Tektronix TDS 744A, TDS 784A, TDS 684A User Manual

User Manual

TDS 684A, TDS 744A & TDS 784A Digitizing Oscilloscopes

070-8991-02

This document applies for firmware version 1.0 and above.

Copyright  T ektronix, Inc. 1994. 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, TEK, FastFrame, FlexFormat, and InstaVu are registered trademarks of Tektronix, Inc.

WARRANTY

T ektronix warrants that this product will be free from defects in materials and workmanship for a period of three (3) years from the date of shipment. If any such product proves defective during this warranty period, T ektronix, at its option, either will repair the defective product without charge for parts and labor, or will provide a replacement in exchange for the defective product.

In order to obtain service under this warranty, Customer must notify Tektronix of the defect before the expiration of the warranty period and make suitable arrangements for the performance of service. Customer shall be responsible for packaging and shipping the defective product to the service center designated by T ektronix, with shipping charges prepaid. T ektronix shall pay for the return of the product to Customer if the shipment is to a location within the country in which the T ektronix service center is located. Customer shall be responsible for paying all shipping charges, duties, taxes, and any other charges for products returned to any other locations.

This warranty shall not apply to any defect, failure or damage caused by improper use or improper or inadequate maintenance and care. T ektronix shall not be obligated to furnish service under this warranty a) to repair damage resulting from attempts by personnel other than T ektronix representatives to install, repair or service the product; b) to repair damage resulting from improper use or connection to incompatible equipment; or c) to service a product that has been modified or integrated with other products when the effect of such modification or integration increases the time or difficulty of servicing the product.

THIS WARRANTY IS GIVEN BY TEKTRONIX WITH RESPECT TO THIS PRODUCT IN LIEU OF ANY OTHER WARRANTIES, EXPRESSED OR IMPLIED. TEKTRONIX AND ITS VENDORS DISCLAIM ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PAR TICULAR PURPOSE. TEKTRONIX’ RESPONSIBILITY TO REPAIR OR REPLACE DEFECTIVE PRODUCTS IS THE SOLE AND EXCLUSIVE REMEDY PROVIDED TO THE CUST OMER 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.

German Postal Information

Certificate of the Manufacturer/Importer

We hereby certify that the TDS 684A, TDS 744A, and TDS 784A Digitizing Oscilloscopes and all factory-installed options comply with the RF Interference Suppression requirements of Postal Regulation Vfg. 243/1991, amended per Vfg. 46/1992.

The German Postal Service was notified that the equipment is being marketed. The German Postal Service has the right to re-test the series and to verify that it complies.

TEKTRONIX

Bescheinigung des Herstellers/Importeurs

Hiermit wird bescheinigt, daß das TDS 684A, TDS 744A, and TDS 784A Digitizing Oscilloscopes und alle fabrikinstallierten Optionen in Übereinstimmung mit den Bestimmungen der Amtsblatt-Verfügung Vfg. 243/1991 und Zusatzverfügung 46/1992 funkentstört sind.

Der Deutschen Bundespost wurde das Inverkehrbringen dieses Gerätes angezeigt und die Berechtigung zur Überprüfung der Serie auf Einhalten der Bestimmungen eingeräumt.

TEKTRONIX

NOTICE to the user/operator: The German Postal Service requires that systems assembled by the operator/user of this instrument must

also comply with Postal Regulation, Vfg. 243/1991, Par. 2, Sect. 1. HINWEIS für den Benutzer/Betreiber: Die vom Betreiber zusammengestellte Anlage, innerhalb derer dieses Gerät eingesetzt wird, muß

ebenfalls den Voraussetzungen nach Par. 2, Ziff. 1 der Vfg. 243/1991, genügen.

NOTICE to the user/operator: The German Postal Service requires that this equipment, when used in a test setup, may only be

operated if the requirements of Postal Regulation, Vfg. 243/1991, Par. 2, Sect. 1.8.1 are complied with. HINWEIS für den Benutzer/Betreiber: Dieses Gerät darf in Meßaufbauten nur betrieben werden, wenn die Voraussetzungen des Par. 2, Ziff. 1.

8.1 der Vfg. 243/1991 eingehalten werden.

EC Declaration of Conformity

Tektronix Holland N.V. Marktweg 73A 8444 AB Heerenveen The Netherlands

declare under sole responsibility that the

TDS 684A, TDS 744A, and TDS 784A Digitizing Oscilloscopes

meet the intent of Directive 89/336/EEC for Electromagnetic Compatibility. Compliance was demonstrated to the following specifications as listed in the official Journal of the European Communities:

EN 50081–1 Emissions:

EN 55022 Radiated, Class B EN 55022 Radiated, Class B EN 60555–2 Power Harmonics

EN 50082–1 Immunity:

IEC 801–2 Electrostatic Discharge IEC 801–3 RF Radiated IEC 801–4 Fast Transients IEC 801–5 Surge

Getting Started

Operating Basics

General Safety Summary ix. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Preface xiii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Related Manuals xiii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Conventions xiv. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Default Model xiv. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Product Description 1–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Product Specification 1–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Start Up 1–3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Preparation 1–3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Putting into Service 1–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Overview 2–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Operating Interface Maps 2–3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Tutorial 2–9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Setting Up for the Examples 2–9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Example 1: Displaying a Waveform 2–13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Example 2: Displaying Multiple Waveforms 2–15. . . . . . . . . . . . . . . . . . . . . . . . . . . .

Example 3: T aking Automated Measurements 2–19. . . . . . . . . . . . . . . . . . . . . . . . . .

Example 4: Saving Setups 2–24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Reference

Overview 3–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Acquiring and Displaying Waveforms 3–3. . . . . . . . . . . . . . . . . . . . . . . . .

Coupling Waveforms to the Oscilloscope 3–3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Setting up Automatically: Autoset and Reset 3–5. . . . . . . . . . . . . . . . . . . . . . . . . . .

Selecting Channels 3–7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Scaling and Positioning Waveforms 3–9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Choosing an Acquisition Mode 3–16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Customizing the Display 3–27. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Customizing the Display Color 3–33. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Zooming on Waveforms 3–37. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Using InstaV u Acquisition Mode (TDS 700A Models Only) 3–43. . . . . . . . . . . . . . .

Using FastFrame (TDS 700A Models Only) 3–46. . . . . . . . . . . . . . . . . . . . . . . . . . . .

Triggering on Waveforms 3–49. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Triggering Concepts 3–49. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Triggering from the Front Panel 3–53. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Triggering on a Waveform Edge 3–57. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Triggering Based on Logic 3–60. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Triggering on Pulses 3–70. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

TDS 684A, TDS 744A, & TDS 784A User Manual

Table of Contents

Delayed Triggering 3–80. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Measuring Waveforms 3–87. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

T aking Automated Measurements 3–87. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

T aking Cursor Measurements 3–97. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

T aking Graticule Measurements 3–101. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Optimizing Measurement Accuracy: SPC and Probe Cal 3–102. . . . . . . . . . . . . . . . . .

Saving Waveforms and Setups 3–111. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Saving and Recalling Setups 3–1 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Saving and Recalling Waveforms 3–114. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Managing the File System 3–117. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Printing a Hardcopy 3–120. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Communicating with Remote Instruments 3–128. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Determining Status and Accessing Help 3–133. . . . . . . . . . . . . . . . . . . . . . . .

Displaying Status 3–133. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Displaying Help 3–135. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Using Features for Advanced Applications 3–137. . . . . . . . . . . . . . . . . . . . . .

Limit Testing 3–137. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Waveform Math 3–142. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Fast Fourier Transforms 3–144. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Waveform Differentiation 3–161. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Waveform Integration 3–165. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Appendices

Glossary Index

Appendix A: Options and Accessories A–1. . . . . . . . . . . . . . . . . . . . . . . . . .

Appendix B: Algorithms B–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Appendix C: Packaging for Shipment C–1. . . . . . . . . . . . . . . . . . . . . . . . . .

Appendix D: Factory Initialization Settings D–1. . . . . . . . . . . . . . . . . . . . .

Appendix E: Probe Selection E–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

TDS 684A, TDS 744A, & TDS 784A User Manual

List of Figures

Table of Contents

Figure 1–1: Rear Panel Controls Used in Start Up 1–4. . . . . . . . . . . . . . .

Figure 1–2: ON/STBY Button 1–5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 2–1: Connecting a Probe for the Examples (P6245 shown) 2–9. .

Figure 2–2: SETUP Button Location 2–10. . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 2–3: The Setup Menu 2–10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 2–4: Trigger Controls 2–11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 2–5: The Display After Factory Initialization 2–12. . . . . . . . . . . . .

Figure 2–6: The VERTICAL and HORIZONTAL Controls 2–13. . . . . . .

Figure 2–7: TRIGGER Controls 2–14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 2–8: AUTOSET Button Location 2–14. . . . . . . . . . . . . . . . . . . . . . . .

Figure 2–9: The Display After Pressing Autoset 2–15. . . . . . . . . . . . . . . . .

Figure 2–10: Display Signals Requiring Probe Compensation 2–15. . . . . .

Figure 2–11: The Channel Buttons and Lights 2–16. . . . . . . . . . . . . . . . . . .

Figure 2–12: The Vertical Main Menu and Coupling Side Menu 2–17. . . .

Figure 2–13: The Menus After Changing Channels 2–18. . . . . . . . . . . . . .

Figure 2–14: Measure Main Menu and Select Measurement

Side Menu 2–20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 2–15: Four Simultaneous Measurement Readouts 2–21. . . . . . . . .

Figure 2–16: General Purpose Knob Indicators 2–22. . . . . . . . . . . . . . . . .

Figure 2–17: Snapshot of Channel 1 2–23. . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 2–18: Save/Recall Setup Menu 2–25. . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–1: How Probe Compensation Affects Signals 3–4. . . . . . . . . . . .

Figure 3–2: P6139A Probe Adjustment 3–4. . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–3: The Channel Readout 3–8. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–4: Waveform Selection Priority 3–9. . . . . . . . . . . . . . . . . . . . . . .

Figure 3–5: Scaling and Positioning 3–10. . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–6: Vertical Readouts and Channel Menu 3–11. . . . . . . . . . . . . . .

Figure 3–7: Record View and Time Base Readouts 3–13. . . . . . . . . . . . . . .

Figure 3–8: Horizontal Controls 3–14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–9: Acquisition: Input Analog Signal, Sample,

and Digitize 3–17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–10: Several Points May be Acquired for Each

Point Used 3–17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

TDS 684A, TDS 744A, & TDS 784A User Manual

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Table of Contents

Figure 3–11: Real-Time Sampling 3–17. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–12: Equivalent-Time Sampling 3–18. . . . . . . . . . . . . . . . . . . . . . .

Figure 3–13: How the Acquisition Modes Work 3–21. . . . . . . . . . . . . . . . .

Figure 3–14: Acquisition Menu and Readout 3–23. . . . . . . . . . . . . . . . . . . .

Figure 3–15: Acquire Menu — Stop After 3–25. . . . . . . . . . . . . . . . . . . . . .

Figure 3–16: Aliasing 3–27. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–17: Display Menu — Style 3–29. . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–18: Trigger Point and Level Indicators 3–30. . . . . . . . . . . . . . . . .

Figure 3–19: Display Menu — Setting 3–33. . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–20: Display Menu — Palette Colors 3–35. . . . . . . . . . . . . . . . . . .

Figure 3–21: Display Menu — Map Reference Colors 3–36. . . . . . . . . . . .

Figure 3–22: Display Menu — Restore Colors 3–37. . . . . . . . . . . . . . . . . . .

Figure 3–23: Zoom Mode with Horizontal Lock Set to None 3–39. . . . . . .

Figure 3–24: Dual Window (Preview) Mode 3–41. . . . . . . . . . . . . . . . . . . . .

Figure 3–25: Dual Zoom — Shown in Dual Window (Preview)

Mode 3–42. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–26: Normal DSO Acquisition and Display Mode Versus InstaVu

Mode 3–44. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–27: InstaVu Display 3–45. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–28: Fast Frame 3–46. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–29: Horizontal Menu — FastFrame Setup 3–47. . . . . . . . . . . . . .

Figure 3–30: Triggered Versus Untriggered Displays 3–49. . . . . . . . . . . . .

Figure 3–31: Trigger Holdoff Time Ensures Valid Triggering 3–52. . . . . .

Figure 3–32: Slope and Level Controls Help Define the Trigger 3–53. . . .

Figure 3–33: TRIGGER Controls and Status Lights 3–54. . . . . . . . . . . . . .

Figure 3–34: Example Trigger Readouts — Edge Trigger

Selected 3–56. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–35: Record View, Trigger Position, and Trigger Level Bar

Readouts 3–56. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–36: Edge Trigger Readouts 3–57. . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–37: Main Trigger Menu — Edge Type 3–58. . . . . . . . . . . . . . . . .

Figure 3–38: Violation Zones for Setup/Hold Triggering 3–63. . . . . . . . . .

Figure 3–39: Logic Trigger Readouts — State Class Selected 3–64. . . . . .

Figure 3–40: Logic Trigger Menu 3–65. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–41: Logic Trigger Menu — Time Qualified TRUE 3–67. . . . . . .

Figure 3–42: Triggering on a Setup/Hold Time Violation 3–70. . . . . . . . . .

Figure 3–43: Pulse Trigger Readouts 3–71. . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–44: Main Trigger Menu — Glitch Class 3–73. . . . . . . . . . . . . . . .

Figure 3–45: Main Trigger Menu — Runt Class 3–75. . . . . . . . . . . . . . . . .

TDS 684A, TDS 744A, & TDS 784A User Manual

Table of Contents

Figure 3–46: Main Trigger Menu — Slew Rate Class 3–79. . . . . . . . . . . . .

Figure 3–47: Delayed Runs After Main 3–81. . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–48: Delayed Triggerable 3–81. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–49: How the Delayed Triggers Work 3–82. . . . . . . . . . . . . . . . . . .

Figure 3–50: Delayed Trigger Menu 3–84. . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–51: Graticule, Cursor and Automated Measurements 3–87. . . .

Figure 3–52: Measurement Readouts 3–90. . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–53: Measure Menu 3–91. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–54: Measure Menu — Gating 3–92. . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–55: Measure Menu — Reference Levels 3–93. . . . . . . . . . . . . . . .

Figure 3–56: Measure Delay Menu — Delay To 3–94. . . . . . . . . . . . . . . . . .

Figure 3–57: Snapshot Menu and Readout 3–96. . . . . . . . . . . . . . . . . . . . . .

Figure 3–58: Cursor Types 3–97. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–59: Cursor Modes 3–98. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–60: H Bars Cursor Menu and Readouts 3–99. . . . . . . . . . . . . . . .

Figure 3–61: Paired Cursor Menu and Readouts 3–100. . . . . . . . . . . . . . . .

Figure 3–62: Performing a Signal Path Compensation 3–104. . . . . . . . . . . .

Figure 3–63: Probe Cal Menu and Gain Compensation Display 3–106. . . .

Figure 3–64: Re-use Probe Calibration Data Menu 3–108. . . . . . . . . . . . . . .

Figure 3–65: Save/Recall Setup Menu 3–112. . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–66: Save Waveform Menu 3–115. . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–67: More Menu 3–116. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–68: File Utilities 3–118. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–69: File System — Labeling Menu 3–119. . . . . . . . . . . . . . . . . . . . .

Figure 3–70: Utility Menu — System I/O 3–122. . . . . . . . . . . . . . . . . . . . . . .

Figure 3–71: Hardcopy Formats 3–123. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–72: Date and Time Display 3–124. . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–73: Connecting the Oscilloscope Directly to the

Hardcopy Device 3–125. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–74: Connecting the Oscilloscope and

Hardcopy Device Via a PC 3–127. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–75: Typical GPIB Network Configuration 3–129. . . . . . . . . . . . . .

Figure 3–76: Stacking GPIB Connectors 3–130. . . . . . . . . . . . . . . . . . . . . . .

Figure 3–77: Connecting the Oscilloscope to a Controller 3–131. . . . . . . . .

Figure 3–78: Utility Menu 3–132. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–79: Status Menu — System 3–134. . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–80: Banner Display 3–134. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–81: Initial Help Screen 3–135. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–82: Comparing a Waveform to a Limit Template 3–137. . . . . . . .

TDS 684A, TDS 744A, & TDS 784A User Manual

Table of Contents

Figure 3–83: Acquire Menu — Create Limit Test Template 3–139. . . . . . . .

Figure 3–84: More Menu 3–142. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–85: Dual Waveform Math Main and Side Menus 3–143. . . . . . . .

Figure 3–86: System Response to an Impulse 3–146. . . . . . . . . . . . . . . . . . . .

Figure 3–87: Define FFT Waveform Menu 3–147. . . . . . . . . . . . . . . . . . . . . .

Figure 3–88: FFT Math Waveform in Math1 3–148. . . . . . . . . . . . . . . . . . . .

Figure 3–89: Cursor Measurement of an FFT Waveform 3–150. . . . . . . . . .

Figure 3–90: Waveform Record vs. FFT Time Domain Record 3–151. . . . .

Figure 3–91: FFT Time Domain Record vs.

FFT Frequency Domain Record 3–152. . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–92: How Aliased Frequencies Appear in an FFT 3–156. . . . . . . . .

Figure 3–93: Windowing the FFT Time Domain Record 3–159. . . . . . . . . .

Figure 3–94: FFT Windows and Bandpass Characteristics 3–161. . . . . . . .

Figure 3–95: Derivative Math Waveform 3–163. . . . . . . . . . . . . . . . . . . . . . .

Figure 3–96: Peak-Peak Amplitude Measurement of a

Derivative Waveform 3–164. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–97: Integral Math Waveform 3–167. . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–98: H Bars Cursors Measure an Integral Math Waveform 3–168

Figure B–1: MCross Calculations B–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure B–2: Fall Time B–7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure B–3: Rise Time B–11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure B–4: Choosing Minima or Maxima to Use for

Envelope Measurements B–13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure E–1: Typical High Voltage Probes E–2. . . . . . . . . . . . . . . . . . . . . . .

Figure E–2: A6303 Current Probe Used in the AM 503S Opt. 03 E–4. . .

TDS 684A, TDS 744A, & TDS 784A User Manual

List of Tables

Table of Contents

Table 1–1: Key Features of the TDS Oscilloscopes 1–1. . . . . . . . . . . . . . .

Table 1–2: Fuse and Fuse Cap Part Numbers 1–5. . . . . . . . . . . . . . . . . . .

Table 3–1: Autoset Defaults 3–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 3–2: How Interleaving Affects Sample Rate 3–19. . . . . . . . . . . . . . . .

Table 3–3: Additional Resolution Bits 3–22. . . . . . . . . . . . . . . . . . . . . . . . .

Table 3–4: TDS 744A Sampling Mode Selection

(When Fit to Screen is Off) 3–24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 3–5: TDS 784A Sampling Mode Selection

(When Fit to Screen is Off) 3–25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 3–6: XY Format Pairs 3–32. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 3–7: Pattern and State Logic 3–62. . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 3–8: Pulse Trigger Definitions 3–71. . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 3–9: Measurement Definitions 3–88. . . . . . . . . . . . . . . . . . . . . . . . . .

Table 3–10: Probe Cal Status 3–109. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table A–1: Options A–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table A–2: Standard Accessories A–3. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table A–3: Optional Accessories A–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table A–4: Accessory Software A–5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table D–1: Factory Initialization Defaults D–1. . . . . . . . . . . . . . . . . . . . . .

TDS 684A, TDS 744A, & TDS 784A User Manual

vii

Table of Contents

viii

TDS 684A, TDS 744A, & TDS 784A 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.

Only qualified personnel should perform service procedures.

Injury Precautions

Use Proper Power Cord

Avoid Electric Overload

Ground the Product

Do Not Operate Without

Covers

Use Proper Fuse

Do Not Operate in

Wet/Damp Conditions

Do Not Operate in

Explosive Atmosphere

To avoid fire hazard, use only the power cord specified for this product.

To avoid electric shock or fire hazard, do not apply a voltage to a terminal that is outside the range specified for that terminal.

This product is grounded through the grounding conductor of the power cord. To avoid electric shock, the grounding conductor must be connected to earth ground. Before making connections to the input or output terminals of the product, ensure that the product is properly grounded.

To avoid electric shock or fire hazard, do not operate this product with covers or panels removed.

To avoid fire hazard, use only the fuse type and rating specified for this product.

To avoid electric shock, do not operate this product in wet or damp conditions.

To avoid injury or fire hazard, do not operate this product in an explosive atmosphere.

Keep Probe Surface Clean

To avoid electric shock and erroneous readings, keep probe surface clean.

Product Damage Precautions

Use Proper Power Source

TDS 684A, TDS 744A, & TDS 784A User Manual

Do not operate this product from a power source that applies more than the voltage specified.

General Safety Summary

Provide Proper Ventilation

Do Not Operate With

Suspected Failures

Do Not Immerse in Liquids

To prevent product overheating, provide proper ventilation.

If you suspect there is damage to this product, have it inspected by qualified service personnel.

Clean the probe using only a damp cloth. Refer to cleaning instructions.

Safety Terms and Symbols

Terms in This Manual

These terms may appear in this manual:

WARNING. Warning statements identify conditions or practices that could result in injury or loss of life.

CAUTION. Caution statements identify conditions or practices that could result in damage to this product or other property.

Terms on the Product

These terms may appear on the product: DANGER indicates an injury hazard immediately accessible as you read the

marking. WARNING indicates an injury hazard not immediately accessible as you read the

marking. CAUTION indicates a hazard to property including the product.

TDS 684A, TDS 744A, & TDS 784A User Manual

General Safety Summary

Symbols on the Product

The following symbols may appear on the product:

DANGER

High Voltage

Certifications and Compliances

CSA Certified Power

Cords

CSA Certification includes the products and power cords appropriate for use in the North America power network. All other power cords supplied are approved for the country of use.

Protective Ground

(Earth) T erminal

ATTENTION

Refer to

Manual

Double

Insulated

TDS 684A, TDS 744A, & TDS 784A User Manual

General Safety Summary

xii

TDS 684A, TDS 744A, & TDS 784A User Manual

Preface

Related Manuals

This is the User Manual for the TDS 684A, TDS 744A, and TDS 784A Digitizing Oscilloscopes.

The chapter Getting Started briefly describes the TDS Oscilloscope, prepares you to install it, and tells you how to put it into service.

The chapter Operating Basics covers basic principles of the operation of the oscilloscope. The operating interface illustrations and the tutorial examples rapidly help you understand how your oscilloscope operates.

The chapter Reference teaches you how to perform specific tasks. See page 3–1 for a complete list of operating tasks covered in that chapter.

The Appendices provide an options listing, an accessories listing, and other useful information.

The following documents are related to the use or service of the oscilloscope.  The TDS Family Digitizing Oscilloscopes Programmer Manual (Tektronix

part number 070-8709-xx) describes using a computer to control the

oscilloscope through the GPIB interface.  The TDS 684A, TDS 744A, & TDS 784A Reference (Tektronix part number

070-8999-xx) gives you a quick overview of how to operate the oscilloscope.

 The TDS 684A, TDS 744A, & TDS 784A Performance Verification and

Specifications (Tektronix part number 070-8990-xx) tells how to verify the

performance of the oscilloscope and lists its specifications.  The TDS Family Option 05 Video Trigger Instruction Manual (Tektronix

part number 070-8748-xx) describes use of the video trigger option (for TDS

oscilloscopes equipped with that option only).  The TDS 684A, TDS 744A, & TDS 784A Service Manual (Tektronix part

number 070-8992-xx) provides information for maintaining and servicing

the oscilloscope to the module level.

TDS 684A, TDS 744A, & TDS 784A User Manual

xiii

Preface

Conventions

In this manual, you will find various procedures which contain steps of instructions for you to perform. To keep those instructions clear and consistent, this manual uses the following conventions:

 In procedures, names of front panel controls and menu labels appear in

boldface print.

 Names also appear in the same case (initial capitals or all uppercase) in the

manual as is used on the oscilloscope front panel and menus. Front panel names are all upper case letters, for example, VERTICAL MENU and CH 1.

 Instruction steps are numbered. The number is omitted if there is only one step.  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. Also, whether a name is a main menu or side menu item is clearly indicated: Press VERTICAL

MENU ➞ Coupling (main) ➞ DC (side) ➞ Bandwidth (main) ➞ 250 MHz (side).

) marks each transition between a

Default Model

Using the convention just described results in instructions that are graphically intuitive and simplifies procedures. For example, the instruction just given replaces these five steps:

1. Press the front panel button VERTICAL MENU.

2. Press the main-menu button Coupling.

3. Press the side-menu button DC.

4. Press the main-menu button Bandwidth.

5. Press the side-menu button 250 MHz.

Sometimes you may have to make a selection from a pop-up menu: Press TRIGGER MENU ➞ Type (main) ➞ Edge (pop-up). In this example, you repeatedly press the main menu button Type until Edge is highlighted in the pop-up menu.

This manual documents the TDS 684A, TDS 744A, and TDS 784A Digitizing Oscilloscopes. However, the TDS 684A display screen appears as the default screen wherever a display screen is illustrated in this manual. Also, this manual uses the name “TDS 700A” when providing information common to both the TDS 744A and TDS 784A model oscilloscopes.

xiv

TDS 684A, TDS 744A, & TDS 784A User Manual

Getting Started

Product Description

The Tektronix TDS Oscilloscope is a superb tool for acquiring, displaying, and measuring waveforms. Its performance addresses the needs of both benchtop lab and portable applications with the following features:

T able 1–1: Key Feature s of the TDS Oscilloscopes

Feature TDS 684A TDS 744A TDS 784A

Digitizing rate, maximum

Analog bandwidth 1 GHz 500 MHz 1 GHz Channels Four, each with 8-bit resolution Record lengths, maxi-

mum Acquisition modes Sample, envelope,

Display Color

5 GS/s on each channel simultaneously

15 K samples per channel

and average

Zoom, which allows you to magnify a waveform

2 GS/s 4 GS/s

Up to 50 K standard, up to 250 K (2 channels) and 500 K (1 channel) with Option 1M

Sample, envelope, average, high-resolution, and peak-detect

InstaVu

rates rivaling the fastest analog oscilloscopes

Color Dual Window Zoom, which shows a waveform

magnified and unmagnified on the same display

mode, which updates the display at

TDS 684A, TDS 744A, & TDS 784A User Manual

1–1

Product Description

Product Specification

T able 1–1: Key Feature s of the TDS Oscilloscopes (Cont.)

Feature TDS 784ATDS 744ATDS 684A

Trigger modes Include: edge, logic, and pulse. Video trigger, with option 05, modes

include: NTSC, SECAM, PAL, HDTV, and FlexFormat.

Storage 1.44 Mbyte, 3.5 inch, DOS 3.3-or-later floppy disk.

NVRAM storage for saving waveforms, hardcopies, and setups

I/O Full GPIB programmability.

Hardcopy output using GPIB, RS-232, or Centronics ports

The product specification is found in the technical reference TDS 684A, TDS 744A, & TDS 784A Performance Verification and Specifications that is

shipped as a standard accessory with the TDS Oscilloscope.

1–2

TDS 684A, TDS 744A, & TDS 784A User Manual

Start Up

Preparation

Before you use the TDS Oscilloscope, ensure that it is properly installed and powered on.

To ensure maximum accuracy for your most critical measurements, you should know about signal path compensation and the proper use of the probe you choose to use with your oscilloscope.

Signal Path Compensation

Recommended Probes

Probe Usage

Be sure you compensate your oscilloscope for the surrounding temperature. This action, called Signal Path Compensation (SPC), ensures maximum possible accuracy for your most critical measurements. See Signal Path Compensation on page 3–102 for a description of and operating information on this feature.

The TDS 744A Oscilloscope ships with four general-purpose, P6139A 500 MHz passive probes. The TDS 684A and TDS 784A Oscilloscopes ship without probes. To take advantage of the higher bandwidth of the TDS 684A and TDS 784A Oscilloscopes, order the P6245 Active Probe. See Appendix A: Options and Accessories in this manual for more information on optional-accessory probes for all three oscilloscope models.

Be sure you use the appropriate probe for the measurement. For instance, do not use the P6245 Active Probe to measure signals greater than ±8 volts or with more than ±10 volts of offset since errors in signal measurement will result. (See the User manual for the probe for more information.) Instead, use a passive probe, such as P6139A passive probe, that allows higher voltage measurements. The P6139A probe is for measurements up to ±500 volts.

CAUTION. Using the P6245 Active Probe to measure signals greater than

±40 volts may damage the probe.

Input Coupling

TDS 684A, TDS 744A, & TDS 784A User Manual

Be sure to choose the proper input coupling and impedance for the probe or other cabling you use to couple signals to your oscilloscope. You should read Input Impedance Considerations on page 3–5 for information needed to ensure proper coupling of your input signals.

1–3

Start Up

Putting into Service

To learn how to install, access the front panel, power on, do a self test, and power off the oscilloscope, do the following procedures:

Installation

To properly install and power on the oscilloscope, do the following steps:

1. Be sure you have the appropriate operating environment. Specifications for

temperature, relative humidity, altitude, vibrations, and emissions are included in the TDS 684A, TDS 744A, & TDS 784A Performance Verifica- tion and Specifications manual (Tektronix part number 070-8990-xx).

2. Leave space for cooling. Do this by verifying that the air intake and exhaust

holes on the sides of the cabinet (where the fan operates) are free of any airflow obstructions. Leave at least 5.1 cm (2 inches) free on each side.

WARNING. To avoid electrical shock, be sure that the power cord is disconnected before checking the fuse.

3. Check the fuse to be sure it is the proper type and rating (see Figure 1–1).

You can use either of two fuses. Each fuse requires its own cap (see Table

1–2). The oscilloscope is shipped with the UL approved fuse installed.

4. Check that you have the proper electrical connections. The oscilloscope

requires 90 to 250 VAC

, continuous range, 45 Hz to 440 Hz, and may

RMS

require up to 300 W.

5. Connect the proper power cord from the rear-panel power connector (see

Figure 1–1) to the power system.

1–4

Power Connector

Principal Power Switch

Fuse

Figure 1–1: Rear Panel Controls Used in Start Up

TDS 684A, TDS 744A, & TDS 784A User Manual

T able 1–2: Fuse and Fuse Cap Part Numbers

Fuse Cap

Fuse Fuse Part Number

0.25 inch × 1.25 inch (UL 198.6, 3AG): 6 A FAST, 250 V.

5 mm × 20 mm (IEC 127): 5 A (T), 250 V. 159-0210-00 200-2265-00

159-0013-00 200-2264-00

Part Number

Start Up

Front Cover Removal

Power On

To remove the front cover, grasp its left and right edges and snap it off of the front subpanel. (To reinstall it, align it to the front subpanel and snap it back on.)

To power on the oscilloscope, do the following steps:

1. Check that the rear-panel principal power switch is on (see Figure 1–1). The

principal power switch controls all AC power to the instrument.

2. If the oscilloscope is not powered on (the screen is blank), push the

front-panel ON/STBY button to toggle it on (see Figure 1–2).



ON/STBY Button

Figure 1–2: ON/STBY Button

TDS 684A, TDS 744A, & TDS 784A User Manual

1–5

Start Up

The ON/STBY button controls power to most of the instrument circuits. Power continues to go to certain parts even when this switch is set to STBY.

Once the oscilloscope is installed, it is typical to leave the principal power switch on and use the ON/STBY button instead of the power switch.

Self Test

Power Off

The oscilloscope automatically performs power-up tests each time it is turned on. It will come up with a display screen that states whether or not it passed the self test. To determine the self test results, check the screen. (If the self test passed, the status display screen will be removed after a few seconds.)

If the self test fails, call your local Tektronix Service Center. Depending on the type of failure, you may still be able to use the oscilloscope before it is serviced.

To power off the oscilloscope, toggle the ON/STBY switch.

1–6

TDS 684A, TDS 744A, & TDS 784A User Manual

Operating Basics

Overview

This chapter describes the basic concepts of operating the TDS Oscilloscope. Understanding the basic concepts of your oscilloscope will help you use it much more effectively.

The first section, Operating Interface Maps, quickly shows you how the oscilloscope controls are organized and where you can read about them. It also illustrates the general procedures for operating the menu system. This section includes the titles:

 Front Panel Map  Rear Panel Map  Display Map  To Operate a Menu  To Operate a Pop-Up Menu

The second section, Tutorial, contains example procedures that lead you through the fundamental tasks needed to display a waveform measurement. It also includes an example procedure that teaches you how to store a setup of the oscilloscope controls for later use. This section includes the following tutorial examples:

 Setting Up for the Examples  Example 1: Displaying a Waveform  Example 2: Displaying Multiple Waveforms  Example 3: Taking Automated Measurements  Example 4: Saving Setups

To explore these topics in more depth and to read about topics not covered in this section, see Reference. A list of the topics covered begins on Page 3–1.

TDS 684A, TDS 744A, & TDS 784A User Manual

2–1

Overview

2–2

TDS 684A, TDS 744A, & TDS 784A User Manual

Operating Interface Maps

This section contains illustrations, or maps, of the display, the front and rear panels, and the menu system of the TDS Oscilloscope. These maps will help you understand and operate the oscilloscope. This section also contains a visual guide to using the menu system.

Front Panel Map — Left Side

File System,

page 3–117



Side Menu Buttons, page 2–7

ON/STBY Switch,

page 1–5

Main Menu Buttons,

TDS 684A, TDS 744A, & TDS 784A User Manual

CLEAR MENU Removes Menus from the Display

page 2–7

2–3

Operating Interface Maps

Front Panel Map — Right Side

Measurement System, page 3–87

Cursor Measurements, page 3–97

Saving and Recalling

Waveforms, page 3–114

File System, page 3–117

Autoset, page 3–5

Help, page 3–135

Status, page 3–133

Saving and Recalling

Setups, page 3–111

Selecting Channels,

page 3–7

Waveform Math,

page 3–142

Hardcopy, page 3–120

File System, page 3–117

Acquisition Modes, page 3–20

Cursor Measurements, page 3–97

InstaVu, page 3–43 (TDS 700A models only)

Color, page 3–33

Display Settings, page 3–27 Remote Communication, page 3–128

Probe Calibration, page 3–104

Vertical Controls,

page 3–10

2–4

Zoom, page 3–37

Horizontal Controls,

page 3–13

Ground

Triggering, page 3–49 Delay Triggering, page 3–80 Edge Triggering, page 3–57 Logic Triggering, page 3–60 Pulse Triggering, page 3–70

TDS 684A, TDS 744A, & TDS 784A User Manual

Rear Panel Map

Operating Interface Maps

Principal Power

Switch,

page 1–5

Fuse,

page 1–4

Centronics Connector

Serial Number

RS-232 Connector

Power Connector,

page 1–4

GPIB Connector,

page 3–128

Rear Panel Connectors Security Bracket

SIGNAL OUTPUT –

(Provides Analog Signal Output)

AUX TRIGGER INPUT –

(Provides Auxiliary Trigger Signal Input)

MAIN TRIGGER OUTPUT –

(Provides Main Trigger (TTL) Output)

DELAYED TRIGGER OUTPUT –

(Provides Delayed Trigger (TTL) Output)

VGA Output

TDS 684A, TDS 744A, & TDS 784A User Manual

2–5

Operating Interface Maps

Display Map

acquisition page 3–23

Trigger level on

waveform (may be an

arrow at right side of

screen instead of a bar).

The

status,

Indicates position of

vertical bar cursors in the

waveform record,

page 3–100

Shows what part of the waveform

record is displayed, page 3–13

Trigger

position (T),

page 3–56

The value entered with

the general purpose

or keypad.

knob

The waveform

record icon

When present, the general

purpose knob makes coarse

adjustments; when absent,

fine adjustments.

Cursor measurements, page 3–97

2–6

Channel level and

waveform source.

Vertical scale,

page 3–10

The main menu with

choices of major actions

The side menu with choices of specific actions.

Trigger parameters, page 3–55

Horizontal scale and time

base type, page 3–13

TDS 684A, TDS 744A, & TDS 784A User Manual

To Operate a Menu

1 Press front-panel menu button. (Press SHIFT first if button label is blue.)



Operating Interface Maps

2 Press one of these buttons to select from main menu.

3 Press one of these buttons to select from side menu (if displayed).

4 If side menu item has an adjustable value (shown in reverse video), adjust it with the general purpose knob or keypad.

TDS 684A, TDS 744A, & TDS 784A User Manual

2–7

Operating Interface Maps

To Operate a Pop-Up Menu



2–8

Press to display pop-up menus.

Press it again

to make selection.

Alternatively, press SHIFT first to make

selection in the opposite direction.

A pop-up selection changes the other

main menu titles.

TDS 684A, TDS 744A, & TDS 784A User Manual

Press here to

remove menus from

screen.

Tutorial

This section quickly makes you acquainted with some of the fundamental operations required to use the TDS Oscilloscope to take measurements. Start this tutorial by doing Setting Up for the Examples on this page.

Setting Up for the Examples

Perform the following tasks to connect input signals to the TDS Oscilloscope, to reset it, and to become acquainted with its display screen. Once completed, these tasks ready the oscilloscope for use in the examples that follow.

Connect the Input Signal

Remove all probes and signal inputs from the input BNC connectors along the lower right of the front panel. Then, using an appropriate probe (such as the P6245), connect from the CH 1 connector of the oscilloscope to the PROBE COMPENSATION connectors. (See Figure 2–1.)

Signal Gnd

Figure 2–1: Connecting a Probe for the Examples (P6245 shown)

TDS 684A, TDS 744A, & TDS 784A User Manual

2–9

Tutorial

NOTE. See Appendix A: Options and Accessories for optional probes you can order and use with this product.

Reset the Oscilloscope

SETUP Button

Do the following steps to reset the oscilloscope to a known factory default state before doing the examples. (You can reset the oscilloscope anytime you begin a new task and need to “start fresh” with known default settings.)

1. Press the save/recall SETUP button to display the Setup menu. (See

Figure 2–2.)

Figure 2–2: SETUP Button Location

The oscilloscope displays main menus along the bottom of the screen. Figure 2–3 shows the Setup main menu.

2–10

OK Confirm Factory Init

Menu Item and Button

Recall Factory Setup

Menu Item and Button

Figure 2–3: The Setup Menu

2. Press the button directly below the Recall Factory Setup menu item.

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The display shows side menus along the right side of the screen. The buttons

to select these side menu items are to the right of the side menu.

Because an accidental instrument reset could destroy a setup that took a long

time to create, the oscilloscope asks you to verify the Recall Factory Setup

selection. (See Figure 2–3.)

3. Press the button to the right of the OK Confirm Factory Init side menu item.

NOTE. This manual uses the following notation to represent the sequence of selections you made in steps 1, 2 and 3: Press save/recall SETUP ➞ Recall

Factory Setup (main) ➞ OK Confirm Factory Init (side).

Note that a clock icon appears on screen. The oscilloscope displays this icon

when performing operations that take longer than several seconds.

4. Press SET LEVEL TO 50% (see Figure 2–4) to be sure the oscilloscope

triggers on the input signal.

SET LEVEL TO 50% Button

Figure 2–4: Trigger Controls

Examine the Display

Elements

TDS 684A, TDS 744A, & TDS 784A User Manual

Read the following information to become familiar with the oscilloscope display before doing the examples.

Figure 2–5 shows the display that results from the oscilloscope reset. There are several important points to observe:

 The trigger level bar shows that the waveform is triggered at a level near

50% of its amplitude (from step 4).  The trigger position indicator shows that the trigger position of the

waveform is located at the horizontal center of the graticule.

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 The channel reference indicator shows the vertical position of channel 1

with no input signal. This indicator points to the ground level for the channel when its vertical offset is set to 0 V in the vertical menu; when vertical offset is not set to 0 V, it points to the vertical offset level.

 The trigger readout shows that the oscilloscope is triggering on channel 1

(Ch1) on a rising edge, and that the trigger level is about 200–300 mV.

 The time base readout shows that the main time base is set to a horizontal

scale of 500 s/div.

 The channel readout indicates that channel 1 (Ch1) is displayed with DC

coupling. (In AC coupling, ~ appears after the volts/div readout.) The oscilloscope always displays channel 1 at reset.

Trigger Level Bar

Trigger Position Indicator

Channel Reference Indicator

Trigger Readout

Time Base Readout

Channel Readout

Figure 2–5: The Display After Factory Initialization

Right now, the channel, time base, and trigger readouts appear in the graticule area because a menu is displayed. You can press the CLEAR MENU button at any time to remove any menus and to move the readouts below the graticule.

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Example 1: Displaying a Waveform

The TDS Oscilloscope provides front panel knobs for you to adjust a waveform, or it can automatically set up its controls to display a waveform. Do the following tasks to learn how to adjust a waveform and how to autoset the TDS Oscilloscope.

Tutorial

Adjust the Waveform

Display

The display shows the probe compensation signal. It is a 1 kHz square wave of approximately 0.5 V amplitude.

Figure 2–6 shows the main VERTICAL and HORIZONTAL sections of the front panel. Each has SCALE and POSITION knobs. Do the following steps to adjust the size and placement of the waveform using the front-panel knobs:

1. Turn the vertical SCALE knob clockwise. Observe the change in the

displayed waveform and the channel readout at the bottom of the display.

Figure 2–6: The VERTICAL and HORIZONTAL Controls

2. Turn the vertical POSITION knob first one direction, and then the other.

Observe the change in the displayed waveform. Then return the waveform to

the center of the graticule.

3. Turn the horizontal SCALE knob one click clockwise. Observe the time

base readout at the bottom of the display. The time base should be set to

200 s/div now, and you should see two complete waveform cycles on the

display.

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Autoset the Oscilloscope

MAIN LEVEL Knob

When you first connect a signal to a channel and display it, the signal displayed may not be scaled and triggered correctly. Use the autoset function and you should quickly get a meaningful display.

You should have a stable display of the probe compensation waveform from the last step. Do the following steps to first create an unstable display and then to autoset the display:

1. To create an unstable display, slowly turn the trigger MAIN LEVEL knob

(see Figure 2–7) first one direction, and then the other. Observe what happens when you move the trigger level above the highest part of the waveform. Leave the trigger level in that untriggered state.

AUTOSET Button

Figure 2–7: TRIGGER Controls

2. Press AUTOSET (see Figure 2–8) and observe the stable waveform display.

Figure 2–8: AUTOSET Button Location

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Figure 2–9 shows the display after pressing AUTOSET. If necessary, you can adjust the waveform now by using the knobs discussed earlier in this example.

Figure 2–9: The Display After Pressing Autoset

NOTE. If you are using a passive probe, such as the P6139A probe, the corners on your displayed signal may look rounded or pointed. (See Figure 2–10.) If so, then you may need to compensate your probe. See To Compensate Passive Probes on page 3–3.

Figure 2–10: Display Signals Requiring Probe Compensation

Example 2: Displaying Multiple Waveforms

The TDS Oscilloscope can display up to four channels, three math waveforms, and four reference waveforms at one time. Do the following tasks to learn how to display and control more than one waveform at a time.

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Add a Waveform

The VERTICAL section of the front panel contains the channel selection buttons. These buttons are CH 1, CH 2, CH 3, CH 4, and MORE. (See Figure 2–11.)

Figure 2–11: The Channel Buttons and Lights

Each of the channel (CH) buttons has a light behind its label. Right now, the CH 1 light is on. That light indicates that the vertical controls are set to adjust channel 1. Do the following steps to add a waveform to the display:

1. If you are not continuing from the previous example, follow the instructions

on page 2–9 under the heading Setting Up for the Examples.

2. Press SETUP ➞ Recall Factory Setup (main) ➞ OK Confirm Factory

Init (side).

3. Press AUTOSET.

4. Press CH 2.

The display shows a second waveform, which represents the signal on channel 2. Since there is nothing connected to the CH 2 input connector, this waveform is a flat line. There are several other important things to observe:

 The channel readout on the display now shows the settings for both Ch1

and Ch2.

 There are two channel indicators at the left edge of the graticule. Right

now, they overlap.

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 The light above the CH 2 button is now on, and the CH 1 light is off.

Because the knobs control only one channel at a time, the vertical controls are now set to adjust channel 2.

 The trigger readout still indicates that the trigger is detecting trigger

events on Ch1. The trigger source is not changed simply by adding a channel. (You can change the trigger source by using the TRIGGER MENU button to display the trigger menu.)

5. Turn the vertical POSITION knob clockwise to move the channel 2

waveform up on the graticule. You will notice that the channel reference

indicator for channel 2 moves with the waveform.

6. Press VERTICAL MENU ➞ Coupling (main).

The VERTICAL MENU button displays a menu that gives you control over

many vertical channel parameters. (See Figure 2–12.) Although there can be

more than one channel displayed, the vertical menu and buttons only adjust

the selected channel.

Tutorial

Ch2 Reference Indicator

Each menu item in the Vertical menu displays a side menu. Right now, the

Coupling item in the main menu is highlighted, which means that the side

menu shows the coupling choices. At the top of the side menu, the menu title

shows the channel affected by the menu choices. That channel always

matches the lighted channel button.

Side Menu Title

Figure 2–12: The Vertical Main Menu and Coupling Side Menu

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7. Press  (side) to toggle the selection to 50 . That changes the input

coupling of channel 2 from 1 MW to 50 W. The channel readout for channel 2 (near the bottom of the graticule) now shows an W indicator.

Assign Controls to

Another Channel

Pressing a channel (CH) button sets the vertical controls to that channel. It also adds the channel to the display if that waveform is not already displayed. To explore assigning controls to different channels, do the following steps:

1. Press CH 1.

Observe that now the side menu title shows Ch1. (See Figure 2–13), and that the light above CH 1 is lighted. The highlighted menu item in the side menu has changed from the 50 W channel 2 setting to the 1 MW impedance setting of channel 1.

2. Press CH 2 ➞  (side) to toggle the selection to 1M. That returns the

coupling impedance of channel 2 to its initial state.

Side Menu Title

Remove a Waveform

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Figure 2–13: The Menus After Changing Channels

Pressing the WAVEFORM OFF button removes the waveform for the currently selected channel. If the waveform you want to remove is not already selected, select that channel using the channel (CH) button.

1. Press WAVEFORM OFF (under the vertical SCALE knob).

TDS 684A, TDS 744A, & TDS 784A User Manual

Since the CH 2 light was on when you pressed the WAVEFORM OFF

button, the channel 2 waveform was removed.

The channel (CH) lights now indicate channel 1. Channel 1 has become the

selected channel. When you remove the last waveform, all the CH lights are

turned off.

2. Press WAVEFORM OFF again to remove the channel 1 waveform.

Example 3: Taking Automated Measurements

The TDS Oscilloscope can measure many waveform parameters automatically and read out the results on screen. Do the following tasks to discover how to set up the oscilloscope to measure waveforms automatically.

Tutorial

Display Measurements

Automatically

To use the automated measurement system, you must have a stable display of your signal. Also, the waveform must have all the segments necessary for the measurement you want. For example, a rise time measurement requires at least one rising edge, and a frequency measurement needs at least one complete cycle. To take automated measurements, do the following steps:

1. If you are not continuing from the previous example, follow the instructions

on page 2–9 under the heading Setting Up for the Examples.

2. Press SETUP ➞ Recall Factory Setup (main) ➞ OK Confirm Factory

Init (side).

3. Press AUTOSET.

4. Press MEASURE to display the Measure main menu. (See Figure 2–14.)

5. If it is not already selected, press Select Measrmnt (main). The readout for

that menu item indicates which channel the measurement will be taken from.

All automated measurements are made on the selected channel.

The Select Measurement side menu lists some of the measurements that can

be taken on waveforms. There are many different measurements available;

up to four can be taken and displayed at any one time. Pressing the button

next to the –more– menu item brings up the other measurement selections.

6. Press Frequency (side). If the Frequency menu item is not visible, press

–more– (side) repeatedly until the Frequency item appears. Then press

Frequency (side).

Observe that the frequency measurement appears within the right side of the

graticule area. The measurement readout includes the notation Ch1, meaning

that the measurement is taken on the channel 1 waveform. (To take a

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measurement on another channel, select that channel, and then select the measurement.)

Remove Measurement

Readouts

Figure 2–14: Measure Main Menu and Select Measurement Side Menu

7. Press Positive Width (side) ➞ –more– (side) ➞ Rise Time (side) ➞

Positive Duty Cycle (side).

All four measurements are displayed. Right now, they cover a part of the graticule area, including the displayed waveforms.

8. To move the measurement readouts outside the graticule area, press CLEAR MENU. (See Figure 2–15.)

Use the Measure menu to remove waveforms you no longer want. To remove a measurement individually (you can also remove them, as a group), do the following step:

1. Press MEASURE ➞ Remove Measrmnt (main) ➞ Measurement 1, Measurement 2, and Measurement 4 (side) to remove those measurements.

Leave the rise time measurement displayed.

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Change the Measurement

Reference Levels

Press to Remove Menus From Screen

Figure 2–15: Four Simultaneous Measurement Readouts

By default, the measurement system will use the 10% and 90% levels of the waveform for taking the rise time measurement. You can change these values to other percentages or change them to absolute voltage levels.

To examine the current values, press Reference Levels (main) ➞ High Ref (side).

The General Purpose Knob. The general purpose knob, the large knob, is now set to adjust the high reference level (Figure 2–16.)

There are several important things to observe on the screen:  The knob icon appears at the top of the screen. The knob icon indicates that

the general purpose knob has just been set to adjust a parameter.

 The upper right corner of the screen shows the readout High Ref: 90%.  The High Ref side menu item is highlighted, and a box appears around the

90% readout in the High Ref menu item. The box indicates that the general purpose knob is currently set to adjust that parameter.

Turn the general purpose knob left and right, and then use it to adjust the high level to 80%. That sets the high measurement reference to 80%.

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Hint: To make large changes quickly with the general purpose knob, press the SHIFT button before turning the knob. When the light above the SHIFT button is on and the display says Coarse Knobs in the upper-right corner, the general purpose knob speeds up significantly.

General Purpose Knob

Setting and Readout

General Purpose Knob Icon

Highlighted Menu Item with Boxed Readout Value

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Figure 2–16: General Purpose Knob Indicators

The Numeric Keypad. Any time the general purpose knob is set to adjust a

numeric parameter, you can enter the value as a number using the keypad instead of using the knob. Always end the entry of a number by pressing ENTER (

The numeric keypad also provides multipliers for engineering exponents, such as m for milli, M for mega, and  for micro. To enter these multiplier values, press the SHIFT button, and then press the multiplier.

1. Press Low Ref (side).

2. On the numeric keypad, press the 2, the 0, and the ENTER (

) buttons, which sets the low measurement reference to 20%. Observe that the rise-time value has changed.

3. Press Remove Measrmnt (main) ➞ All Measurements (side). That returns

the display to its original state.

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Displaying a Snapshot of

Automated Measurements

You have seen how to display up to four individual automated measurements on screen. You can also pop up a display of almost all of the automated measurements available in the Select Measrmnts side menus. This snapshot of measurements is taken on the waveform currently selected using the channel selection buttons.

As when displaying individual measurements, you must have a stable display of your signal, and that signal must have all the segments necessary for the measurement you want.

1. Press Snapshot (main) to pop up a snapshot of all available single waveform

measurements. (See Figure 2–17.) The snapshot display includes the label Ch 1, meaning that the measure-

ments displayed are taken on the channel 1 waveform. You take a snapshot of a waveform in another channel by first selecting that channel using the channel selection buttons.

The snapshot measurements do not continuously update. Snapshot executes a one-time capture of all measurements and does not update those measurements unless it is performed again.

Figure 2–17: Snapshot of Channel 1

2. Press Again (side) to do another snapshot and update the snapshot measure-

ments.

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3. Press Remove Measrmnt (main) to remove the snapshot display. (You can

Example 4: Saving Setups

The TDS Oscilloscope can save its controls settings and recall them later to quickly re–establish a setup. It provides ten storage locations to store up to ten setups. It also provides a file system, so that you can also save setups to a floppy disk. Do the following procedures to learn how to save, and then recall, a setup.

NOTE. Besides being able to save several complete setups, the oscilloscope remembers all the parameter settings when you power it off. That feature lets you power on and continue where you left off without having to reconstruct the setup in effect when you powered off the oscilloscope.

also press CLEAR MENU, but a new snapshot will be executed the next time you display the Measure menu.)

Save a Setup

First, you need to create an instrument setup you want to save. Perform the following steps to create and save a setup that is complex enough that you might prefer not to go through all these steps each time you want that display:

1. If you are not continuing from the previous example, follow the instructions

on page 2–9 under the heading Setting Up for the Examples.

2. Press SETUP ➞ Recall Factory Setup (main) ➞ OK Confirm Factory

Init (side).

3. Press ➞ AUTOSET.

4. Press MEASURE ➞ Select Measrmnt (main) ➞ Frequency (side). (Press

the –more– side menu item if the Frequency selection does not appear in the side menu.)

5. Press CH 2 ➞ CLEAR MENU.

6. Press SAVE/RECALL SETUP ➞ Save Current Setup (main) to display

the Setup main menu. (See Figure 2–18.)

CAUTION. Setup locations in the side menu appear with the label user if they contain a stored setup or with the label factory if they do not. To avoid overwriting (and losing forever) a saved setup, choose a setup location labeled factory. (Setup locations labeled factory have the factory setup stored as a default and can be used to store current setups without disturbing previously stored setups.)

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Recall a Setup

Figure 2–18: Save/Recall Setup Menu

7. Press one of the To Setup side menu buttons to store the current instrument

settings into that setup location. Remember which setup location you selected for use later.

There are more setup locations than can be listed at one time in the side menu. The –more– side menu item gives you access to all the setup locations.

Once you have saved a particular setup, you can change the settings as you wish, knowing that you can come back to that setup at any time.

8. Press MEASURE ➞ Positive Width (side) to add that measurement to the

display.

To recall the setup, press SAVE/RECALL SETUP ➞ Recall Saved Set- up (main) ➞ Recall Setup (side) for the setup location you used in the last exercise. The positive width measurement is now removed from the display because you selected it after you saved the setup.

The step just performed completes the examples. You can restore the default settings by pressing SETUP ➞ Recall Factory Setup (main) ➞ OK Confirm Factory Init (side).

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Reference

Overview

This chapter describes in detail how to perform the operating tasks you must do to measure, test, process, or save and document your waveforms. It leads with three sections on the fundamental tasks of acquiring, stably displaying, and taking measurements on waveforms:

 Acquiring and Displaying Waveforms  Triggering on Waveforms  Measuring Waveforms

Once you have acquired and measured waveforms, you may want to save and restore them or the control setups used to acquire and measure them. Or you may want to save the display screen, complete with waveform and setup information, to include them with the documents you produce with your desk top publishing system. You may even want to digitally process them (add, multiply, or divide them; integrate, differentiate or take an FFT of them). The following two topics cover these tasks:

 Saving Waveforms and Setups

Acquiring and Displaying

Waveforms

 Using Features for Advanced Applications

When performing any operation task, you might want to display a comprehensive listing of its current control settings on screen. Or you may find it handy to display operating information about front panel controls and menus instead of looking them up in this manual. The following topic tells you how to do both:

 Determining Status and Accessing Help

The topics just listed contain steps that you perform to accomplish the task that the topic defines. You should read Conventions on page xiv of Preface before reading about these tasks.

Each topic just listed comprises more basic operation tasks and topics. A list of these tasks follows.

Coupling Waveforms to the Oscilloscope 3–3. . . . . . . . . . . . . . . . . . . . . . . . .

Setting up Automatically: Autoset and Reset 3–5. . . . . . . . . . . . . . . . . . . . . .

Selecting Channels 3–7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Scaling and Positioning Waveforms 3–9. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Choosing an Acquisition Mode 3–16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Customizing the Display 3–27. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Customizing the Display Color 3–33. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Zooming on Waveforms 3–37. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Using InstaV u Acquisition Mode (TDS 700A Models Only) 3–43. . . . . . . .

Using FastFrame (TDS 700A Models Only) 3–46. . . . . . . . . . . . . . . . . . . . .

Triggering on Waveforms

Measuring Waveforms

Saving Waveforms and

Setups

Determining Status and

Accessing Help

Triggering Concepts 3–49. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Triggering from the Front Panel 3–53. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Triggering on a Waveform Edge 3–57. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Triggering Based on Logic 3–60. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Triggering on Pulses 3–70. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Delayed Triggering 3–80. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Taking Automated Measurements 3–87. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Taking Cursor Measurements 3–97. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Taking Graticule Measurements 3–101. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Optimizing Measurement Accuracy: SPC and Probe Cal 3–102. . . . . . . . . . . . .

Saving and Recalling Setups 3–111. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Saving and Recalling Waveforms 3–114. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Managing the File System 3–117. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Printing a Hardcopy 3–120. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Communicating with Remote Instruments 3–128. . . . . . . . . . . . . . . . . . . . . . . .

Displaying Status 3–133. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Displaying Help 3–135. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Using Features for

Advanced Applications

3–2

Limit Testing 3–137. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Waveform Math 3–142. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Fast Fourier Transforms 3–144. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Waveform Differentiation 3–161. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Waveform Integration 3–165. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

TDS 684A, TDS 744A, & TDS 784A User Manual

Acquiring and Displaying W aveforms

To use the TDS Oscilloscope to measure or monitor waveforms, you need to know how to acquire, select, and display those waveforms properly. To help you do so, this section describes how to do the following tasks:

 How to couple waveforms to the oscilloscope channels  How to select channels to turn on and off their display  How to size and position the selected channel on screen  How to use the menus to set vertical (coupling, offset, and bandwidth) and

horizontal (time base, record length, and so on) parameters

This section also describes how to choose the appropriate acquisition mode for acquiring your waveform, how to customize the display (including selecting the color of the display elements), and how to use the Zoom, FastFrame, and InstaVu features.

Coupling Waveforms to the Oscilloscope

To Compensate

Passive Probes

Tektronix produces a variety of probes and cables suitable for connecting various types of signals to the input channels of this product. This subsection covers two topics important to coupling: Probe Compensation and Input Impedance

Considerations.

Tektronix ships the P6139A passive probe with the TDS 744A Oscilloscope as a standard accessory. The TDS 684A and TDS 784A Oscilloscopes ship without standard probes but Tektronix recommends you order the P6245 active probe to take advantage of the 1 GHz bandwidth of these two oscilloscopes.

Tektronix also offers a variety of BNC cabling and connectors to couple a variety of signal sources to its input channels. See your Tektronix Sales representative for the specific items offered for signal coupling.

When using a passive probe with any product, compensate it to ensure maximum distortion-free input to the oscilloscope and to avoid high frequency amplitude errors (see Figure 3–1). To compensate your probe, do the following steps:

1. Connect the probe to the probe compensation signal on the front panel.

2. Press AUTOSET.

3. Press VERTICAL MENU ➞ Bandwidth (main) ➞ 20 MHz (side).

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Figure 3–1: How Probe Compensation Affects Signals

4. If you need to change the input impedance, press Coupling (main). Then

Probe Compensated Correctly

Probe Overcompensated

Probe Undercompensated

toggle the side menu selection W to get the correct impedance.

5. TDS 700A models only: Press SHIFT ACQUIRE MENU ➞ Mode (main) ➞

Hi Res (side).

6. TDS 684A only: Press SHIFT ACQUIRE MENU ➞ Mode (main) ➞

Average (side). Use the keypad to set Averages to 5.

7. Adjust the probe until you see a square wave with a perfectly flat top on the

display. Figure 3–2 shows where the adjustment is located.

3–4

Figure 3–2: P6139A Probe Adjustment

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Acquiring and Displaying Waveforms

Input Impedance

Considerations

To ensure proper coupling of your input signals to the oscilloscope, consider the following points when you use 50 W coupling with any channel:

 The oscilloscope does not accurately display frequencies under 200 kHz if

AC coupling is selected.

 The oscilloscope reduces the maximum volts/division setting for the channel

to 1 V from 10 V (to 10 V from 100 V with a X10 probe attached), since input amplitudes appropriate for the higher settings would overload the 50 W input.

 The oscilloscope switches to 50 W and disables AC coupling (and switches

coupling to DC if AC is selected) if you connect an active probe, such as the P6245 probe. Such probes also reduce the maximum volts/div to 10 V as just described. This behavior results in 50 W, nonAC coupling, which is appropriate for such probes.

NOTE. If you remove an active probe, the oscilloscope does not switch coupling back to 1 M (nor AC if it was previously selected). Nor does it restore a volts/division setting limited due to 50  selection when you restore 1 M coupling. In general, you must set channel scale, input coupling, and impedance appropriate for your input coupling scheme. Be sure to switch to 1 M for any input signal not from a 50  system.

To Find More Information

To find a procedure for changing the coupling and input impedance settings, see To Change Vertical Parameters on page 3–12.

To find a list of available probes, see Accessory Probes, on page A–4. To find a guide for selecting probes for a variety of applications, see Appen-

dix E: Probe Selection, on page E-1.

Setting up Automatically: Autoset and Reset

The TDS Oscilloscope can automatically obtain and display a stable waveform of usable size. It can also be reset to its factory default settings. This subsection describes how to execute Autoset and reset, and lists the default settings in effect after an Autoset.

Autoset automatically sets up the front panel controls based on the characteristics of the input signal. It is much faster and easier than a manual control-by-control setup. Autoset adjusts controls in these categories: Acquisition, Display,

Horizontal, Trigger, and Vertical.

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To Autoset the

Oscilloscope

List of Autoset Defaults

Do the following steps to automatically set up the oscilloscope:

1. Press the channel selection button (such as CH 1) corresponding to your

input channel to make it active.

2. Press AUTOSET. If you use Autoset when one or more channels are displayed, the oscilloscope

selects the lowest numbered channel for horizontal scaling and triggering. Vertically, all channels in use are individually scaled. If you use Autoset when no channels are displayed, the oscilloscope will turn on channel one (CH 1) and scale it.

NOTE. Autoset may change vertical position in order to position the waveform appropriately. It always sets vertical offset to 0 V.

Table 3–1 lists the autoset defaults.

T able 3–1: Autoset Defaults

Control Changed by Autoset to

Selected channel Numerically lowest of the displayed channels Acquire Mode Sample Acquire Repetitive Signal

(TDS 700A Models Only) Acquire Stop After RUN/STOP button only Display Style Vectors Display Intensity — Overall If less than 50%, set to 75% Display Format YT FastFrame (TDS 700A

Models Only) Horizontal Position Centered within the graticule window Horizontal Scale As determined by the signal frequency Horizontal Time Base Main Only Horizontal Record Length Unchanged Horizontal Lock Unchanged InstaVu Acquisitions

(TDS 700A Models Only)

Off

Unchanged

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Limit Test Off

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T able 3–1: Autoset Defaults (Cont.)

Control Changed by Autoset to

Trigger Position Unchanged Trigger T ype Edge Trigger Source Numerically lowest of the displayed channels (the selected

channel) Trigger Level Midpoint of data for the trigger source Trigger Slope Positive Trigger Coupling DC Trigger Holdoff Default Holdoff: Set equal to 5 horizontal divisions

Adjustable Holdoff: 250 ns

Selection in Mode and Holdoff menu determines whether the

default holdoff value or the adjustable hold value is used. Vertical Scale As determined by the signal level

To Reset the Oscilloscope

Selecting Channels

Vertical Coupling DC unless AC was previously set. AC remains unchanged. Vertical Bandwidth Full Vertical Offset 0 volts Zoom Off

Do the following steps to reset the oscilloscope to its factory default settings:

1. Press the Save/Recall SETUP button to display the Setup menu (see Fig- ure 3–3). Press the button directly below the Recall Factory Setup menu item.

2. Press the button to the right of the OK Confirm Factory Init side menu item.

3. Press the SET LEVEL TO 50% button (front panel) to be sure the

oscilloscope triggers on the input signal.

The TDS Oscilloscope applies all actions based on a specific waveform, such as taking measurements or applying any changes it receives to the vertical control settings, to the selected waveform. You can select a channel waveform, a math waveform, or a reference waveform. This subsection describes how to select a waveform and how you can turn the display of a waveform off.

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To Identify the

Selected Channel

Channel Reference

Indicator

Channel Readout

To determine which channel is currently selected, check the channel readout. It shows the selected channel in inverse video in the lower left corner of the display. The channel reference indicator for the selected channel also appears in reverse video along the left side of the display. (See Figure 3–3.)

To Select and

Remove Waveforms

Figure 3–3: The Channel Readout

To select a channel, use the channel selection buttons on the right of the display. These buttons labeled CH 1, CH 2, CH 3, CH 4, and MORE select a channel and display it if its off. (The MORE button allows you to select internally stored Math and Ref waveforms for display and manipulation.) The selected channel is indicated by the lighting the LED above the button of the selected channel.

Do the following steps to first display and then remove waveforms from the display:

1. Press CH 1, CH 2, CH 3, or CH 4 to turn on as many of these channels as

desired. The one you select last (or first if you only select one) becomes the selected channel. Selecting a channel turns it on if it is not already on.

You do not use the channel selection buttons to select the trigger source. Instead you select the trigger source in the Main Trigger menu or Delayed Trigger menu.

2. Press WAVEFORM OFF to turn OFF the display of the selected channel

waveform. It will also remove from the display any automated measurements being made on that waveform.

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3. To select a math waveform you have created or a reference waveform you have stored, press MORE and select the waveform from the More menu. Press WAVEFORM OFF while the MORE button is lit to remove the display of the waveform selected in the More menu.

Waveform Priority

To Find More Information

When you turn off a waveform, the oscilloscope automatically selects the next highest priority waveform. Figure 3–4 shows the order of priority.

1. CH1

2. CH2

3. CH3

4. CH4

1. MATH1

2. MATH2

3. MATH3

4. REF1

5. REF2

6. REF3

7. REF4

Figure 3–4: Waveform Selection Priority

Note Figure 3–4 shows two orders of priority due to the following rules: If you are turning off more than one waveform and you start by turning off a channel waveform, all channels will be turned off before going to the MORE waveforms. If you start by turning off the MORE waveforms, all the MORE waveforms will be turned off before going to the channel waveforms.

If you turn off a channel that is a trigger source, it continues to be the trigger source even though the waveform is not displayed.

To read about selecting reference waveforms, see Saving and Recalling Waveforms on page 3–114.

To read about selecting (and creating) math waveforms, see Waveform Math on page 3–142.

Scaling and Positioning Waveforms

The TDS Oscilloscope allows you to scale (change the vertical or horizontal size) and position (move up, down, left, or right) waveforms on screen for best display. (Figure 3–5 shows the results of both vertical and horizontal scaling and positioning.) This subsection first tells you how to quickly check and set vertical and horizontal scales, positions, and other parameters, such as vertical bandwidth and horizontal record length.

To Check Position

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To quickly see the position of the waveform in the display, check the Channel Reference and the Record View icons. (See Figure 3–5.)

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The Channel Reference icon, at the left side of the display, points to ground on the waveform record when offset is set to 0 V. The oscilloscope contracts or expands the selected waveform around this point when you change the vertical scale.

The Record View, at the top of the display, indicates where the trigger occurs and what part of the waveform record is displayed.

Record View

Channel Reference Icon

Original Position Positioned Vertically Positioned Horizontally

To Check the Vertical Scale

To Change Vertical Scale

and Position

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Original Scale Scaled Horizontally

Scaled Vertically

Figure 3–5: Scaling and Positioning

Check the Vertical Readout at the bottom-left part of the display to read the volts/division setting for each displayed channel (the selected channel is in inverse video). (See Figure 3–6.)

The TDS Oscilloscope permits you to change vertical scale and position quickly from the front panel using dedicated control knobs. To change the vertical scale and position:

1. Turn the vertical SCALE knob. Note only the scale of the selected wave-

form changes.

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As you turn the vertical SCALE knob clockwise, the value decreases resulting in higher resolution because you see a smaller part of the waveform. As you turn it counterclockwise the scale increases allowing you to see more of the waveform but with lower resolution.

2. Turn the vertical POSITION knob. Again, note that only the selected waveform changes position.

3. To make positioning faster, press the SHIFT button. When the light above the SHIFT button is on and the display says Coarse Knobs in the upper right corner, the POSITION knob positions waveforms more quickly.

The POSITION knob simply adds screen divisions to the reference point of the selected waveform. Adding divisions moves the waveform up and subtracting them moves the waveform down. You also can adjust the waveform position using the offset option in the Vertical menu (discussed later in this section).

Vertical Readout

Figure 3–6: Vertical Readouts and Channel Menu

By changing the vertical scale, you can focus on a particular portion of a waveform. By adjusting the vertical position, you can move the waveform up or down on the display. Adjustment of vertical position is particularly useful when you are comparing two or more waveforms.

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To Change

Vertical Parameters

To select the coupling, bandwidth, and offset for the selected waveform, use the Vertical menu (Figure 3–6). This menu also lets you numerically change the position or scale instead of using the vertical knobs. To make such changes, do the following procedures:

Coupling. To choose the type of coupling for attaching the input signal to the vertical attenuator for the selected channel and to set its input impedance:

Press VERTICAL MENU ➞ Coupling (main) ➞ DC, AC, GND, or W (side).

 DC coupling shows both the AC and DC components of an input signal.  AC coupling shows only the alternating components of an input signal.  Ground (GND) coupling disconnects the input signal from the acquisition.  Input impedance lets you select either 1 M W or 50 W impedance.

NOTE. If you select 50  impedance with AC coupling, the digitizing oscillo- scope will not accurately display frequencies under 200 kHz.

Also, when you connect an active probe to the oscilloscope (such as the P6245), the input impedance of the oscilloscope automatically becomes 50 . If you then connect a passive probe (like the P6139A), you need to set the input impedance back to 1 M.

The maximum volts/div setting is reduced from 10 V to 1 V when you select 50  impedance. See the discussion Input Impedance Considerations on page 3–5.

Bandwidth. Bandwidth refers to the range of frequencies that an oscilloscope can acquire and display accurately (that is, with less than 3 dB attenuation). To select the upper limit for the higher frequency components, change the bandwidth of the selected channel:

Press VERTICAL MENU ➞ Bandwidth (main) ➞ Full, 250 MHz, or 20 MHz (side).

Fine Scale. To make fine adjustments to the vertical scale, press VERTICAL MENU ➞ Fine Scale (main) and use the general purpose knob or the keypad.

Position. To adjust the vertical position to a specific number of divisions, press

VERTICAL MENU ➞ Position (main) and use the general purpose knob or the keypad to set the offset value. Press Set to 0 divs (side) if you want to reset the reference point of the selected waveform to the center of the display.

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Offset. Use offset to subtract DC bias before examining a waveform. For example, you might want to display a small ripple (for example, 100 mV of ripple) on a power supply output (for example, a +15 V output). Adjust offset to keep the ripple on screen while setting the vertical scale sensitive enough to best display the ripple.

To adjust offset, press VERTICAL MENU ➞ Offset (main). Then use the general purpose knob or keypad to set the vertical offset. Press Set to 0 V (side) if you want to reset the offset to zero.

To Check the

Horizontal Status

Record View Readout

Time Base Readout

Check the Record View to determine the size and location of the waveform record and the location of the trigger relative to the display. (See Figure 3–7.)

Check the Time Base readout at the lower right of the display to see the time/division settings and the time base (main or delayed) being referred to. (See Figure 3–7. Also see Figure 3–5 on page 3–10.) Since all live waveforms use the same time base, the oscilloscope only displays one time base and time/division setting for all the active channels.

Figure 3–7: Record View and Time Base Readouts

To Change Horizontal

Scale and Position

TDS 684A, TDS 744A, & TDS 784A User Manual

The TDS Oscilloscope provides control of horizontal position and scale using either the horizontal front panel knobs.

By changing the horizontal scale, you can move the waveform right or left to see different portions of the waveform. That is particularly useful when you are using larger record sizes and cannot view the entire waveform on one screen.

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To change the horizontal scale and position:

1. Turn the horizontal POSITION and horizontal SCALE knobs. (See

2. If you want the POSITION knob to move faster, press the SHIFT button.

Figure 3–8.)

When the light above the shift button is on and the display says Coarse Knobs in the upper right corner, the POSITION knob positions waveforms more quickly.

To Change Horizontal

Parameters

Figure 3–8: Horizontal Controls

When you select a channel, the horizontal SCALE knob scales all channel waveforms displayed at the same time. If you select a math or reference waveform, the knob scales only the selected waveform.

When you select a channel, the horizontal POSITION knob positions all channel, reference, and math waveforms displayed at the same time when Horizontal Lock is set to Lock in the Zoom menu. See Zoom a Waveform on page 3–38.

To select the waveform record length and the trigger position, use the Horizontal menu. You can also use this menu to change the horizontal position or scale instead of using the horizontal knobs. You can select the delayed time base (see Delayed Triggering on page 3–80) or choose the frames on the waveform that you want to see (see Using FastFrame on page 3–46).

Trigger Position. The trigger point marks time zero in a waveform record. All record points before the trigger event make up the pretrigger portion of the waveform record. Every record point after the trigger event is part of the

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posttrigger portion. All timing measurements in the waveform record are made relative to the trigger event. To define the trigger point position:

Press HORIZONTAL MENU ➞ Trigger Position (main) ➞ Set to 10%, Set to 50%, or Set to 90% (side), or use the general purpose knob or the keypad to change the value.

Record Length. The number of points that make up the waveform record is defined by the record length. To set the waveform record length:

1. Press HORIZONTAL MENU ➞ Record Length (main). Select the record length desired from the side menu. Press –more– to see additional choices. The available record lengths are as follows:

 The TDS 684A Oscilloscope provides record lengths of 500, 1000,

2500, 5000, and 15000 points.

 The TDS 700A Oscilloscopes provide record lengths of 500, 1,000,

2,500, 5,000, 15,000, and 50,000 plus, with option 1M, 75,000, 100,000, 130,000, 250,000, and 500,000. Option 1M is available only at the time of original purchase and is not available for the TDS 684A.

NOTE. TDS 700A Models: Hi Res acquisition mode requires twice the acquisition memory of other acquisition modes, therefore, the maximum record length available is 15,000 points for TDS 700A Oscilloscopes without option 1M and 50,000 points with option 1M. Turning Hi Res on switches the setting for record length accordingly, thereby keeping the oscilloscope from running out of memory.

2. To fit an acquired waveform to the visible screen, regardless of record length, press HORIZONTAL MENU ➞ Record Length (main). Then toggle Fit to Screen to ON from the side menu. This feature fits the waveform automatically much like you could do manually — by turning zoom mode on and changing the time/division until the waveform fits the screen. To turn off this feature, toggle Fit to Screen to OFF.

Horizontal Scale. To change the horizontal scale (time per division) numerically in the menu instead of using the Horizontal SCALE knob:

Press HORIZONTAL MENU ➞ Horiz Scale (main) ➞ Main Scale or Delayed Scale (side), and use the keypad or the general purpose knob to change the scale values.

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Horizontal Position. To set the horizontal position to specific values in the menu instead of using the Horizontal POSITION knob:

Press HORIZONTAL MENU ➞ Horiz Pos (main) ➞ Set to 10%, Set to 50%, or Set to 90% (side) to choose how much of the waveform will be displayed to the left of the display center.

You can also control whether changing the horizontal position setting affects all displayed waveforms, just the live waveforms, or only the selected waveform. See Zoom a Waveform, on page 3–38 for the steps to set the horizontal lock feature.

To Select the

Delayed Time Base

To Find More Information

You also can select Delayed Runs After Main or Delayed Triggerable. Use the main time base for most applications. Use the delayed time base when you want to delay an acquisition so it captures and displays events that follow other events. See To Find More Information below.

To perform tutorials that teach selecting, scaling, and positioning of waveforms, see Example 1: Displaying a Waveform on page 2–13 and Example 2: Displaying Multiple Waveforms on page 2–15.

To learn how to use delay with waveforms, see Delayed Triggering on page 3–80. To learn how to magnify waveforms, see Zooming on Waveforms, on page 3–37.

Choosing an Acquisition Mode

The TDS Oscilloscopes are digital products that can acquire and process your input signal in a variety of modes. To help you choose the best mode to use for your signal measurement task, this subsection first describes:

 How the oscilloscope samples and digitizes an input signal  How the different acquisition modes (such as interpolation) affect this process

Sampling and Digitizing

3–16

 How to select among these modes Following these descriptions are procedures for selecting the sampling and

acquisition modes, beginning with Checking the Acquisition Readout on page 3–23.

Acquisition is the process of sampling the analog input signal, digitizing it to convert it into digital data, and assembling it into a waveform record. (See Figure 3–9.) The oscilloscope creates a digital representation of the input signal by sampling the voltage level of the signal at regular time intervals. The sampled and digitized points are stored in memory along with corresponding timing information. You can use this digital representation of the signal for display, measurements, or further processing.

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+5.0 V

0 V 0 V 0 V 0 V

Input Signal Sampled Points Digital Values

–5.0 V

+5.0 V

–5.0 V

Figure 3–9: Acquisition: Input Analog Signal, Sample, and Digitize

The oscilloscope uses the samples it takes (see Figure 3–11) to create a waveform record containing a user-specified number of data or record points. Each record point represents a certain voltage level that occurs a determined amount of time from the trigger event.

The oscilloscope may take more samples than the number of points in your waveform record. In fact, the oscilloscope may take several samples for each record point (see Figure 3–10). The digitizer can use any extra samples to perform additional processing, such as averaging or looking for minimum and maximum values. The methods of sampling and acquisition modes you choose determine how the oscilloscope assembles the sample points it acquires into the waveform record.

Interval for one waveform record point.

Real-time Sampling

Samples for a record point.

Figure 3–10: Several Points May be Acquired for Each Point Used

The two general methods of sampling are real-time and equivalent-time. The TDS 684A Oscilloscope uses only real-time sampling; the TDS 700A Oscilloscopes use both real- and equivalent-time sampling.

In real-time sampling, the oscilloscope digitizes all the points it acquires after one trigger event (see Figure 3–11). Always use real-time sampling to capture single-shot or transient events.

Record Points

Sampling Rate

Figure 3–11: Real-T ime Sampling

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Equivalent-Time Sampling

A TDS 700A model oscilloscope (the TDS 684A uses only real time sampling) uses equivalent time sampling to extend its sample rate over its real-time maximum sampling rate, but only under two conditions:

 You must have turned equivalent-time on in the Acquisition menu.  You must have set the oscilloscope to a sampling rate that is too fast to allow

it to get enough samples with which to create a waveform record using real-time sampling.

If both conditions are the case, the oscilloscope takes a few samples with each trigger event and eventually obtains enough samples to construct a waveform record. In short, the oscilloscope makes multiple acquisitions of a repetitive waveform to obtain the sample density required for a waveform record. (See Figure 3–12.) By doing so, the oscilloscope lets you accurately acquire signals with frequencies much higher than its maximum real-time bandwidth would allow. Equivalent-time sampling should only be used on repetitive signals.

Record Points

1st Acquisition Cycle

Interpolation

2nd Acquisition Cycle

3rd Acquisition Cycle

nth Acquisition Cycle

Figure 3–12: Equivalent-Time Sampling

The type of equivalent-time sampling the oscilloscope uses is called random equivalent-time sampling. Although it takes the samples sequentially in time, it

takes them randomly with respect to the trigger. Random sampling occurs because the oscilloscope sample clock runs asynchronously with respect to the input signal and the signal trigger. The oscilloscope takes samples independently of the trigger position and displays them based on the time difference between the sample and the trigger.

Your oscilloscope can interpolate between the samples it acquires. Like for equivalent time sampling, it does so only when it cannot obtain all the real samples it needs to fill up its waveform record. For instance, setting the horizontal SCALE to progressively faster acquisition rates leaves progressively shorter time periods for the waveform record. Therefore, the oscilloscope must sample faster to acquire the samples (record points) needed to fill up the record.

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No. of Channels

Digitizers Used

No. of Channels Turned On

Digitizers Used Per Channel

Eventually the time period established by scale setting does not allow enough time to get all the real samples needed to fill the record.

The situation just described occurs if you set the Horizontal SCALE knob to a time base setting that is faster than 10 ns (TDS 684A). (The setting varies with the number of channels for TDS 700A models; see Tables 3–4 and 3–5 beginning on page 3–24.) The oscilloscope then interpolates to create the intervening points in the waveform record. There are two options for interpolation: linear or sin(x)/x. (TDS 700A models can also equivalent time sample to acquire more samples; see Equivalent-Time Sampling on page 3–18.)

Linear interpolation computes record points between actual acquired samples by using a straight line fit. It assumes all the interpolated points fall in their appropriate point in time on that straight line. Linear interpolation is useful for many waveforms such as pulse trains.

Sin(x)/x interpolation computes record points using a curve fit between the actual values acquired. It assumes all the interpolated points fall along that curve. That is particularly useful when acquiring more rounded waveforms such as sine waves. Actually, it is appropriate for general use, although it may introduce some overshoot or undershoot in signals with fast rise times.

Interleaving

NOTE. When using either type of interpolation, you may want to set the display style so that the real samples are displayed intensified relative to the interpolated samples. The instructions under Select the Display Style on page 3–28 explain how to turn on intensified samples.

A TDS 700A Oscilloscope can interleave its channels to attain higher digitizing rates without equivalent time sampling or interpolating. The oscilloscope applies the digitizing resources of unused channels (that is, channels that are turned off) to sample those that are in use (turned on). Table 3–2 lists how interleaving more than one digitizer to sample a channel extends the maximum digitizing rate.

T able 3–2: How Interleaving Affects Sample Rate

Maximum Digitizing Rate TDS 744A TDS 784A

One Four 2 Gs/second 4 Gs/second Two Two 1 Gs/second 2 Gs/second Three or Four One 500 Ms/second 1 Gs/second

When real-time sampling. (Gs = Gigasamples; Ms = Megasamples.)

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Once you set horizontal scale to exceed the maximum digitizing rate for the number of channels in use (see Table 3–2), the oscilloscope will not be able to get enough samples to create a waveform record. At that point, the oscilloscope will either interpolate to calculate additional samples or it will switch from real to equivalent time sampling to obtain additional samples. (See Interpolation on page 3–18 and Equivalent-Time Sampling on page 3–18.)

The Acquisition Modes

All three TDS Oscilloscopes support the following three acquisition modes: Sample, Envelope, and Average. TDS 700A Oscilloscopes support two additional acquisition modes: Peak Detect and Hi Res. Keep in mind which modes apply to your model oscilloscope as you read the following descriptions.

Sample (the mode most commonly used), Peak Detect, and Hi Res modes operate in real time on a single trigger event, provided that the oscilloscope can acquire enough samples for each trigger event. Envelope and Average modes operate on multiple acquisitions; the oscilloscope averages or envelopes several waveforms on a point-by-point basis. (For TDS 700A models only, Hi Res, Envelope, and Average modes are not available when in InstaVu mode; see Incompatible Modes on page 3–45.)

Figure 3–13 illustrates the different modes and lists the benefits of each. It will help you select the appropriate mode for your application. Refer to it as your read the following descriptions of each mode.

Sample Mode. In Sample mode, the oscilloscope creates a record point by saving the first sample (of perhaps many) during each acquisition interval. (An acquisition interval is the time covered by the waveform record divided by the record length.) Sample mode is the default mode.

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Envelope Mode. Envelope mode lets you acquire and display a waveform record

that shows the extremes in variation over several acquisitions. You specify the number of acquisitions over which to accumulate the data. The oscilloscope saves the highest and lowest values in two adjacent intervals similar to the Peak Detect mode. But Envelope mode, unlike Peak Detect, gathers peaks over many trigger events.

After each trigger event, the oscilloscope acquires data and then compares the min/max values from the current acquisition with those stored from previous acquisitions. The final display shows the most extreme values for all the acquisitions for each point in the waveform record.

Average Mode. Average mode lets you acquire and display a waveform record that is the averaged result of several acquisitions. This mode reduces random noise. The oscilloscope acquires data after each trigger event using Sample mode. It then averages the record point from the current acquisition with those stored from previous acquisitions.

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Single Waveform Acquisition

Acquiring and Displaying Waveforms

Samples Acquired in Four

Acquisition Intervals

Interval 1 2 3 4

Use for fastest acquisition rate. This is the default mode.

Uses highest and lowest samples in

two intervals (TDS 700A Models Only)

Use to reveal aliasing and for glitch detection. Provides the benefits of enveloping with the speed of a single acquisition.

Calculates average of all samples in

interval (TDS 700A Models Only)

Acquisition

Mode

Interval 1 2 3 4

Sample

Uses first sample in

interval

Peak Detect

Hi Res

Displayed

Record Points

Waveform Drawn

on CRT

Use to reduce apparent noise. Provides the benefits of averaging with the speed of a single acquisition.

Multiple Waveform Acquisitions

Three Acquisitions from One Source

Acquisition 1 2 3

Uses Peak Detect Mode for Each Acquisition

Use to reveal variations in the signal across time.

Uses Sample Mode for Each Acquisition

Use to reduce apparent noise in a repetitive signal.

Acquisition

Mode

Envelope

Finds highest and

lowest record points over

many acquisitions

Average

Calculates average value for

each record point over

many acquisitions

Figure 3–13: How the Acquisition Modes Work

Waveform Drawn

on CRT

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Peak Detect Mode. TDS 700A models only: Peak Detect mode alternates between saving the highest sample in one acquisition interval and lowest sample in the next acquisition interval. Peak Detect mode only works with real-time, noninterpolated sampling.

If you set the time base so fast that it requires real-time interpolation or equivalent-time sampling, the mode automatically changes from Peak Detect to Sample, although the menu selection will not change.

Hi Res Mode. TDS 700A models only: Hi Res mode averages all samples taken during an acquisition interval to create a record point. The average results in a higher-resolution, lower-bandwidth waveform.

A key advantage of Hi Res is its potential for increasing resolution regardless of the input signal. Table 3–3 and the equations shown below illustrate how you can obtain up to 15 significant bits with Hi res mode. Note that the resolution improvements are limited to speeds slower than 100 ns/div. Also, resolutions above 15 bits are not allowed by internal hardware and computation limitations.

Si = Sampling Interval for TDS 744A = 1 ns t = Sample Interval =

TimeDiv

Number Of Points/Div

Nd = Number of points per decimation interval = Resolution Enhancement (bits) =

0.5  LOG2(Nd) 3 extra bits

5 msDiv

50 PointsDiv

= 100 ns

= 100

Bits of Resolution = Resolution Enhancement (3 bits) + 8 bits 11 bits

Hi Res mode only works with real-time, noninterpolated sampling. If you set the time base so fast that it requires real-time interpolation or equivalent-time sampling, the mode automatically becomes Sample even though the menu selection will not change.

T able 3–3: Additional Resolution Bits

Time Base Speed Bits of Resolution

100 ns and faster 8 bits 200 ns to 500 ns 9 bits 1 s to 2 s 10 bits 5 s to 10 s 11 bits 20 s to 50 s 12 bits 100 s to 200 s 13 bits 500 s 14 bits 1 ms and slower 15 bits

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Checking the

Acquisition Readout

To determine the acquisition sampling rate, the acquisition state (running or stopped), and the acquisition mode, check the Acquisition readout at the top of the display. (See Figure 3–14.) The state “Run:” shows the sample rate and acquisition mode. The state “Stop:”shows the number of acquisitions acquired since the last stop or major change.

Selecting an

Acquisition Mode

Figure 3–14: Acquisition Menu and Readout

The oscilloscope provides several modes (see The Acquisition Modes on page 3–20) for acquiring and converting analog data into digital form. To choose how the oscilloscope will create points in the waveform record:

1. Press SHIFT ACQUIRE MENU ➞ Mode (main). (See Figure 3–14.)

2. TDS 684A: Press Sample, Envelope, or Average (side) or ... TDS 700A Models: Press Sample, Peak Detect, Hi Res, Envelope, or

Average (side). (InstaVu mode must be off to use Hi Res, Envelope, or

Average modes.)

3. If you selected Envelope or Average, enter the number of waveform records to be enveloped or averaged using the keypad or the general purpose knob.

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NOTE. TDS 700A models only: Selecting Hi Res mode in the Acquire menu will automatically reduce the record length to a value that prevents overflow of acquisition memory. Because Hi Res mode uses twice the acquisition memory that the other acquisition modes use, allowing selection of the longer horizontal record lengths with Hi Res mode would cause the oscilloscope to run out of memory.

Selecting Repetitive

Sampling

TDS 700A models only: To limit the oscilloscope to real-time sampling or let it choose between real-time or equivalent-time sampling:

Press SHIFT ACQUIRE MENU ➞ Repetitive Signal (main) ➞ ON or OFF (side).

 ON (Enable ET) uses both the real-time and the equivalent-time sampling

as appropriate.

 OFF (Real Time Only) limits the oscilloscope to real-time sampling. If the

oscilloscope cannot accurately get enough samples for a complete waveform, it will interpolate.

The sampling speeds and the number of channels you choose affect the mode the oscilloscope uses to sample waveforms. If the time base is set slow enough, the oscilloscope always uses real-time sampling; if set fast enough, it always uses equivalent-time sampling or interpolation. For speeds in between, the oscilloscope creates waveform records differently depending on the number of input channels turned on. See Table 3–4 for the TDS 744A or Table 3–5 for the TDS 784A.

T able 3–4: TDS 744A Sampling Mode Selection (When Fit to Screen is Off)

Time Base1One Channel Two Channels Three or Four Channels

u50 ns Real-time Real-time Real-time

50 ns Real-time Real-time Equiv.-time or interpolate 25 ns Real-time Equiv.-time or interpolate Equiv.-time or interpolate

t25 ns Equiv .-time or Interpolate Equiv .-time or Interpolate Equiv .-time or Interpolate

“u” means “slower than”; “t” means “faster than.”

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T able 3–5: TDS 784A Sampling Mode Selection (When Fit to Screen is Off)

Time Base1One Channel Two Channels Three or Four Channels

u25 ns Real-time Real-time Real-time

25 ns Real-time Real-time Equiv.-time or interpolate

12.5 ns Real-time Equiv.-time or interpolate Equiv.-time or interpolate

t12.5 ns Equiv .-time or Interpolate Equiv.-time or Interpolate Equiv.-time or Interpolate

“u” means “slower than”; “t” means “faster than.”

NOTE. The oscilloscope will use the interpolation method selected in the display menu to fill in the missing record points — either linear or sin(x)/x interpolation. See Interpolation on page 3–18 for a discussion of interpolation.

Stop After

To choose the event that signals the oscilloscope to stop acquiring waveforms, do the following step:

Press SHIFT ACQUIRE MENU ➞ Stop After (main) ➞ RUN/STOP button only, Single Acquisition Sequence, or Limit Test Condition Met (side). (See Figure 3–15.) (TDS 700A models only: single acquisition and limit testing are ignored in InstaVu mode; see Incompatible Modes on page 3–45.)

Figure 3–15: Acquire Menu — Stop After

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 Press RUN/STOP button only (side) to use the RUN/STOP button to start

 Press Single Acquisition Sequence (side). That selection lets you run a

or stop acquiring. Pressing the RUN/STOP button once will stop the acquisitions. The upper left hand corner in the display will say “Stop” and show the number of acquisitions. If you press the button again, the oscilloscope will resume taking acquisitions.

single sequence of acquisitions by pressing the RUN/STOP button. In Sample, Peak Detect, or Hi Res mode, the oscilloscope will acquire a waveform record with the first valid trigger event and stop. (Peak Detect and Hi Res are only available on TDS 700A models.)

In Envelope or Average mode, the oscilloscope will make the specified number of acquisitions to complete the averaging or enveloping task.

TDS 700A models only: If the oscilloscope is in equivalent-time mode and you press Single Acquisition Sequence (side), it will continue to recognize trigger events and acquire samples until the waveform record is filled.

Preventing Aliasing

NOTE. To quickly select Single Acquisition Sequence without displaying the Acquire and Stop After menus, press SHIFT FORCE TRIG. Now the RUN/STOP button operates as just described. (You still must display the Acquire menu and then the Stop After menu to leave Single Acquisition Sequence operation.)

 Press Limit Test Condition Met (side) to acquire waveforms until

waveform data exceeds the limits specified in the limit test. Then acquisition stops. At that point, you can also specify other actions for the oscilloscope to take, using the selections available in the Limit Test Setup main menu.

NOTE. In order for the oscilloscope to stop an acquisition when limit test conditions have been met, limit testing must be turned ON using the Limit Test Setup main menu.

Setting up limit testing requires several more steps. See Limit Testing, on page 3–137.

Under certain conditions, a waveform may be aliased on screen. Read the following description about aliasing and the suggestions for preventing it.

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About Aliasing. When a waveform aliases, it appears on screen with a frequency

lower than the actual waveform being input or it appears unstable even though the light next to TRIG’D is lighted. Aliasing occurs because the oscilloscope cannot sample the signal fast enough to construct an accurate waveform record. (See Figure 3–16.)

TDS 684A, TDS 744A, & TDS 784A User Manual

Actual High-Frequency Waveform

Apparent Low-frequency

Waveform Due to Aliasing

Sampled Points

Acquiring and Displaying Waveforms

Figure 3–16: Aliasing

Methods to Check and Eliminate. To quickly check for aliasing, slowly increase

the horizontal scale (time per division setting). If the shape of the displayed waveform changes drastically or becomes stable at a faster time base setting, your waveform was probably aliased.

To avoid aliasing, be sure to sample the input signal at a rate more than twice as fast as the highest frequency component. For example, a signal with frequency components of 500 MHz would need to be sampled at a rate faster than 1 Gigasamples/second to represent it accurately and avoid to aliasing. The following tips may help you eliminate aliasing on a signal:

 Try adjusting the horizontal scale.  Try pressing the AUTOSET button.  Try switching the acquisition mode (in the acquisition menu) to Envelope

 Try pressing the InstaVu acquisition button. (TDS 700A models only).

Customizing the Display

The TDS Oscilloscope can display waveform records and other display elements in different ways. This subsection describes how to adjust the oscilloscope display style, intensity level, graticule, and format.

(all three TDS models) or Peak Detect (TDS 700A models only). Envelope searches for samples with the highest and lowest values over multiple acquisitions; Peak Detect mode does the same but in a single acquisition. Either can detect faster signal components over time.

InstaVu mode results in waveform displays similar to those obtained using analog oscilloscope, due to its fast waveform capture rate.

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NOTE. TDS 700A models only: This subsection assumes you are using Normal acquisitions mode and gives display settings for this mode. If you select InstaVu acquisitions, procedures for making Style, Format, and Readout display settings differ and some selections are not permitted. See Using InstaVuT Acquisition Mode, on page 3–43, for setup differences and Incompatible Modes on page 3–45.

Change Display Settings

Select the Display Style

To bring up the Display menu: Press DISPLAY ➞ Settings (main) ➞ Display (pop-up). The Display menu allows you to adjust the style, intensity level, graticule, and

format features described below. The Color menu allows you to alter color settings for various display components such as waveforms and text. To find more information on color, see Customizing the Display Color on page 3–33.

TDS 684A only: Press DISPLAY ➞ Style (main) ➞ Vectors, Intensified Samples, Dots, Infinite Persistence, or Variable Persistence (side) (See Figure 3–17.)

TDS 700A models only: Press DISPLAY ➞ Mode (main) ➞ Normal (pop-up) ➞ Style (main) ➞ Vectors, Intensified Samples, Dots, Infinite Persistence, or Variable Persistence (side)

Vectors style displays vectors (lines) between the record points. Dots style displays waveform record points as dots. Intensified Samples style also displays waveform record points as dots. However,

the points actually sampled are displayed in the color labeled “Zone” in the Display Colors menus.

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In addition to choosing Intensified Samples in the side menu, the oscilloscope must be interpolating (equivalent time must be off for TDS 700A models) or Zoom must be on with its horizontal expansion greater that 1X. See Interpola-

tion on page 3–18; see Zooming on Waveforms on page 3–37. Variable Persistence style accumulates the record points on screen and displays

them only for a specific time interval. In that mode, the display behaves like that of an analog oscilloscope. You enter the time for that option with the keypad or the general purpose knob. Record points are also displayed with colors that vary depending on the persistence of the point. See Choose a Palette on page 3–33.

Infinite Persistence style accumulates the record points until you change some control (such as scale factor) causing the display to be erased.

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NOTE. TDS 700A models only: See Using InstaVuT Acquisition Mode, on page 3–43, for differences in how Style setup differs for InstaVu mode.

Adjust Intensity

Set Display Readout

Options

Figure 3–17: Display Menu — Style

Intensity lets you set text/graticule and waveform intensity (brightness) levels.

To set the intensity: Press DISPLAY ➞ Intensity (main) ➞ Text/Grat or Waveform (side). Enter

the intensity percentage values with the keypad or the general purpose knob. All intensity adjustments operate over a range from 20% (close to fully off) to

100% (fully bright).

Readout options control whether the trigger indicator, trigger level bar, and current date and time appear on the display. The options also control what style trigger level bar, long or short, is displayed.

1. TDS 684A: Press DISPLAY ➞ Readout Options (main). TDS 700A Models: Press DISPLAY ➞ Mode (main) ➞ Normal

(pop-up) ➞ Format/RO (main).

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2. Toggle Display ‘T’ @ Trigger Point (side) to select whether or not to

3. Press Trigger Bar Style (side) to select either the short or the long trigger

4. Press Display Date/Time (side) to turn it on or off. Push Clear Menu to see

display ‘T’ indicating the trigger point. You can select ON or OFF. (The trigger point indicates the position of the trigger in the waveform record.)

bar or to turn the trigger bar off. (See Figure 3–18. Note that both styles are shown for illustrating purposes, but you can only display one style at a time.)

The trigger bar is only displayed if the trigger source is an active, displayed waveform. Also, two trigger bars are displayed when delay triggerable acquisitions are displayed — one for the main and one for the delayed timebase. The trigger bar is a visual indicator of the trigger level.

Sometimes, especially when using the hardcopy feature, you may want to display the current date and time on screen. (To find more information displaying and setting date and time, see Date/Time Stamp the Hardcopy on page 3–123.)

the current date and time.

Trigger Point Indicator

Trigger Bar—Long Style

-or-

Trigger Bar—Short Style

Figure 3–18: Trigger Point and Level Indicators

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Select Interpolation Filter

Select the Graticule Type

The display filter types are sin(x)/x interpolation and linear interpolation. To switch between interpolation filters:

Press DISPLAY ➞ Filter (main) ➞ Sin(x)/x Interpolation or Linear Interpo- lation (side).

NOTE. When the horizontal scale is set to the faster rates (10 ns/div for the TDS 684A; see Tables 3–4 and 3–5 beginning on page 3–24 for rates specific to the two TDS 700A models) or when using the ZOOM feature to expand waveforms horizontally, interpolation occurs. (The filter type, linear or sin(x)/(x), depends on which is set in the Display menu.) Otherwise, interpolation is not used. See Interpolation on page 3–18 for a discussion of interpolation.

To change the graticule: Press DISPLAY ➞ Graticule (main) ➞ Full, Grid, Cross Hair, Frame, NTSC

or PAL (side).

Full provides a grid, cross hairs and a frame. Grid displays a frame and a grid.

Select the Format

Cross Hair provides cross hairs, and a frame. Frame displays just a frame. NTSC provides a grid useful for measuring NTSC-class waveforms. PAL provides a grid useful for measuring PAL-class waveforms.

NOTE. Selecting either NTSC or PAL graticules automatically changes the vertical scale, position settings, coupling, and sets to zero any vertical offset of any channel displayed. These settings are not restored after switching to other graticule types. Therefore, you might want to recall the factory setup or other stored setup after selecting a different graticule.

The oscilloscope displays waveforms in either of two formats: YT and XY. To set the display axis format:

TDS 684A: Press DISPLAY ➞ Format (main) ➞ XY or YT (side). TDS 700A models: Press DISPLAY ➞ Mode (main) ➞ Normal (pop-up) ➞

Format/RO (main) ➞ XY or YT (side).

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YT is the conventional oscilloscope display format. It shows a signal voltage (the vertical axis) as it varies over time (the horizontal axis).

XY format compares the voltage levels of two waveform records point by point. That is, the oscilloscope displays a graph of the voltage of one waveform record against the voltage of another waveform record. This mode is particularly useful for studying phase relationships.

When you choose the XY format, any channel or reference displayed is assigned to the axis indicated in Table 3–6 and displayed as part of an XY pair. If only one source in an XY pair is displayed, the oscilloscope automatically turns on the other source to complete the XY pair when you select XY. Moreover, once XY is on, selecting either source in a pair turns the pair on; pressing WAVEFORM OFF for either source in the pair removes both sources from the display.

T able 3–6: XY Format Pairs

XY Pair X-Axis Source Y-Axis Source

Ch 1 and Ch 2 Ch 1 Ch 2 Ch 3 and Ch 4 Ch 3 Ch 4 Ref 1 and Ref 2 Ref 1 Ref 2 Ref 3 and Ref 4 Ref 3 Ref 4

Since selecting YT or XY affects only the display, the horizontal and vertical scale and position knobs and menus control the same parameters regardless of the mode selected. Specifically, in XY mode, the horizontal scale will continue to control the time base and the horizontal position will continue to control which portion of the waveforms are displayed.

XY format is a dot-only display, although it can have persistence. The Vector style selection has no effect when you select XY format.

You cannot display Math waveforms in XY format. They will disappear from the display when you select XY.

NOTE. Use of XY at higher room temperatures or with higher intensity display formats, such as the white fields in the Hardcopy palette, can temporarily degrade display quality.

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Customizing the Display Color

The TDS Oscilloscope can display information in different colors. This subsection describes how to use the Color menu to choose the colors in which the various display objects appear.

Acquiring and Displaying Waveforms

Change the Display Color

To bring up the Color menu:

1. Press DISPLAY to show the Display menu.

2. Press Settings in the main menu until you select Color from the pop-up

menu. (See Figure 3–19.)

Figure 3–19: Display Menu — Setting

The Color menu allows you to alter color settings for various display components such as waveforms and text. The Display menu allows you to adjust the style, intensity level, graticule, and format features. To find more information on display, see Change the Display Settings on page 3–28.

Choose a Palette

TDS 684A, TDS 744A, & TDS 784A User Manual

To choose a palette of 13 colors from a menu of preset palettes:

1. Choose the starting palette by selecting Palette from the main menu.

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Acquiring and Displaying Waveforms

2. Select one of the available palettes in the side menu. Choose from Normal,

3. If you are using a persistence display and want to vary the color of each

NOTE. Use at higher room temperatures or with higher intensity display formats, such as the white fields in the Hardcopy Preview palette, can temporarily degrade display quality.

You can select the Hardcopy Preview palette when using certain color hardcopy formats. The default colors in the this palette comprise a white background and fully saturated primary colors which generally produce the best result.

Bold, Hardcopy Preview or Monochrome.

point depending on its persistence, choose Persistence Palettes. Then choose Temperature, Spectral, or Gray Scale from the resulting side menu. Choose View Palette to preview your selection on the display. Press Persistence Palette to quit preview mode. Press Clear Menu to return to the Palette menu.

Change the Palette Colors

To change the color of the current palette, select a color and vary these attributes: Hue, which is the wavelength of light reflected from the surface. It varies

continuously along the color spectrum as produced by a rainbow. Lightness, which is the amount of light reflected from the surface. It varies from

black, to the nominal color, to white. Saturation, which is the intensity of color. Completely desaturated color is gray.

Completely saturated color of any hue is that color at its most intense level.

1. Select the main menu Change Colors item. (See Figure 3–20.)

2. Select one of the 13 colors by pressing (repeatedly) Color in the side menu.

3. If you want to use the factory default for this color, press the side menu Reset to Factory Color.

4. Choose Hue from the side menu and use the general purpose knob or keypad

to select the desired hue. Values range from 0 to 359. Sample values are: 0 = blue, 60 = magenta, 120 = red, 180 = yellow, 240 = green, and 300 = cyan.

5. Choose Lightness from the side menu and use the general purpose knob or keypad to select the lightness you desire. A value of 0 results in black. A value of 50 provides the nominal color. A value of 100 results in white.

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6. Choose Saturation from the side menu and use the general purpose knob or

keypad to select the saturation you desire. A value of 100 provides a pure color. A value of 0 provides gray.

ScrTxt

Set Math Waveform Color

Set Reference Waveform

Color

Figure 3–20: Display Menu — Palette Colors

To define math waveform colors:

1. Choose to define math waveform colors by selecting the main menu Map Math item.

2. Select one of the three math waveforms by pressing Math in the side menu.

3. If you want to assign the selected math waveform to a specific color, press Color and cycle through the choices.

4. If you want the selected math waveform to be the same color as the

waveform it is based on, select Color Matches Contents. If the math waveform is based on dual waveforms, the math waveform will use the color of the first constituent waveform.

To return to the factory defaults, select Reset to Factory Color.

To define reference waveform colors:

1. Press Map Reference in the main menu. (See Figure 3–21.)

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2. Select one of the four reference waveforms by pressing Ref in the side menu.

3. To assign the selected reference waveform to a specific color, press

4. To make the selected reference waveform the same color as the waveform it

To return to the factory defaults, select Reset to Factory Color.

(repeatedly) Color and choose the value.

is based on, select Color Matches Contents.

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Select Options

Restore Colors

Figure 3–21: Display Menu — Map Reference Colors

To define what color to show where a waveform crosses another waveform:

1. Press the Options main menu item.

2. Toggle Collision Contrast to ON in the side menu to mark collision zones

with a special color.

To restore colors to their factory default settings:

1. Press the main menu Restore Colors item. (See Figure 3–22.)

2. Select the object(s) you want to restore by pressing Reset Current Palette To Factory, Reset All Palettes To Factory or Reset All Mappings To Factory in the side menu.

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Acquiring and Displaying Waveforms

Zooming on Waveforms

Using with Waveforms

Figure 3–22: Display Menu — Restore Colors

The TDS Oscilloscope can expand or compress (zoom in or out) on a waveform without changing the acquisition parameters (sample rate, record length, and so on). This subsection describes how to use Zoom and how it interacts with the selected waveform. It also describes how interpolation can affect Zoom.

Use Zoom (press the ZOOM button) when you want to temporarily expand a waveform to inspect small feature(s) on that waveform. For example, to temporarily expand the front corner of a pulse to inspect its aberrations, use Zoom to expand it horizontally and vertically. After you are finished, you can return to your original horizontal scale setting by pressing one menu button. (Zoom is also handy if you have acquired a waveform at the fastest time per division and want to further expand the waveform horizontally.)

To help you use zoom effectively, consider how it operates on waveforms. When zooming vertically, the oscilloscope expands or contracts the selected waveform only. Also, the oscilloscope only positions the selected waveform when in Zoom.

When zooming horizontally, Zoom expands either the selected waveform, all live waveforms, or all live and reference waveforms, depending on the setting for Horizontal Lock in the Zoom menu.

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When zooming horizontally or vertically, Zoom expands or contracts the waveform by the zoom factor in 1X, 2X, and 5X steps.

Interpolation and Zoom

Checking the Zoom Factor

To help you use Zoom effectively, consider how it is affected by interpolation. When you zoom on a waveform, you expand a portion of it. If the expansion requires the oscilloscope to show more points for that portion than it has acquired, it interpolates.

The method the oscilloscope uses to interpolate, linear or sin(x)/x, can affect the way Zoom displays your waveform. If you selected sin(x)/x (the default), it may introduce some overshoot or undershoot to the waveform edges. If such is the case, change the interpolation method to linear, following the instructions on page 3–40.

To read about the two interpolation methods, see Interpolation on page 3–18. To differentiate between the real and interpolated samples, set the display style to Intensified Samples. (See Select the Display Style on page 3–28.)

To quickly determine the zoom factor of a zoomed waveform, select it and check the Zoom readout. It shows the selected waveform by number, along with the horizontal and vertical expansion factors.

The Zoom readout appears at the top of the display when zoom is on. (See Figure 3–23 on page 3–39.) The TDS 700A models do not display the Zoom readout when in dual-window (preview) mode.

Zoom a Waveform

To use Zoom, select a waveform, turn Zoom on, and magnify that waveform using the vertical and horizontal scale knobs:

1. Press any of waveform selection buttons CH 1 through CH 4 on the right side of the display. Or press MORE and select a math or reference waveform from the More menu.

2. Press ZOOM.

3. TDS 684A only: Press ON (side) in the Zoom menu. The ZOOM front-panel

button should light up. TDS 700A models only: Press ZOOM ➞ Mode (main) ➞ ON (side). The

ZOOM front-panel button should light up. Toggle Dual Zoom to OFF in the side menu.

4. Adjust the vertical zoom factor for the selected waveform using the vertical SCALE knob. Adjust the vertical position of the zoomed waveform using the vertical POSITION knob.

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5. Adjust the horizontal zoom factor using the horizontal SCALE knob. Adjust

the horizontal position of the zoomed waveform using the horizontal POSITION knob.

Depending on the selection for Horizontal Lock in the side menu, Zoom affects the displayed waveforms as follows:

None — only the waveform currently selected can be magnified and positioned horizontally (Figure 3–23).

Live — all “live” (as opposed to reference) waveforms can be magnified and positioned horizontally at the same time. If a reference or math waveform is selected and Horizontal Lock set to Live, only the selected reference or math waveform is magnified and positioned.

All — all waveforms displayed (live, math, and reference) can be magnified and positioned horizontally at the same time.

Only the selected

waveform (the top one)

changes size.

Figure 3–23: Zoom Mode with Horizontal Lock Set to None

6. TDS 684A only: Press Horizontal Lock (side) to choose which waveforms to zoom horizontally. Repeatedly press Horizontal Lock (side) to cycle through the three choices.

TDS 700A models only: Press ZOOM ➞ Lock (main) ➞ All, Live, or None (side).

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NOTE. Although Zoom must be turned on to control which waveforms Zoom affects, the setting for Horizontal Lock affects which waveforms the horizontal control positions whether Zoom is on or off. The rules for the three settings are listed in step 5 on page 3–39.

Set Interpolation

Reset Zoom

Using Dual Window Mode

(TDS 700A Models Only)

To change the interpolation method used, press DISPLAY ➞ Settings (main) ➞ Display (pop-up) ➞ Filter (main) ➞ Sin(x)/x Interpolation or Linear Interpolation (side).

To reset all zoom factors to their defaults, do the following step: TDS 684A only: Press ZOOM ➞ Reset Zoom Factors (side). Press ZOOM ➞

Off (side) to return to normal oscilloscope (not zoom) operation. TDS 700A models only: Press ZOOM ➞ Reset (main) ➞ Reset Live Factors

or Reset All Factors (side). Reset Live Factors resets only for live waveforms, as opposed to reference waveforms; Reset All Factors resets for all waveforms.

A TDS 700A Series oscilloscope can display and control a waveform that is both zoomed and unzoomed (magnified and unmagnified). To do so, its creates two 1/2 height graticules, or windows, and displays the magnified waveform in the upper, and the unmagnified waveform in the lower graticule. To use Dual Window Zoom (also called zoom preview mode), do the following steps:

1. Press Zoom ➞ Mode (main) ➞ Preview (side). Note that the oscilloscope

displays the box-enclosed area on the waveform as magnified in the top graticule. (See Figure 3–24.)

3–40

2. To scale or position the unmagnified waveform, press Selected Grati-

cule (main) ➞ Lower (side). Use the vertical and horizontal knobs to scale

and position the unmagnified waveform in the box. Note that as you scale or move the unmagnified waveform relative to the

box, the oscilloscope alters the magnified display accordingly to include only the waveform portion within the box.

3. To scale or position the magnified waveform, press Selected Grati-

cule (main) ➞ Upper (side). Use the vertical and horizontal knobs to scale

and position the magnified waveform. Note that as you scale or move the magnified waveform, the oscilloscope

scales or moves the box relative to the unmagnified waveform, so the box encloses only the waveform portion magnified in the upper graticule.

TDS 684A, TDS 744A, & TDS 784A User Manual

Zoomed (Magnified) Waveforms

Nonzoomed Waveforms, with Box

Indicators at Corners Denoting

the Selected Graticule

Acquiring and Displaying Waveforms

In Dual Window Zoom mode, the oscilloscope does not display the zoom magnification factors; however, it does display the scale factors (volts/division and time/division) for the zoomed waveform.

Dual Zoom a Waveform

(TDS 700A Models Only)

To Set Dual Zoom Offset

Figure 3–24: Dual Window (Preview) Mode

To select Dual Zoom, press ZOOM ➞ Mode (main) ➞ Dual Zoom (side) to toggle it to ON. (See Figure 3–25.)

Dual zoom displays a second zoomed view of the selected unzoomed waveform. The second zoomed view is offset in time from the first zoomed view. Also, zoom must be enabled (side menu set to On or Preview) to see the Dual Zoom displays.

To set the offset in time of the second zoomed waveform from the first, press ZOOM ➞ Mode (main) ➞ Dual Zoom Offset (side). Then turn the general purpose knob or use the keypad to set the offset.

Dual Zoom offset is always positive. The oscilloscope sets the offset as close to the requested value as possible. An offset request of 0.0 insures that the zoom boxes are butted up against each other, regardless of the zoom factor.

The horizontal zoom and scale factors determine the minimum offset time available. Both zoom boxes always enclose equal amounts of time with the second box always offset from the first by a time equal to one box. Doubling the

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zoom factor halves the time enclosed by either box and, therefore, halves the minimum offset time.

The oscilloscope retains any value input that is less than the minimum time available as a “request” if you enter that value using the keypad. Increasing the zoom factor or decreasing the horizontal scale to a setting that allows the requested value sets offset time to that value. You cannot set offset to less than the minimum offset time available when using the general purpose knob.

Selected Graticule

Zoomed Waveform Edges

Zoom Boxes

Unzoomed Waveform

Figure 3–25: Dual Zoom — Shown Dual Window (Preview) Mode

NOTE. To make setting up Dual Zoom easier, turn on Preview in the side menu. In this dual-window mode, the zoomed display appears in the top graticule, while the lower graticule shows the two zoomed portions enclosed in two boxes on the unzoomed waveform. Adjusting offset moves the right box relative to the left box, which remains stationary. The associated zoomed waveform in the upper graticule moves to track the offset changes. You can also adjust the waveform relative to the zoom boxes by selecting the lower graticule and adjusting the vertical and horizontal control knobs. See Using Dual Window Mode on page 3–40.

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Acquiring and Displaying Waveforms

Using InstaVu Acquisition Mode (TDS 700A Models Only)

The TDS 744A and TDS 784A Oscilloscopes can use InstaVu acquisition mode to reduce the dead time between waveform updates that normally occur when digitizing storage oscilloscopes (DSOs) acquire waveforms. InstaVu mode can capture and display transient deviations, such as glitches or runt pulses, often missed during longer dead times that accompany normal DSO display. This subsection describes how to use InstaVu mode and how it differs from normal acquisition mode.

Waveform Capture Rate

To Use InstaVu Mode

Figure 3–26 illustrates how InstaVu acquisition mode differs from the normal acquisition mode used by digital storage oscilloscopes. Note that normal mode follows a “capture waveform–digitize waveform-update waveform memory–display waveform” cycle. Normal mode misses short term deviations occurring during the long dead times. Typical waveform capture rates are 50 waveforms per second.

InstaVu mode increases the waveform capture rate to up to 400,000 waveforms per second, updating the waveform array many times between displays. This very fast frame rate greatly increases the probability that runts, glitches, and other short term changes will accumulate in waveform memory. The oscilloscope then displays the waveform at the normal display rate using variable or infinite persistence. You can control how long the waveform persists on screen by selecting variable persistence and setting a decay constant.

To turn on InstaVu mode, do either of the two following steps:

1. Press the front-panel button InstaVu. (See Figure 3–27.)

2. Press DISPLAY ➞ Mode (main). Push Mode again to toggle to InstaVu

mode. (See Figure 3–27.)

To turn InstaVu off, press InstaVu. Alternatively, press DISPLAY ➞ Mode (main), and then press Mode again to toggle to Normal mode.

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Acquiring and Displaying Waveforms

Normal DSO Mode

1st Acquired

Waveform

Record

Dead Time Dead Time Dead Time

Next Acquired

Waveform

Record

Next Acquired

Waveform

Record

InstaVu Mode

Waveform

Memory

Display Updated Display Updated Display

1st Set of Acquired Waveform Records

Waveform

Memory

Bit Map

Waveform

Memory

Next Set of Acquired

Waveform Records

Waveform

Memory

Bit Map

Waveform

Memory

Next Set of Acquired

Waveform Records

Waveform

Memory

Bit Map

Variable Persistence

Display

Updated Variable

Persistence Display

Figure 3–26: Normal DSO Acquisition and Display Mode Versus InstaVu Mode

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TDS 684A, TDS 744A, & TDS 784A User Manual

Updated Variable

Persistence Display

Acquiring and Displaying Waveforms

To Set the InstaVu Style

To Set the InstaVu

Readout Options

Figure 3–27: InstaVu Display

To change the InstaVu display style, do the following steps:

1. Press DISPLAY ➞ Mode (main) ➞ InstaVu (pop-up) ➞ Style (main).

2. Select between Vectors and Dots in the side menu. (Dots display is the

factory default setting.)

3. Select between Infinite Persistence and Variable Persistence in the side menu. (Variable Persistence is the factory default setting.)

4. Use the general purpose knob or keypad to adjust the persistence time (decay rate) if you have selected Variable Persistence.

To change the InstaVu readout options, do the following steps:

1. Press DISPLAY ➞ Mode (main) ➞ InstaVu (pop-up) ➞ Readout Options (main).

2. Toggle Display T Trigger Point, Trigger Bar Style and Display Date/ Time in the side menu to the settings desired.

Incompatible Modes

TDS 684A, TDS 744A, & TDS 784A User Manual

Several modes/features are unavailable when InstaVu mode is selected:  Auto trigger, FastFrame, Limit Testing, XY display, and Zoom modes

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Tektronix TDS 744A, TDS 784A, TDS 684A User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

User Manual

Table of Contents

Getting Started

Operating Basics

Reference

Appendices

Glossary Index

List of Figures

List of Tables

General Safety Summary

Injury Precautions

Product Damage Precautions

Safety Terms and Symbols

Certifications and Compliances

Preface

Related Manuals

Conventions

Default Model

Product Description

Product Specification

Start Up

Preparation

Putting into Service

Overview

Operating Interface Maps

Rear Panel Map

Display Map

To Operate a Menu

To Operate a Pop-Up Menu

Tutorial

Setting Up for the Examples

Example 1: Displaying a Waveform

Example 2: Displaying Multiple Waveforms

Add a Waveform

Example 3: Taking Automated Measurements

Example 4: Saving Setups

Overview

Acquiring and Displaying W aveforms

Coupling Waveforms to the Oscilloscope

Setting up Automatically: Autoset and Reset

Selecting Channels

Scaling and Positioning Waveforms

Choosing an Acquisition Mode

Customizing the Display

Customizing the Display Color

Zooming on Waveforms