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Tektronix TDS 684A, TDS 744A, TDS 784A Interpolation and Zoom, Checking the Zoom Factor, Zoom a Waveform

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Acquiring and Displaying Waveforms

3–38 TDS 684A, TDS 744A, & TDS 784A User Manual

When zooming horizontally or vertically, Zoom expands or contracts the

waveform by the zoom factor in 1X, 2X, and 5X steps.

To help you use Zoom effectively, consider how it is affected by interpolation.

When you zoom on a waveform, you expand a portion of it. If the expansion

requires the oscilloscope to show more points for that portion than it has

acquired, it interpolates.

The method the oscilloscope uses to interpolate, linear or sin(x)/x, can affect the

way Zoom displays your waveform. If you selected sin(x)/x (the default), it may

introduce some overshoot or undershoot to the waveform edges. If such is the

case, change the interpolation method to linear, following the instructions on

page 3–40.

To read about the two interpolation methods, see Interpolation on page 3–18. To

differentiate between the real and interpolated samples, set the display style to

Intensified Samples. (See Select the Display Style on page 3–28.)

To quickly determine the zoom factor of a zoomed waveform, select it and check

the Zoom readout. It shows the selected waveform by number, along with the

horizontal and vertical expansion factors.

The Zoom readout appears at the top of the display when zoom is on. (See

Figure 3–23 on page 3–39.) The TDS 700A models do not display the Zoom

readout when in dual-window (preview) mode.

To use Zoom, select a waveform, turn Zoom on, and magnify that waveform

using the vertical and horizontal scale knobs:

1. Press any of waveform selection buttons CH 1 through CH 4 on the right

side of the display. Or press MORE and select a math or reference waveform

from the More menu.

2. Press ZOOM.

3. TDS 684A only: Press ON (side) in the Zoom menu. The ZOOM front-panel

button should light up.

TDS 700A models only: Press ZOOM ➞ Mode (main) ➞ ON (side). The

ZOOM front-panel button should light up. Toggle Dual Zoom to OFF in the

side menu.

4. Adjust the vertical zoom factor for the selected waveform using the vertical

SCALE knob. Adjust the vertical position of the zoomed waveform using

the vertical POSITION knob.

Interpolation and ZoomChecking the Zoom FactorZoom a Waveform

Contents

Main Page WARRANTY Certificate of the Manufacturer/Importer German Postal Information Bescheinigung des Herstellers/Importeurs EC Declaration of Conformity Page Table of Contents Getting Started Operating Basics Reference Appendices Glossary Index List of Figures Page Page Page List of Tables Page General Safety Summary Injury Precautions Product Damage Precautions Safety Terms and Symbols Certifications and Compliances Page Preface Related Manuals Conventions Default Model Page TDS 684A, TDS 744A, & TDS 784A User Manual 11 Product Description Product Specification Start Up Preparation Input Coupling Signal Path Compensation Recommended Probes Probe Usage Putting into Service Installation Front Cover Removal Power On Self Test Power Off Page Overview Page Operating Interface Maps Front Panel Map Left Side 24 TDS 684A, TDS 744A, & TDS 784A User Manual Front Panel Map Right Side TDS 684A, TDS 744A, & TDS 784A User Manual 25 Rear Panel Map 26 TDS 684A, TDS 744A, & TDS 784A User Manual Display Map To Operate a Menu To Operate a Pop-Up Menu Tutorial Setting Up for the Examples Connect the Input Signal Reset the Oscilloscope Examine the Display Elements Page Example 1: Displaying a Waveform Adjust the Waveform Display Autoset the Oscilloscope Example 2: Displaying Multiple Waveforms Add a Waveform Page Assign Controls to Another Channel Remove a Waveform Example 3: Taking Automated Measurements Display Measurements Automatically Remove Measurement Readouts Change the Measurement Reference Levels Page Displaying a Snapshot of Automated Measurements Example 4: Saving Setups Save a Setup Recall a Setup Page Page Overview Acquiring and Displaying Waveforms Page Acquiring and Displaying Waveforms Coupling Waveforms to the Oscilloscope To Compensate Passive Probes Page Setting up Automatically: Autoset and Reset Input Impedance Considerations To Autoset the Oscilloscope List of Autoset Defaults Selecting Channels To Reset the Oscilloscope To Identify the Selected Channel To Select and Remove Waveforms Scaling and Positioning Waveforms Waveform Priority To Check Position To Check the Vertical Scale To Change Vertical Scale and Position Page To Change Vertical Parameters To Check the Horizontal Status To Change Horizontal Scale and Position To Change Horizontal Parameters Page Choosing an Acquisition Mode To Select the Delayed Time Base Sampling and Digitizing Real-time Sampling Equivalent-Time Sampling Interpolation Interleaving The Acquisition Modes Acquiring and Displaying Waveforms Multiple Waveform Acquisitions Figure 313: How the Acquisition Modes Work TDS 684A, TDS 744A, & TDS 784A User Manual 321 Single Waveform Acquisition Page Page Selecting Repetitive Sampling Stop After Preventing Aliasing Customizing the Display Change Display Settings Select the Display Style Adjust Intensity Set Display Readout Options Page Select Interpolation Filter Select the Graticule Type Select the Format Page Customizing the Display Color Change the Display Color Choose a Palette Change the Palette Colors Set Math Waveform Color Set Reference Waveform Color Select Options Restore Colors Zooming on Waveforms Using with Waveforms Interpolation and Zoom Checking the Zoom Factor Zoom a Waveform Page Set Interpolation Reset Zoom Using Dual Window Mode (TDS 700A Models Only) Dual Zoom a Waveform (TDS 700A Models Only) To Set Dual Zoom Offset Page Using InstaVu Acquisition Mode (TDS 700A Models Only) Waveform Capture Rate To Use InstaVu Mode Acquiring and Displaying Waveforms 344 TDS 684A, TDS 744A, & TDS 784A User Manual Normal DSO Mode Figure 326: Normal DSO Acquisition and Display Mode Versus InstaVu Mode InstaVu Mode Page Using FastFrameT (TDS 700A Models Only) Page Page Triggering on Waveforms Triggering Concepts The Trigger Event Trigger Sources Trigger Types Trigger Modes Trigger Holdoff Trigger Coupling Trigger Position Triggering from the Front Panel Slope and Level Delayed Trigger System To set MAIN LEVEL To Set to 50% To Force a Trigger To Single Trigger To Check Trigger Status Page Triggering on a Waveform Edge Trigger Menu To Check Edge Trigger Status To Select Edge Triggering To Select a Source To Specify Coupling To Set Mode & Holdoff Triggering Based on Logic To Set Slope To Set Level Pattern and State Classes Setup and Hold Class Triggering on Waveforms TDS 684A, TDS 744A, & TDS 784A User Manual 363 To Check Logic Trigger Status To Trigger on a Pattern Page To Define a Time Qualified Pattern Trigger To State Trigger To Trigger on Setup/ Hold Time Violations Page Triggering on Pulses Page To Trigger on a Glitch Page To Trigger on a Runt Pulse Page Trigger Based on Pulse Width To Trigger Based on Slew Rate Page Page Delayed Triggering Page Triggering on Waveforms 382 TDS 684A, TDS 744A, & TDS 784A User Manual Delayed Triggerable By Events Figure 349: How the Delayed Triggers Work Delayed Triggerable By Time To Run After Delay To Trigger After Delay Page Page Page Measuring Waveforms Taking Automated Measurements Measurement List Measuring Waveforms TDS 684A, TDS 744A, & TDS 784A User Manual 389 Table 39: Measurement Definitions (Cont.) Measurement Readouts Display Measurements Remove Measurements Gate Measurements Define High-Low Setup Define Reference Levels Take a Delay Measurement Take a Snapshot of Page Taking Cursor Measurements Cursor Types Cursor Modes Cursor Readouts Select the Cursor Function Set Mode and Adjust the Cursors Taking Graticule Measurements Select Cursor Speed Select Time Units Select Amplitude Units Optimizing Measurement Accuracy: SPC and Probe Cal Measure Waveform Amplitude Measure Waveform Time Signal Path Compensation Page Probe Cal Page Page Page Page Page Page Saving Waveforms and Setups Saving and Recalling Setups To Save a Setup To Recall a Setup Page Saving and Recalling Waveforms To Save a Waveform Page To Recall a Waveform From Disk To Enable Autosave Managing the File System To Run the File Utilities To Access the File Utilities To Delete To Rename To Copy To Print To Create a Directory Printing a Hardcopy To Set Confirm Delete To Set Overwrite Lock To Format Supported Formats To Set Up for Making Hardcopies Page Page To Print Directly to a Hardcopy Device To Save to a Floppy Disk To Print Using a Controller Communicating with Remote Instruments To Prepare for Remote Operation To Set Up for Remote Operation Page Page Determining Status and Accessing Help Displaying Status Displaying the Banner Page Displaying Help Page Using Features for Advanced Applications Limit Testing To Create Limit Test Template Page To Select a Limit Test Source To Specify the Limit Test Response Single Waveform Comparisons Multiple Waveform Comparisons Waveform Math To Use Single Wfm Math To Use Dual Wfm Math Fast Fourier Transforms To Average a Math S To Create an FFT Page Page To Take Cursor Measurements of an FFT To Take Automated Measurements of an FFT The FFT Frequency Domain Record Page Page Record Length Acquisition Mode Zoom and Interpolation Undersampling (Aliasing) Considerations for Phase Displays Page FFT Windows Page Page Waveform Differentiation To Create a Derivative of a Page Page Waveform Integration Using Zoom To Create a Integral Math To Take Cursor Page To Take Automated DC Offset Using Zoom Page Page Appendix A: Options and Accessories Options Appendix A: Options and Accessories A2 TDS 684A, TDS 744A, & TDS 784A User Manual Table A1: Options (Cont.) Standard Accessories Optional Accessories Accessory Probes Accessory Software Warranty Information Service Assurance Page Appendix B: Algorithms Measurement Variables High, Low HighRef, MidRef, LowRef, Mid2Ref Other Variables MCross Calculations Page Measurement Algorithms Amplitude Area Burst Width Cycle Area Cycle Mean Frequency High Low Maximum Mean Minimum Negative Duty Cycle Negative Overshoot Negative Width Peak to Peak Period Phase Positive Duty Cycle Positive Overshoot Positive Width Rise Time RMS: Measurements on Envelope Waveforms Integration Algorithm Page Missing or Out-of-Range Samples Appendix C: Packaging for Shipment Page TDS 684A, TDS 744A, & TDS 784A User Manual D1 Appendix D: Factory Initialization Settings D2 TDS 684A, TDS 744A, & TDS 784A User Manual TDS 684A, TDS 744A, & TDS 784A User Manual D3 D4 TDS 684A, TDS 744A, & TDS 784A User Manual TDS 684A, TDS 744A, & TDS 784A User Manual D5 Page Appendix E: Probe Selection Passive Voltage Probes General Purpose (High Input Resistance) Probes Low Impedance (ZO) Probes High Voltage Probes Active Voltage Probes High Speed Active Probes Differential Probes Fixtured Active Probes Current Probes Optical Probes Time-to-Voltage Converter Page Page Glossary Page Page Page Page Page Page Page Page Page Page Page Page TDS 684A, TDS 744A, & TDS 784A User Manual Index1 Index Numbers A Index2 TDS 684A, TDS 744A, & TDS 784A User Manual B C TDS 684A, TDS 744A, & TDS 784A User Manual Index3 D Index4 TDS 684A, TDS 744A, & TDS 784A User Manual TDS 684A, TDS 744A, & TDS 784A User Manual Index5 E F G Index6 TDS 684A, TDS 744A, & TDS 784A User Manual H TDS 684A, TDS 744A, & TDS 784A User Manual Index7 I K L M Index8 TDS 684A, TDS 744A, & TDS 784A User Manual TDS 684A, TDS 744A, & TDS 784A User Manual Index9 N Index10 TDS 684A, TDS 744A, & TDS 784A User Manual O P TDS 684A, TDS 744A, & TDS 784A User Manual Index11 Q R Index12 TDS 684A, TDS 744A, & TDS 784A User Manual S TDS 684A, TDS 744A, & TDS 784A User Manual Index13 T Index14 TDS 684A, TDS 744A, & TDS 784A User Manual U V W TDS 684A, TDS 744A, & TDS 784A User Manual Index15 X Y Z