Tektronix TDS 694C User Manual

User Manual

TDS 694C Digital Real-Time Oscilloscope

071-0473-00

This document supports firmware version 1.0 and above.

Copyright © T ektronix, Inc. All rights reserved. Licensed software products are owned by Tektronix or its suppliers and are protected by United States copyright laws and international treaty provisions.

Use, duplication, or disclosure by the Government is subject to restrictions as set forth in subparagraph (c)(1)(ii) of the Rights in T echnical Data and Computer Software clause at DFARS 252.227-7013, or subparagraphs (c)(1) and (2) of the Commercial Computer Software – Restricted Rights clause at F AR 52.227-19, as applicable.

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

Printed in the U.S.A. T ektronix, Inc., P.O. Box 1000, Wilsonville, OR 97070–1000 TEKTRONIX and TEK are registered trademarks of T ektronix, Inc.

WARRANTY

T ektronix warrants that 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.

Getting Started

Operating Basics

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

Preface xi. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Related Manuals xi. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Conventions xi. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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

TDS 694C Features 1–3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Product Specification 1–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Start Up 1–5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Preparation 1–5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Putting into Service 1–5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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

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

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

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

Example 2: Displaying Multiple Waveforms 2–16. . . . . . . . . . . . . . . . . . . . . . . . . . . .

Example 3: T aking Automated Measurements 2–20. . . . . . . . . . . . . . . . . . . . . . . . . .

Example 4: Saving Setups 2–26. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Reference

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

Acquiring and Displaying Waveforms 3–5. . . . . . . . . . . . . . . . . . . . . . . . .

Coupling Waveforms to the Oscilloscope 3–5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Setting up Automatically: Autoset and Reset 3–6. . . . . . . . . . . . . . . . . . . . . . . . . . .

Selecting Channels 3–8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Scaling and Positioning Waveforms 3–10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Choosing an Acquisition Mode 3–17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Customizing the Display 3–25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Customizing the Display Color 3–30. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Zooming on Waveforms 3–34. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Triggering on Waveforms 3–41. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Triggering Concepts 3–41. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Triggering from the Front Panel 3–46. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Triggering on a Waveform Edge 3–49. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Triggering Based on Logic 3–53. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Triggering on Pulses 3–69. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Delayed Triggering 3–82. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Measuring Waveforms 3–89. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

T aking Automated Measurements 3–90. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

T aking Cursor Measurements 3–100. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

TDS 694C User Manual

Table of Contents

T aking Graticule Measurements 3–105. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Displaying Histograms 3–106. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Optimizing Measurement Accuracy: SPC and Probe Cal 3–110. . . . . . . . . . . . . . . . . .

Saving Waveforms and Setups 3–117. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Saving and Recalling Setups 3–117. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Saving and Recalling Waveforms and Acquisitions 3–120. . . . . . . . . . . . . . . . . . . . . .

Managing the File System 3–124. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Printing a Hardcopy 3–129. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Communicating with Remote Instruments 3–139. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Determining Status and Accessing Help 3–143. . . . . . . . . . . . . . . . . . . . . . . .

Displaying Status 3–143. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Displaying the Banner 3–145. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Displaying Help 3–145. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Using Features for Advanced Applications 3–147. . . . . . . . . . . . . . . . . . . . . .

Limit Testing 3–147. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Waveform Math 3–152. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Fast Fourier Transforms 3–155. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Waveform Differentiation 3–174. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Waveform Integration 3–179. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Appendices

Glossary Index

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

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

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

Appendix D: Probe Selection D–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Appendix E: Inspection and Cleaning E–1. . . . . . . . . . . . . . . . . . . . . . . . . .

Appendix F: Programmer Disk F–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

TDS 694C User Manual

List of Figures

Table of Contents

Figure 1–1: Rear Panel Controls Used in Start Up 1–7. . . . . . . . . . . . . . .

Figure 1–2: ON/STBY Button 1–8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 2–1: Deskew Fixture Connections

(two P6249 probes shown) 2–9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 2–2: Connecting a Probe for the Examples

(P6249 shown) 2–10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 2–3: SETUP Button Location 2–10. . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 2–4: The Setup Menu 2–11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 2–5: Trigger Controls 2–12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 2–6: The Display After Factory Initialization 2–13. . . . . . . . . . . . .

Figure 2–7: The VERTICAL and HORIZONTAL Controls 2–14. . . . . . .

Figure 2–8: TRIGGER Controls 2–15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 2–9: AUTOSET Button Location 2–16. . . . . . . . . . . . . . . . . . . . . . . .

Figure 2–10: The Display After Pressing Autoset 2–16. . . . . . . . . . . . . . . .

Figure 2–11: The Channel Buttons and Lights 2–17. . . . . . . . . . . . . . . . . . .

Figure 2–12: The Vertical Main Menu and Coupling

Side Menu 2–19. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 2–13: The Menus After Changing Channels 2–20. . . . . . . . . . . . . .

Figure 2–14: Measure Main Menu and Select Measurement

Side Menu 2–22. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 2–15: Four Simultaneous Measurement Readouts 2–23. . . . . . . . .

Figure 2–16: General Purpose Knob Indicators 2–24. . . . . . . . . . . . . . . . .

Figure 2–17: Snapshot of Channel 1 2–26. . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 2–18: Save/Recall Setup Menu 2–27. . . . . . . . . . . . . . . . . . . . . . . . . .

TDS 694C User Manual

Figure 3–1: The Channel Readout 3–8. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–2: Waveform Selection Priority 3–9. . . . . . . . . . . . . . . . . . . . . . .

Figure 3–3: Scaling and Positioning 3–11. . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–4: Vertical Readouts and Channel Menu 3–12. . . . . . . . . . . . . . .

Figure 3–5: Record View and Time Base Readouts 3–14. . . . . . . . . . . . . . .

Figure 3–6: Horizontal Controls 3–15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–7: Acquisition: Input Analog Signal,

Sample, and Digitize 3–18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–8: Several Points May be Acquired for

Each Point Used 3–18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–9: Real-Time Sampling 3–19. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Figure 3–10: How the Acquisition Modes Work 3–21. . . . . . . . . . . . . . . . .

Figure 3–11: Acquisition Menu and Readout 3–22. . . . . . . . . . . . . . . . . . . .

Figure 3–12: Acquire Menu — Stop After 3–23. . . . . . . . . . . . . . . . . . . . . .

Figure 3–13: Aliasing 3–24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–14: Display Menu — Style 3–26. . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–15: Trigger Point and Level Indicators 3–27. . . . . . . . . . . . . . . . .

Figure 3–16: Display Menu — Setting 3–30. . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–17: Display Menu — Palette Colors 3–32. . . . . . . . . . . . . . . . . . .

Figure 3–18: Display Menu — Map Reference Colors 3–33. . . . . . . . . . . .

Figure 3–19: Display Menu — Restore Colors 3–34. . . . . . . . . . . . . . . . . . .

Figure 3–20: Zoom Mode with Horizontal Lock Set to None 3–37. . . . . . .

Figure 3–21: Dual Window (Preview) Mode 3–38. . . . . . . . . . . . . . . . . . . . .

Figure 3–22: Dual Zoom — Shown Dual Window

(Preview) Mode 3–40. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–23: Triggered Versus Untriggered Displays 3–42. . . . . . . . . . . . .

Figure 3–24: Trigger Holdoff Time Ensures Valid Triggering 3–44. . . . . .

Figure 3–25: Slope and Level Controls Help Define the Trigger 3–45. . . .

Figure 3–26: TRIGGER Controls and Status Lights 3–46. . . . . . . . . . . . . .

Figure 3–27: Example Trigger Readouts — Edge

Trigger Selected 3–48. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–28: Record View, Trigger Position, and Trigger Level Bar

Readouts 3–49. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–29: Edge Trigger Readouts 3–50. . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–30: Main Trigger Menu — Edge Type 3–50. . . . . . . . . . . . . . . . .

Figure 3–31: Violation Zones for Setup/Hold Triggering 3–56. . . . . . . . . .

Figure 3–32: Logic Trigger Readouts — State Class Selected 3–57. . . . . .

Figure 3–33: Logic Trigger Menu 3–58. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–34: Logic Trigger Menu — Time Qualified TRUE 3–60. . . . . . .

Figure 3–35: Triggering on a Setup/Hold Time Violation 3–64. . . . . . . . . .

Figure 3–36: TLA 714 to TDS 694C 3–66. . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–37: TLA 720 to TDS 694C 3–66. . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–38: Pulse Trigger Readouts 3–70. . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–39: Main Trigger Menu — Glitch Class 3–72. . . . . . . . . . . . . . . .

Figure 3–40: Main Trigger Menu — Runt Class 3–75. . . . . . . . . . . . . . . . .

Figure 3–41: Main Trigger Menu — Slew Rate Class 3–80. . . . . . . . . . . . .

Figure 3–42: Delayed Runs After Main 3–83. . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–43: Delayed Triggerable 3–83. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–44: How the Delayed Triggers Work 3–85. . . . . . . . . . . . . . . . . . .

Figure 3–45: Delayed Trigger Menu 3–87. . . . . . . . . . . . . . . . . . . . . . . . . . .

TDS 694C User Manual

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Figure 3–46: Histogram, Graticule, Cursor and

Automated Measurements 3–89. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–47: Measurement Readouts with Statistics 3–93. . . . . . . . . . . . . .

Figure 3–48: Measure Menu 3–94. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–49: Measure Menu — Gating 3–95. . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–50: Measure Menu — Reference Levels 3–97. . . . . . . . . . . . . . . .

Figure 3–51: Measure Delay Menu — Delay To 3–98. . . . . . . . . . . . . . . . . .

Figure 3–52: Snapshot Menu and Readout 3–99. . . . . . . . . . . . . . . . . . . . . .

Figure 3–53: Cursor Types 3–101. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–54: Cursor Modes 3–102. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–55: H Bars Cursor Menu and Readouts 3–103. . . . . . . . . . . . . . . .

Figure 3–56: Paired Cursor Menu and Readouts 3–104. . . . . . . . . . . . . . . .

Figure 3–57: Histogram Menu and Vertical Histogram 3–107. . . . . . . . . . .

Figure 3–58: Performing a Signal Path Compensation 3–111. . . . . . . . . . . .

Figure 3–59: Probe Cal Menu and Gain Compensation Display 3–113. . . .

Figure 3–60: Re-use Probe Calibration Data Menu 3–115. . . . . . . . . . . . . . .

Figure 3–61: Save/Recall Setup Menu 3–118. . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–62: Save Waveform Menu 3–121. . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–63: More Menu 3–123. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–64: File Utilities 3–125. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–65: File System — Labeling Menu 3–126. . . . . . . . . . . . . . . . . . . . .

Figure 3–66: Utility Menu — System I/O 3–131. . . . . . . . . . . . . . . . . . . . . . .

Figure 3–67: Hardcopy Formats 3–132. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–68: Date and Time Display 3–133. . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–69: Connecting the Oscilloscope Directly to the

Hardcopy Device 3–134. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–70: Connecting the Oscilloscope and Hardcopy

Device Via a PC 3–137. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–71: Typical GPIB Network Configuration 3–140. . . . . . . . . . . . . .

Figure 3–72: Stacking GPIB Connectors 3–140. . . . . . . . . . . . . . . . . . . . . . .

Figure 3–73: Connecting the Oscilloscope to a Controller 3–141. . . . . . . . .

Figure 3–74: Utility Menu 3–142. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–75: Status Menu — System 3–144. . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–76: Banner Display 3–145. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–77: Initial Help Screen 3–146. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–78: Comparing a Waveform to a Limit Template 3–148. . . . . . . .

Figure 3–79: Acquire Menu — Create Limit Test Template 3–149. . . . . . . .

Figure 3–80: More Menu 3–153. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–81: Dual Waveform Math Main and Side Menus 3–154. . . . . . . .

TDS 694C User Manual

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Figure 3–82: System Response to an Impulse 3–157. . . . . . . . . . . . . . . . . . . .

Figure 3–83: Define FFT Waveform Menu 3–158. . . . . . . . . . . . . . . . . . . . . .

Figure 3–84: FFT Math Waveform in Math1 3–160. . . . . . . . . . . . . . . . . . . .

Figure 3–85: Cursor Measurement of an FFT Waveform 3–161. . . . . . . . . .

Figure 3–86: Waveform Record vs. FFT Time Domain Record 3–163. . . . .

Figure 3–87: FFT Time Domain Record vs. FFT Frequency

Domain Record 3–164. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–88: How Aliased Frequencies Appear in an FFT 3–168. . . . . . . . .

Figure 3–89: Windowing the FFT Time Domain Record 3–171. . . . . . . . . .

Figure 3–90: FFT Windows and Bandpass Characteristics 3–174. . . . . . . .

Figure 3–91: Derivative Math Waveform 3–176. . . . . . . . . . . . . . . . . . . . . . .

Figure 3–92: Peak-Peak Amplitude Measurement of a

Derivative Waveform 3–177. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–93: Integral Math Waveform 3–181. . . . . . . . . . . . . . . . . . . . . . . . .

Figure 3–94: H Bars Cursors Measure an Integral Math

Waveform 3–182. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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

Figure B–2: Fall Time B–9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure B–3: Rise Time B–14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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

Measurements B–16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure D–1: Typical High Voltage Probes D–3. . . . . . . . . . . . . . . . . . . . . . .

Figure D–2: A6303 Current Probe Used in the

AM 503S Opt. 03 D–5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure F–1: Equipment Needed to Run the Example Programs F–1. . . .

TDS 694C User Manual

List of Tables

Table of Contents

Table 1–1: Key Features of TDS 694C 1–3. . . . . . . . . . . . . . . . . . . . . . . . .

Table 1–2: Fuse and fuse cap part numbers 1–7. . . . . . . . . . . . . . . . . . . .

Table 3–1: Autoset defaults 3–7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 3–2: XY Format pairs 3–29. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 3–3: Pattern and State Logic 3–54. . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 3–4: Pulse trigger definitions 3–70. . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 3–5: Measurement definitions 3–90. . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 3–6: Measurement definitions 3–109. . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 3–7: Probe cal status 3–116. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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

Table A–2: Standard accessories A–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table A–3: Optional accessories A–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table A–4: Recommended probe cross reference A–3. . . . . . . . . . . . . . . .

Table A–5: Accessory software A–5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table E–1: External inspection check list E–2. . . . . . . . . . . . . . . . . . . . . .

TDS 694C User Manual

vii

Table of Contents

viii

TDS 694C User Manual

General Safety Summary

Review the following safety precautions to avoid injury and prevent damage to this product or any products connected to it. To avoid potential hazards, use this product only as specified.

Only qualified personnel should perform service procedures.

To Avoid Fire or Personal Injury

Use Proper Power Cord. Use only the power cord specified for this product and

certified for the country of use. Use Proper V oltage Setting. Before applying power, ensure that the line selector is

in the proper position for the power source being used. Connect and Disconnect Properly . Do not connect or disconnect probes or test

leads while they are connected to a voltage source. Ground the Product. 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.

Observe All Terminal Ratings. To avoid fire or shock hazard, observe all ratings and markings on the product. Consult the product manual for further ratings information before making connections to the product.

Connect the ground lead of the probe to earth ground only. Do not apply a potential to any terminal, including the common terminal, that

exceeds the maximum rating of that terminal. Do Not Operate Without Covers. Do not operate this product with covers or panels

removed.

TDS 694C User Manual

Use Proper Fuse. Use only the fuse type and rating specified for this product. Avoid Exposed Circuitry. Do not touch exposed connections and components

when power is present. Do Not Operate With Suspected Failures. If you suspect there is damage to this

product, have it inspected by qualified service personnel.

Do Not Operate in Wet/Damp Conditions. Do Not Operate in an Explosive Atmosphere. Keep Product Surfaces Clean and Dry . Provide Proper Ventilation. Refer to the manual’s installation instructions for

details on installing the product so it has proper ventilation.

General Safety Summary

Symbols and Terms

T erms 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.

T erms 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.

Symbols on the Product. The following symbols may appear on the product:

Electrostatic Discharge

CAUTION

Refer to Manual

WARNING

High Voltage

Double

Insulated

Protective Ground

(Earth) Terminal

Acquisition circuitry in the TDS 694C is very susceptible to damage from electrostatic discharge and from overdrive signals.

To prevent electrostatic damage to the TDS 694C, be sure to operate the oscilloscope only in a static-controlled environment. Be sure to discharge to ground any electrostatic charge that may be present on cables and probes before attaching them to the oscilloscope.

To prevent damage from electrostatic discharge, install short-circuit terminations on unused input connectors. Always use a wrist strap with internal impedance (provided with your instrument) when handling your oscilloscope or making connections.

TDS 694C User Manual

Preface

Related Manuals

This is the User Manual for the TDS 694C Oscilloscopes The chapter Getting Started briefly describes the TDS 694C Oscilloscopes,

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. H The TDS Family Digitizing Oscilloscopes Programmer Manual (a diskette

that is included with the user manual) describes using a computer to control the oscilloscope through the GPIB interface.

Conventions

TDS 694C User Manual

H The TDS 500D, TDS 600C & TDS 700D Digitizing Oscilloscopes Reference

(Quick Reference) gives you a quick overview of how to operate the

oscilloscope.

H The TDS 500D, TDS 600C, & TDS 700D Technical Reference (Performance

Verification and Specifications) tells how to verify the performance of the

oscilloscope and lists its specifications.

H The TDS 500B, TDS 600B, TDS 600B, & TDS 700A Service Manual

provides information for maintaining and servicing the oscilloscope to the module level.

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:

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

boldface print.

Preface

H 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.

H Instruction steps are numbered. The number is omitted if there is only one step. H When steps require that you make a sequence of selections using front panel

controls and menu buttons, an arrow ( ➞ ) marks each transition between a

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).

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.

xii

TDS 694C User Manual

Product Description

The Tektronix TDS 694C Digital Real-Time 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 key features:

H An analog bandwidth of 3 GHz simultaneous on 4 channels H A maximum sample rate of up to 10 GS/s simultaneous on 4 channels H Records lengths up to 120 K H Up to 29 automatic measurements and measurement statistics (see Taking

Automated Measurements on page 3–88)

H 1% DC vertical gain accuracy (see TDS 500D, TDS600B & TDS 700D

Technical Reference manual)

H Internal floppy disk storage and compatible with Iomega 100 Mbyte Zip

drive (see Saving Waveforms and Setups on page 3–115)

H Optional internal hard drive H Trigger modes include edge, logic, pulse, delay, modes (see Triggering on

Waveforms on page 3–39)

H Java application support H TLA 700 Logic Analyzer cross-triggering support

TDS 694C User Manual

1–1

Product Description

H Advanced features include limit testing (see Limit Testing on page 3–145),

FFT (see Fast Fourier Transforms on page 3–153), waveform differentiation

and integrations (see Waveform Differentiation and Waveform Integration

starting on page 3–172), waveform histograms (see Displaying Histograms

on page 3–104) H Adjustable channel deskew for increased measurement accuracy (see

Channel/Probe Deskew on page 3–109) H Full GPIB programmability (see Communicating with Remote Instruments

on page 3–137 and the TDS Family Programmer Manual disk)

H Wide array of probing solutions (see Accessory Probes on page 0–3 and

Probe Selection on page 0–1) H CE, FCC, UL, and CAN/CSE compliant (see TDS 500D, TDS600B &

TDS 700D Technical Reference manual)

H All 4 channels have 8-bit resolution. (See Table 1–1 on page 1–3.) H Dual Window Zoom, which shows a waveform magnified and unmagnified

on the same display (see Using Dual Window Mode on page 3–35) H Sample, envelope, average, and peak-detect modes (see Table 1–1,

on page 1–3.)

1–2

TDS 694C User Manual

TDS 694C Features

Product Description

Table 1–1 lists some key TDS 694C features that are covered in this manual.

T able 1–1: Key Features of TDS 694C

Feature TDS 694C

No. of channels 4

Digitizing rate, max. 10 GS/s

No. of Channels. @ maximum rate 4

Analog Bandwidth 3 GHz

Record Lengths, max. To 120 K/Channel

Advanced DSP Math

Storage, Floppy Disk Std.

I/0 includes RS–232 and Centronics

iomega Zip Drive support Std.

Std.

2 2 2 2

Input Impedance 50 W only

Advanced digital signal processing provides FFT s, integrals, and derivatives of waveforms. See Option 2F on page 0–2.

Std. denotes a standard product feature as opposed to a feature included as part of an option.

GPIB I/O included with all models.

TDS 694C User Manual

1–3

Product Description

Product Specification

The product specification is found in the technical reference TDS 500D, TDS 600C, & TDS 700D Technical Reference (Performance Verification and Specifications) that is shipped as a standard accessory with the TDS 694C Oscil-

loscopes.

1–4

TDS 694C User Manual

Start Up

Preparation

Before you use the TDS 694C Oscilloscopes, 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 3–108 for a description of and operating information on this feature.

The TDS 694C Oscilloscopes ships without probes. To take advantage of the higher bandwidth of these oscilloscopes, order P6249 or P6158 probes.

For a list of recommended optional-accessory probes see Accessory Probes on page A–3. Probes that require a 1 MW input, like the P6139A, will not work on the TDS 694C.

Be sure you use the appropriate probe for the measurement. (See the User manual for the probe for more information.)

CAUTION. Using the P6249 or P6245 Active Probe to measure signals greater than ±40 volts may damage the probe. Using the P6158 Voltage Divider Probe to measure signals greater than ±22 V

may damage the probe.

RMS

Putting into Service

TDS 694C User Manual

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

1–5

Start Up

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 500D, TDS 600C, & TDS 700D Technical Reference

(Performance Verification and Specifications)Technical Reference (Perfor-

mance Verification and Specifications) manual (Tektronix part number

071-0496-xx).

CAUTION. To prevent damage to the instrument caused by over heating, the TDS 694C must have adequate airflow. Verify air intake and exhaust ventilation in the cabinet as specified in Step 2.

2. Leave space for cooling for both rackmount and bench configurations. Do

this by verifying that the air intake and exhaust holes on the sides and

bottom of the cabinet are free of any airflow obstructions. Leave at least

5.1 cm (2 inches) free on both sides. Leave 2.5 cm (1.0 inch) minimum

space on the bottom of rackmount instruments, the height of the feet will

provide adequate space for bench configurations.

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 100 to 240 VAC

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

RMS

require up to 450 W.

1–6

TDS 694C User Manual

Power Connector

Principal Power Switch

Fuse

Start Up

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

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

Figure 1–1) to the power system.

Front Cover Removal

Power On

T able 1–2: Fuse and fuse cap part numbers

Fuse cap part

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

number

To remove the front cover, grasp the left and right edges and snap the cover off of the front subpanel. (To reinstall the cover, 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).

TDS 694C User Manual

1–7

Start Up

ON/STBY Button

Self Test

Power Off

Figure 1–2: ON/STBY Button

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.

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.

1–8

TDS 694C User Manual

Overview

This chapter describes the basic concepts of operating the TDS 694C Digital Real-Time 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:

H Front Panel Map H Rear Panel Map H Display Map H To Operate a Menu H 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:

TDS 694C User Manual

H Setting Up for the Examples H Example 1: Displaying a Waveform H Example 2: Displaying Multiple Waveforms H Example 3: Taking Automated Measurements H 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.

2–1

Overview

2–2

TDS 694C 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 694C Oscilloscopes. 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 3–122

Side Menu Buttons, page 2–7

ON/STBY Switch,

page 1–7

TDS 694C User Manual

CLEAR MENU Removes Menus from the Display

Main Menu Buttons,

page 2–7

2–3

Operating Interface Maps

Front Panel Map — Right Side

Measurement System, page 3–88

Cursor Measurements, page 3–98

Saving and Recalling

Waveforms, page 3–118

File System, page 3–122

Autoset, page 3–4

Help, page 3–143

Status, page 3–141

Saving and Recalling

Setups, page 3–115

Selecting Channels,

page 3–6

Waveform Math,

page 3–150

Hardcopy, page 3–127

File System, page 3–122

Acquisition Modes, page 3–17

Cursor Measurements, page 3–98

Color, page 3–28

Display Settings, page 3–23 Remote Communication, page 3–137

Probe Calibration, page 3–109

Vertical Controls,

page 3–9

2–4

Zoom, page 3–32

Horizontal Controls,

page 3–13

Ground

Triggering, page 3–39 Delay Triggering, page 3–80 Edge Triggering, page 3–47 Logic Triggering, page 3–51 Pulse Triggering, page 3–67

TDS 694C User Manual

Rear Panel Map

Operating Interface Maps

Principal Power

Switch,

page 1–7

Fuse,

page 1–6

Centronics Connector, page 3–127

Zip Drive, page 3–126

Serial Number

RS-232 Connector,

page 3–127

Power Connector,

page 1–6

GPIB Connector,

page 3–137

Rear Panel Connectors Security Bracket

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 694C User Manual

2–5

Operating Interface Maps

Display Map

acquisition page 3–20

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 3–102

Shows what part of the waveform

record is displayed, page 3–12

Trigger

position (T),

page 3–46

The value entered with

the general purpose

knob

or keypad.

The waveform

record icon

Shows what part of

waveform record

When present, the general

purpose knob makes coarse

adjustments; when absent,

fine adjustments.

the acquisition

record is in the

Cursor measurements, page 3–98

Channel level and

waveform source.

2–6

Vertical scale,

page 3–9

The main menu with

choices of major actions

The side menu with choices of specific actions.

Trigger parameters, page 3–46

Horizontal scale and time

base type, page 3–13

TDS 694C 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 694C 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.

Press here to

remove menus from

screen.

TDS 694C User Manual

Tutorial

This section quickly makes you acquainted with some of the fundamental operations required to use the TDS 694C Oscilloscopes 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 694C Oscilloscopes, 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 P6249), connect from the CH 1 connector of the oscilloscope to the PROBE COMPENSATION connectors. (See Figure 2–2.)

NOTE. See Appendix A: Options and Accessories for optional probes you can order and use with this product. Use the probe deskew fixture to ensure optimum probe connections.

P6249 probes

GroundSignal

TDS 694C User Manual

Figure 2–1: Deskew Fixture Connections (two P6249 probes shown)

2–9

Tutorial

Figure 2–2: Connecting a Probe for the Examples (P6249 shown)

Reset the Oscilloscope

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 2–3.)

SETUP Button

Deskew fixture

2–10

Figure 2–3: SETUP Button Location

TDS 694C User Manual

OK Confirm Factory Init

Menu Item and Button

Recall Factory Setup

Menu Item and Button

Tutorial

The oscilloscope displays main menus along the bottom of the screen. Figure 2–4 shows the Setup main menu.

Figure 2–4: The Setup Menu

2. Press the button directly below the Recall Factory Setup menu item. 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 2–4.)

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 2–5) to be sure the oscilloscope triggers on the input signal.

TDS 694C User Manual

2–11

Tutorial

SET LEVEL TO 50% Button

Figure 2–5: Trigger Controls

Examine the Display

Elements

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

Figure 2–6 shows the display that results from the oscilloscope reset. There are several important points to observe:

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

50% of its amplitude (from step 4).

H The trigger position indicator shows that the trigger position of the

waveform is located at the horizontal center of the graticule.

H 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.

2–12

TDS 694C User Manual

Trigger Level Bar

Trigger Position Indicator

Channel Reference Indicator

Trigger Readout

Time Base Readout

Channel Readout

Tutorial

H 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.

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

scale of 500 ms/div.

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

coupling. The oscilloscope always displays channel 1 at reset.

Figure 2–6: 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.

Example 1: Displaying a Waveform

The TDS 694C Oscilloscopes 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 694C Oscilloscopes.

TDS 694C User Manual

2–13

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 2–7 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.

2–14

Figure 2–7: 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 ms/div now, and you should see two complete waveform cycles on the display.

TDS 694C User Manual

Tutorial

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 2–8) 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.

Figure 2–8: TRIGGER Controls

2. Press AUTOSET (see Figure 2–9) and observe the stable waveform display.

NOTE. The oscilloscope triggers on the input signal. Sometimes the oscilloscope triggers on high frequency signal components that are not visible using the current setup. You may see these signal components at higher HORIZONTAL SCALE settings. You can reduce these signal components using shorter probe ground and signal leads.

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AUTOSET Button

Figure 2–9: AUTOSET Button Location

Figure 2–10 shows the display after pressing AUTOSET. If necessary, you can adjust the waveform now by using the knobs discussed earlier in this example.

Figure 2–10: The Display After Pressing Autoset

Example 2: Displaying Multiple Waveforms

The TDS 694C Oscilloscopes 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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Tutorial

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:

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

and Ch2.

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

now, they overlap.

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H 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.

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

events on channel one. 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.

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.

7. Press GND (side) to toggle the selection to ground (GND). That changes the

input coupling of channel 2 from DC to GND. The channel readout for channel 2 (near the bottom of the graticule) now shows a ground indicator.

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Ch2 Reference Indicator

Tutorial

Side Menu Title

Assign Controls to

Another Channel

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

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 GND channel 2 setting to the DC coupling setting of channel 1.

2. Press CH 2 ➞ DC (side) to toggle the selection to DC. That returns the input coupling of channel 2 to its initial state.

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Side Menu Title

Figure 2–13: The Menus After Changing Channels

Remove a Waveform

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).

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 694C Oscilloscopes 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.

Display Measurements

Automatically

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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

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

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Tutorial

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 measurements 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 Level Setup (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: H 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.

H The upper right corner of the screen shows the readout High Ref: 90%. H 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.

TDS 694C User Manual

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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Tutorial

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 m for micro. To enter these multiplier values, press the SHIFT button, and then press the multiplier.

TDS 694C User Manual

1. Press Low Ref (side).

Tutorial

Displaying a Snapshot of

Automated Measurements

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

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.

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.

) 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.

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

ments.

3. Press Remove Measrmnt (main) to remove the snapshot display. (You can also press CLEAR MENU, but a new snapshot will be executed the next time you display the Measure menu.)

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Figure 2–17: Snapshot of Channel 1

Example 4: Saving Setups

The TDS 694C Oscilloscopes 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, an optional hard disk, or an external Zip drive. 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.

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:

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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.

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Tutorial

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.)

TDS 694C User Manual

Figure 2–18: Save/Recall Setup Menu

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Tutorial

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.

Recall a Setup

To recall the setup, press SAVE/RECALL SETUP ➞ Recall Saved Setup (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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TDS 694C User Manual

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:

H Acquiring and Displaying Waveforms H Triggering on Waveforms H 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:

H Saving Waveforms and Setups H 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:

H 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 xi of Preface before reading about these tasks.

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

TDS 694C User Manual

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Overview

Acquiring and Displaying

Waveforms

Triggering on Waveforms

Measuring Waveforms

Coupling Waveforms to the Oscilloscope 3–5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Setting up Automatically: Autoset and Reset 3–6. . . . . . . . . . . . . . . . . . . . . . . . . . .

Selecting Channels 3–8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Scaling and Positioning Waveforms 3–10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Choosing an Acquisition Mode 3–17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Customizing the Display 3–25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Customizing the Display Color 3–30. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Zooming on Waveforms 3–35. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Triggering Concepts 3–43. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Triggering from the Front Panel 3–48. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Triggering on a Waveform Edge 3–51. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Triggering Based on Logic 3–55. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Triggering on Pulses 3–67. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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

T aking Automated Measurements 3–88. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

T aking Cursor Measurements 3–98. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

T aking Graticule Measurements 3–103. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Displaying Histograms 3–104. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Optimizing Measurement Accuracy: SPC and Probe Cal 3–108. . . . . . . . . . . . . . . . . .

Saving Waveforms and

Setups

Determining Status and

Accessing Help

Using Features for

Advanced Applications

Saving and Recalling Setups 3–115. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Saving and Recalling Waveforms and Acquisitions 3–118. . . . . . . . . . . . . . . . . . . . . .

Managing the File System 3–122. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Printing a Hardcopy 3–127. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Communicating with Remote Instruments 3–137. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Displaying Status 3–141. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Displaying the Banner 3–143. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Displaying Help 3–143. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Limit Testing 3–145. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Waveform Math 3–150. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Fast Fourier Transforms 3–153. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Waveform Differentiation 3–172. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Waveform Integration 3–177. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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TDS 694C User Manual

Acquiring and Displaying Waveforms

To use the TDS 694C Oscilloscopes 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:

H How to couple waveforms to the oscilloscope channels H How to select channels to turn on and off their display H How to size and position the selected channel on screen H 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).

Coupling Waveforms to the Oscilloscope

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.

To Find More Information

TDS 694C User Manual

The TDS 694C Oscilloscopes ships without probes. Tektronix recommends you order and use the P6249, P6339 or P6158 probes. These probes take advantage of the higher bandwidth of these models.

Tektronix also offers a variety of optical probes, differential probes, adapters, and BNC cabling and connectors to couple a variety of signal sources to the input channels. See Options and Accessories on page A–1 or your Tektronix Sales representative for the specific items offered for signal coupling.

To find a procedure for changing the coupling and input impedance settings, see To Change Vertical Parameters on page 3–11.

To find a list of available probes, see Accessory Probes on page A–3. To find a guide for selecting probes for a variety of applications, see Appen-

dix D: Probe Selection on page D–1.

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Acquiring and Displaying Waveforms

Setting up Automatically: Autoset and Reset

The TDS 694C Oscilloscopes 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.

To Autoset the

Oscilloscope

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. If an offsetable level II probe is attached, AUTOSET will adjust offset to center the signal in the dynamic range of the probe.

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Acquiring and Displaying Waveforms

List of Autoset Defaults

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 Stop After RUN/STOP button only Deskew, Channel/Probe Unchanged Display Style Vectors Display Intensity — Overall If less than 50%, set to 75% Display Format YT 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 Horizontal Fit-to-Screen Unchanged Limit Test Off 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 Vertical Coupling DC Vertical Offset 0 volts, except offsetable probes, the offset will be set to the

mid point of the signal Zoom Off

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Acquiring and Displaying Waveforms

To Reset the Oscilloscope

Selecting Channels

To Identify the

Selected Channel

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 3–1). 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 694C Oscilloscopes 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.

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 3–1.)

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Channel Reference

Indicator

Channel Readout

Figure 3–1: The Channel Readout

TDS 694C User Manual

Acquiring and Displaying Waveforms

To Select and

Remove Waveforms

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.

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

When you turn off a waveform, the oscilloscope automatically selects the next highest priority waveform. Figure 3–2 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 3–2: Waveform Selection Priority

Note Figure 3–2 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.

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Acquiring and Displaying Waveforms

To Find More Information

To read about selecting reference waveforms, see Saving and Recalling Waveforms on page 3–118.

To read about selecting (and creating) math waveforms, see Waveform Math on page 3–150.

Scaling and Positioning Waveforms

The TDS 694C Oscilloscopes 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 3–3 shows the results of both vertical and horizontal scaling and positioning.) This section 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

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

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.

To Check 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.

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 3–4.)

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TDS 694C User Manual

Channel Reference Icon

Acquiring and Displaying Waveforms

Original Position Positioned Vertically Positioned Horizontally

To Change Vertical Scale

and Position

Original Scale Scaled Horizontally

Scaled Vertically

Figure 3–3: Scaling and Positioning

The TDS 694C Oscilloscopes 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 waveform changes.

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.

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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 3–4: 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, and offset for the selected waveform, use the Vertical menu (Figure 3–4). 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:

NOTE. The TDS 694C requires a P6339 probe for AC coupling, 10 MW input impedance, and bandwidth selections to appear in the menus.

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, GND, or (side).

H DC coupling shows both the AC and DC components of an input signal. H Ground (GND) coupling disconnects the input signal from the acquisition.

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.

To Set External

Attenuation

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.

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 +5 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.

You can set an external attenuation (or gain) in addition to the attenuation specified by the probe.

To set external attenuation, press VERTICAL MENU ➞ Probe Func-

tions (main) ➞ External Attenuation or External Attenuation in dB (side). External Attenuation — Use the general purpose knob or the keypad to set the

external attenuation as a multiplier.

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External Attenuation in dB — Use the general purpose knob or the keypad to set the external attenuation in dB.

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 3–5.)

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 3–5. Also see Figure 3–3 on page 3–9.) 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.

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

Figure 3–5: Record View and Time Base Readouts

 

 



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To Change Horizontal

Scale and Position

The TDS 694C Oscilloscopes provides control of horizontal position and scale using the horizontal front panel knobs.

By changing the horizontal position, 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.

To change the horizontal scale and position:

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

Figure 3–6.)

2. If you want the POSITION knob to move 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.

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Figure 3–6: 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.

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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 3–33.

To Change Horizontal

Parameters

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).

Trigger Position. The trigger point marks time zero in a waveform or acquisition (in Extended Acquisition mode) record. All record points before the trigger event make up the pretrigger portion of the record. Every record point after the trigger event is part of the posttrigger portion. All timing measurements in the 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: TDS 694C Oscilloscopes have standard record lengths up to 30,000 points.

Record lengths up to 120,000 with Option 1M.

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2. To fit an acquired waveform (or with Extended Acquisition On, an acquisition) 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 3–33 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 2–16.

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 3–32.

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 section first describes:

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

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H 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 3–20.

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Sampling and Digitizing

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 3–7.) 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.

+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 3–7: Acquisition: Input Analog Signal, Sample, and Digitize

The oscilloscope uses the samples it takes (see Figure 3–9) 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 3–8). The digitizer can use any extra samples to perform additional processing, such as 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.

Samples for a record point.

Figure 3–8: Several Points May be Acquired for Each Point Used

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Real-time Sampling

Interpolation

The general method of sampling are real-time and equivalent-time. The TDS 694C Oscilloscopes use only real-time sampling.

In real-time sampling, the oscilloscope digitizes all the points it acquires after one trigger event (see Figure 3–9). Always use real-time sampling to capture single-shot or transient events.

Record Points

Sampling Rate

Figure 3–9: Real-Time Sampling

Your oscilloscope can interpolate between the samples it acquires. 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. 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 Acquisition Modes

The situation just described occurs if you set the Horizontal SCALE knob to a time base setting that is faster than 5 ns. The oscilloscope then interpolates to create the intervening points in the waveform record. There are two options for interpolation: linear or sin(x)/x.

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.

The TDS 694C oscilloscope supports the following four acquisition modes:

Sample, Envelope, Average, and Peak Detect.

Sample (the mode most commonly used), Peak Detect 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

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acquisitions; the oscilloscope averages or envelopes several waveforms on a point-by-point basis.

Figure 3–10 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.

Envelope Mode. In Envelope mode, the oscilloscope acquires and displays a waveform record that shows the extremes in variation over several acquisitions (you specify the number of acquisitions). 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.

Peak Detect Mode. 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, the mode automatically changes from Peak Detect to Sample, although the menu selection will not change.

NOTE. For record lengths of 30,000 points of less, the Peak Detect sample interval will be 100ps. For record lengths of 50,000 points or greater, the Peak Detect sample interval will be 400ps.

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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

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

Acquisition

Mode

Interval 1 2 3 4

Sample

Uses first sample in

interval

Peak Detect

two intervals

Displayed

Record Points

Multiple Waveform Acquisitions

Three Acquisitions from One Source

Acquisition

Mode

Waveform Drawn

on CRT

Waveform Drawn

on CRT

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.

Figure 3–10: How the Acquisition Modes Work

Envelope

Finds highest and

lowest record points over

many acquisitions

Average

Calculates average value for

each record point over

many acquisitions

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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 3–11.) 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.

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Selecting an

Acquisition Mode

Stop After

Figure 3–11: Acquisition Menu and Readout

The oscilloscope provides several modes (see The Acquisition Modes on page 3–17) 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 3–11.)

2. Press Sample, Envelope, Average, or Peak Detect (side) or ...

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.

To choose the event that stops the 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 3–12.)

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Figure 3–12: Acquire Menu — Stop After

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

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.

RUN/STOP Foot Switch performs the same function as the RUN/STOP button only. The foot switch is recommended when both hands are needed

to probe two test points. To toggle the RUN/STOP function you can easily step on the foot switch. The foot switch connects to the TDS 694C Oscilloscope’s RS–232 port located on the rear panel. See Appendix A: Table A–2,

for Standard accessories

Set Communications Parameters. To set up the communication parameters for a foot switch attached directly to the oscilloscope RS-232 port:

Press SHIFT ➞ UTILITY ➞ System (main) ➞ I/O (pop-up) ➞ Config- ure (main) ➞ Foot Switch RUN/STOP (side).

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

single sequence of acquisitions by pressing the RUN/STOP button. In Sample, Peak Detect, the oscilloscope will acquire a waveform record with the first valid trigger event and stop.

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

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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.)

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

NOTE. 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.

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.

Setting up limit testing requires several more steps. See Limit Testing on page 3–145.

Preventing Aliasing

Actual High-Frequency Waveform

Apparent Low-frequency

Waveform Due to Aliasing

Sampled Points

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

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 3–13.)

Figure 3–13: Aliasing

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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.

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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 to avoid aliasing. The following tips may help you eliminate aliasing on a signal:

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

Customizing the Display

The TDS 694C Oscilloscopes can display waveform records and other display elements in different ways. This section describes how to adjust the oscilloscope display style, intensity level, graticule, and format.

Acquiring and Displaying Waveforms

Peak Detect. 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.

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 3–28.

Press DISPLAY ➞ Settings (main) ➞ Display (pop-up) ➞ Style (main) ➞

Vectors, Dots, Intensified Samples, Infinite Persistence, or Variable Persistence (side). (See Figure 3–14.)

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.

In addition to choosing Intensified Samples in the side menu, the oscilloscope must be interpolating or Zoom must be on with its horizontal expansion greater that 1X. See Interpolation on page 3–17; see Zooming on Waveforms on page 3–32.

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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 3–29.

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

Adjust Intensity

Set Display Readout

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Options

Figure 3–14: Display Menu — Style

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

To set the intensity: Press DISPLAY ➞ Settings (main) ➞ Display (pop-up) ➞ 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.

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1. Press DISPLAY ➞ Settings (main) ➞ Display (pop-up) ➞ Readout

Options (main).

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

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.)

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

bar or to turn the trigger bar off. (See Figure 3–15. 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 time base. The trigger bar is a visual indicator of the trigger level.

Trigger Point Indicator

Trigger Bar—Long Style

-or-

Trigger Bar—Short Style

Figure 3–15: Trigger Point and Level Indicators

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

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 3–130.)

the current date and time.

Select Interpolation Filter

Select the Graticule Type

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

DISPLAY ➞ Settings (main) ➞ Display (pop-up) ➞ Filter (main) ➞ Sin(x)/x Interpolation or Linear Interpolation (side).

NOTE. When the horizontal scale is set to the faster rates (2 ns/div for the TDS 694C) 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 3–17 for a discussion of interpolation.

To change the graticule: Press DISPLAY ➞ Settings (main) ➞ Display (pop-up) ➞ 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. Cross Hair provides cross hairs, and a frame.

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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.

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Select the Format

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

Press DISPLAY ➞ Settings (main) ➞ Display (pop-up) ➞ Format (main) ➞ XY or YT (side).

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 3–2 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 3–2: 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.

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Customizing the Display Color

The TDS 694C Oscilloscopes can display information in different colors. This section describes how to use the Color menu to choose the colors in which the various display objects appear.

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 3–16.)

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 3–23.

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Figure 3–16: Display Menu — Setting

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Choose a Palette

Change the Palette Colors

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.

2. Select one of the available palettes in the side menu. Choose from Normal, Bold, Hardcopy Preview or Monochrome.

3. If you are using a persistence display and want to vary the color of each

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.

NOTE. 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.

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. Hue is not available on monochrome oscilloscopes.

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. Saturation is not available on monochrome oscilloscopes.

1. Color oscilloscopes: Select the main menu Change Colors item. (See Figure 3–17.)

If changing the colors of a persistence palette: press Palette (main) ➞ Persistence Palettes (side) ➞ View Palette (main). Then select the palette you want to change from the side menu and select the main menu Change

Colors for item.

2. Select one of the colors by pressing (repeatedly) Color (Color Index if

changing a persistence palette) in the side menu.

3. If you want to use the factory default for this color or color index, 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:

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5. Choose Lightness from the side menu and use the general purpose knob or

6. Choose Saturation from the side menu and use the general purpose knob or

0 = blue, 60 = magenta, 120 = red, 180 = yellow, 240 = green, and 300 = cyan.

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.

keypad to select the saturation you desire. A value of 100 provides a pure color. A value of 0 provides gray.

Set Math Waveform Color

ScrTxt

Figure 3–17: 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.

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Acquiring and Displaying Waveforms

To return to the factory defaults, select Reset to Factory Color.

Set Reference Waveform

Color

To define reference waveform colors:

1. Press Map Reference in the main menu. (See Figure 3–18.)

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 (repeatedly) Color and choose the value.

4. To make the selected reference waveform the same color as the waveform it

is based on, select Color Matches Contents.

To return to the factory defaults, select Reset to Factory Color.

Select Options

Restore Colors

TDS 694C User Manual

Figure 3–18: 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:

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Acquiring and Displaying Waveforms

1. Press the main menu Restore Colors item. (See Figure 3–19.)

2. Select the object(s) you want to restore by pressing Reset Current Palette To Factory, Reset All Palettes To Factory (Reset Palette on monochrome oscilloscopes), or Reset All Mappings To Factory in the side menu.

Zooming on Waveforms

Using with Waveforms

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Figure 3–19: Display Menu — Restore Colors

The TDS 694C Oscilloscopes can expand or compress (zoom in or out) on a waveform without changing the acquisition parameters (sample rate, record length, and so on). This section 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.

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.

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Acquiring and Displaying Waveforms

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.

When zooming horizontally or vertically, Zoom expands or contracts the waveform by the zoom factor.

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 3–35.

To read about the two interpolation methods, see Interpolation on page 3–17. To differentiate between the real and interpolated samples, set the display style to Intensified Samples. (See Select the Display Style on page 3–23.)

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 3–20 on page 3–35.) Dual-window (preview) mode does not display the Zoom readout.

Zoom a Waveform

TDS 694C User Manual

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. Press ZOOM ➞ Mode (main) ➞ ON (side). The ZOOM front-panel button

should light up. Toggle Dual Zoom to OFF in the side menu.

3. 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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Acquiring and Displaying Waveforms

4. Adjust the horizontal zoom factor using the horizontal SCALE knob. Adjust

5. Press ZOOM ➞ Lock (main) ➞ All, Live, or None (side).

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 3–20).

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.

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 4 on page 3–34.

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Only the selected

waveform (the top one)

changes size.

Acquiring and Displaying Waveforms

Set Interpolation

Reset Zoom

Using Dual Window Mode

Figure 3–20: Zoom Mode with Horizontal Lock Set to None

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: 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.

The oscilloscope can display and control a waveform that is both zoomed and unzoomed (magnified and unmagnified). To do so, it 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 3–21.)

TDS 694C User Manual

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.

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Acquiring and Displaying Waveforms

3. To scale or position the magnified waveform, press Selected Grati-

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.

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.

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.

Zoomed (Magnified) Waveforms

Nonzoomed Waveforms, with Box

Indicators at Corners Denoting

the Selected Graticule

Dual Zoom a Waveform

Figure 3–21: Dual Window (Preview) Mode

To select Dual Zoom, press ZOOM ➞ Mode (main) ➞ Dual Zoom (side) to toggle it to ON. (See Figure 3–22.)

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.

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Acquiring and Displaying Waveforms

To Set Dual Zoom Offset

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 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.

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 Dual Zoom 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 3–35.

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Acquiring and Displaying Waveforms

Selected Graticule

Zoomed Waveform Edges

Zoom Boxes

Unzoomed Waveform

Figure 3–22: Dual Zoom — Shown Dual Window (Preview) Mode

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TDS 694C User Manual

Triggering on Waveforms

To use the TDS 694C Oscilloscopes to measure or monitor waveforms, you need to know how to trigger a stable display of those waveforms. Toward that end, this section first covers the following topics:

H Trigger Concepts which details some basic principles of triggering and

describes triggering elements: type, source, coupling, holdoff, mode, and so on.

H Triggering from the Front Panel which describes how to use the front-panel

triggering controls each of which is common to most, if not all, the trigger types the oscilloscope provides.

Once these basics are covered, this section describes how to trigger using the various trigger types provided by the Main trigger system: edge, logic, and pulse.

H To use the “general purpose” trigger type, edge, see Triggering on a

Waveform Edge on page 3–47.

H To logic trigger based on an input pattern, state, or setup/hold violation, see

Triggering Based on Logic on page 3–51.

Triggering Concepts

H To pulse trigger based on various pulse types (glitch, runt) or their parame-

ters (width, slew rate) see Triggering on Pulses on page 3–67.

This section concludes with details about and instructions for using the Delayed time base and Delayed trigger system to delay the acquisition of a waveform relative to a trigger event. (See Delayed Triggering on page 3–80.)

Triggers determine when the oscilloscope stops acquiring and displays a waveform. They help create meaningful waveforms from unstable jumbles or blank screens. (See Figure 3–23.) The oscilloscope has three types of triggers: edge, logic, pulse.

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Triggering on Waveforms

Triggered Waveform Untriggered Waveforms

Figure 3–23: Triggered Versus Untriggered Displays

The Trigger Event

Trigger Sources

The trigger event establishes the time-zero point in the waveform record. All points in the record are located in time with respect to that point. The oscilloscope continuously acquires and retains enough sample points to fill the pretrigger portion of the waveform record (that part of the waveform that is displayed before, or to the left of, the triggering event on screen). When a trigger event occurs, the oscilloscope starts acquiring samples to build the posttrigger portion of the waveform record (displayed after, or to the right of, the trigger event). Once a trigger is recognized, the digitizing oscilloscope will not accept another trigger until the acquisition is complete.

You can derive your trigger from the following sources: Input channels provide the most commonly used trigger source. You can select

any one of the four input channels. The channel you select as a trigger source will function whether it is displayed or not.

AC Line Voltage is the trigger source most often used when you are looking at signals related to the power line frequency. Examples include devices such as lighting equipment and power supplies. Because the oscilloscope generates the trigger, you do not have to input a signal to create the trigger.

Auxiliary Trigger is the trigger source most often used in doing digital design and repair. For example, you might want to trigger with an external clock, a logic analyzer or with a signal from another part of the circuit. To use the auxiliary trigger, connect the external triggering signal to the Auxiliary Trigger input connector on the oscilloscope rear panel.

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Triggering on Waveforms

Trigger Types

Trigger Modes

The digitizing oscilloscope provides three standard triggers for the main trigger system: edge, pulse, and logic. Option 05 provides a video trigger. The standard triggers are described individually starting on page 3–47. A brief definition of each type follows:

Edge is the “basic” trigger. You can use it with both analog and digital test circuits. An edge trigger event occurs when the trigger source (the signal the trigger circuit is monitoring) passes through a specified voltage level in the specified direction (the trigger slope).

Pulse is a special-purpose trigger primarily used on digital circuits. The five classes of pulse triggers are glitch, runt, width, slew rate and timeout. Pulse triggering is available on the main trigger only.

Logic is a special-purpose trigger primarily used on digital logic circuits. Two of the classes, pattern and state, trigger based on the Boolean operator you select for the trigger sources. Triggering occurs when the Boolean conditions are satisfied. A third class, setup/hold, triggers when data in one trigger source changes state within the setup and hold times that you specify relative to a clock in another trigger source. Logic triggers are available on the main trigger system only.

The trigger mode determines how the oscilloscope behaves in the absence of a trigger event. The oscilloscope provides two trigger modes, normal and automatic.

Normal trigger mode enables the oscilloscope to acquire a waveform only when it is triggered. If no trigger occurs, the oscilloscope will not acquire a waveform. (You can push FORCE TRIGGER to force the oscilloscope to make a single acquisition.)

Automatic trigger mode (auto mode) enables the oscilloscope to acquire a waveform even if a trigger does not occur. Auto mode uses a timer that starts after a trigger event occurs. If another trigger event is not detected before the timer times out, the oscilloscope forces a trigger anyway. The length of time it waits for a trigger event depends on the time base setting.

Be aware that auto mode, when forcing triggers in the absence of valid triggering events, does not sync the waveform on the display. In other words, successive acquisitions will not be triggered at the same point on the waveform; therefore, the waveform will appear to roll across the screen. Of course, if valid triggers occur the display will become stable on screen.

Since auto mode will force a trigger in the absence of one, auto mode is useful in observing signals where you are only concerned with monitoring amplitude level. Although the unsynced waveform may “roll” across the display, it will not freeze as it would in normal trigger mode. Monitoring of a power supply output is an example of such an application.

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Triggering on Waveforms

Trigger Holdoff

When the oscilloscope recognizes a trigger event, it disables the trigger system until acquisition is complete. In addition, the trigger system remains disabled during the holdoff period that follows each acquisition. You can set holdoff time to help ensure a stable display.

For example, the trigger signal can be a complex waveform with many possible trigger points on it. Though the waveform is repetitive, a simple trigger might get you a series of patterns on the screen instead of the same pattern each time.

A digital pulse train is a good example of a complex waveform. (See Figure 3–24.) Each pulse looks like any other, so many possible trigger points exist. Not all of these will result in the same display. The holdoff period allows the oscilloscope to trigger on the correct edge, resulting in a stable display.

Holdoff is settable from 250 ns (minimum holdoff available) to 12 seconds (maximum holdoff available). To see how to set holdoff, see To Set Mode & Holdoff on page 3–49.

You can also set a default holdoff. The default hold is the “general purpose” holdoff for most triggering signals and varies with the horizontal scale. It is equal to 5 divisions times the current time/division settings.

Acquisition

Interval

Acquisition

Interval

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Trigger Level

Indicates

Trigger Points

Trigger Coupling

Holdoff Holdoff

Triggers are not recognized during holdoff time.

Holdoff

Figure 3–24: Trigger Holdoff Time Ensures Valid Triggering

Trigger coupling determines what part of the signal is passed to the trigger circuit. All trigger types except edge triggering use only DC coupling; edge triggering can use all available coupling types: AC, DC, Low Frequency Rejection, High Frequency Rejection, and Noise Rejection: See To Specify Coupling on page 3–49 for a description of each coupling mode.

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Triggering on Waveforms

Trigger Position

Slope and Level

The adjustable feature trigger position defines where on the waveform record the trigger occurs. It lets you properly align and measure data within records. The part of the record that occurs before the trigger is the pretrigger portion. The part that occurs after the trigger is the posttrigger portion.

To help you visualize the trigger position setting, the top part of the display has an icon indicating where the trigger occurs in the waveform record. You select in the Horizontal menu what percentage of the waveform record will contain pretrigger information.

Displaying pretrigger information can be valuable when troubleshooting. For example, if you are trying to find the cause of an unwanted glitch in your test circuit, it might trigger on the glitch and make the pretrigger period large enough to capture data before the glitch. By analyzing what happened before the glitch, you may uncover clues about its source.

The slope control determines whether the oscilloscope finds the trigger point on the rising or the falling edge of a signal. (See Figure 3–25.)

You set trigger slope by first selecting Slope in the Main Trigger menu and then selecting between the rising or falling slope icons in the side menu that appears.

The level control determines where on that edge the trigger point occurs. (See Figure 3–25.) The oscilloscope lets you set the main trigger level with the trigger MAIN LEVEL knob.

Delayed Trigger System

Positive-Going Edge Negative-Going Edge

Trigger level

can be adjusted

vertically.

Trigger slope can be positive or negative.

Figure 3–25: Slope and Level Controls Help Define the Trigger

The oscilloscope also has a delayed trigger system that provides an edge trigger (no pulse or logic triggers). When using the delayed time base, you can also delay the acquisition of a waveform for a user-specified time or a user-specified number of delayed trigger events (or both) after a main trigger event. See Delayed Triggering on page 3–80 to learn how to use delay.

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Triggering on Waveforms

Triggering from the Front Panel

The trigger buttons and knob let you quickly adjust the trigger level or force a trigger. (See Figure 3–26.) The trigger readout and status screen lets you quickly determine the state of the trigger system. You use the following trigger controls and readouts for all trigger types except where noted.

To set MAIN LEVEL

Trigger Status Lights

To manually change the trigger level when edge triggering (or certain threshold levels when logic or pulse triggering), turn the MAIN LEVEL knob. It adjusts the trigger level (or threshold level) instantaneously no matter what menu, if any, is displayed.

Figure 3–26: TRIGGER Controls and Status Lights

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To Set to 50%

To quickly obtain an edge trigger or a glitch or width pulse trigger, press SET LEVEL TO 50%. The oscilloscope sets the trigger level to the halfway point

between the peaks of the trigger signal. Set Level to 50% has no effect when trigger type is logic or video.

You can also set the level to 50% in the Trigger menu under the main menu item Level if edge trigger or glitch or width pulse trigger is selected.

Note that the MAIN LEVEL knob and menu items apply only to the main trigger level. To modify the delayed trigger level, use the Level item in the Delayed Trigger menu.

TDS 694C User Manual

Triggering on Waveforms

To Force a Trigger

To Single Trigger

To force the oscilloscope to immediately start acquiring a waveform record even without a trigger event, press the FORCE TRIG front panel button.

Forcing a trigger is useful when in normal trigger mode and the input signal is not supplying a valid trigger. By pressing FORCE TRIG, you can quickly confirm that there is a signal present for the oscilloscope to acquire. Once that is established, you can determine how to trigger on it (press SET LEVEL TO 50%, check trigger source setting, and so on).

The oscilloscope recognizes and acts upon FORCE TRIG even when you press it before the end of pretrigger holdoff. However, the button has no effect if the acquisition system is stopped.

To trigger on the next valid trigger event and then stop, press SHIFT FORCE TRIG. Now press the RUN/STOP button each time you want to initiate the single sequence of acquisitions.

To leave Single Trig mode, press SHIFT ACQUIRE MENU ➞ Stop Af- ter (main) ➞RUN/STOP Button Only (side).

See the description under Stop After on page 3–20 for further discussion of single sequence acquisitions.

To Check Trigger Status

To ascertain the state and setup of the triggering circuit, use the trigger status lights, readout, and screen.

Trigger Status Lights. To quickly determine trigger status, check the three status lights TRIG’D, READY, and ARM in the Trigger control area. (See Figure 3–26.)

H When TRIG’D is lighted, it means the oscilloscope has recognized a valid

trigger and is filling the posttrigger portion of the waveform.

H When READY is lighted, it means the oscilloscope can accept a valid trigger

event and the oscilloscope is waiting for that event to occur.

H When ARM is lighted, it means the trigger circuitry is filling the pretrigger

portion of the waveform record.

H When both TRIG’D and READY are lighted, it means the oscilloscope has

recognized a valid main trigger and is waiting for a delayed trigger. When the oscilloscope recognizes a delayed trigger, it will fill in the posttrigger portion of the delayed waveform.

H When ARM, TRIG’D, and READY are all off, the digitizer is stopped.

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Triggering on Waveforms

Trigger Readout. To quickly determine the settings of some key trigger parameters, check the Trigger readout at the bottom of the display. (See Figure 3–27.) The readouts differ for edge, logic, and pulse triggers.

Main Time Base Time/Div

Main Time Base

Main Trigger

Source = Ch 1

Main Trigger Slope = Rising Edge

Main Trigger Level

Figure 3–27: Example Trigger Readouts — Edge Trigger Selected

Record View. To determine where the trigger point is located in the waveform

record and with respect to the display, check the record view at the top of the display. (See Figure 3–28.)

Trigger Position and Level Indicators. To see the trigger point and level on the waveform display, check the graphic indicators Trigger Position and T rigger Bar. Figure 3–28 shows the trigger point indicator and trigger level bar.

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Both the trigger point indicator and level bar are displayed from the Display menu. See Set Display Readout Options on page 3–24 for more information.

The trigger point indicator shows position. It can be positioned horizontally off screen, especially with long record length settings. The trigger level bar shows only the trigger level. It remains on screen, regardless of the horizontal position, as long as the channel providing the trigger source is displayed.

Trigger Status Screen. To see a more comprehensive status listing of the settings for the main and delayed trigger systems, press SHIFT STATUS ➞ STA- TUS (main) ➞Trigger (side).

TDS 694C User Manual

Trigger Position Relative to the

Display and Waveform Record

Trigger Point Indicator

Indicating the Trigger Position

on the Waveform Record

Trigger Bar Indicating the Trigger

Level on the Waveform Record

Triggering on Waveforms

Figure 3–28: Record View, Trigger Position, and Trigger Level Bar Readouts

Trigger Menu

Each trigger type (edge, logic, and pulse) has its own main trigger menu, which is described as each type is discussed in this section. To select the trigger type, press TRIGGER MENU ➞ Type (main) ➞Edge, Logic, or Pulse (pop-up).

Triggering on a Waveform Edge

The TDS 694C Oscilloscopes can trigger on an edge of a waveform. An edge trigger event occurs when the trigger source passes through a specified voltage

level in a specified direction (the trigger slope). You will likely use edge triggering for most of your measurements. This subsection describes how to use edge triggering — how to select edge type, source, coupling, slope, and level. It also details how to select trigger mode, auto or normal, for all trigger types.

To Check Edge

Trigger Status

To quickly check if edge triggers are selected, check the Trigger readout. When edge triggers are selected, the trigger readout displays the trigger source, as well as the trigger slope and level. (See Figure 3–29.)

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Triggering on Waveforms

To Select Edge Triggering

Main Time Base Time/Div

Main Time Base

Main Trigger

Source = Ch 1

Main Trigger Slope = Rising Edge

Main Trigger Level

Figure 3–29: Edge Trigger Readouts

Use the edge trigger menu to select edge triggering and to perform the procedures for source, coupling, slope, trigger level, mode, and holdoff that follow.

To bring up the Edge Trigger menu, press TRIGGER MENU ➞ Type (main) ➞Edge (pop-up). (See Figure 3–30.)

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Figure 3–30: Main Trigger Menu — Edge Type

TDS 694C User Manual

Tektronix TDS 694C User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Table of Contents

Getting Started

Operating Basics

Reference

Appendices

List of Figures

List of Tables

General Safety Summary

Preface

Related Manuals

Conventions

Product Description

TDS 694C Features

Product Specification

Start Up

Preparation

Putting into Service

Overview

Operating Interface Maps

Front Panel Map — Left Side

Front Panel Map — Right Side

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 Waveforms

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

Triggering on Waveforms

Triggering Concepts

Triggering from the Front Panel

Triggering on a Waveform Edge