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User and Service Guide

Publication number 54615-97019 June 2000

For Safety Information, Warranties, and Regulatory information, see the pages behind the index. Copyright Agilent Technologies 19931996, 2000 All Rights Reserved

Agilent 54615B, 54616B, and 54616C Oscilloscopes

A General-Purpose Oscilloscope

The Agilent 54615B, 54616B, and 54616C oscilloscopes offer exceptional waveform viewing and measurements in a small, lightweight package. These dual channel, 500 MHz bandwidth oscilloscopes are designed for use in labs where high speed analog and digital circuits are being tested. These oscilloscopes give you:

1 ns peak detect 1 GSa/s sample rate (54615B)
2 GSa/s sample rate (54616B and 54616C)



500 MHz bandwidth, and 1 ns/div Main and Delayed time bases Selectable input impedance Protection of the internal 50 ohm load Adjustable time nulling to remove the effects of cabling 250 MHz single-shot bandwidth (54615B) 500 MHz single-shot bandwidth (54616B and 54616C)

Color display (54616C)
These oscilloscopes are very easy to use because of their familiar controls and real time display. You can discard your viewing hood as these oscilloscopes have none of the viewing problems that are associated with analog oscilloscopes. A bright, crisp display is obtained at all sweep speeds and delayed sweep magnifications. Storage is as simple as pressing a button. View events ahead of the trigger using negative time. Cursors and automatic measurements greatly simplify your analysis tasks. You can upgrade this oscilloscope for hardcopy or remote control with the addition of an interface module. Unattended waveform monitoring and additional waveform math, such as FFT, can be added with the addition of one of the Measurement/Storage modules. Bring your scope and PC together with BenchLink software. BenchLink, which runs under Windows, allows easy transfer of scope traces and waveform data to your PC for incorporation into documents or storage.

ii

Accessories supplied



Two 1.5 meter, 10:1 Rugged 500 MHz Passive Probes (10073B) Power cord for country of destination This User and Service Guide Programmer's Guide with Microsoft Windows Help file, ascii help file, and sample programs.

Accessories available



34810B BenchLink/Scope Software 54650A GPIB Interface Module 54652B Serial/Parallel Interface Module 54654A Operator's Training Kit 54657A GPIB Measurement/Storage Module 54659B Serial/Parallel Measurement/Storage Module 1185A Carrying Case 1186A Rackmount Kit 10020A Resistive Divider (1:1 through 100:1) Passive Probe Kit 10070B 1.5 meter, 1:1 Passive Probe 10076A 100:1 1 MHz High Voltage Passive Divider Probe N2771A 1000:1 1 MHz High Voltage Passive Divider Probe 1141A 1:1 200 MHz Differential Active Probe. Probe power accessed directly from oscilloscope rear panel. from oscilloscope rear panel.

1144A 10:1 800 MHz Active Probe. Probe power accessed directly 1145A 10:1 750 MHz Small-Geometry Dual Active Probe for surface
mount devices. Probe power accessed directly from oscilloscope rear panel.

iii

Options available

Option 001 RS-03 Magnetic Interference Shielding Added to CRT
(54615B and 54616B only)

Option 002 RE-02 Display Shield Added to CRT (54615B and
54616B only)



Option 005 Enhanced TV/Video Trigger Option 101 Accessory Pouch and Front-Panel Cover Option 103 Operator's Training Kit (54654A) Option 104 Carrying Case (1185A) Option 106 BenchLink/Scope Software (34810B) Option 090 Deletes Probes Option 1CM Rackmount Kit Power Cords (see the table of Replaceable Parts in chapter 4, Service)

iv

In This Book 1 2
This is the User and Service Guide for the Agilent 54615B, 54616B, and 54616C Oscilloscopes. This guide contains five chapters. First Time Users Chapter 1 is a quick start guide that gives you a brief overview of the oscilloscope. Advanced users Chapter 2 is a series of exercises that guide you through the operation of the oscilloscope. TV/Video triggering Chapter 3 shows how to use enhanced TV/Video triggering if you have Option 005 installed in your oscilloscope. Service technicians Chapter 4 contains the service information for the oscilloscope. There are procedures for verifying performance, adjusting, troubleshooting, and replacing assemblies in the oscilloscope. Reference information Chapter 5 lists the characteristics of the oscilloscope. The Oscilloscope at a Glance

Operating your Oscilloscope Using Option 005 Enhanced TV/Video Trigger Service

3 4 5

Performance Characteristics

Glossary

Index

v

vi

Contents

1 The Oscilloscope at a Glance
To connect a signal to the oscilloscope 15 To display a signal automatically 17 To set up the vertical window 18 To expand the vertical signal 110 To set up the time base 111 To trigger the oscilloscope 113 To use roll mode 116

Using Color (54616C only) 117
To select the color palettes and observe colors 118 To print in color 120

2 Operating Your Oscilloscope
To use delayed sweep 23 To use storage oscilloscope operation 26 To capture a single event 28 To capture glitches or narrow pulses 210 To trigger on a complex waveform 212 To make frequency measurements automatically 214 To make time measurements automatically 216 To make voltage measurements automatically 219 To make cursor measurements 223 To remove cabling errors from time interval measurements 227 To view asynchronous noise on a signal 228 To reduce the random noise on a signal 230 To save or recall traces 233 To save or recall front-panel setups 234 To reset the instrument setup 235 To use the XY display mode 236 To analyze video waveforms 240

Contents-1

Contents

3 Using Option 005 Enhanced TV/Video Trigger
To select TV display grid 34 To autoscale on a video signal 34 To trigger on a specific line of video 35 To trigger on all TV line sync pulses 37 To trigger on a specific field of the video signal 38 To trigger on all fields of the video signal 39 To trigger on odd or even fields 310 To make cursor measurements 312 To use delayed sweep 314 To analyze video waveforms with Option 005 316 To window in on harmonic distortion using FFT 318 To connect to other instruments 320

4 Service
To return the oscilloscope to Agilent Technologies 44

Verifying Oscilloscope Performance 45
To check the output of the CALIBRATOR 46 To verify voltage measurement accuracy 48 To verify bandwidth 410 To verify horizontal t and 1/t accuracy 413 To verify trigger sensitivity 415 To verify Vertical Output on Option 005 418

Adjusting the Oscilloscope 421
To adjust the power supply 422 To perform the self-calibration 425 To adjust the high-frequency pulse response 427 To adjust the display (54615B/16B only) 429 To adjust the Option 005 offset (R15) 431

Contents-2

Contents

Troubleshooting the Oscilloscope 432
To construct your own dummy load 433 To check out the oscilloscope 434 To clear error messages 437 To check the Low Voltage Power Supply 441 To run the internal self-tests 442 To troubleshoot Option 005 445

Replacing Parts in the Oscilloscope 445
To replace an assembly 446 To remove the fan 447 To remove the front panel 447 To remove the display 449 To remove the system board 449 To remove the attenuator 450 To remove and replace an acquisition hybrid 451 To remove and replace a hybrid connector 453 To remove the power supply 454 To remove the keyboard 455 To remove the handle 456 To remove the Option 005 board 456 To order a replacement part 457

5 Performance Characteristics
Vertical System 52 Horizontal System 54 Trigger System 55 TV Functions 56 XY Operation 56 Display System 56 Acquisition System 57

Contents-3

Contents

Advanced Functions 58 Power Requirements 58 General (54615B and 54616B only) 59 General (54616C only) 511 General (54615B, 54616B, and 54616C) 512 Option 005 General Performance Characteristics 513 Option 005 Trigger System 514

Glossary Index

Contents-4

1

Perform self-calibration first For the oscilloscope to perform most accurately in the ambient temperature where it will be used, the self-calibration procedure described on page 4-25 should first be performed. Allow the unit to operate for at least 30 minutes before performing the self-calibration.

The Oscilloscope at a Glance

The Oscilloscope at a Glance

One of the first things you will want to do with your new oscilloscope is to become acquainted with its front panel. Therefore, we have written the exercises in this chapter to familiarize you with the controls you will use most often. The front panel has knobs, grey keys, and white keys. The knobs are used most often and are similar to the knobs on other oscilloscopes. The grey keys bring up softkey menus on the display that allow you access to many of the oscilloscope features. The white keys are instant action keys and menus are not associated with them. Throughout this book, the front-panel keys are denoted by a box around the name of the key, and softkeys are denoted by a change in the text type. For example, Source is the grey front-panel key labeled Source under the trigger portion of the front panel, and Line is a softkey. The word Line appears at the bottom of the display directly above its corresponding softkey. Figure 1-1 is a diagram of the front panel controls and input connectors. Figure 1-2 is a status line example. The status line, located at the top of of the display, lets you quickly determine the setup of the oscilloscope. In this chapter you will learn to read at a glance the setup of the oscilloscope from the status line. Figure 1-3 is a diagram showing which grey keys to press to bring up the various softkey menus.

12

Figure 11
Storage keys General controls Trigger controls

Channel controls

External trigger control

Channel inputs Horizontal controls

External trigger input

Front Panel Controls

Delayed sweep is on, 200 ns/div Main sweep 500 s/div

Figure 12

Sample rate display (Main/Delayed) Channel 2 is on, 4 V/div Channel 1 is on, ac coupled, inverted, 100 mV/div Display Status Line Indicators

Autostore is on Auto triggered, positive slope, trigger source is channel 1 Peak detect is on

13

Figure 13

Press this key

To obtain this menu

Press this key

To obtain this menu

Softkey Menu Reference

14

The Oscilloscope at a Glance To connect a signal to the oscilloscope

To connect a signal to the oscilloscope
The 54615B is a two-channel, 500 MHz bandwidth, 1 GSa/s sample rate oscilloscope with an external trigger input. The 54616Band 54616C are two-channel, 500 MHz bandwidth, 2 GSa/s sample rate oscilloscopes with an external trigger input. The input impedance of these oscilloscopes is selectable either 50 or 1 M. The 50 mode matches 50 cables commonly used in making high frequency measurements. This impedance matching gives you the most accurate measurements since reflections are minimized along the signal path. The 1 M mode is for use with probes and for general purpose measurements. The higher impedance minimizes the loading effect of the oscilloscope on the circuit under test. In this exercise you connect a signal to the channel 1 input. To avoid damage to your new oscilloscope, make sure that the voltage level of the signal you are using is less than or equal to 250 V (dc plus the peak ac). For a complete list of the characteristics see chapter 5, "Performance Characteristics." CAUTION Do not exceed 5 Vrms in 50 mode. When input protection is enabled in 50 mode, the 50 load will disconnect if greater than 5 Vrms is detected. However the inputs could still be damaged, depending on the time constant of the signal.

CAUTION

The 50 input protection mode only functions when the oscilloscope is powered on.

Use a cable or a probe to connect a signal to channel 1. The oscilloscope has automatic probe sensing . If you are using the
probes supplied with the oscilloscope, or other probes with probe sensing, then the input impedance and probe attenuation factors will be automatically set up by the oscilloscope when automatic probe sensing is turned on. The default setting is to have automatic probe sensing on. This is indicated by the selection of Auto n under the Probe softkey, where n is 1, 10, 20, or 100. If you are not using automatic probe sensing, then follow these next two steps.

15

The Oscilloscope at a Glance To connect a signal to the oscilloscope

To set the input impedance, press

1 . Select the desired Input impedance of 50 or 1M. To set the probe attenuation factor press 1 . Select the Next Menu softkey. Next toggle the Probe softkey to change the attenuation factor to match the probe you are using.

You should compensate 10:1 probes to match their characteristics to the oscilloscope. A poorly compensated probe can introduce measurement errors. To compensate a probe, follow these steps. 1 Connect the 10:1 probe from channel 1 to the front-panel probe compensation signal on the oscilloscope. 2 Press Autoscale . 3 Use a nonmetallic tool to adjust the trimmer capacitor on the probe for the flattest pulse possible as displayed on the oscilloscope.

Figure 14
Overcompensation causes pulse peaking.

Figure 15
Correct compensation with a flat pulse top.

Figure 16
Undercompensation causes pulse rolloff.

16

The Oscilloscope at a Glance To display a signal automatically

To display a signal automatically
The oscilloscope has an Autoscale feature that automatically sets up the oscilloscope to best display the input signal. Using Autoscale requires signals with a frequency greater than or equal to 50 Hz and a duty cycle greater than 0.5%. When you press Autoscale , the oscilloscope turns on and scales all channels that have signals applied, and selects a time base range based on the trigger source. The trigger source is selected from inputs that have a signal applied. The priority of trigger source assignment is External Trigger, input 1, then input 2. Autoscale will, in both 50 and 1M impedance modes, reset the Coupling to DC, the Bandwidth Limit (BW Lim) to Off, all Verniers to Off, and Signal Inversion (Invert) to Off. Input protection in 50 mode is not affected by Autoscale. 1 Connect a signal to the oscilloscope. 2 Press Autoscale . When you press Autoscale , the oscilloscope changes the front-panel setup to display the signal. However, if you pressed Autoscale unintentionally, you can use the Undo Autoscale feature. To use this feature, perform the following step.

Press

, then press the Undo Autoscale softkey. The oscilloscope returns to the configuration in effect before you pressed Autoscale .
Setup

17

The Oscilloscope at a Glance To set up the vertical window

To set up the vertical window
The following exercise guides you through the vertical keys, knobs, and status line. 1 Center the signal on the display with the Position knob. The Position knob moves the signal vertically, and it is calibrated. Notice that as you turn the Position knob, a voltage value is displayed for a short time indicating how far the ground reference is located from the center of the screen. Also notice that the ground symbol on the right side of the display moves in conjunction with the Position knob.

Measurement hints If the channel is dc coupled, you can quickly measure the dc component of the signal by simply noting its distance from the ground symbol. If the channel is ac coupled, the dc component of the signal is removed allowing you to use greater sensitivity to display the ac component of the signal.

18

The Oscilloscope at a Glance To set up the vertical window

2 Change the vertical setup and notice that each change affects the

status line differently.
You can quickly determine the vertical setup from the status line in the display.

Change the vertical sensitivity with the Volts/Div knob and notice that it
causes the status line to change.

Press

1

.

A softkey menu appears on the display, and the channel turns on (or remains on if it was already turned on).

Toggle each of the softkeys and notice which keys cause the status line to
change. Channels 1 and 2 have a vernier softkey that allows the Volt/Div knob to change the vertical step size in smaller increments. These smaller increments are calibrated, which results in accurate measurements even with the vernier turned on.

To turn the channel off, either press
left-most softkey. Invert operating hint

1

a second time or press the

When you are triggered on the signal you are inverting, the inversion applies only to the displayed waveform, not to the trigger signal. Therefore, the trigger slope of the displayed waveform is inverted from the trigger slope icon diplayed on the status line.

19

The Oscilloscope at a Glance To expand the vertical signal

To expand the vertical signal
When changing the Volts/Div for analog channels, you can have the signal expand (or compress) about the center screen or about the ground point.

To expand the signal about center screen, press

Print/Utility

.

Then select System Config and Expand Vertical Center. To expand the signal about ground, press Print/Utility . Then select System Config and Expand Vertical Ground.

110

The Oscilloscope at a Glance To set up the time base

To set up the time base
The following exercise guides you through the time base keys, knobs, and status line. 1 Turn the Time/Div knob and notice the change it makes to the status

line.
The Time/Div knob changes the sweep speed from 1 ns to 5 s in a 1-2-5 step sequence, and the value is displayed in the status line. The sample rate is also displayed on the status line. 2 Change the horizontal setup and notice that each change affects the

status line differently.

Press

Main/Delayed

.

A softkey menu appears on the display with six softkey choices.

Toggle each of the softkeys and notice which keys cause the status line to
change.

111

The Oscilloscope at a Glance To set up the time base

Turn the Delay knob and notice that its value is displayed in the status line.
The Delay knob moves the main sweep horizontally, and it pauses at 0.00 s, mimicking a mechanical detent. At the top of the graticule is a solid triangle ( w ) symbol and an open triangle ( ) symbol. The w symbol indicates the trigger point and it moves in conjunction with the Delay knob. The symbol indicates the time reference point. If the time reference softkey is set to left, the is located one graticule in from the left side of the display. If the time reference softkey is set to center, the is located at the center of the display. The delay number tells you how far the reference point is located from the trigger point w. All events displayed left of the trigger point w happened before the trigger occurred, and these events are called pretrigger information or negative time. You will find this feature very useful because you can now see the events that led up to the trigger point. Everything to the right of the trigger point w is called posttrigger information. The amount of delay range (pretrigger and posttrigger information) available is dependent on the sweep speed selected. See "Horizontal System" in chapter 5, for more details.

112

The Oscilloscope at a Glance To trigger the oscilloscope

To trigger the oscilloscope
The following exercise guides you through the trigger keys, knobs, and status line. 1 Turn the trigger Level knob and notice the changes it makes to the

display.
As you turn the Level knob or press a trigger menu key, for a short time two things happen on the display. First, the trigger level is displayed in inverse video. If the trigger is dc coupled, it is displayed as a voltage. If the trigger is ac coupled or if LF reject was selected, it is displayed as a percentage of the trigger range. Second, if the trigger source is turned on, a line is displayed showing the location of the trigger level (as long as ac coupling or low frequency reject are not selected). 2 Change the trigger setup and notice that each change affects the

status line differently.

Press

Source

.

A softkey menu appears on the display showing the trigger source choices.

Toggle each of the softkeys and notice that each key causes the status line
to change.

Press

External Trigger

.

A softkey menu appears on the display showing the external trigger choices.

113

The Oscilloscope at a Glance To trigger the oscilloscope

Press

Mode

.

A softkey menu appears on the display with five trigger mode choices.

Toggle the Single and TV softkeys and notice that they affect the status
line differently. (You can only select TV if the trigger source is either channel 1 or 2.) When the oscilloscope is triggering properly, the trigger mode portion of the status line is blank.

What happens if the oscilloscope loses trigger? If Auto Level is the trigger mode, Auto flashes in the status line. If dc coupled, the oscilloscope resets the trigger level to the center of the signal. If ac coupled, the oscilloscope resets the trigger level to halfway between the minimum and maximum amplitudes as displayed on the screen. In addition, every time you press the Auto Level softkey, the oscilloscope resets the trigger level. If Auto is the trigger mode, Auto flashes in the status line and the oscilloscope free runs. If either Normal or TV is the trigger mode, the trigger setup flashes in the status line.

114

The Oscilloscope at a Glance To trigger the oscilloscope

Press

Slope/Coupling

.

A softkey menu appears on the display. If you selected Auto level, Auto, Normal, or Single as a trigger mode, six softkey choices are displayed. If you selected TV as a trigger source, five other softkey choices are available.

Toggle each of the softkeys and notice which keys affect the status line. External trigger input coupling (ac or dc) is selected from the External
Trigger menu. 3 Adjust the Holdoff knob and observe how it changes the display. Holdoff keeps the trigger from rearming for an amount of time that you set. Holdoff is often used to stabilize the display of complex waveforms. The Holdoff range is from 300.0 ns to about 13.5 s. When you adjust the Holdoff knob, the current holdoff time is briefly displayed in inverse video near the bottom of the display. For an example of using Holdoff, refer to the section, "To trigger on a complex waveform" on page 2-12. To set a long holdoff time, go to a slower sweep speed. The value used to increment the holdoff depends upon the sweep speed or time/div selection. However, the actual holdoff value is a fixed number; it is not a percentage of sweep speed. For a time/div setting of 5 ns/div, the holdoff increment is 50 ns. For a time/div setting of 5 s/div, the holdoff increment is 100 ms.

115

The Oscilloscope at a Glance To use roll mode

To use roll mode
Roll mode continuously moves data across the display from right to left. Roll mode allows you to see dynamic changes on low frequency signals, such as when you adjust a potentiometer. Two frequently used applications of roll mode are transducer monitoring and power supply testing. 1 Press Mode . Then press the Auto Lvl , Auto, or Normal softkey. 2 Press Main/Delayed . 3 Press the Roll softkey. The oscilloscope is now untriggered and runs continuously. Also notice that the time reference softkey selection changes to center and right. 4 Press Mode . Then press the Single softkey. In Single, the oscilloscope fills either 1/2 of the display if Cntr is selected for the time reference, or 9/10 of the display if Rght is selected for the time reference, then it searches for a trigger. As soon as a trigger is found, the display is filled from the reference point (Cntr or Rght) to the right edge of the display. The oscilloscope then stops acquiring data. You can also make automatic measurements in the roll mode. If time measurements are made while the data is rolling, slight errors are incurred (less than 2%.) The most accurate time measurements are made on rolled data when the acquisition is stopped. Roll mode operating hints Math functions, averaging, and peak detect are not available in roll mode. Holdoff and horizontal delay are not active in roll mode. Both a free running (nontriggered) display and a triggered display (available in the single mode only) are available in roll mode. Roll mode is available at sweep speeds of 200 ms/div and slower for the 54615B and 54616B. Roll mode is available at sweep speeds of 500 ms/div and slower for the 54616C.

116

Using Color (54616C only)

With the 54616C color oscilloscope, you can select any of the seven available color palettes to assign colors to channels, cursors, stored waveforms, and text. The seven color palettes allow additional customization, which allows you to easily distinguish between channel waveforms. In addition, when making measurements on a channel, wherever the channel number appears on screen, it is highlighted in the selected color. The color palettes are individually named, and you can choose the palette that best suits your needs. You can change from the Default palette to any of the following:

Alternate 1 works well for people who are colorblind. The colors in Alternate 2 are compatible with those used in
545xx-series oscilloscopes.

A Monochrome palette is also available. In each palette, different colors are used for cursors, waveforms, softkeys, and Autostore. The background is always black, unless you select the Inverse palettes, which use a white background. Softkeys and the grid are always in white, except in the Inverse palettes, which set them to black. This section shows you how to:



Alternate 3 sets the cursors to yellow. Inverse 1 works well for hard copies. Inverse 2 works well for overhead transparencies.

Select the color palettes and observe colors Print in color

117

The Oscilloscope at a Glance To select the color palettes and observe colors

To select the color palettes and observe colors
1 Press Display . The name of the selected palette appears under the Palette softkey. 2 Press the Palette softkey. Continue to cycle through the palettes and

observe colors applied to the cursors, waveforms, and softkeys.
Notice that the softkeys are white in all palettes, except the Inverse palettes, where they are black. 3 Press the Grid softkey until Full is displayed. The graticule is always white, except in the Inverse palettes, where it is black. 4 Toggle the Grid softkey until Frame is displayed. 5 Press Cursors . Press Active Cursor t2 then Active Cursor V2. A single color shows all the cursors in the display area. 6 Press Autostore . Turn the Position knob both directions on an

active channel and notice the stored waveform.
The autostored waveforms are displayed in blue when using the Default and Alternate color palettes, cyan in the Inverse color palettes, and white in the MonoChrome palette. 7 Press Autostore

to turn it off. Then press Erase .

118

The Oscilloscope at a Glance To select the color palettes and observe colors

The following table shows the color palettes and the palette colors mapped to the display components. Table 1-1 Color Palettes and Mapping of Colors to Display Components
Palette Default Color green yellow magenta cyan white white white blue black red cyan yellow magenta white white white blue black cyan yellow green magenta white white white blue black Display Component cursors waveform1 waveform2 functions overlapping waveforms softkeys graticule autostore background cursors waveform1 waveform2 functions overlapping waveforms softkeys graticule autostore background cursors waveform1 waveform2 functions overlapping waveforms softkeys graticule autostore background Palette Alternate 3 Color yellow magenta cyan green white white white blue black magenta red blue green black black black cyan white black red blue magenta black black black cyan white Display Component cursors waveform1 waveform2 functions overlapping waveforms softkeys graticule autostore background cursors waveform1 waveform2 functions overlapping waveforms softkeys graticule autostore background cursors waveform1 waveform2 functions overlapping waveforms softkeys graticule autostore background

Alternate 1

Inverse 1

Alternate 2

Inverse 2

In the monochrome palette, all of the display components are in white, except the background, which is black.

119

The Oscilloscope at a Glance To print in color

To print in color
1 Press Print/Utility . The 54616C can print to an HP DeskJet Color printer when using an Interface Module with either an RS-232 interface or parallel interface (there are no color printers with an GPIB interface.) 2 Press the Hardcopy Menu softkey. Then press Format until HP DJColor is

displayed.
This selects the HP DeskJet Color Printer format. 3 If you are using a 54652B or 54659B serial/parallel interface module, toggle the Destination softkey to either RS-232 or Parallel. 4 Press the Previous Menu softkey, then press the Print Screen softkey. The current display will be sent out the parallel port to the HP DeskJet color printer attached to your oscilloscope, and printed in color. See also Refer to the Interface Modules for Agilent 54600-Series Instuments I/O Function Guide for other input/output and printing functions.

120

2

Operating Your Oscilloscope

Operating Your Oscilloscope

By now you are familiar with the VERTICAL, HORIZONTAL, and TRIGGER groups of the front-panel keys. You should also know how to determine the setup of the oscilloscope by looking at the status line. If you are unfamiliar with this information, we recommend you read chapter 1, "The Oscilloscope at a Glance." This chapter takes you through two new groups of front-panel keys: STORAGE, and the group of keys that contains the Measure, Save/Recall, and Display keys. You will also add to your knowledge of the HORIZONTAL keys by using delayed sweep. We recommend you perform all of the following exercises so you become familiar with the powerful measurement capabilities of your oscilloscope.

Perform self-calibration first For the oscilloscope to perform most accurately in the ambient temperature where it will be used, the self-calibration procedure described on page 4-25 should first be performed. Allow the unit to operate for at least 30 minutes before performing the self-calibration.

22

Operating Your Oscilloscope To use delayed sweep

To use delayed sweep
Delayed sweep is a magnified portion of the main sweep. You can use delayed sweep to locate and horizontally expand part of the main sweep for a more detailed (high resolution) analysis of signals. The following steps show you how to use delayed sweep. Notice that the steps are very similar to operating the delayed sweep in analog oscilloscopes. 1 Connect a signal to the oscilloscope and obtain a stable display. 2 Press Main/Delayed . 3 Press the Delayed softkey. The screen divides in half. The top half displays the main sweep, and the bottom half displays an expanded portion of the main sweep. This expanded portion of the main sweep is called the delayed sweep. The top half also has two solid vertical lines called markers. These markers show what portion of the main sweep is expanded in the lower half. The size and position of the delayed sweep are controlled by the Time/Div and Delay knobs. The Time/Div next to the symbol is the delayed sweep sec/div. The delay value is displayed for a short time at the bottom of the display.

To display the delay value of the delayed time base, either
press
Main/Delayed

or turn the Delay knob.

To change the main sweep Time/Div, you must turn off the delayed sweep.
Delayed sweep operating hint When in delayed sweep, the displayed sample rate applies to the main sweep. The delayed sweep sample rate is always equal to or greater than the main sweep sample rate. Main and delayed sweeps are obtained in alternate acquistions. Single sweep in delayed mode acquires on trigger for main and one trigger for delayed.

23

Operating Your Oscilloscope To use delayed sweep

Since both the main and delayed sweeps are displayed, there are half as many vertical divisions so the vertical scaling is doubled. Notice the changes in the status line.

To display the delay time of the delayed sweep, either press
Main/Delayed or turn the delay knob. The delay value is displayed near the bottom of the display. 4 Set the time reference (Time Ref) to either left (Lft) or center (Cntr).

Figure 2-1 shows the time reference set to left. The operation is like the delayed sweep of an analog oscilloscope, where the delay time defines the start of the delayed sweep. Figure 2-1

Delayed sweep markers

Time reference set to left

24

Operating Your Oscilloscope To use delayed sweep

Figure 2-2 shows the time reference set to center. Notice that the markers expand around the area of interest. You can place the markers over the area of interest with the delay knob, then expand the delayed sweep with the time base knob to increase the resolution. Figure 2-2

Delayed sweep markers

Time reference set to center

25

Operating Your Oscilloscope To use storage oscilloscope operation

To use storage oscilloscope operation
There are four front-panel storage keys. They are white instant action keys that change the operating mode of the oscilloscope. The following steps demonstrate how to use these storage keys. 1 Connect a signal to the oscilloscope and obtain a stable display. 2 Press Autostore . Notice that STORE replaces RUN in the status line. For easy viewing, the stored waveform is displayed in half bright and the most recent trace is displayed in full bright. Autostore is useful in a number of applications.



Displaying the worst-case extremes of varying waveforms Capturing and storing a waveform Measuring noise and jitter Capturing events that occur infrequently

26

Operating Your Oscilloscope To use storage oscilloscope operation

3 Using the position knob in the Vertical section of the front panel,

move the trace up and down about one division.
Notice that the last acquired waveform is in full bright and the previously acquired waveforms are displayed in half bright.

To characterize the waveforms, use the cursors. See "To make cursor
measurements" on page 2-23.

To clear the display, press Erase . To exit the Autostore mode, press either
or Autostore .

Run

Summary of storage keys Run The oscilloscope acquires data and displays the most recent trace. Stop The display is frozen. Autostore The oscilloscope acquires data, displaying the most recent trace in full bright and previously acquired waveforms in half bright. Erase Clears the display.

27

Operating Your Oscilloscope To capture a single event

To capture a single event
To capture a single event, you need some knowledge of the signal in order to set up the trigger level and slope. For example, if the event is derived from TTL logic, a trigger level of 2 volts should work on a rising edge. The following steps show you how to use the oscilloscope to capture a single event. 1 Connect a signal to the oscilloscope. 2 Set up the trigger.

Press Press

Source

. Select a trigger source with the softkeys. . Select a trigger slope with the softkeys.

Slope/Coupling

Turn the Level knob to a point where you think the trigger should work.
3 Press Mode , then press the Single softkey. 4 Press Erase 5 Press Run . Pressing the Run key arms the trigger circuit. When the trigger conditions are met, data appears on the display representing the data points that the oscilloscope obtained with one acquisition. Pressing the Run key again rearms the trigger circuit and erases the display.

to clear previous measurements from the display.

28

Operating Your Oscilloscope To capture a single event

6 If you need to compare several single-shot events, press Autostore . Like the Run key, the Autostore key also arms the trigger circuit. When the trigger conditions are met, the oscilloscope triggers. Pressing the Autostore key again rearms the trigger circuit without erasing the display. All the data points are retained on the display in half bright with each trigger allowing you to easily compare a series of single-shot events. After you have acquired a single-shot event, pressing a front-panel key, softkey, or changing a knob can erase the event from the display. If you press the Stop key, the oscilloscope will recover the event and restore the oscilloscope settings.

To clear the display, press Erase . To exit the Autostore mode, press either

Run

or Autostore . Notice that RUN replaces STORE in the status line, indicating that the oscilloscope has exited the Autostore mode.

Operating hint With display vectors on, the maximum single-shot bandwidth is: 54615B 250 MHz for single- and two-channel operation (1 GSa/s, normal display, display vectors on.) 54616B/16C 500 MHz for single- and two-channel operation (2 GSa/s, normal display, display vectors on.) With display vectors off, the oscilloscopes display the actual captured samples.

29

Operating Your Oscilloscope To capture glitches or narrow pulses

To capture glitches or narrow pulses
A glitch is a rapid change in the waveform that is usually narrow as compared to the waveform. This oscilloscope has two modes of operation that you can use for glitch capture: peak detect and Autostore. 1 Connect a signal to the oscilloscope and obtain a stable display. 2 Find the glitch. Use peak detect for narrow pulses or glitches.

To select peak detect, press
softkey.

Display

. Next, press the Peak Det

Peak detect operates at sweep speeds from 5 s/div to 500 ns/div. When operating, Pk is displayed in the status line in inverse video. At sweep speeds faster than 500 ns/div, Pk is displayed in normal video, which indicates that peak detect is not operating. However, the acquisition system is sampling at 1 GSa/s so glitches greater than 1 ns will not be missed. Peak detect operating hint In peak detect, the A/D converters are sampling at 1 GSa/s. However, not all samples are written to the display. Only the min and the max samples in each of the waveform graticules's 500 pixel columns are written to the display.

210

Operating Your Oscilloscope To capture glitches or narrow pulses

Autostore operating hints Use Autostore for the following cases: Waveforms that are changing. Waveforms that you want to view and compare with stored waveforms. Narrow pulses or glitches that occur infrequently.

Press

Autostore

.

You can use peak detect and Autostore together. Peak detect captures the glitch, while Autostore retains the glitch on the display in half bright video. 3 Characterize the glitch with delayed sweep. Peak detect functions in both the main sweep and the delayed sweep. To characterize the glitch with delayed sweep follow these steps.

Press

Main/Delayed

. Next press the Delayed softkey.

To obtain a better resolution of the glitch, expand the time base. To set the expanded portion of the main sweep over the glitch, use the
Delay knob.

To characterize the glitch, use the cursors or the automatic measurement
capabilities of the oscilloscope.

211

Operating Your Oscilloscope To trigger on a complex waveform

To trigger on a complex waveform
The difficulty in viewing a complex waveform is triggering on the signal. Figure 2-3 shows a complex waveform that is not synchronized with the trigger. The simplest trigger method is to trigger the oscilloscope on a sync pulse that is associated with the waveform. See "To trigger the oscilloscope" on page 1-13. If there is no sync pulse, use the following procedure to trigger on a periodic complex waveform. 1 Connect a signal to the oscilloscope. 2 Set the trigger level to the middle of the waveform. 3 Adjust the Holdoff knob to synchronize the trigger of the

oscilloscope with the complex waveform.
By setting the Holdoff to synchronize the trigger, the oscilloscope ignores the trigger that results in figure 2-3, and waits for the trigger that results in figure 2-4. Also notice in figure 2-3 that the trigger is stable, but the waveform is not synchronized with the trigger.

Holdoff operating hints 1 The advantage of digital holdoff is that it is a fixed number. As a result, changing the time base settings does not affect the holdoff number; so, the oscilloscope remains triggered. In contrast, the holdoff in analog oscilloscopes is a function of the time base setting making it necessary to readjust the holdoff each time you change the time base setting. 2 The rate of change of the holdoff adjustment knob depends on the time base setting you have selected. If you need a lengthy holdoff setting, increase the time/div setting on the time base, then make your coarse holdoff adjustment. Now switch back to the original time/div setting and make the fine adjustment to reach the exact amount you want.

212

Operating Your Oscilloscope To trigger on a complex waveform

Figure 2-3

Stable trigger, but the waveform is not synchronized with the trigger

Figure 2-4

Holdoff synchronizes the waveform with the trigger

In Figure 2-4, the holdoff is set to about 25 s (the duration of the pattern.)

213

Operating Your Oscilloscope To make frequency measurements automatically

To make frequency measurements automatically
The automatic measurement capability of the oscilloscope makes frequency measurements easy, as the following steps demonstrate. 1 Connect a signal to the oscilloscope and obtain a stable display. 2 Press Time . A softkey menu appears with six softkey choices. 3 Toggle the Source softkey to select a channel for the frequency

measurement. 4 Press the Freq softkey.
The oscilloscope automatically measures the frequency and displays the result on the lower line of the display. The number in parentheses after the word Freq is the number of the channel that the oscilloscope used for the measurement. The oscilloscope retains in memory and displays the three most current selected measurements. If you make a fourth measurement, the left-most is dropped.

214

Operating Your Oscilloscope To make frequency measurements automatically

If the Show Meas softkey is turned on, cursors are displayed on the waveform that show the measurement points for the right-most measurement result. If you select more than one measurement, you can show a previous measurement by reselecting the measurement.

To find the Show Meas softkey, press the Next Menu softkey.
The oscilloscope makes automatic measurements on the first displayed event. Figure 2-5 shows how to use delayed sweep to isolate an event for a frequency measurement. If the measurement is not possible in the delayed time base horizontal mode, then the main time base is used. If the waveform is clipped, it may not be possible to make the measurement. Figure 2-5

Delayed time base isolates an event for a frequency measurement

215

Operating Your Oscilloscope To make time measurements automatically

To make time measurements automatically
You can measure the following time parameters with the oscilloscope: frequency, period, duty cycle, width, rise time, and fall time. The following exercise guides you through the Time keys by making a rise time measurement. Figure 2-6 shows a pulse with some of the time measurement points. 1 Connect a signal to the oscilloscope and obtain a stable display. When the signal has a well-defined top and bottom (see figure 2-8), the rise time and fall time measurements are made at the 10% and 90% levels. If the oscilloscope cannot find a well-defined top or bottom (see figure 2-9), the maximum and minimum levels are used to calculate the 10% and 90% points. Figure 2-6

216

Operating Your Oscilloscope To make time measurements automatically

2 Press Time . A softkey menu appears with six softkey choices. Three of the softkeys are time measurement functions. Source Selects a channel for the time measurement. Time Measurements Three time measurement choices are available: Freq (frequency), Period, and Duty Cy (duty cycle). These measurements are made at the 50% levels. Refer to figure 2-6. Clear Meas (clear measurement) Erases the measurement results and removes the cursors from the display. Next Menu Replaces the softkey menu with six additional softkey choices. 3 Press the Next Menu softkey. Another time measurement softkey menu appears with six additional choices. Four of the softkeys are time measurement functions. Show Meas (show measurement) Displays the horizontal and vertical cursors where the measurement was taken. Time measurement hint When making time measurements in roll mode, the most accurate results will be seen when the waveform is stopped.

217

Operating Your Oscilloscope To make time measurements automatically

Time Measurements Four additional time measurement choices are available; +Width, -Width, Rise Time, and Fall Time. Width measurements are made at the 50% levels, whereas rise time and fall time measurements are made at the 10% to 90% levels. Previous Menu Returns to the previous softkey menu. 4 Press the Rise Time softkey. The oscilloscope automatically measures the rise time of the signal and displays the result on the display. The oscilloscope makes automatic measurements on the first displayed event. Figure 2-7 shows how to use delayed sweep to isolate an edge for a rise time measurement. Figure 2-7

Delayed sweep isolates a leading edge for a rise time measurement

218

Operating Your Oscilloscope To make voltage measurements automatically

To make voltage measurements automatically
You can measure the following voltage parameters automatically with the oscilloscope: peak-to-peak, average, rms, maximum, minimum, top, and base. The following exercise guides you through the Voltage keys by making an rms voltage measurement. Figures 2-8 and 2-9 show pulses with some of the voltage measurement points. Figure 2-8

Pulse where the top and bottom are well-defined

Figure 2-9

Pulse where the top and bottom are not well-defined

219

Operating Your Oscilloscope To make voltage measurements automatically

1 Connect a signal to the oscilloscope and obtain a stable display. 2 Press Voltage . A softkey menu appears with six softkey choices. Three of the softkeys are voltage measurement functions. Source Selects a channel for the voltage measurement. Voltage Measurements Three voltage measurement choices are available: Vp-p, Vavg, and Vrms The measurements are determined by voltage histograms of the signal. Clear Meas (clear measurement) Erases any measurement results from the display, and removes the horizontal and vertical cursors from the display. Next Menu Replaces the softkey menu with six additional softkey choices.

220

Operating Your Oscilloscope To make voltage measurements automatically

3 Press the Vrms softkey. The oscilloscope automatically measures the rms voltage and displays the result on the display. The oscilloscope makes automatic measurements on the first pulse or period in the display. If a cycle of the waveform cannot be found as shown in the delayed window in figure 2-10, the measurement is made using the delayed window as the cycle. Figure 2-10 shows how to use delayed sweep to isolate a pulse for an rms measurement. Figure 2-10

Delayed sweep isolates an area of interest for an rms voltage measurement

221

Operating Your Oscilloscope To make voltage measurements automatically

4 Press the Next Menu softkey. Another voltage measurement softkey menu appears with six additional choices. Four of the softkeys are voltage measurement functions. Show Meas (show measurement) Displays the horizontal and vertical cursors that show where the measurement was taken on the signal. Voltage Measurements Four additional voltage measurement choices are available: Vmax, Vmin, Vtop, Vbase. Previous Menu Returns to the previous softkey menu.

222

Operating Your Oscilloscope To make cursor measurements

To make cursor measurements
The following steps guide you through the front-panel Cursors key. You can use the cursors to make custom voltage or time measurements on the signal. Examples of custom measurements include rise time measurements from reference levels other than 10-90%, frequency and width measurements from levels other than 50%, channel-to-channel delay measurements, and voltage measurements. See figures 2-11 through 2-16 for examples of custom measurements. 1 Connect a signal to the oscilloscope and obtain a stable display. 2 Press Cursors . A softkey menu appears with six softkey choices. Four of the softkeys are cursor functions. Source Selects a channel for the voltage cursor measurements. Active Cursor There are four cursor choices: V1, and V2 are voltage cursors, while t1, and t2 are time cursors. Use the knob below the Cursors key to move the cursors. When you press the V1 and V2 softkeys simultaneously, both voltage cursors are selected and the voltage cursors move together. When you press the t1 and t2 softkeys simultaneously, both time cursors are selected and the time cursors move together. Clear Cursors Erases the cursor readings and removes the cursors from the display. Toggling the Cursor key to select active cursor If you toggle the front-panel Cursor key, the active cursor will be toggled. For example, if V1 is selected, pressing the Cursor key will select V2. Pressing the cursor key again will select V1.

223

Operating Your Oscilloscope To make cursor measurements

Figure 2-11

Cursors used to measure pulse width at levels other then the 50% points

Figure 2-12

Cursors used to measure the frequency of the ringing on a pulse

224

Operating Your Oscilloscope To make cursor measurements

Figure 2-13

Cursors used to make channel-to-channel delay measurements

Figure 2-14

The cursors track delayed sweep. Expand the display with delayed sweep, then characterize the event of interest with the cursors.

225

Operating Your Oscilloscope To make cursor measurements

Figure 2-15

Pressing t1 and t2 softkeys simultaneously causes the time cursors to move together when the cursor knob is adjusted.

Figure 2-16

By moving the time cursors together, you can check for pulse width variations in a pulse train, as figures 2-15 and 2-16 show.

226

Operating Your Oscilloscope To remove cabling errors from time interval measurements

To remove cabling errors from time interval measurements
When measuring time intervals in the nanosecond range, small differences in cable length can totally obscure the measurement. The following exercise shows how to remove errors that different cable lengths or characteristics introduce to your measurement. The Skew control makes it possible to remove this offset error from your measurement. This process is also referred to as deskewing. 1 Select Time Reference to Center, with the Graticule turned on. 2 Connect the channels to be nulled to a common test point and obtain

a stable display. A fast edge is a good choice.
3 Press Print/Utility , then select the Service Menu softkey, then the Self Cal Menu softkey. This gives you access to the calibration

and skew adjustments. 4 Select Skew 1 > 2 to adjust channel 2 with respect to channel 1. Rotate the knob to bring the channels into time alignment. This nullifies the cable delay.
This adjustment is not affected by pressing Autoscale. If the default setup is selected or default calibration factors are loaded, the skew value will return to zero seconds.

227

Operating Your Oscilloscope To view asynchronous noise on a signal

To view asynchronous noise on a signal
The following exercise shows how to use the oscilloscope to view asynchronous noise on a signal that is not synchronous to the period of the waveform. 1 Connect a noisy signal to the oscilloscope and obtain a stable display. Figure 2-17 shows a waveform with asynchronous noise at the top of the pulse.

Figure 2-17

Asynchronous noise at the top of the pulse

228

Operating Your Oscilloscope To view asynchronous noise on a signal

2 Press Autostore . Notice that STORE is displayed in the status line. 3 Set the Trigger Mode to Normal, then adjust the trigger level into the noise region of the signal. 4 Decrease the sweep speed for better resolution of the asynchronous

noise.

To characterize the asynchronous noise signal, use the cursors.
Figure 2-18

This is a triggered view of the asynchronous noise shown in figure 2-17.

229

Operating Your Oscilloscope To reduce the random noise on a signal

To reduce the random noise on a signal
If the signal you are applying to the oscilloscope is noisy (figure 2-21), you can set up the oscilloscope to reduce the noise on the waveform (figure 2-22). First, you stabilize the displayed waveform by removing the noise from the trigger path. Second, you reduce the noise on the displayed waveform. 1 Connect a noisy signal to the oscilloscope and press
Autoscale

.

2 Obtain a stable display by removing the noise from trigger path; press Slope/Coupling , then select either the LF Reject softkey or the HF Reject softkey. High frequency reject (HF Reject) adds a low pass filter with the 3 dB point at 50 kHz (see figure 2-19). You use HF reject to remove high frequency noise such as AM or FM broadcast stations from the trigger path. Figure 2-19
0 dB 3 dB down point Pass Band 50 kHz HF reject (trigger path)

dc

230

Operating Your Oscilloscope To reduce the random noise on a signal

Low frequency reject (LF Reject) adds a high pass filter with the 3-dB point at 50 kHz (see figure 2-20). Use LF reject to remove low frequency signals such as power line noise from the trigger path. Figure 2-20
0 dB 3 dB down point Pass Band dc

50 kHz LF reject (trigger path)

Noise reject increases the trigger hysteresis band. By increasing the trigger hysteresis band you reduce the possibility of triggering on noise. However, this also decreases the trigger sensitivity so that a slightly larger signal is required to trigger the oscilloscope. Figure 2-21

Random noise on the displayed waveform

231

Operating Your Oscilloscope To reduce the random noise on a signal

3 Use averaging to reduce noise on the displayed waveform. To use averaging follow these steps.

Press

Display

, the press the Average softkey.

Notice that Av appears in the status line.

Toggle the # Average softkey to select the number of averages that best
eliminates the noise from the displayed waveform. The Av letters in the status line indicate how much of the averaging process is finished by turning to inverse video as the oscilloscope performs averaging. The higher the number of averages, the more noise that is removed from the display. However, the higher the number of averages, the slower the displayed waveform responds to waveform changes. You need to choose between how quickly the waveform responds to changes and how much noise there is on the signal. Figure 2-22

On this waveform, 256 averages were used to reduce the noise

232

Operating Your Oscilloscope To save or recall traces

To save or recall traces
The oscilloscope has two pixel memories for storing waveforms. The following exercise guides you through how to store and recall waveforms from pixel memories. 1 Connect a signal to the oscilloscope and obtain a stable display. 2 Press
Trace

.

A softkey menu appears with five softkey selections. Four of the softkeys are trace memory functions. Trace Selects memory 1 or memory 2. Trace Mem Turns on or off the selected memory. Save to Saves the waveform to the selected memory. The front-panel setup is saved to a separate memory location. Clear Erases the selected memory. Recall Setup Recalls the front-panel setup that was saved with the waveform. 3 Toggle the Trace softkey to select memory 1 or memory 2. 4 Press the Save to softkey. The current display is copied to the selected memory. 5 Turn on the Trace Mem softkey to view the stored waveform. The trace is copied from the selected trace memory and is displayed in half bright video.

233

Operating Your Oscilloscope To save or recall front-panel setups

The automatic measurement functions do not operate on stored traces. Remember, the stored waveforms are pictorial information rather than stored data.

If you have not changed the oscilloscope setup, use the cursors to make
the measurements.

If you have changed the oscilloscope setup, press the Recall Setup softkey.
Then,use the cursors to make the measurements.

Trace memory operating hint The standard oscilloscope has volatile trace memories. When you add an interface module to the oscilloscope, the trace memories become nonvolatile.

To save or recall front-panel setups
There are 16 memories for storing front-panel setups. Saving front-panel setups can save you time in situations where several setups are repeated many times. 1 Press Setup . 2 To change the selected memory location, press either the left-most

softkey or turn the knob closest to the Cursors key. 3 Press the Save softkey to save a front-panel setup, then press the Recall
softkey to recall a front-panel setup.

234

Operating Your Oscilloscope To reset the instrument setup

To reset the instrument setup
1 To reset the instrument to the default factory-preset configuration, press Setup . 2 Press the Default Setup softkey. 3 To reset the instrument to the configuration that was present before pressing Autoscale, press the Undo Autoscale softkey. Table 2-1 Default Setup configuration settings
Configuration Item Cursors Trace memories Setup memories Graticule Autostore Time base Display Channels Trigger Mode Trigger Condition Setting Cursors off; time readout is selected; all cursors are set to time/voltage zero. Both trace memory 1 and 2 are off; trace 1 memory is selected. Setup memories are off; setup memory 1 is selected. Grid set to Full Off Time reference center; main, not delayed sweep; main and delay value 0; 100 s/div main time base; sample rate is 5 MSa/s. Vectors On, Display Mode Normal. Channel 1 on, Position 0 V, Volts/Div 100 mV. Auto Level, Coupling DC, Reject Off, Noise Reject Off. Rising edge of channel 1

See Also

"To Clear Error Messages" in the troubleshooting section of Service chapter 4.

235

Operating Your Oscilloscope To use the XY display mode

To use the XY display mode
The XY display mode converts the oscilloscope from a volts versus time display to a volts versus volts display. You can use various transducers so the display could show strain versus displacement, flow versus pressure, volts versus current, or voltage versus frequency. This exercise shows a common use of the XY display mode by measuring the phase shift between two signals of the same frequency with the Lissajous method. 1 Connect a signal to channel 1, and a signal of the same frequency but

out of phase to channel 2. 2 Press Autoscale , press Main/Delayed , then press the XY softkey. 3 Center the signal on the display with the Position knobs, and use the Volts/Div knobs and the vertical Vernier softkeys to expand the signal for convenient viewing.
sin = A C or , where = phase shift (in degrees) between the two signals. B D

Figure 2-23

236

Operating Your Oscilloscope To use the XY display mode

XY display mode operating hint Before entering xy display mode, center both channels on screen in the main sweep and adjust sweep speed to obtain greater than or equal to 1 cycle of the lowest frequency input signal on screen. When you select the XY display mode, the time base is turned off. Channel 1 is the X-axis input, channel 2 is the Y-axis input. 4 Press Cursors . 5 Set the Y2 cursor to the top of the signal, and set Y1 to the bottom of

the signal.
Note the Y value at the bottom of the display. In this example we are using the Y cursors, but you could have used the X cursors instead. If you use the X cursors, make sure you center the signal in the Y axis. Figure 2-24

237

Operating Your Oscilloscope To use the XY display mode

6 Move the Y1 and Y2 cursors to the center of the signal. Again, note the Y value. Figure 2-25

7 Calculate the phase difference using formula below. sin = second Y 143.8 = 300.0 first Y

= 28.64 degrees of phase shift

238

Operating Your Oscilloscope To use the XY display mode

Figure 2-26

Signals are 90 out of phase

Figure 2-27

Signals are in phase

239

Operating Your Oscilloscope To analyze video waveforms

To analyze video waveforms
Enhanced TV/Video Trigger This section discusses basic TV video triggering. If you have Option 005 Enhanced TV/Video Trigger installed in your oscilloscope, refer to Chapter 3 "Using Option 005 Enhanced TV/Video Trigger." The TV sync separator in the oscilloscope has an internal clamp circuit. This removes the need for external clamping when you are viewing unclamped video signals. TV triggering requires two vertical divisions of display, either channel 1 or channel 2 as the trigger source, and the selection of internal trigger. Turning the trigger level knob in TV trigger does not change the trigger level because the trigger level is automatically set to the sync pulse tips. For this exercise connect the oscilloscope to the video output terminals on a television. Then set up the oscilloscope to trigger on the start of Field 2. Use the delayed sweep to window in on the vertical interval test signals (VITS), which are in Line 18 for most video standards (NTSC, PAL, SECAM). 1 Connect a TV signal to channel 1, then press Autoscale . 2 Press Display , then press the Peak Det softkey. 3 Press Mode , then press the TV softkey. 4 Press Slope/Coupling , then press the Field 2 softkey. Polarity Selects either positive or negative sync pulses. Field 1 Triggers on the field 1 portion of the video signal. Field 2 Triggers on the field 2 portion of the video signal. Line Triggers on all the TV line sync pulses. HF Rej Controls a 500 kHz low pass filter in the trigger path.

240

Operating Your Oscilloscope To analyze video waveforms

5 Set the time base to 200 s/div, then center the signal on the display

with the delay knob (delay about 800 s).

6 Press Main/Delayed , then press the Delayed softkey. 7 Set the delayed sweep to 20 s/div, then set the expanded portion

over the VITS (delay about 920 s, dependent on broadcast channel).

Figure 2-28

Frame 2 windowed on the VITS in Line 18

241

Operating Your Oscilloscope To analyze video waveforms

Delay in TV line units hint The oscilloscope has the ability to display delay in TV-line units. Using the TV field trigger mode activates this line-counting feature. When Field 1 or Field 2 is selected as the trigger source, delay can be set in terms of time or line number. Both-fields triggering in the oscilloscope hint The oscilloscope can trigger on the vertical sync pulse in both TV fields at the same time. This allows you to view noninterlaced video signals which are common in computer monitors. To trigger on both sync pulses, press Field 1 and Field 2 at the same time. TV trigger operating hints The color burst changes phase between odd (Fields 1 and 3) and even (Fields 2 and 4). It looks double-triggered. Increase the holdoff to greater than the frame width to fine tune your trigger stability. For example, use a holdoff value of around 63 ms for NTSC, and around 76 ms for PAL. When looking at live video (usually a field), use peak detect to improve the appearance of the display. When making cursor measurements, use Autostore since you are usually looking for pulse flatness and extremes. When using line trigger, use minimum holdoff to display all the lines. Due to the relationship between the horizontal and vertical sync frequencies the display looks like it is untriggered, but it is very useful for TV waveform analysis and adjustment because all of the lines are displayed.

242

3

Using Option 005 Enhanced TV/Video Trigger

Using Option 005 Enhanced TV/Video Trigger

Basic TV/video triggering This section discusses Enhanced TV/Video triggering. If you do not have Option 005 installed in your oscilloscope, refer to the last section in Chapter 2 "To analyze video waveforms" for basic TV triggering procedures.

You can use the Option 005 Enhanced TV/Video trigger with your oscilloscope. One of the first things you will want to do with your oscilloscope's new Option 005 Enhanced TV/Video trigger is to become acquainted with its menu choices. Therefore, we have written the exercises in this chapter to familiarize you with its basic controls. To use the TV/Video trigger, you must be familiar with your oscilloscope. In summary, the front panel of the oscilloscope has knobs, grey keys, and white keys. The knobs are used most often and are similar to the knobs on other oscilloscopes. The grey keys bring up softkey menus on the display that allow you access to many of the oscilloscope features. The white keys are instant action keys and menus are not associated with them. The status line of the oscilloscope, located at the top of of the display, lets you quickly determine the setup of the oscilloscope. When Option 005 is installed in your oscilloscope, the Display menu has the extra Grid (graticule) choice of TV.
Use NTSC Instead of PAL-M To trigger on a PAL-M signal, use NTSC. The line and field rates are identical.

32

Using Option 005 Enhanced TV/Video Trigger

Option 005 gives you an Enhanced TV/Video Trigger for the oscilloscope, allowing highly detailed analysis of TV waveforms. This option offers:



NTSC, PAL, PAL-M, SECAM and generic video formats Video autoscale