 12 Look Over Requirements and Restrictions, see page 12 Go to Installation, see page 13 Connecting to a System Under Test, see page 16 Start Running the Application, see page 19

There are no standard accessories for this product.

TDSDVD Optical Storage Analysis Application

Getting Started

Compatibility

This table lists the oscilloscopes that support the TDSDVD application.

Application

TDSDVD* Optical Storage Analysis and Measurements V 1.0.0* and above

* For a current list of supported models, see the Software and Drivers category on www.tektronix.com.

Oscilloscope Model

TDS7054, TDS7104 V 2.1.0 and above TDS7154, TDS7254, TDS7404 CSA7154, CSA7404 V 2.0.0 and above TDS5052, TDS5054, TDS5104

Requirements and Restrictions

To operate the TDSDVD application, the Sun Microsystems Java Run-Time Environment (JRE) version 1.4 (or greater) must be installed on the oscilloscope. The TDSDVD installation program automatically installs the proper version of JRE. If you accidentally delete the JRE on your oscilloscope, you will need to reinstall the TDSDVD application.

This application assumes that the following conditions are met to obtain measurements:

• The data source signal is a continuous physical data disk recording of nT pulses with no gaps or non-nT type data.

Oscilloscope Software Version

V 2.0.0 and above

V 1.0.7 and above

• The clock period (T) of the data source signal is constant.

The following table lists memory requirements for taking six measurements at one time on long record length data samples.

Record Length Windows RAM

Up to 4 M samples 4 M samples and above* * Taking measurements on 4 M (or greater) data records can take significant time to process. Running the application on a PC with a 1 GHz or greater processor can reduce processing time.

Required Recommended

256 MB 256 MB

256 MB 512 MB

12 TDSDVD Optical Storage Analysis Application

Getting Started

Installation

To install the TDSDVD application software on an oscilloscope, refer to the

Optional Applications Software on a Windows-Based Oscilloscope Installation Manual, which is part of the optional applications CD and documentation kit.

The installation manual contains the following information:

• A list of applications, compatible oscilloscopes, and relevant software and firmware version numbers

• How to apply the option label

• Installation procedures

• How to enable an application

• How to install the application on a PC

• How to configure the PC-installed application to communicate with an

oscilloscope using a GPIB or LAN connection

You can find the corresponding Portable Document Format (PDF) file for the installation manual in the Documents directory of the Optional Applications Software on a Windows-Based Oscilloscope CD at C\Program Files\Tek Applications\tdsdvd.

Note.

The CD booklet in the CD case only contains information on installing the application from the CD and on how to apply a new label.

PC Installation

You can install the TDSDVD application on a PC with Windows 98 or Windows 2000 operating systems. Operating the application from a PC allows the application to use the additional processing power of the PC.

Note.

Ensure that the PC has access to the oscilloscope with the enabled application, either over a local area network (LAN) or through a GPIB cable.

To set up a PC to control the application over a LAN or GPIB cable, you need to do the following tasks:

• How to download updates from the Tektronix web site

• Setting Up the Oscilloscope for Remote Access, located on page 14

• Installing the Application Software on the PC, located on page 14

• Installing TekVISA Communications Software on the PC, located on

page 14

• Configuring TekVISA , located on page 15

TDSDVD Optical Storage Analysis Application

Getting Started

Setting Up the Oscilloscope for Remote Access

To set up the oscilloscope for remote LAN access, follow these steps:

1. From the menu bar of the oscilloscope, select Utilities > LAN Server Status. The VXI-11 Server Control menu appears.

2. Select the Start command button to start the server. A VXI-11 Server Control icon appears on the Windows status bar.

To set up the oscilloscope for remote GPIB access, follow these steps:

1. Install a GPIB card in your PC. For information on GPIB cards, you can access the National Instrument web site.

2. Follow the instructions from the manufacturer and connect a GPIB cable between your PC and oscilloscope.

3. From the oscilloscope menu bar, select Utilities> GPIB Configuration.

4. Select the Talk/Listen button and the On option.

5. Select address 1.

Installing Application Software on the PC

To install the TDSDVD application on a PC, follow these steps:

1. Insert the Optional Applications Software for Windows-Based Oscilloscopes CD-ROM in the CD drive on your PC. The PC may automatically start the Installation Browser program. If the PC does not start the Installation Browser program, follow these steps:

2. Select the My Computer icon.

3. In the Exploring - My Computer window, select the D: (CD-ROM) drive and select the Launch.exe file.

4. Follow the on-screen instructions given by the InstallShield Wizard. Select the OK button if prompted to install the JRE (Java Run-time Environment).

5. Reboot the PC to complete the application software installation process.

Installing TekVISA Communications Software on the PC

This application requires TekVISA API drivers to communicate with an oscilloscope over a network. The TekVISA software is the Tektronix version of the PC VISA API drivers.

To install TekVISA software on your PC, follow these steps:

1. Insert the oscilloscope product software CD-ROM disc into your PC CDROM drive.

2. Navigate to the TekVISA directory on the CD-ROM.

14 TDSDVD Optical Storage Analysis Application

Getting Started

3. In the TekVISA directory, double-click Setup.exe to open the TekVISA Install Wizard.

4. Follow the instructions in the Install Wizard. Select Complete when prompted for the installation type.

You can also download the latest TekVISA software from the Tektronix web site: To do so, follow these steps:

1. Access the www.tektronix.com web site.

2. Select Software & Drivers (in the Resources column) to display the Software and Firmware Finder page.

3. Enter tekvisa in the Find by model number or keyword field.

4. Select Go. The search returns a list of the available TekVISA software to download.

5. Select the TekVISA software appropriate for your oscilloscope. View the web page for instructions on how to download TekVISA to your oscilloscope or PC.

Configuring TekVISA

To configure TekVISA software, you must first determine the hostname of the oscilloscope with the TDSDVD application enabled. To do so, follow these steps:

1. Minimize the oscilloscope (select File> Minimize from the menu bar).

2. Right click the Network Neighborhood icon.

3. Select Properties.

4. Select the Identification tab.

5. Write down (take mental note) the oscilloscope name, also referred to as

To configure TekVISA software to communicate with an oscilloscope, follow these steps:

1. On the PC, select Start > Programs > TekVISA > TekVISA

2. Verify that the host name of the oscilloscope matches the name of the

the host name.

Configuration to display the TekVISA configuration menu.

instrument with the GPIB8 designator in the list of TekVISA Remote Hosts.

If the names do not match, you must remove the incorrect instrument name from the list of remote hosts. To remove a name from the list and add a correct name, follow these steps:

1. In the list of Remote Hosts, select the host name with the GPIB8 VISA designator.

TDSDVD Optical Storage Analysis Application

Getting Started

2. Select Remove.

3. Select OK. The PC removes the item.

4. In the Remote Hosts menu, select the Add button to display the Add Remote Host menu.

5. Enter the host name of the oscilloscope with the TDSDVD application enabled in the Host Name field.

6. Enter GPIB8 in the Visa Name field. The application communicates with the oscilloscope only on GPIB8.

7. Select OK.

8. Select the Find button in the TekVISA Resources window. The PC adds the GPIB8::1::INSTR to the list; it may take a few moments for the list to update.

If GPIB8::1::INSTR does not appear in the list, check that your network cable is properly connected and that you have the correct host name. You might also need to work with your system administrator to resolve connectivity problems.

9. Select Quit to exit the TekVISA Configuration window.

Connecting to a System Under Test

Connecting to a System Under Test (SUT)

WARNING: To avoid injury to eyes, wear eye protection if the

possibility of exposure to high-intensity rays or laser radiation exists.

WARNING: To avoid electric shock, remove power 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.

See Also

Primary Setup: Measuring Data Using Extracted Clock on page 17 Secondary Setup: Measuring Data Using Actual Clock on page 17

16 TDSDVD Optical Storage Analysis Application

Getting Started

Primary Setup: MeasuringData Using an Extracted Clock

Use the primary setup to measure the optical drive data signal using an extracted or ideal (synthesized) clock signal. Connect the optical storage drive to the oscilloscope as shown below.

Secondary Setup: Measuring Data Using the Actual Clock

Use the secondary setup to measure optical data signal using the actual acquired clock signal. Connect the optical storage drive to the oscilloscope as shown below.

TDSDVD Optical Storage Analysis Application

Getting Started

18 TDSDVD Optical Storage Analysis Application

Operating Basics

Running the Application

To run the application on an oscilloscope, select File > Run Application > Optical Storage Analysis from the oscilloscope menu bar.

The application uses a Windows interface. When you run the application, the oscilloscope display shrinks to half size and appears in the top half of the screen, and then Windows loads the application.

Note.

If you get the error message “Exit the currently running application before starting another, it may mean that the application is already running on the PC. You cannot run the application on the PC and an oscilloscope connected to that PC at the same time. Exit the application on the PC, and then start the application again on the oscilloscope.

To run the application on a PC, select Start > Programs > TekApplications > TDSDVD > Optical Storage Analysis.

Note.

If you get the error message “Attempting to run too many applications concurrently., it may mean that the application is already running on the oscilloscope. You cannot run the application on the PC and the oscilloscope at the same time. Exit the application on the oscilloscope, and then start the application again on the PC.

This message can also mean that you have not enabled the LAN or GPIB servers on the oscilloscope, which the TekVISA software is not correctly configured, or the PC has lost communication with the oscilloscope. Refer to Setting Up the Oscilloscope for Remote Access on page 14 for more information.

It takes a few moments to display the TDSDVD application, which is shown next.

TDSDVD Optical Storage Analysis Application

Operating Basics

See Also

The Application Interface on page 20 Exiting the Application on page 25 Taking Measurements Guidelines on page 27

The Application Interface

The following figure shows the TDSDVD application interface, with labels for the key features, and a table listing the UI functions.

20 TDSDVD Optical Storage Analysis Application

Operating Basics

Application User Interface Controls

Item Description

Menu bar Located at the top of the application display and

Area Visual frame that encloses a set of related

Command buttons Menu tabs Menu functions grouped by category. The tabs

Option button Button that defines a particular command or

List box Box that contains a list of items from which you

Box Box in which you can enter text or numeric

Scroll bar Vertical or horizontal bar at the side or bottom of

Browse Button that displays a window where you can

Keyboard button

contains application menus. Selecting a menu item updates the menu area to show applicable menu tabs, parameters, or information

options Buttons in the Control area that initiate an immediate action

displayed depend on which Menu Bar item is selected. Select a tab to display the associated functions

task

can select one item

values, using the keypad or a Multipurpose knob

a display area used to move the display area for better viewing of information

look through a list of directories and files Icon that displays a virtual keyboard that you can use to enter data into a box

See Also

Command Buttons on page 22 Application Menu Bar on page 24

TDSDVD Optical Storage Analysis Application

Operating Basics

Command Buttons

The Command buttons execute key application tasks, including exiting the application, acquiring data for measurements, and displaying key graphical information. The Command buttons are always available.

22 TDSDVD Optical Storage Analysis Application

Operating Basics

The Command Button Options

Button Description

Hide Returns the oscilloscope to full screen display.

Exit Exits (quits) the TDSDVD application. You have

Eye Activates or deactivates the Eye display of the

TIA Activates or deactivates the Time Interval

TEC Activates the Track Error Count panel which

Scan Activates the AutoScroll panel to zoom and

Start/Stop (Free Run)

Start Single Sequence

Reset All

The application is still running but is behind the oscilloscope display

the option to restore the oscilloscope settings to those present prior to starting the application

live HF signal. This mode requires an active signal. Deselecting returns the oscilloscope to the settings present prior to starting the Eye command

Analysis (TIA) display. You must take a Data Pulse Width measurement prior to selecting the TIA button

displays the tracking error count

scroll through the waveform data Starts or stops the measurement in Free Run mode to make continuous acquisitions

Stops measurement acquisition

Starts a single measurement acquisition

Stops measurement acquisition

Clears all measurement results, including plot and histogram statistics

Acq/No Acq Starts or stops any further acquistion of data.

When No Acq is displayed, Start/Stop is disabled and measurements are taken on the last data acquisition

TDSDVD Optical Storage Analysis Application

Operating Basics

Application Menu Bar

The Menu bar contains the application functions, grouped by category. Selecting a menu item displays a drop-down menu list of functions.

You can also select menu items from the keyboard by pressing and holding the Alt key in combination with the letter underlined in the menu or submenu item. For example, to use the keyboard to display the Measurements > Configure panel, press and hold the Alt key, press the M key, and then press the C key.

See Also

The Application Menus on page 57

Minimizing and Maximizingthe Application

To minimize the application, select Measurements > Minimize. This maximizes the oscilloscope and places the application behind the oscilloscope display. The application remains displayed when you minimize the oscilloscope.

To maximize the application from the Windows task bar, select TDSDVD in the Windows task bar.

To maximize the application from the oscilloscope, select the App button on the oscilloscope screen.

Accessing Oscilloscope Functions

When you access oscilloscope functions, the oscilloscope fills the display. You can access oscilloscope functions in the following ways:

• Select the Hide button in the application display to place the application window behind the oscilloscope display.

24 TDSDVD Optical Storage Analysis Application

Operating Basics

• Choose the Menu-bar or Toolbar mode on the oscilloscope and access menus.

• Press front-panel buttons.

To return to the application, select the App button on the oscilloscope screen.

Exiting the Application

To exit the application, select the Exit button. When you exit the application, you can select to keep the oscilloscope setup currently in use with the application or to restore the oscilloscope setup that was present before you started the application.

Application Directories

The application uses specific directories to save and recall setup files and uses specific file name extensions to identify the file type.

The following table lists default directory names.

Directory Used for

C:\Program Files\ TekApplications\tdsdvd C:\TekApplications\tdsdvd\data Saved measurement results

C:\TekApplications\tdsdvd\log Data log files C:\TekApplications\tdsdvd\setup Setup files C:\TekApplications\tdsdvd\waveforms Waveform files C:\TekApplications\tdsdvd\example programs

File Name Extensions

File name extension Description

.csv Comma-separated value file, used to store

.ini Application setup initialization file. The .ini file is saved

.set Oscilloscope setup file that is saved and recalled at the

.wfm Waveform file that can be recalled into reference

Application executable files

list files

Application plug-in example files

measurement data (individual measurement data or logged measurement data)

on the instrument (oscilloscope or PC workstation) that is running the application

same time as an .ini file; both files will have the same name. The .set file is always saved on the oscilloscope

memory

TDSDVD Optical Storage Analysis Application

Operating Basics

26 TDSDVD Optical Storage Analysis Application

Taking Measurements

About Taking Measurements

This section describes the steps to set up and take a measurement, how to replace the default signal process block functions with MATLAB or DLL user-developed software, and other common application tasks. You can also do the application Tutorial, located on page 49, which demonstrates most of the application functions.

These examples assume the following conventions:

• The TDSDVD application is installed and enabled on the oscilloscope.

• The oscilloscope is connected to the system under test (SUT) using the

appropriate probes.

See Also

Installation on page 13 Taking Measurements Guidelines on page 27 Selecting a Measurement Standard on page 31

Taking Measurements Guidelines

Use the following guidelines when setting up and taking measurements with this application:

• The data source signal must be a continuous physical data disk recording of nT pulses with no gaps or non-nT type data.

• The clock period (T) of the data source signal must be constant, but not necessarily known.

• The application does not change the oscilloscope, acquisition record length, or sample rate settings in any of the operation modes, including data and clock Autoset. You must set the desired record length and sample rate for the application to correctly acquire, process, and measure the signal. In general, the sample rate should be at least 10 times the signal clock frequency, and the record length set to display at least 10 to 20 pulses.

• The DVD application measurement accuracy depends on the input parameter settings. The application is a collection of tools designed for general measurement and analysis of optical storage-specific signals without being restricted to a specific standard or signal. As a result, using the application to measure specific signals generally requires iterations between configuring the application parameters and analysis and validation of the measurement results (by viewing the resultant waveforms).

TDSDVD Optical Storage Analysis Application

Taking Measurements

• The Extracted Clock and data/clock Autoset functions are meant to be a convenient way to obtain approximate values for the corresponding parameters, and produce roughly correct measurement results based on minimal user interaction. For more accurate results, use the Ideal (synthesized) clock mode and enter the known clock period. If the clock period is not known, a good starting point is to use the estimated clock period value calculated by the application using the Extracted clock.

You can also enter data/clock threshold and hysteresis values to further refine measurement results. The hysteresis band should be set to a value that allows the application to discriminate between noise and the actual pulses in the signal. The Autoset function will select a sufficient value most of the time. However, the hysteresis of a signal will vary depending on conditions such as probes and test points. Therefore, the hysteresis may need slight adjustments based on these conditions. The threshold value selected by the Autoset function will also vary depending on the conditions described above, so the threshold value may also require minor changes.

• Using a synthesized clock speeds up the application considerably, as calculating the clock period is computationally time-consuming.

• The sampled input signal (live or stored) is not necessarily the signal being measured. If you route the input signal through the Equalizer or Low Pass Filter pre-processing blocks, the application measures the resultant signal from these blocks.

• The Data Source threshold and hysteresis settings apply to the data signal after signal pre-processing, and not to the sampled input source signal. The exception to this is when the signal processing path bypasses all signal process blocks and sends the input signal directly to the application.

• The data threshold and hysteresis parameters directly affect how accurately the application categorizes the nT data pulses (pits and spaces). If the clock is Extracted, then the accuracy of the clock period (T) estimation is another factor directly affecting the nT pulse categorization, and depends on its turn on the same data threshold and hysteresis.

• The Slicer Initial Threshold parameter is important. Because the Slicer bandwidth is usually small, an incorrect initial threshold setting can generate very long pulses categorized as having a very large nT (as they are offset heavily from the threshold). View the Leveled waveform signal (View > Waveforms > Leveled) and verify that the signal is centered on the zero volt line, as shown in the following figure.

28 TDSDVD Optical Storage Analysis Application

Taking Measurements

If the Slicer Initial Threshold parameter is incorrect, the Leveled signal is not centered on zero volts, but slowly adjusts to the zero volt level depending on the Slicer bandwidth value, as shown in the below figure.

If you are measuring from the LPF output then a good initial value for the Slicer Initial Threshold parameter is the Autoset calculated data Threshold parameter value. Viewing the LPF signal (which is the Slicer input) also gives good basis for estimating an Initial Threshold value for the slicer.

TDSDVD Optical Storage Analysis Application

Taking Measurements

Amplitude-related measurements depend on peak-to-peak and decision level measurements on specific nT pulse pairs (and adjacent pit and space with the same nT). A lack of results for these measurements can be because specified nT pairs were not found in the input signal. The fact that both pulses and spaces for a specified nT were found (for example, as indicated by getting results for High and Low measurements) does not mean that any pit or space with the specified nT was adjacent to another specified nT pit or space. If no results are returned for a measurement such as Asymmetry, the Divisor nT value in the Configure panel may need to be adjusted. In the Results panel, select the detailed results for a measurement that does have results and search for a row that has the same nT value for both the Subject and Adjacent columns. Enter this value in the Divisor nT field of the Configure panel.

Acquiring the Data Signal

To acquire the optical storage drive signal, follow these steps:

1. Connect the oscilloscope to the SUT. The default application signal source input is Ch 1, and the default clock signal source input is Ch 2.

2. Push the oscilloscope AUTOSET button to acquire and display a signal.

3. Change the oscilloscope horizontal settings to adjust the sample rate. In general, the sample rate should be at least 10 times the signal clock frequency, and the record length set to display at least 10 to 20 pulses.

Displaying an Eye Waveform

The Eye button displays an eye waveform of the active data signal. You can use this to validate the input data source signal.

30 TDSDVD Optical Storage Analysis Application

+ 86 hidden pages

Tektronix TDSDVD User manual

Specifications and Main Features

Frequently Asked Questions

User Manual