User Manual TDS 684A, TDS 744A & TDS 784A Digitizing Oscilloscopes 070-8991-02 This document applies for firmware version 1.0 and above.
Copyright Tektronix, Inc. 1994. All rights reserved. Licensed software products are owned by Tektronix or its suppliers and are protected by United States copyright laws and international treaty provisions. Use, duplication, or disclosure by the Government is subject to restrictions as set forth in subparagraph (c)(1)(ii) of the Rights in Technical Data and Computer Software clause at DFARS 252.
WARRANTY Tektronix 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, Tektronix, 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.
German Postal Information Certificate of the Manufacturer/Importer We hereby certify that the TDS 684A, TDS 744A, and TDS 784A Digitizing Oscilloscopes and all factory-installed options comply with the RF Interference Suppression requirements of Postal Regulation Vfg. 243/1991, amended per Vfg. 46/1992. The German Postal Service was notified that the equipment is being marketed. The German Postal Service has the right to re-test the series and to verify that it complies.
EC Declaration of Conformity We Tektronix Holland N.V. Marktweg 73A 8444 AB Heerenveen The Netherlands declare under sole responsibility that the TDS 684A, TDS 744A, and TDS 784A Digitizing Oscilloscopes meet the intent of Directive 89/336/EEC for Electromagnetic Compatibility.
Table of Contents General Safety Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix xiii Related Manuals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Default Model . . . . . . . . . . . . . . . .
Table of Contents Delayed Triggering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3–80 Measuring Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3–87 Taking Automated Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Taking Cursor Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Taking Graticule Measurements . . . . . . . . . . . . . . . . .
Table of Contents List of Figures Figure 1–1: Rear Panel Controls Used in Start Up . . . . . . . . . . . . . . . Figure 1–2: ON/STBY Button . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–4 1–5 Figure 2–1: Connecting a Probe for the Examples (P6245 shown) . . Figure 2–2: SETUP Button Location . . . . . . . . . . . . . . . . . . . . . . . . . . . Figure 2–3: The Setup Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Figure 2–4: Trigger Controls . . . . . . . . . . .
Table of Contents Figure 3–11: Real-Time Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3–17 Figure 3–12: Equivalent-Time Sampling . . . . . . . . . . . . . . . . . . . . . . . 3–18 Figure 3–13: How the Acquisition Modes Work . . . . . . . . . . . . . . . . . 3–21 Figure 3–14: Acquisition Menu and Readout . . . . . . . . . . . . . . . . . . . . 3–23 Figure 3–15: Acquire Menu — Stop After . . . . . . . . . . . . . . . . . . . . . . 3–25 Figure 3–16: Aliasing . . . . . . . . . . . . . . .
Table of Contents Figure 3–46: Main Trigger Menu — Slew Rate Class . . . . . . . . . . . . . Figure 3–47: Delayed Runs After Main . . . . . . . . . . . . . . . . . . . . . . . . . Figure 3–48: Delayed Triggerable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Figure 3–49: How the Delayed Triggers Work . . . . . . . . . . . . . . . . . . . Figure 3–50: Delayed Trigger Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . Figure 3–51: Graticule, Cursor and Automated Measurements . . . .
Table of Contents Figure 3–83: Acquire Menu — Create Limit Test Template . . . . . . . . Figure 3–84: More Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Figure 3–85: Dual Waveform Math Main and Side Menus . . . . . . . . Figure 3–86: System Response to an Impulse . . . . . . . . . . . . . . . . . . . . Figure 3–87: Define FFT Waveform Menu . . . . . . . . . . . . . . . . . . . . . . Figure 3–88: FFT Math Waveform in Math1 . . . . . . . . . . . . . . . . . . . .
Table of Contents List of Tables Table 1–1: Key Features of the TDS Oscilloscopes . . . . . . . . . . . . . . . Table 1–2: Fuse and Fuse Cap Part Numbers . . . . . . . . . . . . . . . . . . . 1–1 1–5 Table 3–1: Autoset Defaults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 3–2: How Interleaving Affects Sample Rate . . . . . . . . . . . . . . . . Table 3–3: Additional Resolution Bits . . . . . . . . . . . . . . . . . . . . . . . . .
Table of Contents viii TDS 684A, TDS 744A, & TDS 784A User Manual
General Safety Summary Review the following safety precautions to avoid injury and prevent damage to this product or any products connected to it. Only qualified personnel should perform service procedures. Injury Precautions Use Proper Power Cord To avoid fire hazard, use only the power cord specified for this product. Avoid Electric Overload To avoid electric shock or fire hazard, do not apply a voltage to a terminal that is outside the range specified for that terminal.
General Safety Summary Provide Proper Ventilation Do Not Operate With Suspected Failures Do Not Immerse in Liquids To prevent product overheating, provide proper ventilation. If you suspect there is damage to this product, have it inspected by qualified service personnel. Clean the probe using only a damp cloth. Refer to cleaning instructions. Safety Terms and Symbols Terms in This Manual These terms may appear in this manual: WARNING.
General Safety Summary Symbols on the Product The following symbols may appear on the product: DANGER High Voltage Protective Ground (Earth) Terminal ATTENTION Refer to Manual Double Insulated Certifications and Compliances CSA Certified Power Cords CSA Certification includes the products and power cords appropriate for use in the North America power network. All other power cords supplied are approved for the country of use.
General Safety Summary xii TDS 684A, TDS 744A, & TDS 784A User Manual
Preface This is the User Manual for the TDS 684A, TDS 744A, and TDS 784A Digitizing Oscilloscopes. The chapter Getting Started briefly describes the TDS Oscilloscope, prepares you to install it, and tells you how to put it into service. The chapter Operating Basics covers basic principles of the operation of the oscilloscope. The operating interface illustrations and the tutorial examples rapidly help you understand how your oscilloscope operates.
Preface Conventions In this manual, you will find various procedures which contain steps of instructions for you to perform. To keep those instructions clear and consistent, this manual uses the following conventions: In procedures, names of front panel controls and menu labels appear in boldface print. Names also appear in the same case (initial capitals or all uppercase) in the manual as is used on the oscilloscope front panel and menus.
Getting Started
Product Description The Tektronix TDS Oscilloscope is a superb tool for acquiring, displaying, and measuring waveforms.
Product Description Table 1–1: Key Features of the TDS Oscilloscopes (Cont.) Feature TDS 684A TDS 744A TDS 784A Trigger modes Include: edge, logic, and pulse. Video trigger, with option 05, modes include: NTSC, SECAM, PAL, HDTV, and FlexFormat . Storage 1.44 Mbyte, 3.5 inch, DOS 3.3-or-later floppy disk. NVRAM storage for saving waveforms, hardcopies, and setups I/O Full GPIB programmability.
Start Up Before you use the TDS Oscilloscope, ensure that it is properly installed and powered on. Preparation 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 Be sure you compensate your oscilloscope for the surrounding temperature.
Start Up Putting into Service To learn how to install, access the front panel, power on, do a self test, and power off the oscilloscope, do the following procedures: Installation To properly install and power on the oscilloscope, do the following steps: 1. Be sure you have the appropriate operating environment.
Start Up Table 1–2: Fuse and Fuse Cap Part Numbers Front Cover Removal Power On Fuse Fuse Part Number Fuse Cap Part Number 0.25 inch × 1.25 inch (UL 198.6, 3AG): 6 A FAST, 250 V. 159-0013-00 200-2264-00 5 mm × 20 mm (IEC 127): 5 A (T), 250 V. 159-0210-00 200-2265-00 To remove the front cover, grasp its left and right edges and snap it off of the front subpanel. (To reinstall it, align it to the front subpanel and snap it back on.) To power on the oscilloscope, do the following steps: 1.
Start Up The ON/STBY button controls power to most of the instrument circuits. Power continues to go to certain parts even when this switch is set to STBY. Once the oscilloscope is installed, it is typical to leave the principal power switch on and use the ON/STBY button instead of the power switch. Self Test 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.
Operating Basics
Overview This chapter describes the basic concepts of operating the TDS Oscilloscope. Understanding the basic concepts of your oscilloscope will help you use it much more effectively. The first section, Operating Interface Maps, quickly shows you how the oscilloscope controls are organized and where you can read about them. It also illustrates the general procedures for operating the menu system.
Overview 2–2 TDS 684A, TDS 744A, & TDS 784A User Manual
Operating Interface Maps This section contains illustrations, or maps, of the display, the front and rear panels, and the menu system of the TDS Oscilloscope. These maps will help you understand and operate the oscilloscope. This section also contains a visual guide to using the menu system.
Operating Interface Maps Front Panel Map — Right Side Measurement System, page 3–87 Cursor Measurements, page 3–97 Saving and Recalling Waveforms, page 3–114 File System, page 3–117 Hardcopy, page 3–120 File System, page 3–117 Acquisition Modes, page 3–20 Cursor Measurements, page 3–97 Autoset, page 3–5 InstaVu, page 3–43 (TDS 700A models only) Help, page 3–135 Status, page 3–133 Saving and Recalling Setups, page 3–111 Color, page 3–33 Display Settings, page 3–27 Remote Communication, page 3–128 Se
Operating Interface Maps Rear Panel Map Principal Power Switch, page 1–5 Fuse, page 1–4 Centronics Connector Serial Number RS-232 Connector Power Connector, page 1–4 GPIB Connector, page 3–128 Rear Panel Connectors VGA Output Security Bracket SIGNAL OUTPUT – (Provides Analog Signal Output) AUX TRIGGER INPUT – (Provides Auxiliary Trigger Signal Input) MAIN TRIGGER OUTPUT – (Provides Main Trigger (TTL) Output) DELAYED TRIGGER OUTPUT – (Provides Delayed Trigger (TTL) Output) TDS 684A, TDS 744A, &
Operating Interface Maps Display Map The acquisition status, page 3–23 Indicates position of vertical bar cursors in the waveform record, page 3–100 Trigger position (T), page 3–56 Shows what part of the waveform record is displayed, page 3–13 The value entered with the general purpose knob or keypad. The waveform record icon Trigger level on waveform (may be an arrow at right side of screen instead of a bar). Cursor measurements, page 3–97 The side menu with choices of specific actions.
Operating Interface Maps To Operate a Menu 1 Press front-panel menu button. (Press SHIFT first if button label is blue.) 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.
Operating Interface Maps To Operate a Pop-Up Menu Press to display pop-up menus. Press it again to make selection. Press here to remove menus from screen. Alternatively, press SHIFT first to make selection in the opposite direction. A pop-up selection changes the other main menu titles.
Tutorial This section quickly makes you acquainted with some of the fundamental operations required to use the TDS Oscilloscope to take measurements. Start this tutorial by doing Setting Up for the Examples on this page. Setting Up for the Examples Perform the following tasks to connect input signals to the TDS Oscilloscope, to reset it, and to become acquainted with its display screen. Once completed, these tasks ready the oscilloscope for use in the examples that follow.
Tutorial NOTE. See Appendix A: Options and Accessories for optional probes you can order and use with this product. 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 2–2.
Tutorial The display shows side menus along the right side of the screen. The buttons to select these side menu items are to the right of the side menu. Because an accidental instrument reset could destroy a setup that took a long time to create, the oscilloscope asks you to verify the Recall Factory Setup selection. (See Figure 2–3.) 3. Press the button to the right of the OK Confirm Factory Init side menu item. NOTE.
Tutorial The channel reference indicator shows the vertical position of channel 1 with no input signal. This indicator points to the ground level for the channel when its vertical offset is set to 0 V in the vertical menu; when vertical offset is not set to 0 V, it points to the vertical offset level. The trigger readout shows that the oscilloscope is triggering on channel 1 (Ch1) on a rising edge, and that the trigger level is about 200–300 mV.
Tutorial Example 1: Displaying a Waveform The TDS Oscilloscope provides front panel knobs for you to adjust a waveform, or it can automatically set up its controls to display a waveform. Do the following tasks to learn how to adjust a waveform and how to autoset the TDS Oscilloscope. Adjust the Waveform Display The display shows the probe compensation signal. It is a 1 kHz square wave of approximately 0.5 V amplitude. Figure 2–6 shows the main VERTICAL and HORIZONTAL sections of the front panel.
Tutorial Autoset the Oscilloscope 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.
Tutorial Figure 2–9 shows the display after pressing AUTOSET. If necessary, you can adjust the waveform now by using the knobs discussed earlier in this example. Figure 2–9: The Display After Pressing Autoset NOTE. If you are using a passive probe, such as the P6139A probe, the corners on your displayed signal may look rounded or pointed. (See Figure 2–10.) If so, then you may need to compensate your probe. See To Compensate Passive Probes on page 3–3.
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.
Tutorial The light above the CH 2 button is now on, and the CH 1 light is off. Because the knobs control only one channel at a time, the vertical controls are now set to adjust channel 2. The trigger readout still indicates that the trigger is detecting trigger events on Ch1. The trigger source is not changed simply by adding a channel. (You can change the trigger source by using the TRIGGER MENU button to display the trigger menu.) 5.
Tutorial 7. Press (side) to toggle the selection to 50 . That changes the input coupling of channel 2 from 1 MW to 50 W. The channel readout for channel 2 (near the bottom of the graticule) now shows an W indicator. Assign Controls to Another Channel Pressing a channel (CH) button sets the vertical controls to that channel. It also adds the channel to the display if that waveform is not already displayed. To explore assigning controls to different channels, do the following steps: 1. Press CH 1.
Tutorial Since the CH 2 light was on when you pressed the WAVEFORM OFF button, the channel 2 waveform was removed. The channel (CH) lights now indicate channel 1. Channel 1 has become the selected channel. When you remove the last waveform, all the CH lights are turned off. 2. Press WAVEFORM OFF again to remove the channel 1 waveform. Example 3: Taking Automated Measurements The TDS Oscilloscope can measure many waveform parameters automatically and read out the results on screen.
Tutorial measurement on another channel, select that channel, and then select the measurement.) 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.
Tutorial Press to Remove Menus From Screen Figure 2–15: Four Simultaneous Measurement Readouts Change the Measurement Reference Levels By default, the measurement system will use the 10% and 90% levels of the waveform for taking the rise time measurement. You can change these values to other percentages or change them to absolute voltage levels. To examine the current values, press Reference Levels (main) ➞ High Ref (side). The General Purpose Knob.
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 Figure 2–16: General Purpose Knob Indicators The Numeric Keypad.
Tutorial Displaying a Snapshot of Automated Measurements You have seen how to display up to four individual automated measurements on screen. You can also pop up a display of almost all of the automated measurements available in the Select Measrmnts side menus. This snapshot of measurements is taken on the waveform currently selected using the channel selection buttons.
Tutorial 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.) Example 4: Saving Setups The TDS Oscilloscope can save its controls settings and recall them later to quickly re–establish a setup. It provides ten storage locations to store up to ten setups. It also provides a file system, so that you can also save setups to a floppy disk.
Tutorial Figure 2–18: Save/Recall Setup Menu 7. Press one of the To Setup side menu buttons to store the current instrument settings into that setup location. Remember which setup location you selected for use later. There are more setup locations than can be listed at one time in the side menu. The –more– side menu item gives you access to all the setup locations. Once you have saved a particular setup, you can change the settings as you wish, knowing that you can come back to that setup at any time. 8.
Tutorial 2–26 TDS 684A, TDS 744A, & TDS 784A User Manual
Reference
Overview This chapter describes in detail how to perform the operating tasks you must do to measure, test, process, or save and document your waveforms. It leads with three sections on the fundamental tasks of acquiring, stably displaying, and taking measurements on waveforms: Acquiring and Displaying Waveforms Triggering on Waveforms Measuring Waveforms Once you have acquired and measured waveforms, you may want to save and restore them or the control setups used to acquire and measure them.
Overview Zooming on Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Using InstaVu Acquisition Mode (TDS 700A Models Only) . . . . . . . . Using FastFrame (TDS 700A Models Only) . . . . . . . . . . . . . . . . . . . . . 3–37 3–43 3–46 Triggering on Waveforms Triggering Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Triggering from the Front Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Acquiring and Displaying Waveforms To use the TDS Oscilloscope to measure or monitor waveforms, you need to know how to acquire, select, and display those waveforms properly.
Acquiring and Displaying Waveforms Probe Compensated Correctly Probe Overcompensated Probe Undercompensated Figure 3–1: How Probe Compensation Affects Signals 4. If you need to change the input impedance, press Coupling (main). Then toggle the side menu selection W to get the correct impedance. 5. TDS 700A models only: Press SHIFT ACQUIRE MENU ➞ Mode (main) ➞ Hi Res (side). 6. TDS 684A only: Press SHIFT ACQUIRE MENU ➞ Mode (main) ➞ Average (side). Use the keypad to set Averages to 5. 7.
Acquiring and Displaying Waveforms Input Impedance Considerations To ensure proper coupling of your input signals to the oscilloscope, consider the following points when you use 50 W coupling with any channel: The oscilloscope does not accurately display frequencies under 200 kHz if AC coupling is selected.
Acquiring and Displaying Waveforms 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.
Acquiring and Displaying Waveforms Table 3–1: Autoset Defaults (Cont.
Acquiring and Displaying Waveforms To Identify the Selected Channel To determine which channel is currently selected, check the channel readout. It shows the selected channel in inverse video in the lower left corner of the display. The channel reference indicator for the selected channel also appears in reverse video along the left side of the display. (See Figure 3–3.
Acquiring and Displaying Waveforms 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 3–4 shows the order of priority. 1. CH1 2. CH2 3. CH3 4. CH4 1. MATH1 2. MATH2 3.
Acquiring and Displaying Waveforms The Channel Reference icon, at the left side of the display, points to ground on the waveform record when offset is set to 0 V. The oscilloscope contracts or expands the selected waveform around this point when you change the vertical scale. The Record View, at the top of the display, indicates where the trigger occurs and what part of the waveform record is displayed.
Acquiring and Displaying Waveforms As you turn the vertical SCALE knob clockwise, the value decreases resulting in higher resolution because you see a smaller part of the waveform. As you turn it counterclockwise the scale increases allowing you to see more of the waveform but with lower resolution. 2. Turn the vertical POSITION knob. Again, note that only the selected waveform changes position. 3. To make positioning faster, press the SHIFT button.
Acquiring and Displaying Waveforms To Change Vertical Parameters To select the coupling, bandwidth, and offset for the selected waveform, use the Vertical menu (Figure 3–6). This menu also lets you numerically change the position or scale instead of using the vertical knobs. To make such changes, do the following procedures: Coupling.
Acquiring and Displaying Waveforms Offset. Use offset to subtract DC bias before examining a waveform. For example, you might want to display a small ripple (for example, 100 mV of ripple) on a power supply output (for example, a +15 V output). Adjust offset to keep the ripple on screen while setting the vertical scale sensitive enough to best display the ripple. To adjust offset, press VERTICAL MENU ➞ Offset (main). Then use the general purpose knob or keypad to set the vertical offset.
Acquiring and Displaying Waveforms To change the horizontal scale and position: 1. Turn the horizontal POSITION and horizontal SCALE knobs. (See Figure 3–8.) 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.
Acquiring and Displaying Waveforms posttrigger portion. All timing measurements in the waveform record are made relative to the trigger event. To define the trigger point position: Press HORIZONTAL MENU ➞ Trigger Position (main) ➞ Set to 10%, Set to 50%, or Set to 90% (side), or use the general purpose knob or the keypad to change the value. Record Length. The number of points that make up the waveform record is defined by the record length. To set the waveform record length: 1.
Acquiring and Displaying Waveforms 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.
Acquiring and Displaying Waveforms +5.0 V 0V Input Signal Sampled Points +5.0 V 0V 0V –5.0 V Digital Values 0V –5.0 V Figure 3–9: Acquisition: Input Analog Signal, Sample, and Digitize The oscilloscope uses the samples it takes (see Figure 3–11) to create a waveform record containing a user-specified number of data or record points. Each record point represents a certain voltage level that occurs a determined amount of time from the trigger event.
Acquiring and Displaying Waveforms Equivalent-Time Sampling A TDS 700A model oscilloscope (the TDS 684A uses only real time sampling) uses equivalent time sampling to extend its sample rate over its real-time maximum sampling rate, but only under two conditions: You must have turned equivalent-time on in the Acquisition menu. You must have set the oscilloscope to a sampling rate that is too fast to allow it to get enough samples with which to create a waveform record using real-time sampling.
Acquiring and Displaying Waveforms Eventually the time period established by scale setting does not allow enough time to get all the real samples needed to fill the record. The situation just described occurs if you set the Horizontal SCALE knob to a time base setting that is faster than 10 ns (TDS 684A). (The setting varies with the number of channels for TDS 700A models; see Tables 3–4 and 3–5 beginning on page 3–24.
Acquiring and Displaying Waveforms Once you set horizontal scale to exceed the maximum digitizing rate for the number of channels in use (see Table 3–2), the oscilloscope will not be able to get enough samples to create a waveform record. At that point, the oscilloscope will either interpolate to calculate additional samples or it will switch from real to equivalent time sampling to obtain additional samples. (See Interpolation on page 3–18 and Equivalent-Time Sampling on page 3–18.
Acquiring and Displaying Waveforms Single Waveform Acquisition Samples Acquired in Four Acquisition Intervals Interval 1 2 3 Acquisition Mode 4 Displayed Record Points Interval 1 2 3 Waveform Drawn on CRT 4 Sample Uses first sample in interval Use for fastest acquisition rate. This is the default mode. Peak Detect Uses highest and lowest samples in two intervals (TDS 700A Models Only) Use to reveal aliasing and for glitch detection.
Acquiring and Displaying Waveforms Peak Detect Mode. TDS 700A models only: Peak Detect mode alternates between saving the highest sample in one acquisition interval and lowest sample in the next acquisition interval. Peak Detect mode only works with real-time, noninterpolated sampling. If you set the time base so fast that it requires real-time interpolation or equivalent-time sampling, the mode automatically changes from Peak Detect to Sample, although the menu selection will not change. Hi Res Mode.
Acquiring and Displaying Waveforms Checking the Acquisition Readout To determine the acquisition sampling rate, the acquisition state (running or stopped), and the acquisition mode, check the Acquisition readout at the top of the display. (See Figure 3–14.) The state “Run:” shows the sample rate and acquisition mode. The state “Stop:”shows the number of acquisitions acquired since the last stop or major change.
Acquiring and Displaying Waveforms NOTE. TDS 700A models only: Selecting Hi Res mode in the Acquire menu will automatically reduce the record length to a value that prevents overflow of acquisition memory. Because Hi Res mode uses twice the acquisition memory that the other acquisition modes use, allowing selection of the longer horizontal record lengths with Hi Res mode would cause the oscilloscope to run out of memory.
Acquiring and Displaying Waveforms Table 3–5: TDS 784A Sampling Mode Selection (When Fit to Screen is Off) Time Base1 One Channel Two Channels Three or Four Channels u25 ns Real-time Real-time Real-time 25 ns Real-time Real-time Equiv.-time or interpolate 12.5 ns Real-time Equiv.-time or interpolate Equiv.-time or interpolate Equiv.-time or Interpolate Equiv.-time or Interpolate Equiv.-time or Interpolate t12.5 ns 1 “u” means “slower than”; “t” means “faster than.” NOTE.
Acquiring and Displaying Waveforms 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. Press Single Acquisition Sequence (side). That selection lets you run a single sequence of acquisitions by pressing the RUN/STOP button.
Acquiring and Displaying Waveforms Actual High-Frequency Waveform Apparent Low-frequency Waveform Due to Aliasing Sampled Points Figure 3–16: Aliasing Methods to Check and Eliminate. To quickly check for aliasing, slowly increase the horizontal scale (time per division setting). If the shape of the displayed waveform changes drastically or becomes stable at a faster time base setting, your waveform was probably aliased.
Acquiring and Displaying Waveforms NOTE. TDS 700A models only: This subsection assumes you are using Normal acquisitions mode and gives display settings for this mode. If you select InstaVu acquisitions, procedures for making Style, Format, and Readout display settings differ and some selections are not permitted. See Using InstaVuT Acquisition Mode, on page 3–43, for setup differences and Incompatible Modes on page 3–45.
Acquiring and Displaying Waveforms NOTE. TDS 700A models only: See Using InstaVuT Acquisition Mode, on page 3–43, for differences in how Style setup differs for InstaVu mode. Figure 3–17: Display Menu — Style Adjust Intensity Intensity lets you set text/graticule and waveform intensity (brightness) levels. To set the intensity: Press DISPLAY ➞ Intensity (main) ➞ Text/Grat or Waveform (side). Enter the intensity percentage values with the keypad or the general purpose knob.
Acquiring and Displaying Waveforms 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 3–18. Note that both styles are shown for illustrating purposes, but you can only display one style at a time.
Acquiring and Displaying Waveforms Select Interpolation Filter The display filter types are sin(x)/x interpolation and linear interpolation. To switch between interpolation filters: Press DISPLAY ➞ Filter (main) ➞ Sin(x)/x Interpolation or Linear Interpolation (side). NOTE.
Acquiring and Displaying Waveforms 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.
Acquiring and Displaying Waveforms Customizing the Display Color The TDS Oscilloscope can display information in different colors. This subsection describes how to use the Color menu to choose the colors in which the various display objects appear. Change the Display Color To bring up the Color menu: 1. Press DISPLAY to show the Display menu. 2. Press Settings in the main menu until you select Color from the pop-up menu. (See Figure 3–19.
Acquiring and Displaying Waveforms 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.
Acquiring and Displaying Waveforms 6. Choose Saturation from the side menu and use the general purpose knob or keypad to select the saturation you desire. A value of 100 provides a pure color. A value of 0 provides gray. ScrTxt Figure 3–20: Display Menu — Palette Colors Set Math Waveform Color 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.
Acquiring and Displaying Waveforms 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.
Acquiring and Displaying Waveforms Figure 3–22: Display Menu — Restore Colors Zooming on Waveforms The TDS Oscilloscope can expand or compress (zoom in or out) on a waveform without changing the acquisition parameters (sample rate, record length, and so on). This subsection describes how to use Zoom and how it interacts with the selected waveform. It also describes how interpolation can affect Zoom.
Acquiring and Displaying Waveforms When zooming horizontally or vertically, Zoom expands or contracts the waveform by the zoom factor in 1X, 2X, and 5X steps. Interpolation and Zoom 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.
Acquiring and Displaying Waveforms 5. Adjust the horizontal zoom factor using the horizontal SCALE knob. Adjust the horizontal position of the zoomed waveform using the horizontal POSITION knob. Depending on the selection for Horizontal Lock in the side menu, Zoom affects the displayed waveforms as follows: None — only the waveform currently selected can be magnified and positioned horizontally (Figure 3–23).
Acquiring and Displaying Waveforms NOTE. Although Zoom must be turned on to control which waveforms Zoom affects, the setting for Horizontal Lock affects which waveforms the horizontal control positions whether Zoom is on or off. The rules for the three settings are listed in step 5 on page 3–39. Set Interpolation Reset Zoom To change the interpolation method used, press DISPLAY ➞ Settings (main) ➞ Display (pop-up) ➞ Filter (main) ➞ Sin(x)/x Interpolation or Linear Interpolation (side).
Acquiring and Displaying Waveforms In Dual Window Zoom mode, the oscilloscope does not display the zoom magnification factors; however, it does display the scale factors (volts/division and time/division) for the zoomed waveform.
Acquiring and Displaying Waveforms 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.
Acquiring and Displaying Waveforms Using InstaVu Acquisition Mode (TDS 700A Models Only) The TDS 744A and TDS 784A Oscilloscopes can use InstaVu acquisition mode to reduce the dead time between waveform updates that normally occur when digitizing storage oscilloscopes (DSOs) acquire waveforms. InstaVu mode can capture and display transient deviations, such as glitches or runt pulses, often missed during longer dead times that accompany normal DSO display.
Acquiring and Displaying Waveforms Normal DSO Mode 1st Acquired Waveform Record Next Acquired Waveform Record Dead Time Next Acquired Waveform Record Dead Time Dead Time Waveform Memory Waveform Memory Waveform Memory Display Updated Display Updated Display InstaVu Mode 1st Set of Acquired Waveform Records Next Set of Acquired Waveform Records Next Set of Acquired Waveform Records Waveform Memory Bit Map Waveform Memory Bit Map Waveform Memory Bit Map Variable Persistence Display Updated
Acquiring and Displaying Waveforms Figure 3–27: InstaVu Display To Set the InstaVu Style To change the InstaVu display style, do the following steps: 1. Press DISPLAY ➞ Mode (main) ➞ InstaVu (pop-up) ➞ Style (main). 2. Select between Vectors and Dots in the side menu. (Dots display is the factory default setting.) 3. Select between Infinite Persistence and Variable Persistence in the side menu. (Variable Persistence is the factory default setting.) 4.
Acquiring and Displaying Waveforms H Envelope, Average, Hi Res, and Single Acquisition Sequence acquisition modes and Autosave mode H Delayed time base H Record lengths longer than 500 samples H Interpolation (equivalent time sampling is used instead) H Vectors when in equivalent time mode (waveforms are displayed as Dots instead). (To determine under what conditions the oscilloscope normally interpolates or uses equivalent time, see Selecting Repetitive Sampling on page 3–24.
Acquiring and Displaying Waveforms If you are using the FastFrame mode, you can jump to the desired frame. To use FastFrame, do the following steps: 1. Press HORIZONTAL MENU ➞ FastFrame Setup (main) ➞ FastFrame (side) to toggle on or off the use of FastFrame (see Figure 3–29). 2. Press Frame Length or Frame Count (side) and use the general purpose knob to enter FastFrame parameters. Frame Length refers to the number of samples in each acquisition.
Acquiring and Displaying Waveforms FastFrame Operating Characteristics. Consider the following operating characteristics when using FastFrame: 3–48 Envelope, Average, and Hi Res form the envelope or average following the last frame of the concatenated record. For example, if Average or Hi Res acquisition modes are selected and the frame count is 10, segments 1 through 10 will show Sample or Hi Res frames, and frame 11 will show the average of frames 1 through 10.
Triggering on Waveforms To use the TDS Oscilloscope to measure or monitor waveforms, you need to know how to trigger a stable display of those waveforms.
Triggering on Waveforms 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).
Triggering on Waveforms in another trigger source. Logic triggers are available on the main trigger system only. Video (available as option 05) is a special trigger used on video circuits. It helps you investigate events that occur when a video signal generates a horizontal or vertical sync pulse. Supported classes of video triggers include NTSC, PAL, SECAM, and high definition TV signals. Trigger Modes The trigger mode determines how the oscilloscope behaves in the absence of a trigger event.
Triggering on Waveforms 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. Acquisition Interval Acquisition Interval Trigger Level Indicates Trigger Points Holdoff Holdoff Holdoff Triggers are not recognized during holdoff time. Figure 3–31: Trigger Holdoff Time Ensures Valid Triggering Holdoff is settable from 250 ns (minimum holdoff available) to 12 seconds (maximum holdoff available).
Triggering on Waveforms 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.
Triggering on Waveforms Trigger Status Lights Figure 3–33: TRIGGER Controls and Status Lights To set MAIN LEVEL To Set to 50% 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. To quickly obtain an edge trigger or a glitch or width pulse trigger, press SET LEVEL TO 50%.
Triggering on Waveforms To Single Trigger 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 After (main) ➞ RUN/STOP Button Only (side). See the description under Stop After on page 3–25 for further discussion of single sequence acquisitions.
Triggering on Waveforms Main Time Base Time/Div Main Time Base Main Trigger Source = Ch 1 Main Trigger Slope = Rising Edge Main Trigger Level Figure 3–34: 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 3–35.
Triggering on Waveforms Both the trigger point indicator and level bar are displayed from the Display menu. See Set Display Readout Options on page 3–29 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.
Triggering on Waveforms To Select Edge Triggering 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 3–37.
Triggering on Waveforms LF Rej removes the low frequency portion of the triggering signal. Low frequency rejection attenuates signals below 80 kHz. Noise Rej provides lower sensitivity. Noise Rej requires additional signal amplitude for stable triggering, reducing the chance of falsely triggering on noise. NOTE. When you select Line as the trigger source, the oscilloscope uses AC coupling to couple a sample of the AC line voltage to the trigger circuits.
Triggering on Waveforms 3. To change to the factory default holdoff setting for the current horizontal scale setting, press Default Holdoff (side). NOTE. If you select Default Holdoff, the default holdoff time will vary with the horizontal scale setting to maintain a good value for general purpose triggering at that scale. However, if you select Holdoff (as opposed to Default Holdoff), the time set in the Holdoff menu item is used at all horizontal scale settings.
Triggering on Waveforms setup and hold times relative to a clock. This subsection describes how to use these three classes of logic triggering: pattern, state, and setup/hold. A pattern trigger occurs when the logic inputs to the logic function you select cause the function to become TRUE (or at your option FALSE).
Triggering on Waveforms For state triggering, the oscilloscope waits until the end of trigger holdoff and then waits until the edge of channel 4 transitions in the specified direction. At that point, the oscilloscope samples the inputs from the other channels and triggers if the conditions defined in Table 3–7 are met.
Triggering on Waveforms does not become stable long enough before the clock (setup time violation) or that does not stay stable long enough after the clock (hold time violation).
Triggering on Waveforms of Figure 3–38.) The oscilloscope can then detect and trigger on violations of a time range that occurs before or one that occurs after the clock. NOTE. Keep hold time to at least 2 ns less than the clock period or the oscilloscope cannot trigger. To Check Logic Trigger Status To quickly check if logic triggers are selected and if so, what class, check the Trigger readout.
Triggering on Waveforms Figure 3–40: Logic Trigger Menu To Define Pattern Inputs. To set the logic state for each of the input channels (Ch1, Ch2, ...): 1. Press TRIGGER MENU ➞ Type (main) ➞ Logic (pop-up) ➞ Class (main) ➞ Pattern (pop-up) ➞ Define Inputs (main) ➞ Ch1, Ch2, Ch3, or Ch4 (side). 2. Repeatedly press each input selected in step 1 to choose either High (H), Low (L), or Don’t Care (X) for each channel. To Set Thresholds. To set the logic threshold for each channel: 1.
Triggering on Waveforms To Define the Logic. To choose the logic function you want applied to the input channels (see page 3–61 for definitions of the logic functions for both pattern and state triggers): Press TRIGGER MENU ➞ Type (main) ➞ Logic (pop-up) ➞ Class (main) ➞ Pattern (pop-up) ➞ Define Logic (main) ➞ AND, OR, NAND, or NOR (side). Set Trigger When.
Triggering on Waveforms It compares the times and, if the time TRUE is longer (for TRUE for more than) or shorter (for TRUE for less than), then it triggers a waveform display at the point the logic condition became FALSE. This time can be, and usually is, different from the time set for TRUE for more than or TRUE for less than. In Figure 3–41, the delay between the vertical bar cursors is the time the logic function is TRUE.
Triggering on Waveforms 2. Choose either High (H), Low (L), or Don’t Care (X) (side) for the first three channels. The choices for Ch4 are rising edge and falling edge. Set Thresholds. To set the logic threshold for each channel: 1. Press TRIGGER MENU ➞ Type (main) ➞ Logic (pop-up) ➞ Class (main) ➞ State (pop-up) ➞ Set Thresholds (main) ➞ Ch1, Ch2, Ch3, or Ch4 (side). 2. Use the MAIN TRIGGER LEVEL knob, the general purpose knob, or the keypad to set each threshold. Define Logic.
Triggering on Waveforms Define the Clock Source and Edge. To select the channel that is to contain the clock signal and the edge to use to clock: 1. Press TRIGGER MENU ➞ Type (main) ➞ Logic (pop-up) ➞ Class (main) ➞ Setup/Hold (pop-up) ➞ Clock Source (main) ➞ Ch1, Ch2, Ch3, or Ch4 (side). 2. Press any one of Ch1, Ch2, Ch3, or Ch4 (side). Do not select the same channel that you selected for the clock source. 3. Press Clock Edge (side) to toggle between the rising and falling edges.
Triggering on Waveforms Positive setup time always leads the clock edge; positive hold time always follows the clocking edge. Setup time always leads the hold time by at least 2 ns (TS + TH ≥ 2 ns). Attempting to set either time to reduce the 2 ns limit adjusts the other time to maintain the limit. Cursors measure the setup/hold violation zone which equals setup time + hold time (30 ns). Data (Ch1) transition occurs within 10 ns after the clock violating hold time limit.
Triggering on Waveforms subsection describes how to use each of the four classes of pulse triggers: glitch, runt, width, and slew rate triggering. A glitch trigger occurs when the trigger source detects a pulse narrower (or wider) in width than some specified time. It can trigger on glitches of either polarity. Or you can set the glitch trigger to reject glitches of either polarity.
Triggering on Waveforms Table 3–8: Pulse Trigger Definitions (Cont.) Name To Trigger on a Glitch Definition Runt positive Triggering occurs if the oscilloscope detects a positive pulse that crosses one threshold going positive but fails to cross a second threshold before recrossing the first going negative.
Triggering on Waveforms Figure 3–44: Main Trigger Menu — Glitch Class Select the Source. To specify which channel becomes the pulse trigger source: Press TRIGGER MENU ➞ Type (main) ➞ Pulse (pop-up) ➞ Source (main) ➞ Ch1, Ch2, Ch3, or Ch4 (side). The source selected becomes the trigger source for all four trigger classes. Select the Polarity & Width. To specify polarity (positive, negative, or either) and width of the glitch, do the following steps: 1.
Triggering on Waveforms If you choose Accept Glitch, the oscilloscope will trigger only on pulses narrower than the width you specified. If you select Reject Glitch, it will trigger only on pulses wider than the specified width. Set the Level. To set the trigger level with the Level main menu (or the front panel trigger LEVEL knob), press TRIGGER MENU ➞ Type (main) ➞ Pulse (pop-up) ➞ Level (main) ➞ Level, Set to TTL, Set to ECL, or Set to 50% (side).
Triggering on Waveforms Negative looks for negative-going runt pulses. Either looks for both positive and negative runt pulses. Set to Trig When. To determine how wide a runt pulse the oscilloscope will trigger on: 1. Press TRIGGER MENU ➞ Type (main) ➞ Pulse (pop-up) ➞ Class (main) ➞ Runt (pop-up) ➞ Trig When (main). 2. Press Occurs to trigger on all runt pulses regardless of width. 3. Press Runt is Wider Than (side) to trigger only on runt pulses that exceed the width you set.
Triggering on Waveforms Hint: To use the Trigger Bar feature to set the threshold levels on the pulse train, press DISPLAY ➞ Readout Options (main) ➞ Trigger Bar Style (side) until Long appears in that menu item. Note the position of the trigger indicator in Figure 3–45 on page 3–75. Triggering occurs at the point the pulse returns over the first (lower) threshold going negative without crossing the second threshold level (upper).
Triggering on Waveforms Set to Trig When. To set the range of widths (in units of time) the trigger source will search for and to specify whether to trigger on pulses that are outside this range or within this range, do the following steps: 1. Press TRIGGER MENU ➞ Type (main) ➞ Pulse (pop-up) ➞ Class (main) ➞ Width (pop-up) ➞ Trig When (main). 2. Press Within Limits (side) if you want the oscilloscope to trigger on pulses that fall within the specified range.
Triggering on Waveforms Positive monitors the slew rate of the positive-going edges of pulses. The edge must first cross the lower threshold and then cross the upper threshold. Negative monitors the slew rate of the negative-going edges of pulses. The edge must first cross the upper threshold and then cross the lower threshold. Either monitors positive- and negative-going edges of pulses. The edge may first cross either threshold and then cross the other. Set the Slew Rate.
Triggering on Waveforms whether to trigger on edges with slew rates faster than or slower than that indicated in readout, do the following step: Press TRIGGER MENU ➞ Type (main) ➞ Pulse (pop-up) ➞ Class (main) ➞ Slew Rate (pop-up) ➞ Trigger When (main) ➞ Trigger if Faster Than or Trigger if Slower Than (side). (See Figure 3–46.) NOTE. If you select Trigger if Faster Than and the oscilloscope does not trigger, it may be because the pulse edge is too fast rather than too slow.
Triggering on Waveforms To understand what happens when you slew rate trigger, study Figure 3–46 as you consider the following points: The main menu shows the oscilloscope is set to trigger based on the slew rate of a pulse input to the trigger source, Ch 1. It is set to monitor the positive-polarity pulse edges of the trigger source and to trigger on any edge with a slew rate faster than the slew rate setting.
Triggering on Waveforms edge trigger and certain classes of main pulse triggers. This subsection describes how to delay the acquisition of waveforms. (The Delayed time base is not available in InstaVu mode (TDS 700A models only); see Incompatible Modes on page 3–45.) There are two different ways to delay the acquisition of waveforms: delayed runs after main and delayed triggerable. Only delayed triggerable uses the delayed trigger system.
Triggering on Waveforms Posttrigger Record Pretrigger Record Delayed Runs After Main Delayed Trigger Waveform Record Main Trigger Point Main Trigger Source Time Delay (From Horiz Menu) Start Posttrigger Acquisition Delayed Triggerable By Events Delayed Trigger Waveform Record Main Trigger Point Main Trigger Source Delayed Trigger Source Waiting for nth Event (Where n=5) Start Posttrigger Acquisition (Trigger on nth Delayed Trigger Event) Delayed Triggerable By Time Delayed Trigger Waveform Record
Triggering on Waveforms NOTE. Due to hardware limitations, the delayed time base cannot be made triggerable when the main trigger type is Logic, any class, or when the main trigger type is Pulse with Runt or Slew Rate classes selected. For these settings, the oscilloscope will force the delayed time base to be in Runs After mode. To Run After Delay You use the Horizontal menu to select and define either delayed runs after main or delayed triggerable.
Triggering on Waveforms By pressing Intensified (side), you can display an intensified zone that shows where the delayed timebase record may occur (a valid delay trigger event must be received) relative to the main trigger on the main time base. For Delayed Triggerable After mode, the start of the intensified zone corresponds to the possible start point of the delayed time base record.
Triggering on Waveforms menu. You will still need to display the Horizontal menu if you wish to leave Delayed Triggerable. The Source menu lets you select which input will be the delayed trigger source. 8. Press Source (main) ➞ Ch1, Ch2, Ch3, Ch4, or DC Aux (side). NOTE. Selecting DC Aux as source in BOTH the main and delayed triggering menus forces main and delayed trigger levels to adjust in tandem.
Triggering on Waveforms 3–86 TDS 684A, TDS 744A, & TDS 784A User Manual
Measuring Waveforms To make the best use of the TDS Oscilloscope when taking measurements, you need to know how to use the three types, or classes, of measurements it can take.
Measuring Waveforms Automatic measurements are taken over the entire waveform record or, if you specify gated measurements (see page 3–91), over the region specified by the vertical cursors. Automated measurements are not taken just on the displayed portions of waveforms. The oscilloscope can also display almost all of the measurements at once — see Take a Snapshot of Measurements on page 3–95.
Measuring Waveforms Table 3–9: Measurement Definitions (Cont.) Name Definition Low The value used as 0% whenever High Ref, Mid Ref, and Low Ref values are needed (as in fall time and rise time measurements). May be calculated using either the min/max or the histogram method. With the min/max method it is the minimum value found. With the histogram method, it refers to the most common value found below the midpoint. Measured over the entire waveform or gated region. Maximum Voltage measurement.
Measuring Waveforms Measurement Readouts With no menus displayed, the measurement readouts appear far right of the display graticule. (See Figure 3–52.) You can display and continuously update as many as four measurements at any one time. With any menu displayed, the readouts move to the right side of the graticule area. Measurement Readout Area Figure 3–52: Measurement Readouts Measurement 1 is the top readout. Measurement 2 is below it, and so forth.
Measuring Waveforms Be careful when taking automatic measurements on noisy signals. You might measure the frequency of the noise and not the desired waveform. Your oscilloscope helps identify such situations by displaying a low signal amplitude or low resolution warning message. Figure 3–53: Measure Menu Remove Measurements The Remove Measrmnt selection provides explicit choices for removing measurements from the display according to their readout position.
Measuring Waveforms 2. Using the general purpose knob, move the selected (the active) cursor. Press SELECT to change which cursor is active. Displaying the cursor menu and turning V Bar cursors off will not turn gating off. (Gating arrows remain on screen to indicate the area over which the measurement is gated.) You must turn gating off in the Gating side menu. NOTE. Cursors are displayed relative to the selected waveform.
Measuring Waveforms Histogram sets the values statistically. It selects the most common value either above or below the midpoint (depending on whether it is defining the high or low reference level). Since this statistical approach ignores short term aberrations (overshoot, ringing, etc.), histogram is the best setting for examining pulses. Min-max uses the highest and lowest values of the waveform record.
Measuring Waveforms 2. Press High Ref, Mid Ref, Low Ref, or Mid2 Ref (side). High Ref — Sets the high reference level. The default is 90%. Mid Ref — Sets the middle reference level. The default is 50%. Low Ref — Sets the low reference level. The default is 10%. Mid2 Ref — Sets the middle reference level used on the second waveform specified in the Delay or Phase Measurements. The default is 50%.
Measuring Waveforms 3. Press MEASURE ➞ Select Measrmnt (main) ➞ Delay (side) ➞ Edges (main). A side menu of delay edges and directions will appear. Choose from one of the combinations displayed on the side menu using the following information: The selection you choose defines which edges you want the delayed measurement to be made between. The upper waveform on each icon represents the from waveform and the lower one represents the to waveform.
Measuring Waveforms Snapshot Display Figure 3–57: Snapshot Menu and Readout Consider the following rules when taking a snapshot: 3–96 Be sure to display the waveform properly before taking a snapshot. Snapshot does not warn you if a waveform is improperly scaled (clipped, low signal amplitude, low resolution, etc.). To vary the source for taking a snapshot, simply select another channel, math, or ref memory waveform and then execute snapshot again.
Measuring Waveforms To Find More Information To perform a tutorial that shows you how to take automatic measurements, see Example 3: Taking Automated Measurements on page 2–19. To learn how the oscilloscope calculates each automatic measurement, see Appendix B: Algorithms on page B–1. Taking Cursor Measurements The TDS Oscilloscope provides cursors that measure the difference (either in time or voltage) between two locations in a waveform record.
Measuring Waveforms NOTE. When cursors measure certain math waveforms, the measurement may not be of time, frequency, or voltage. Cursor measurement of those math waveforms that are not of time, frequency, or voltage is described in Waveform Math, which begins on page 3–142. Cursor Modes There are two cursor modes: independent and tracking. (See Figure 3–59.) In independent mode, you move only one cursor at a time using the general purpose knob. The active, or selected, cursor is a solid line.
Measuring Waveforms TDS 700A Models Only: In FastFrame mode, the @ shows the time position of the selected cursor relative to the trigger point of the frame that the selected cursor is in. The D shows the time difference between the two cursors only if both cursors are in the same frame. Paired. The value after one D shows the voltage difference between the two Xs; the other D shows the time (or frequency) difference between the two long vertical bars.
Measuring Waveforms Position of Vertical Bar Cursors (Useful for Locating Cursors Outside the Display) Cursor Readout (Paired) Non-selected Cursor (Dashed Vertical Bar) Selected Cursor (Solid Vertical Bar) Figure 3–61: Paired Cursor Menu and Readouts Set Mode and Adjust the Cursors To select the cursor mode and adjust the cursors in either mode, do the following steps: 1.
Measuring Waveforms adjust the distance of the solid cursor relative to the dashed cursor. Press SELECT again to resume tracking. Select Cursor Speed To change the cursors speed, press SHIFT before turning the general purpose knob. The cursor moves faster when the SHIFT button is lighted and the display reads Coarse Knobs in the upper right corner. Select Time Units You can choose to display vertical bar cursor results in units of time or frequency.
Measuring Waveforms Measure Waveform Amplitude To measure the amplitude of a waveform, do the following steps: 1. Press the channel selection button of the channel you wish to measure. Note the vertical scale factor for the channel in the channel readout on screen. 2. Count the graticule divisions between two features to be measured and multiply by the vertical scale factor.
Measuring Waveforms Run an SPC anytime you wish to ensure that the measurements you make are made with the most accuracy possible. You should also run an SPC if the temperature has changed more than 5 C since the last SPC was performed. NOTE. When making measurements at volts/division settings less than or equal to 5 mV, you should run SPC at least once per week. Failure to do so may result in the oscilloscope not meeting warranted performance levels at those volts/div settings.
Measuring Waveforms Figure 3–62: Performing a Signal Path Compensation Probe Cal The TDS Oscilloscope lets you compensate the probe, based on the channel it is connected to, to improve the gain and offset accuracy of the probe. By executing Probe Cal on a channel with its probe installed, you can optimize the oscilloscope capability to make accurate measurements using that channel and probe.
Measuring Waveforms NOTE. Probe Cal is not recommended with the P6139A passive probe. This probe typically has little gain and offset error, and therefore, the improvement in performance after a Probe Cal is not worth the time needed to do the Probe Cal. Probe Cal makes significant performance improvements when performed with active probes or older passive probes.
Measuring Waveforms When gain compensation completes, the following actions occur: The clock icon will disappear. If offset compensation is required for the probe installed, the Probe Offset Compensation message will replace the Probe Gain Compensation message. If gain compensation did not complete successfully, you may get a “Probe is not connected” message (examine the probe connections to the digitizing oscilloscope, be sure the probe tip is properly installed in its retractor, etc.
Measuring Waveforms 13. Press SHIFT UTILITY ➞ System (main) ➞ Diag/Err (pop-up) ➞ Error Log (main). If there are too many error messages to be seen on screen, rotate the general purpose knob clockwise to scroll to the last message. 14. Note the compensation error amount. Skip to step 19. 15. Disconnect the probe from any signal you may have connected it to. Leave the probe installed on its channel. 16. Press OK Compensate Offset (side). 17. Wait for offset compensation to complete (one to three minutes).
Measuring Waveforms When you install a probe or power on the oscilloscope with probes installed, the oscilloscope tests the probe at each input. Depending on the probe it finds on each input, it takes one of the following actions: If the probe has a TEKPROBE interface (such an interface can convey additional information, such as a unique identification number), the oscilloscope determines whether it is the same probe for which data was stored.
Measuring Waveforms If the Re-use Probe Calibration data? menu is displayed, you can choose one of the following options: Press OK Use Existing Data (side) to use the Probe Cal data last stored to compensate the probe. Press OK Erase Probe Cal Data (side) to erase the Probe Cal data last stored and use the probe uncompensated. Press CLEAR MENU on the front panel to retain the Probe Cal data last stored and use the probe uncompensated. NOTE.
Measuring Waveforms 3–110 TDS 684A, TDS 744A, & TDS 784A User Manual
Saving Waveforms and Setups The TDS Oscilloscope can save and recall the waveforms you measure and the setups you use to measure them. It can also output or save a copy of its display screen.
Saving Waveforms and Setups 2. To store to a setup internally, choose one of the ten internal storage locations from the side menu To Setup 1, To Setup 2, ... (see Figure 3–65). Now the current setup is stored in that location. 3. To store a setup to disk, press To File (side). Then use the general purpose knob to select the exact file from the resulting scrollbar list. Finally, press Save To Selected File (side) to complete the operation. NOTE.
Saving Waveforms and Setups Recalling a setup will not change the menu that is currently displayed. If you recall a setup that is labeled factory in the side menu, you will recall the factory setup. (The conventional method for recalling the factory setup is described below.) To Recall the Factory Setup To reset your oscilloscope to the factory defaults: Press SAVE/RECALL SETUP ➞ Recall Factory Setup (main) ➞ OK Confirm Factory Init (side).
Saving Waveforms and Setups Saving and Recalling Waveforms TDS Oscilloscope provides four internal reference memories in any of which you can store a waveform. Waveform thus stored are retained even when you turn the oscilloscope off or unplug it. The oscilloscope also can save waveforms to floppy disk. This subsection describes how to save, delete, and display reference waveforms. The oscilloscope can display up to 11 waveforms at one time.
Saving Waveforms and Setups To Change Format (TDS 700A Models) TDS 700A Models Only: To select the format that the oscilloscope uses to save waveforms to a disk, press save/recall WAVEFORM ➞ Save Format (main) ➞ Internal, MathCad, or Spreadsheet (side). Internal creates files (.WFM) in the internal format of the oscilloscope. MathCad creates files (.DAT) in a format usable by MathCad. Spreadsheet creates files (.CSV) in a format usable by spreadsheets (Excel, Lotus 1-2-3, and Quattro Pro.
Saving Waveforms and Setups Note that in Figure 3–67, the main menu items Ref2, Ref3, and Ref4 appear shaded while Ref1 does not. References that are empty appear shaded in the More main menu. To Recall a Waveform From Disk To recall a waveform from disk to an internal reference memory, press SAVE/ RECALL WAVEFORM ➞ Recall Wfm To Ref (main) ➞ Recall From File (side) Then use the general purpose knob to select the exact file from the resulting scrollbar list. Only files with .WFM extensions are displayed.
Saving Waveforms and Setups To rearm the oscilloscope for taking a new autosave single acquisition sequence, press RUN/STOP. To avoid loss of reference waveforms, you can save them to floppy disk (use the SAVE/RECALL WAVEFORM menu), before rearming the oscilloscope. Consider the following operating characteristics when using autosave. To Run the File Utilities Autosave saves all “live” waveforms; that is, waveforms displayed in CH 1 – CH 4. To be saved, the live waveforms must be displayed on screen.
Saving Waveforms and Setups NOTE. The amount of free space on the disk is shown in the upper right corner of the display. The oscilloscope shows the amount in Kbytes (or in Mbytes if the free space is 1 Mbyte or more). To convert the amount to bytes, you simply multiply the Kbytes amount times 1024. Thus, the 690 Kbytes shown in Figure 3–68 = 690 Kbytes x 1024 bytes/Kbyte = 706,560 bytes.
Saving Waveforms and Setups menu to enter each letter. When you have entered the name, press the side menu OK Accept item. Figure 3–69: File System — Labeling Menu To Copy To copy a file or directory, turn the general purpose knob until it scrolls the cursor over the name of the file to copy. Then, press the side menu Copy button. The file menu will reappear with the names of directories to copy to. Select a directory and press the side-menu button labelled Copy to Selected Directory.
Saving Waveforms and Setups The labeling menu should appear. Turn the general purpose knob or use the main-menu arrow keys to select each letter. Press Enter Char from the main menu to enter each letter. When you have entered the name, press the side menu OK Accept item. (See Figure 3–69.) To Set Confirm Delete To turn on or off the confirm delete message, toggle the side menu Confirm Delete button. When the confirm delete option is OFF, the oscilloscope can immediately delete files or directories.
Saving Waveforms and Setups Supported Formats The oscilloscope prints hardcopies of its display in many formats, which allows you to choose from a wide variety of hardcopy devices. It also makes it easier for you to place oscilloscope screen copies into a desktop publishing system.
Saving Waveforms and Setups To Set Up for Making Hardcopies Before you make a hardcopy, you need to set up communications and hardcopy parameters. Do the following procedures to set up for making hardcopies. Set Communications Parameters. To set up the communication parameters for a printer attached directly to the oscilloscope GPIB, RS-232 or Centronics port: Press SHIFT ➞ UTILITY ➞ System (main) ➞ I/O (pop-up) ➞ Configure (main) ➞ Hardcopy (Talk Only) (side). (See Figure 3–70.
Saving Waveforms and Setups Landscape Format Portrait Format Figure 3–71: Hardcopy Formats 4. Press SHIFT ➞ HARDCOPY MENU ➞ Palette (main) ➞ Hardcopy or Current (side) to specify a hardcopy palette. Current uses the current palette settings to create the hardcopy, while Hardcopy sets the hardcopy palette to an optimal setting for hardcopy devices. 5. Press SHIFT ➞ HARDCOPY MENU ➞ Port (main) to specify the output channel to send your hardcopy through. The choices are GPIB, RS–232, Centronics, and File.
Saving Waveforms and Setups Date and Time Display Figure 3–72: Date and Time Display Set the Date and Time. You might need to set the date and time of the oscilloscope. To set those parameters, do the following steps. 1. Press SHIFT ➞ UTILITY ➞ Config (pop-up) ➞ Set Date & Time (main) ➞ Year, Day Month, Hour, or Minute (side). 2. Use the general purpose knob or the keypad to set the parameter you have chosen to the value desired. (The format when using the keypad is day.month. For example, use 23.
Saving Waveforms and Setups To Print Directly to a Hardcopy Device To make your hardcopies, use the procedures that follow. Connect to a Hardcopy Device. To connect the oscilloscope directly to a hardcopy device, determine which interface and cable the device uses, and connect accordingly. (See Figure 3–73.) Some devices, such as the Tektronix HC100 Plotter, use the GPIB interface. Many printers, such as the Tektronix HC200, use Centronics interfaces.
Saving Waveforms and Setups Clear the Spool. To remove all hardcopies from the spool, press SHIFT ➞ HARDCOPY MENU ➞ Clear Spool (main) ➞ OK Confirm Clear Spool (side). The oscilloscope takes advantage of any unused RAM when spooling hardcopies to printers. The size of the spool is, therefore, variable.
Saving Waveforms and Setups stored hardcopies from disk into your desktop publishing software that runs on a PC-compatible computer. To Print Using a Controller To make your hardcopies, use the procedures that follow. Connect to a Hardcopy Device. To connect a controller with two ports between the oscilloscope and the hardcopy device, connect from the oscilloscope GPIB connector (rear panel) to the controller GPIB port and from the controller RS-232 or Centronics port to the hardcopy device.
Saving Waveforms and Setups NOTE. If you defined another name, use it instead of “DEV1”. Also, remember that the device address of the oscilloscope as set with the IBCONF.EXE program should match the address set in the oscilloscope Utility menu (typically, use “1”). 4. Type: IBWRT “HARDCOPY START” NOTE. Be sure the oscilloscope Utility menu is set to Talk/Listen and not Hardcopy (Talk Only) or you will get an error message at this step.
Saving Waveforms and Setups To Prepare for Remote Operation To transfer data between the oscilloscope and other instruments over the GPIB, do the following tasks to make sure the instruments support GPIB protocols and observe GPIB Interface requirements. Check for GPIB Protocols. Make sure the instruments to be connected support the GPIB protocols.
Saving Waveforms and Setups Obtain the Proper Interconnect Cabling. To connect the oscilloscope to a GPIB network, obtain at least one GPIB cable. Connecting two GPIB devices requires an IEEE Std 488.1-1987 GPIB cable (available from Tektronix, part number 012-0991-00). The standard GPIB cable connects to a 24-pin GPIB connector located on the rear panel of the oscilloscope. The connector has a D-type shell and conforms to IEEE Std 488.1-1987. You can stack GPIB connectors on top of each other.
Saving Waveforms and Setups Controller Digitizing Oscilloscope (Rear Panel) GPIB Connector Figure 3–77: Connecting the Oscilloscope to a Controller Select GPIB Port. To select the GPIB port, press SHIFT ➞ UTILITY ➞ System (main) ➞ I/O (pop-up) ➞ Port (main) ➞ GPIB (pop-up). Configure the GPIB Port. You must set two important GPIB parameters: mode and address.
Saving Waveforms and Setups GPIB Configuration Menu Figure 3–78: Utility Menu To Find More Information See Printing a Hardcopy, on page 3–120. See the TDS Programmer Manual, Tektronix part number 070-8709-XX.
Determining Status and Accessing Help The TDS Oscilloscope can display the status of its internal systems. It also provides an on-line help system.
Determining Status and Accessing Help Firmware Version Figure 3–79: Status Menu — System Figure 3–80: Banner Display 3–134 TDS 684A, TDS 744A, & TDS 784A User Manual
Determining Status and Accessing Help Displaying Help To use the on-line help system: Press HELP to provide on-screen information on any front panel button, knob or menu item. (See Figure 3–81.) Figure 3–81: Initial Help Screen When you press that button, the instrument changes mode to support on-line help. Press HELP again to return to regular operating mode.
Determining Status and Accessing Help 3–136 TDS 684A, TDS 744A, & TDS 784A User Manual
Using Features for Advanced Applications The TDS Oscilloscope provides powerful features for testing and digitally processing the waveforms you acquire.
Using Features for Advanced Applications To use limit testing, you must do four tasks: Create the limit test template from a waveform. Specify the channel to compare to the template. Specify the action to take if incoming waveform data exceeds the set limits. Turn limit testing on so that the parameters you have specified will take effect.
Using Features for Advanced Applications Figure 3–83: Acquire Menu — Create Limit Test Template 4. Press ±V Limit (side). Enter the vertical (voltage) tolerance value using the general purpose knob or keypad. 5. Press ±H Limit (side). Enter the horizontal (time) tolerance value using the general purpose knob or keypad. Tolerance values are expressed in fractions of a major division.
Using Features for Advanced Applications NOTE. To view the waveform data as well as the template envelope, it might be useful to select the Dots display style. (See Select the Display Style on page 3–28.) To Select a Limit Test Source Now specify the channel that will acquire the waveforms to be compared against the template you have created: 1.
Using Features for Advanced Applications NOTE. The button labeled Stop After Limit Test Condition Met corresponds to the Limit Test Condition Met menu item in the Stop After main menu. You can turn this button on in the Limit Test Setup menu, but you cannot turn it off. In order to turn it off, press Stop After and specify one of the other choices in the Stop After side menu. 3. Ensure that Limit Test (side) reads ON. If it reads OFF, press Limit Test (side) once to toggle it to ON.
Using Features for Advanced Applications Waveform Math The TDS Oscilloscope provides a means for you to mathematically manipulate your waveforms. For example, you might have a waveform clouded by background noise. You can obtain a cleaner waveform by subtracting the background noise from your original waveform. This section describes the invert, add, subtract, divide, and multiply waveform math features.
Using Features for Advanced Applications 3. Press Set Function to (side) repeatedly to cycle it to inv (invert), intg, or diff. Waveform integration (intg) is described on page 3–165, and waveform differentiation (diff) is described on page 3–161. 4. To create the math waveform, press OK Create Math Wfm (side). To Use Dual Wfm Math To create a math waveform that requires two waveform sources, do the following steps: 1.
Using Features for Advanced Applications 5. Press OK Create Math Wfm (side) to perform the function. To Average a Math Waveform You can also select whether or not you wish to average a certain math waveform; to do so, perform the following steps: 1. Press MORE ➞ Math1, Math2, or Math3 (main) to select the math waveform to be averaged. 2. Press Average (side) and enter a value with the general purpose knob or the keypad.
Using Features for Advanced Applications The FFT computes and displays the frequency content of a waveform you acquire as an FFT math waveform.
Using Features for Advanced Applications Normal Waveform of an Impulse Response FFT Waveform of the Magnitude Response FFT Waveform of the Phase Response Figure 3–86: System Response to an Impulse To Create an FFT To obtain an FFT of your waveform, do the following steps: 1. Connect the waveform to the desired channel input and select that channel. 2. Adjust the vertical and horizontal scales and trigger the display (or press AUTOSET).
Using Features for Advanced Applications Figure 3–87: Define FFT Waveform Menu 7. Press Set FFT Vert Scale to (side) repeatedly to choose from the following vertical scale types: dBV RMS — Magnitude is displayed using log scale, expressed in dB relative to 1 VRMS where 0 dB =1 VRMS. Linear RMS — Magnitude is displayed using voltage as the scale. Phase (deg) — Phase is displayed using degrees as the scale, where degrees wrap from –180 to +180 .
Using Features for Advanced Applications Hamming — Very good window for resolving frequencies that are very close to the same value with somewhat improved amplitude accuracy over the rectangular window. Hanning — Very good window for measuring amplitude accuracy but degraded for resolving frequencies. Blackman-Harris — Best window for measuring the amplitude of frequencies but worst at resolving frequencies.
Using Features for Advanced Applications To Take Cursor Measurements of an FFT Once you have displayed an FFT math waveform, use cursors to measure its frequency amplitude or phase angle. 1. Be sure MORE is selected in the channel selection buttons and that the FFT math waveform is selected in the More main menu. 2. Press CURSOR ➞ Mode (main) ➞ Independent (side) ➞ Function (main) ➞ H Bars (side). 3.
Using Features for Advanced Applications Figure 3–89: Cursor Measurement of an FFT Waveform 10. Press Function (main) ➞ Paired (side). 11. Use the technique just outlined to place the vertical bar of each paired cursor to the points along the horizontal axis you are interested in. 12. Read the amplitude between the X of the two paired cursors from the top-most : readout.
Using Features for Advanced Applications FFTs May Not Use All of the Waveform Record. The FFT math waveform is a display of the magnitude or phase data from the FFT frequency domain record. This frequency domain record is derived from the FFT time domain record, which is derived from the waveform record. All three records are described below. Waveform Record — the complete waveform record acquired from an input channel and displayed from the same channel or a reference memory.
Using Features for Advanced Applications FFTs Transform Time Records to Frequency Records. The FFT time domain record just described is input for the FFT. Figure 3–91 shows the transformation of that time domain data record into an FFT frequency domain record. The resulting frequency domain record is one half the length of the FFT input because the FFT computes both positive and negative frequencies. Since the negative values mirror the positive values, only the positive values are displayed.
Using Features for Advanced Applications Offset, Position, and Scale The following topics contain information to help you display your FFT properly. Adjust for a Non-Clipped Display. To properly display your FFT waveform, scale the source waveform so it is not clipped. You should scale and position the source waveform so it is contained on screen. (Off screen waveforms may be clipped, resulting in errors in the FFT waveform).
Using Features for Advanced Applications Acquisition Mode Selecting the right acquisition mode can produce less noisy FFTs. Set up in Sample. Use sample mode until you have set up and turned on your FFT. Sample mode can acquire repetitive and nonrepetitive waveforms and does not affect the frequency response of the source waveform. Hi Res and Average Reduce Noise. If the pulse is repetitive, Average mode may be used to reduce noise in the signal at a cost of slower display response.
Using Features for Advanced Applications Sin(x)/x interpolation may distort the magnitude and phase displays of the FFT depending on which window was used. You can easily check the effects of the interpolation by switching between sin(x)/x and linear interpolation and observing the difference in measurement results on the display. If significant differences occur, use linear interpolation.
Using Features for Advanced Applications Amplitude Nyquist Frequency Point Frequency Aliased Frequencies Actual Frequencies Figure 3–92: How Aliased Frequencies Appear in an FFT Considerations for Phase Displays When you set up an FFT math waveform to display the phase angle of the frequencies contained in a waveform, you should take into account the reference point the phase is measured against. You may also need to use phase suppression to reduce noise in your FFTs.
Using Features for Advanced Applications For records with a 100 K length (TDS 700A models with Option 1M only), set the trigger position to 5%. Use the horizontal position knob to move the trigger T on screen to the center horizontal graticule line. Do not use the 15 K (all models), 30 K (TDS 700A models), 75 K, or 130 K (TDS 700A models equipped with Option 1M) to impulse test using FFTs. These record lengths do not allow easy alignment of the zero reference point for phase measurements.
Using Features for Advanced Applications FFT Windows To learn how to optimize your display of FFT data, read about how the FFT windows data before computing the FFT math waveform. Understanding FFT windowing can help you get more useful displays. Windowing Process. The oscilloscope multiplies the FFT time domain record by one of four FFT windows before it inputs the record to the FFT function. Figure 3–93 shows how the time domain record is processed.
Using Features for Advanced Applications FFT Time Domain Record Xs FFT Window FFT Time Domain Record After Windowing FFT FFT Frequency Domain Record Figure 3–93: Windowing the FFT Time Domain Record You can often determine the best window empirically by first using the window with the most frequency resolution (rectangular), then proceeding toward that window with the least (Blackman-Harris) until the frequencies merge.
Using Features for Advanced Applications Window Characteristics. When evaluating a window for use, you may want to examine how it modifies the FFT time domain data. Figure 3–94 shows each window, its bandpass characteristic, bandwidth, and highest side lobe. Consider the following characteristics: The narrower the central lobe for a given window, the better it can resolve a frequency.
Using Features for Advanced Applications FFT Window Type Bandpass Filter –3 dB Bandwidth Highest Side Lobe 0 dB -20 Rectangular Window 0.89 –13 dB 1.28 –43 dB 1.28 –32 dB 1.
Using Features for Advanced Applications Derivative waveforms are used in the measurement of slew rate of amplifiers and in educational applications. You can store and display a derivative math waveform in a reference memory, then use it as a source for another derivative waveform. The result is the second derivative of the waveform that was first differentiated.
Using Features for Advanced Applications Derivative Math Waveform Source Waveform Figure 3–95: Derivative Math Waveform To Take Automated Measurements Once you have displayed your derivative math waveform, you can use automated measurements to make various parameter measurements. Do the following steps to display automated measurements of the waveform: 1. Be sure MORE is selected in the channel selection buttons and that the differentiated math waveform is selected in the More main menu. 2.
Using Features for Advanced Applications Figure 3–96: Peak-Peak Amplitude Measurement of a Derivative Waveform Offset, Position, and Scale The settings you make for offset, scale, and position affect the math waveform you obtain. Note the following tips for obtaining a good display: You should scale and position the source waveform so it is contained on screen. (Off screen waveforms may be clipped, resulting in errors in the derivative waveform).
Using Features for Advanced Applications clipped portion. Also, the automated measurement Pk-Pk will display a clipping error message if turned on (see To Take Automated Measurements on page 3–163). If your derivative waveform is clipped, try either of the following methods to eliminate clipping: Reduce the size of the source waveform on screen. (Select the source channel and use the vertical SCALE knob.) Expand the waveform horizontally on screen.
Using Features for Advanced Applications The integral math waveform, derived from the sampled waveform, is computed based on the following equation: n y(n) + scale Where: x(i) ) x(i * 1) T 2 i+1 x(i) is the source waveform y(n) is a point in the integral math waveform scale is the output scale factor T is the time between samples Since the resultant math waveform is an integral waveform, its vertical scale is in volt-seconds (its horizontal scale is in seconds).
Using Features for Advanced Applications Integral Math Waveform Source Waveform Figure 3–97: Integral Math Waveform To Take Cursor Measurements Once you have displayed your integrated math waveform, use cursors to measure its voltage over time. 1. Be sure MORE is selected (lighted) in the channel selection buttons and that the integrated math waveform is selected in the More main menu. 2. Press CURSOR ➞ Mode (main) ➞ Independent (side) ➞ Function (main) ➞ H Bars (side). 3.
Using Features for Advanced Applications Integral Math Waveform Source Waveform Figure 3–98: H Bars Cursors Measure an Integral Math Waveform 7. Press Function (main) ➞ V Bars (side). Use the general purpose knob to align one of the two vertical cursors to a point of interest along the horizontal axis of the waveform. 8. Press SELECT to select the alternate cursor. 9. Align the alternate cursor to another point of interest on the math waveform. 10.
Using Features for Advanced Applications To Take Automated Measurements Offset, Position, and Scale DC Offset Read the time difference between the long vertical bars of the paired cursors from the : readout. You can also use automated measurements to measure integral math waveforms. Use the same procedure as is found under To Take Automated Measurements on page 3–163.
Using Features for Advanced Applications If you wish to see the zoom factor (2X, 5X, etc.) you need to turn Zoom on: press ZOOM ➞ On (side). The vertical and horizontal zoom factors appear on screen. Whether Zoom is on or off, you can press Reset Zoom Factors (side) to return the zoomed integral waveform to no magnification.
Appendices
Appendix A: Options and Accessories This appendix describes the various options as well as the standard and optional accessories that are available for the TDS Oscilloscope.
Appendix A: Options and Accessories Table A–1: Options (Cont.) A–2 Option # Label Description 1M (TDS 7X4A) 130,000 record length (TDS 7X4A) Extend TDS 7X4A record length from 50,000 standard to 500,000 samples on one channel, 250,000 on two channels, and 130,000 samples on three or four channels. 1R Rackmount Oscilloscope comes configured for installation in a 19 inch wide instrument rack. For later field conversions, order kit # 016-1136-00.
Appendix A: Options and Accessories Table A–1: Options (Cont.) Option # Label 95 Calibration Data Report 96 Calibration Certificate Description Certificate of Calibration which states this instrument meets or exceeds all warranted specifications and has been calibrated using standards and instruments whose accuracies are traceable to the National Institute of Standards and Technology, an accepted value of a natural physical constant, or a ratio calibration technique.
Appendix A: Options and Accessories Optional Accessories You can also order the optional accessories listed in Table A–3.
Appendix A: Options and Accessories Accessory Software AM 503S — DC/AC Current probe system, AC/DC. Uses A6302 Current Probe. AM 503S Option 03: DC/AC Current probe system, AC/DC. Uses A6303 Current Probe. P6021 AC Current probe. 120 Hz to 60 MHz. P6022 AC Current probe. 935 kHz to 120 MHz. CT-1 Current probe — designed for permanent or semi-permanent in-circuit installation. 25 kHz to 1 GHz, 50 W input.
Appendix A: Options and Accessories A–6 CALXXXX provides one year of calibration support. It is available in one year increments up to five years.
Appendix B: Algorithms The TDS Oscilloscope can take 25 automatic measurements. By knowing how it makes these calculations, you may better understand how to use your oscilloscope and how to interpret your results. Measurement Variables The oscilloscope uses a variety of variables in its calculations. These include: High, Low is the value used as the 100% level in measurements such as fall time and rise time.
Appendix B: Algorithms The oscilloscope calculates the histogram-based and values as follows: 1. It makes a histogram of the record with one bin for each digitizing level (256 total). 2. It splits the histogram into two sections at the halfway point between and (also called ). 3. The level with the most points in the upper histogram is the value, and the level with the most points in the lower histogram is the value.
Appendix B: Algorithms Other Variables The oscilloscope also measures several values itself that it uses to help calculate measurements. RecordLength — is the number of data points in the time base. You set it with the Horizontal menu Record Length item. Start — is the location of the start of the measurement zone (X-value). It is 0.0 samples unless you are making a gated measurement. When you use gated measurements, it is the location of the left vertical cursor.
Appendix B: Algorithms MCross1Polarity — is the polarity of first crossing (no default). It can be rising or falling. StartCycle — is the starting time for cycle measurements. It is a floating-point number with values between 0.0 and ( – 1.0), inclusive. = EndCycle — is the ending time for cycle measurements. It is a floating-point number with values between 0.0 and ( – 1.0), inclusive.
Appendix B: Algorithms Measurement Algorithms The automated measurements are defined and calculated as follows. Amplitude Area = – The arithmetic area for one waveform. Remember that one waveform is not necessarily equal to one cycle. For cyclical data you may prefer to use the cycle area rather than the arithmetic area. if = then return the (interpolated) value at .
Appendix B: Algorithms Cycle Mean Amplitude (voltage) measurement. The mean over one waveform cycle. For non-cyclical data, you might prefer to use the Mean measurement. If = then return the (interpolated) value at . ŕ = ( )dt ( * ) For details of the integration algorithm, see page B–12. Cycle RMS The true Root Mean Square voltage over one cycle.
Appendix B: Algorithms 2. From this sample, continue the search to find the first (negative) crossing of . The time of this crossing is . (Use linear interpolation if necessary.) 3. From , continue the search, looking for a crossing of . Update if subsequent crossings are found. When a crossing is found, it becomes . (Use linear interpolation if necessary.) 4.
Appendix B: Algorithms Low 0% (lowest) voltage reference value calculated. (See High, Low on page B–1.) Using the min-max measurement technique: Low = Min Maximum Amplitude (voltage) measurement. The maximum voltage. Typically the most positive peak voltage. Examine all Waveform[ ] samples from Start to End inclusive, and set Max equal to the greatest magnitude Waveform[ ] value found. Mean The arithmetic mean for one waveform. Remember that one waveform is not necessarily equal to one cycle.
Appendix B: Algorithms Note that this value should never be negative (unless High or Low are set out-of-range). Negative Width Timing measurement. The distance (time) between (default = 50%) amplitude points of a negative pulse. If = ‘–’ then = – else = – Peak to Peak Amplitude measurement. The absolute difference between the maximum and minimum amplitude. = – Period Timing measurement.
Appendix B: Algorithms # = " ## * " ## " $ " If the target waveform leads the reference waveform, phase is positive; if it lags, negative. Phase is not available in the Snapshot display. Positive Duty Cycle Timing measurement. The ratio of the positive pulse width to the signal period, expressed as a percentage. # $ & $ is defined in Positive Width, following. If " = 0 or undefined then return an error.
Appendix B: Algorithms 2. From this sample, continue the search to find the first (positive) crossing of . The time of this crossing is the low rise time or . (Use linear interpolation if necessary.) 3. From , continue the search, looking for a crossing of . Update if subsequent crossings are found. If a crossing is found, it becomes the high rise time or . (Use linear interpolation if necessary.) 4.
Appendix B: Algorithms Integration Algorithm The integration algorithm used by the oscilloscope is as follows: ŕ W(t)dt B is approximated by ŕ W(t)dt where: B ^ A A W(t) is the sampled waveform ^ ( )is the continuous function obtained by linear interpolation of W(t) A and B are numbers between 0.0 and –1.0 If A and B are integers, then: ŕ W(t)dt + s B ^ A ) 1) ȍ W(i) ) W(i 2 B*1 i+A where s is the sample interval.
Appendix B: Algorithms If all pairs straddle , use maxima. See Figure B–4. The Burst Width measurement always uses both maxima and minima to determine crossings. MidRef Both min and max samples are above MidRef, so use minima. Both min and max samples are below MidRef, so use maxima.
Appendix B: Algorithms Missing or Out-of-Range Samples If some samples in the waveform are missing or off-scale, the measurements will linearly interpolate between known samples to make an “appropriate” guess as to the sample value. Missing samples at the ends of the measurement record will be assumed to have the value of the nearest known sample.
Appendix C: Packaging for Shipment If you ship the TDS Oscilloscope, pack it in the original shipping carton and packing material. If the original packing material is not available, package the instrument as follows: 1. Obtain a corrugated cardboard shipping carton with inside dimensions at least 15 cm (6 in) taller, wider, and deeper than the oscilloscope. The shipping carton must be constructed of cardboard with 170 kg (375 pound) test strength. 2.
Appendix C: Packaging for Shipment C–2 TDS 684A, TDS 744A, & TDS 784A User Manual
Appendix D: Factory Initialization Settings Recalling the factory setup establishes the initialization settings shown in Table D–1 to set the TDS Oscilloscope to a known default state.
Appendix D: Factory Initialization Settings Table D–1: Factory Initialization Defaults (Cont.
Appendix D: Factory Initialization Settings Table D–1: Factory Initialization Defaults (Cont.) Control Changed by Factory Init to Horizontal – main time/division 500 s Horizontal – main trigger position 50% Horizontal – position 50% Horizontal – record length 500 points (10 divs) Horizontal – time base Main only Limit template ±V Limit ±H Limit 40 mdiv 40 mdiv Limit template destination Ref1 Limit template source Ch1 Limit test sources Ch1 compared to Ref1; all others compared to none.
Appendix D: Factory Initialization Settings Table D–1: Factory Initialization Defaults (Cont.) Control Changed by Factory Init to Logic trigger triggers when ...
Appendix D: Factory Initialization Settings Table D–1: Factory Initialization Defaults (Cont.) Control Changed by Factory Init to Pulse slew rate thresholds Upper Lower Trig if faster than 1.80 V 800 mV Pulse slew rate triggers when ... Trig if faster than Pulse slew rate setting Pulse trigger class Glitch Pulse trigger level 0.0 V Pulse trigger source (Glitch, runt, width, and slew rate) Channel 1 (Ch 1) Pulse width lower limit 2.
Appendix D: Factory Initialization Settings D–6 TDS 684A, TDS 744A, & TDS 784A User Manual
Appendix E: Probe Selection The TDS Oscilloscope can use a variety of Tektronix probes for taking different kinds of measurements. To help you decide what type of probe you need, this section introduces the five major types of probes: passive, active, current, optical, and time-to-voltage probes. See Appendix A: Options and Accessories for a list of the optional probes available; see your Tektronix Products Catalog for more information about a given probe.
Appendix E: Probe Selection Low Impedance (ZO) Probes Maximum amplitude sensitivity using 1X high impedance Large voltage range (between 15 and 500 V) Qualitative or go/no-go measurements Low impedance probes measure frequency more accurately than general purpose probes, but they make less accurate amplitude measurements. They offer a higher bandwidth to cost ratio. These probes must be terminated in a 50 W scope input.
Appendix E: Probe Selection Active Voltage Probes Active voltage probes, sometimes called “FET” probes, use active circuit elements such as transistors. There are three classes of active probes: High speed active Differential active Fixtured active Active voltage measuring probes use active circuit elements in the probe design to process signals from the circuit under test. All active probes require a source of power for their operation.
Appendix E: Probe Selection precisely connect your instrument to your device-under-test. These probes have the same electrical characteristics as high speed, active probes but use a smaller mechanical design. Current Probes Current probes enable you to directly observe and measure current waveforms, which can be very different from voltage signals. Tektronix current probes are unique in that they can measure from DC to 1 GHz.
Appendix E: Probe Selection Optical Probes Optical probes let you blend the functions of an optical power meter with the high-speed analog waveform analysis capability of an oscilloscope. You have the capability of acquiring, displaying, and analyzing optical and electrical signals simultaneously. Applications include measuring the transient optical properties of lasers, LEDs, electro-optic modulators, and flashlamps.
Appendix E: Probe Selection E–6 TDS 684A, TDS 744A, & TDS 784A User Manual
Glossary
Glossary AC coupling A type of signal transmission that blocks the DC component of a signal but uses the dynamic (AC) component. Useful for observing an AC signal that is normally riding on a DC signal. Accuracy The closeness of the indicated value to the true value. Acquisition The process of sampling signals from input channels, digitizing the samples into data points, and assembling the data points into a waveform record. The waveform record is stored in memory.
Glossary Attenuation The degree the amplitude of a signal is reduced when it passes through an attenuating device such as a probe or attenuator. That is, the ratio of the input measure to the output measure. For example, a 10X probe will attenuate, or reduce, the input voltage of a signal by a factor of 10. Automatic trigger mode A trigger mode that causes the oscilloscope to automatically acquire if triggerable events are not detected within a specified time period.
Glossary Cycle area A measurement of waveform area taken over one cycle. Expressed in volt-seconds. Area above ground is positive; area below ground is negative. Cycle mean An amplitude (voltage) measurement of the arithmetic mean over one cycle. Cycle RMS The true Root Mean Square voltage over one cycle. DC coupling A mode that passes both AC and DC signal components to the circuit. Available for both the trigger system and the vertical system.
Glossary Fall time A measurement of the time it takes for the trailing edge of a pulse to fall from a HighRef value (typically 90%) to a LowRef value (typically 10%) of its amplitude. Frequency A timing measurement that is the reciprocal of the period. Measured in Hertz (Hz) where 1 Hz = 1 cycle per second. Gated Measurements A feature that lets you limit automated measurements to a specified portion of the waveform. You define the area of interest using the vertical cursors.
Glossary High The value used as 100% in automated measurements (whenever high ref, mid ref, and low ref values are needed as in fall time and rise time measurements). May be calculated using either the min/max or the histogram method. With the min/max method (most useful for general waveforms), it is the maximum value found. With the histogram method (most useful for pulses), it refers to the most common value found above the mid point. See Appendix B: Algorithms for details.
Glossary Knob A rotary control. Logic state trigger The oscilloscope checks for defined combinatorial logic conditions on channels 1, 2, and 3 on a transition of channel 4 that meets the set slope and threshold conditions. If the conditions of channels 1, 2, and 3 are met then the oscilloscope triggers. Logic pattern trigger The oscilloscope triggers depending on the combinatorial logic condition of channels 1, 2, 3, and 4. Allowable conditions are AND, OR, NAND, and NOR.
Glossary Negative overshoot measurement Amplitude (voltage) measurement. NegativeOvershoot + Low * Min Amplitude 100% Negative width A timing measurement of the distance (time) between two amplitude points — falling-edge MidRef (default 50%) and rising-edge MidRef (default 50%) — on a negative pulse. Normal trigger mode A mode on which the oscilloscope does not acquire a waveform record unless a valid trigger event occurs. It waits for a valid trigger event before acquiring waveform data.
Glossary Pixel A visible point on the display. The oscilloscope display is 640 pixels wide by 480 pixels high. Pop-up Menu A sub-menu of a main menu. Pop-up menus temporarily occupy part of the waveform display area and are used to present additional choices associated with the main menu selection. You can cycle through the options in a pop-up menu by repeatedly pressing the main menu button underneath the pop-up.
Glossary fill a waveform record from a single trigger event. Use real-time sampling to capture single-shot or transient events. Record length The specified number of samples in a waveform. Reference memory Memory in a oscilloscope used to store waveforms or settings. You can use that waveform data later for processing. The oscilloscope saves the data even when the oscilloscope is turned off or unplugged.
Glossary Selected waveform The waveform on which all measurements are performed, and which is affected by vertical position and scale adjustments. The light over one of the channel selector buttons indicates the current selected waveform. Side menu Menu that appears to the right of the display. These selections expand on main menu selections. Side menu buttons Bezel buttons to the right of the side menu display. They allow you to select items in the side menu.
Glossary Waveform interval The time interval between record points as displayed. XY format A display format that compares the voltage level of two waveform records point by point. It is useful for studying phase relationships between two waveforms. YT format The conventional oscilloscope display format. It shows the voltage of a waveform record (on the vertical axis) as it varies over time (on the horizontal axis).
Glossary Glossary–12 TDS 684A, TDS 744A, & TDS 784A User Manual
Index
Index Numbers 1/seconds (Hz), Cursor menu, 3–101 20 MHz, Vertical menu, 3–12 250 MHz, Vertical menu, 3–12 A AC coupling, Glossary–1 AC line voltage, trigger input, 3–50 AC, Main Trigger menu, 3–58 Accept Glitch, Main Trigger menu, 3–73 Accessories, A–1–A–6 Optional, A–4–A–6 Probes, A–4 Software, A–5 Standard, A–3, A–5 Accuracy, Glossary–1 Acquire menu, 3–23 Average, 3–23 Average mode, 3–138 Compare Ch1 to, 3–140 Compare Ch2 to, 3–140 Compare Ch3 to, 3–140 Compare Ch4 to, 3–140 Compare Math1 to, 3–140 Compa
Index Average, Incompatible with InstaVu, 3–46 Average acquisition mode, 3–20, 3–48, Glossary–2 Average mode, Acquire menu, 3–138 Average, Acquire menu, 3–23 Average, More menu, 3–144 B Channel selection, 2–16, 3–8 Main menu, 2–3 Side menu, 2–3 C Bandwidth, Glossary–2 Selecting, 3–12 Bandwidth, Vertical menu, 3–12 Base, Cursor menu, 3–101 Blackman-Harris window, 3–148 BMP, 3–121 BMP Color, Hardcopy menu, 3–122 BMP Mono, Hardcopy menu, 3–122 BNC AUX TRIGGER INPUT, 2–5 DELAYED TRIGGER OUTPUT, 2–5 MAIN TR
Index Color Matches Contents, 3–35, 3–36 Hardcopy, 3–34 Hue, 3–34 Lightness, 3–34 Map Math, 3–35 Map Reference, 3–35 Math, 3–35 Monochrome, 3–34 Normal, 3–34 Options, 3–36 Palette, 3–33 Persistence Palette, 3–34 Ref, 3–36 Reset All Mappings To Factory, 3–36 Reset All Palettes To Factory, 3–36 Reset Current Palette To Factory, 3–36 Reset to Factory Color, 3–34 Restore Colors, 3–36 Saturation, 3–35 Spectral, 3–34 Temperature, 3–34 View Palette, 3–34 Color, Color menu, 3–34, 3–35, 3–36 Color, Display menu, 3–
Index with math waveforms, 3–153, 3–169 DC, Main Trigger menu, 3–58 Define Inputs, Main Trigger menu, 3–65, 3–67, 3–69 Define Logic, Main Trigger menu, 3–66, 3–68 Delay by Events, Delayed Trigger menu, 3–84 Delay by Time, Delayed Trigger menu, 3–84 Delay by, Delayed Trigger menu, 3–84 Delay measurement, 3–94, Glossary–3 Delay time, Glossary–3 Delay To, Measure Delay menu, 3–94 Delayed Only, Horizontal menu, 3–83 Delayed Runs After Main, 3–53–3–86 Delayed Runs After Main, Horizontal menu, 3–16, 3–83 Delayed
Index E Edge trigger, 3–50, 3–57, Glossary–3 How to set up, 3–58–3–86 Readout, 3–57 Edge, Main Trigger menu, 3–57, 3–58 Edges, Measure Delay menu, 3–95 Either, Main Trigger menu, 3–73, 3–74, 3–77 empty, Saved waveform status, 3–114 Encapsulated Postscript, 3–121 Enter Char, Labelling menu, 3–118, 3–119 Envelope, Incompatible with InstaVu, 3–46 Envelope acquisition mode, 3–20, 3–48, Glossary–3 Envelope, Acquire menu, 3–23 EPS Color Img, Hardcopy menu, 3–122 EPS Color Plt, Hardcopy menu, 3–122 EPS Mono Img,
Index Goes TRUE, Main Trigger menu, 3–66, 3–68 GPIB, 2–5, 3–129–3–132, Glossary–4 Connecting to, 3–130 Interconnect cabling, 3–130 Interface requirements, 3–129 Procedures for using, 3–130 Protocols, 3–129 Selecting and configuring the port, 3–131 Typical configuration, 3–129 GPIB, Hardcopy menu, 3–123 GPIB, Utility menu, 3–131 Graticule, 3–31, Glossary–4 Measurements, 3–87 Graticule, Display menu, 3–31–3–48 Grid, Display menu, 3–31 Ground coupling, Glossary–4 GROUP 1, GROUP 2 ...
Index Intensified, 3–83, 3–84 Main Scale, 3–15 Record Length, 3–15 Set to 10%, 3–16 Set to 50%, 3–16 Set to 90%, 3–16 Time Base, 3–83 Trigger Position, 3–15 HORIZONTAL MENU button, 3–53, 3–83 Horizontal POSITION knob, 3–14, 3–39 Horizontal Readouts, 3–13 Horizontal SCALE knob, 3–14, 3–39 HPGL, 3–121 HPGL, Hardcopy menu, 3–122 Hue, Color menu, 3–34 I I/O, Status menu, 3–133 I/O, Utility menu, 3–122 Independent, Cursor menu, 3–100 Infinite Persistence, Display menu, 3–28 Installation, 1–4 InstaVu, 3–43–3–48
Index Main Trigger menu, 3–57, 3–58, 3–64, 3–67, 3–68, 3–72, 3–74, 3–77 AC, 3–58 Accept Glitch, 3–73 AND, 3–66, 3–68 Auto, 3–59 Ch1, Ch2 ...
Index Fall time, 3–88 Frequency, 2–19, 3–88, Glossary–4 Gated, Glossary–4 High, 3–88, Glossary–5 Low, 3–89, Glossary–6 Maximum, 3–89, Glossary–6 Mean, 3–89, Glossary–6 Minimum, 3–89, Glossary–6 Negative duty cycle, 3–89 Negative overshoot, 3–89 Negative width, 3–89 Overshoot, Glossary–8 Peak to peak, 3–89, Glossary–7 Period, 3–89, Glossary–7 Phase, 3–89, Glossary–7 Positive duty cycle, 3–89 Positive overshoot, 3–89 Positive width, 3–89 Propagation delay, 3–88 Readout, 3–90 Reference levels, 2–21 Rise time,
Index Negative overshoot, 3–89 Negative width, 3–89 Negative, Main Trigger menu, 3–73, 3–74, 3–77 No Process, More menu, 3–144 Noise reducing in FFTs, 3–154 reducing in phase FFTs, 3–148, 3–157 Noise Rej, Main Trigger menu, 3–58 NOR, Glossary–7 NOR, Main Trigger menu, 3–66, 3–68 Normal trigger mode, 3–51, Glossary–7 Normal, Color menu, 3–34 Normal, Main Trigger menu, 3–59 NTSC, Display menu, 3–31 Nyquist frequency, 3–155 P6205 Active Probe, 1–3 Packaging, C–1 Paired cursor, 3–97 PAL, Display menu, 3–31 Pa
Index Fixtured active, E–3 General purpose (high input resistance), E–1 High speed, E–3 High voltage, E–2 Low impedance Zo, E–2 Optical, E–5 Option 23 to add, A–2 Option 26 to add, A–2 P6205 Active, 1–3 Passive, 3–3 Passive voltage, E–1–E–6 Selection, E–1–E–6 Time-to-voltage converter, E–5 Product description, 1–1 Propagation delay, 3–88 Pulse trigger, 3–50, 3–70 definition of classes, 3–70 Pulse triggers, definitions of, 3–71 Pulse, Main Trigger menu, 3–57, 3–74, 3–76 Q Quantizing, Glossary–8 R Rack mou
Index Runt trigger, 3–71, 3–72, Glossary–9 How to set up, 3–74–3–86 Runt, Main Trigger menu, 3–74, 3–76 S Sample acquisition mode, 3–20, Glossary–9 Sample interval, Glossary–9 Sample Rate, Maximum, 3–19 Sample, Acquire menu, 3–23 Sampling, 3–17, Glossary–9 Sampling and acquisition mode, 3–24 Sampling and digitizing, 3–16 Saturation, Color menu, 3–35 Save, Setups, 3–111–3–132 Save Current Setup, Save/Recall Setup menu, 3–111 Save Format, Save/Recall Waveform menu, 3–115 Save Waveform, Save/Recall Waveform
Index Source, Delayed Trigger menu, 3–85 Source, Main Trigger menu, 3–58, 3–73, 3–74, 3–76, 3–77 Spectral, Color menu, 3–34 Spooler, Hardcopy, 3–126 Start up, 1–3 State trigger, 3–61, 3–67–3–86 How to set up, 3–67–3–86 State, Main Trigger menu, 3–67, 3–68 Status, Determining setup, 3–133 STATUS button, 3–133 Status menu, 3–133–3–136 Display, 3–133 Firmware version, 3–133 I/O, 3–133 System, 3–133 Trigger, 3–133 Waveforms, 3–133 Stop After Limit Test Condition Met, Acquire menu, 3–140 Stop After, Acquire men
Index Type, Main Trigger menu, 3–57, 3–58, 3–76 Pulse, 3–74 U Undershoot, Glossary–7 user, Saved setup status, 3–111 UTILITY button, 3–103, 3–122, 3–131 Utility Menu OK Erase Ref & Panel Memory, 3–113 Tek Secure Erase Memory, 3–113 Utility menu, 3–122 Configure, 3–122, 3–131 GPIB, 3–131 Hardcopy, 3–131 Hardcopy (Talk Only), 3–122 I/O, 3–122 Off Bus, 3–131 Port, 3–131 System, 3–122 Talk/Listen Address, 3–131 V V Limit, Acquire menu, 3–139 Variable Persistence, Display menu, 3–28 Vectors, 3–28 Vectors disp
Index selecting, 3–158 Windowing, process, 3–158 Windows, descriptions of, 3–147–3–148 X XY Format, 3–31 Incompatible with InstaVu, 3–45 XY format, Glossary–11 XY, Display menu, 3–31 Y YT, Format, 3–31 YT format, Glossary–11 YT, Display menu, 3–31 Z Zoom, 3–37–3–48 And interpolation, 3–38 And waveforms, 3–37 derivative math waveforms, 3–165 Dual Window mode, 3–40 Dual Zoom, 3–41 Dual Zoom Offset, 3–41 Horizontal lock, 3–39 Incompatible with InstaVu, 3–45 on FFT math waveforms, 3–154 on integral math wa
Index Index–16 TDS 684A, TDS 744A, & TDS 784A User Manual
