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User's Guide

Publication Number 54622-97002 March 2000

For Safety Information, Warranties, and Regulatory information, see the pages behind the Index.

©

Copyright Agilent Technologies 2000 All Rights Reserved

Agilent 54621A/22A/24A Oscilloscopes and Agilent 54621D/22D Mixed-Signal Oscilloscopes

The Oscilloscopes at a Glance

Display shows current input signals · All analog and digital (54621D/22D) channels displayed in main and delayed mode · Indicators for channel, time base, digital (54621D/22D) channel activity, trigger and acquisition status · Softkey labels · Measurement results Digital channel controls select, position, and label inputs (54621D/22D) · Turn channels on or off individually or in groups of 8 · Rearrange order of channels to group related signals · Create and display labels to identify channels General controls measure, save and restore results, and configure the oscilloscope · Waveform math including FFT, subtract, multiply, integrate, and differentiate · Use Quick meas to make automatic measurements · Use cursors to make manual measurements · Save or recall measurement configurations or previous results · Autoscale performs simple onebutton setup of the oscilloscope Horizontal Controls select sweep speed and delay parameters · Sweep speeds from 5 ns to 50 s/div · Delay control moves waveform display to point of interest · Delayed mode and delay allow zooming in to show a portion of waveform in detail (split screen)

Run control keys begin and end data acquisition · Run/Stop starts and stops continuous acquisitions · Single performs one acquisition · Infinite persistence accumulates and displays the results of multiple acquisitions Trigger keys define what data the oscilloscope will trigger on · Source key allows conventional oscilloscope triggering · Modes include Edge, Pulse Width, Pattern, TV, Sequence, I2C, and Duration triggering. Softkeys extend the functionality of command keys Select measurement types, operating modes, trigger specifications, label data, and more Channel inputs through a flexible probing system (54621D/22D) · Sixteen channels through a dual 8channel cable with micro-clips · Set logic levels as TTL, CMOS, ECL, or to a user-definable voltage Utilities · Dedicated parallel printer port, controller operation, floppy disk storage Built in Quick Help system · Press and hold any key front-panel key or softkey to get help in 9 languages.

ii

In This Book

This manual will guide you in using the oscilloscopes. This manual is organized in the following chapters: Chapter 1 Getting Started--inspecting, cleaning, and setting up your oscilloscope, using Quick Help. Chapter 2 Front-panel Overview--A quick start guide to get you familiarize you with the front-panel operation. Chapter 3 Triggering the Oscilloscope--how to trigger the oscilloscope using all the various modes. Chapter 4 MegaZoom Concepts and Oscilloscope Operation--acquiring waveforms, horizontal and vertical operation, using digital channels. Chapter 5 Making Measurements--capturing data, using math function, making measurement with cursors and automatic measurements. Chapter 6 Utilities--configuring the I/O, print settings, Quick Help, floppy disk operations, user cal and self cal, setting the clock and screen saver. Chapter 7 Performance Characteristics

iii

iv

Contents

1 Getting Started Setting up the Oscilloscope 1-4

To inspect package contents 1-5 To inspect options and accessories 1-7 To clean the oscilloscope 1-10 To adjust the handle 1-11 To power-on the oscilloscope 1-12 To adjust the display intensity 1-13 To connect the oscilloscope probes 1-14 To use the digital probes (mixed-signal oscilloscope only) To connect a printer 1-19 To connect an RS-232 cable 1-19 To verify basic oscilloscope operation 1-20

1-15

Getting started using the oscilloscope interface Using Quick Help 1-23

1-21

Selecting a language for Quick Help when the oscilloscope starts up 1-23 Selecting a language for Quick Help after you have been operating the oscilloscope 1-24 Loading a language from floppy disk 1-25

2 Front-Panel Overview
Important Oscilloscope Considerations 2-3 54600-series Oscilloscope1 Front Panels 2-7

Front-Panel Operation

2-10

Interpreting the display 2-11 To use analog channels to view a signal 2-12 To use digital channels to view a signal 2-13 To display signals automatically using Autoscale 2-14 To apply the default factory configuration 2-15 To adjust analog channel vertical scaling and position 2-16 To set the vertical expand reference for the analog signal 2-17

Contents-1

Contents

To set analog channel probe attenuation factor 2-17 To display and rearrange the digital channels 2-18 To operate the time base controls 2-19 To start and stop an acquisition 2-20 To make a single acquisition 2-20 To use delayed sweep 2-21 To make cursor measurements 2-22 To make automatic measurements 2-23 To modify the display grid 2-24 To print the display 2-24

3 Triggering the Oscilloscope Selecting Trigger Modes and Conditions 3-3
3-4

To select the Mode and Coupling menu 3-3 To select a trigger mode: Auto Level, Auto, Normal To select trigger Coupling 3-6 To select Noise Reject and HF Reject 3-6 To set holdoff 3-7

Trigger Types

3-9

To use edge triggering 3-10 To use pulse width triggering 3-12 To use pattern triggering 3-15 To use duration triggering 3-17 To use I2C triggering 3-20 To use sequence triggering 3-23 To use TV triggering 3-29

The Trig Out connector

3-39

Contents-2

Contents

4 MegaZoom Concepts and Oscilloscope Operation MegaZoom Concepts 4-3

Deep Memory 4-4 Oscilloscope Responsiveness 4-5 Display Update Rate 4-6 To setup the Analog channels 4-7 To setup the Horizontal time base 4-10 Acquisition Modes 4-16 Display modes 4-20 Pan and Zoom 4-22 To pan and zoom a waveform 4-23

Run/Stop/Single/Infinite Persistence Operation

4-24

Acquiring Data 4-25 Memory Depth/Record Length 4-26 To run and stop an acquisition 4-27 To take a single trace 4-27 To capture a single event 4-28 To use infinite persistence 4-29 To use infinite persistence to store multiple repetitive events To clear the waveform display 4-30

4-29

Configuring the Mixed-Signal Oscilloscope

4-31

To display digital channels using Autoscale 4-31 Interpreting the digital waveform display 4-32 To display and rearrange the digital channels 4-33 To turn individual channels on and off 4-34 To force all channels on or all channels off 4-35 To change the display size of the digital channels 4-35 To change the logic threshold for digital channels 4-36 Using Digital Channels to Probe Circuits 4-37

Contents-3

Contents

Using Labels on the Mixed-Signal Oscilloscope
To turn the label display on or off 4-42 To assign a predefined label to a channel 4-43 To define a new label 4-44 To reset the label library to the factory default 4-46

4-41

Saving and Recalling Traces and Setups

4-47

To Autosave traces and setups 4-48 To save traces and setups to internal memory or to overwrite an existing floppy disk file 4-49 To save traces and setups to a new file on the floppy disk 4-50 To recall traces and setups 4-51 Saving (printing) screen images to floppy disk 4-52 Recalling the factory default setup 4-53

5 Making Measurements Capturing Data 5-3

To use delayed sweep 5-4 To reduce the random noise on a signal 5-6 To capture glitches or narrow pulses with peak detect and infinite persistence 5-10 To use the Roll horizontal mode 5-11 To use the XY horizontal mode 5-12

Math Functions

5-16

Multiply 5-17 Subtract 5-18 Differentiate 5-19 Integrate 5-21 FFT Measurement 5-23

Contents-4

Contents

Cursor Measurements

5-29
5-30

To make cursor measurements

Automatic Measurements

5-35

Making automatic measurements 5-36 Making time measurements automatically 5-37 Making voltage measurements automatically 5-40 Making overshoot and preshoot measurements 5-43

6 Utilities
To configure Quick Help languages 6-3 To configure a printer 6-5 To use the floppy disk 6-7 To set up the I/O port to use a controller To set the clock 6-10 To set up the screen saver 6-11 To perform service functions 6-12 To set other options 6-14

6-8

7 Performance Characteristics
Performance Characteristics 7-3

Index

Contents-5

Contents-6

1

Getting Started

Getting Started

When you use the oscilloscopes to help test and troubleshoot your systems, you may do the following: · Prepare the oscilloscope by connecting it to power and setting up the handle and screen intensity as desired. · Define the measurement problem by understanding the parameters of the system you wish to test, and the expected system behavior. · Set up channel inputs by connecting the probes to the appropriate signal and ground nodes in the circuit under test. · Define the trigger to reference the waveform data at a specific event of interest. · Use the oscilloscope to acquire data, either in continuous or singleshot fashion. · Examine the data and make measurements on it using various features. · Save the measurement or configuration for later re-use or comparison with other measurements. Repeat the process as necessary until you verify correct operation or find the source of the problem.

MegaZoom Technology Operates with Untriggered Data
With the MegaZoom technology built into the oscilloscope, you can operate the oscilloscope with untriggered data. All you do is press Run or Single while in Auto trigger mode, then examine the data to set up a trigger.

1- 2

Getting Started

The oscilloscope's high-speed display can be used to isolate infrequently changing signals. You can then use the characteristics of these signals to help refine the trigger specification. For more information on triggering, data acquisition, data examination and measurement, and configuration, see the later chapters.

Using the Oscilloscope, and Refining the Trigger Specification

1-3

Setting up the Oscilloscope

To prepare your oscilloscope for use, you need to do the following tasks. After you have completed them, you will be ready to use the oscilloscope. In the following topics you will: · · · · · · · · · · · · · inspect package contents inspect options and accessories learn how to clean the oscilloscope adjust the handle power-on the oscilloscope adjust the display intensity connect the oscilloscope probes connect the digital probes (with 54621D and 54622D) connect a printer connect a RS-232 cable verify basic oscilloscope operation get started using the oscilloscope interface learn how to use Quick Help

1- 4

Getting Started To inspect package contents

To inspect package contents
Inspect the shipping container for damage. If your shipping container appears to be damaged, keep the shipping container or cushioning material until you have inspected the contents of the shipment for completeness and have checked the oscilloscope mechanically and electrically. Verify that you received the following items and any optional accessories in the oscilloscope packaging (see figure following). · 54600-Series Oscilloscope (54621A, 21D, 22A, 22D, or 24A) · 10074C 10:1 passive probes: (2) for 54621A, 21D, 22A, or 22D oscilloscopes (4) for 54624A oscilloscope · 54620-68701 digital probe kit (for 54621D or 22D) · Accessory pouch and front-panel cover (standard for 54622A, 22D, and 24A) (optional on 54621A and 21D; order N2726A) · Power cord (see table 1-3) · BenchLinkXL 54600 software and RS-232 cable (for 54622A, 22D, or 24A) BenchLink XL 54600 software is available free on the web at: www.agilent.com/go/megazoom RS-232 cable may be ordered separately, part number 34398A If anything is missing, contact your nearest Agilent Sales Office. If the shipment was damaged, contact the carrier, then contact the nearest Agilent Sales Office. Inspect the oscilloscope · If there is mechanical damage or a defect, or if the oscilloscope does not operate properly or does not pass the performance tests listed in the Service Guide, notify your Agilent Sales Office. · If the shipping container is damaged, or the cushioning materials show signs of stress, notify the carrier and your Agilent Sales Office. Keep the shipping materials for the carrier's inspection. The Agilent Sales Office will arrange for repair or replacement at Agilent's option, without waiting for claim settlement.

1-5

Getting Started To inspect package contents

54600-Series Oscilloscope

54620-68701 digital probe kit* 54620-61801 16-channel cable
Ä

5959-9334 2" Ground lead (qty 5)

Accessories pouch and front-panel cover**

5090-4356 Clip (qty 20)

Power cord

BenchlinkXL 54600 software and serial cable**

10074C Probes

s
sa

* 54621D /22D only ** 54622A/22D/24A only

Package contents for 54600-Series Oscilloscopes

1- 6

Getting Started To inspect options and accessories

To inspect options and accessories
Verify that you received the options and accessories you ordered and that none were damaged. If anything is missing, contact your nearest Agilent Sales Office. If the shipment was damaged, or the cushioning materials show signs of stress, notify the carrier and your Agilent Sales Office. Some of the options and accessories available for the 54600-Series Oscilloscopes are listed in tables 1-1 and 1-2. Contact your Agilent Sales Office for a complete list of options and accessories.

Table 1-1

Options available
Option 003 Description Shielding Option for use in severe environments or with sensitive devices under test­shields both ways (in and out): RS-03 magnetic interface shielding added to CRT, and RE-02 display shield added to CRT to reduce radiated interference. Delete manuals ANSII Z540 compliant calibration with test data 3-year, customer-return calibration service 3-year, customer-return standard compliance calibration service Additional 2-year warranty (5 years total) 5-year, customer-return calibration service 5-year customer-return standard compliance calibration service See table 1-3 for power cord options

0B0 A6J W32 W34 W50 W52 W54

1-7

Getting Started To inspect options and accessories

Table 1-2

Accessories available
Model 1146A 1183A 1185A 1186A 10070C 10072A 10073B 10075A 10076A 10085A 10089A 10100C 10833A 34398A E2613B E2614A E2615B E2616A E2643A E2644A N2726A N2727A N2728A N2757A N2772A N2773A Description Current probe, ac/dc Testmobile scope cart Carrying Case Rackmount Kit 1:1 Passive Probe with ID Fine-pitch probe kit 10:1 500 MHz probe with ID 0.5 mm IC clip kit 100:1, 4 kV 250 MHz probe with ID 16:16 logic cable and terminator (for use with 54621D/22D) 16:2 x 8 logic input probe assembly (shipped standard with 54621D/22D) 50 Termination GPIB cable, 1 m long RS-232 cable (standard with 100 MHz models) 0.5 mm Wedge probe adapter, 3-signal, qty 2 0.5 mm Wedge probe adapter, 8-signal, qty 1 0.65 mm Wedge probe adapter, 3-signal, qty 2 0.65 mm Wedge probe adapter, 8-signal, qty 1 0.5 mm Wedge probe adapter, 16-signal, qty 1 0.65 mm Wedge probe adapter, 16-signal, qty 1 Accessory pouch and front-panel cover (standard with 100 MHz models) Thermal printer and pouch 10 rolls of thermal printer paper GPIB Interface Module 20 MHz differential probe Differential probe power supply

1- 8

Getting Started To inspect options and accessories

Table 1-3 Power Cords
Plug Type Opt 903 (U.S.A.) 124V ** Cable Part No. Plug Description 8120-1378 Straight (NEMA5-15P*) Length in/cm Color 90/228 Jade Gray

Opt 900 (U.K.) 250V

8120-1351

Straight (BS136A*)

90/228

Gray

Opt 901 (Australia) 250V

8120-1369

Straight (NZSS198/ASC*) 79/200

Gray

Opt 902 (Europe) 250V

8120-1689 8120-2857

Straight (CEE7-Y11*) Straight (Shielded)

79/20079/200

Mint Gray Coco Brown

Opt 906 (Switzerland) 250V

8120-2104

Straight (SEV1011*)

79/200

Mint Gray

Opt 912 (Denmark) 220V Opt 917 (Africa )250V

8120-2957

Straight (DHCK107*)

79/200

Mint Gray

8120-4600

Straight (SABS164)

79/200

Jade Gray

Opt 918 (Japan) 100V

8120-4753

Straight Miti

90/230

Dark Gray

* Part number shown for plug is industry identifier for plug only. Cable part number shown is Agilent part number for complete cable including plug. ** These cords are included in the CSA certification approval for the equipment.

1-9

Getting Started To clean the oscilloscope

To clean the oscilloscope
1 Disconnect power from the instrument.
CAUTION Do not use too much liquid in cleaning the oscilloscope. Water can enter the front-panel keyboard, control knobs, or floppy disk damaging sensitive electronic components.

2 Clean the oscilloscope with a soft cloth dampened with a mild soap and water solution. 3 Make sure that the instrument is completely dry before reconnecting to a power source.

1- 10

Getting Started To adjust the handle

To adjust the handle
1 Grasp the handle pivot points on each side of the instrument and pull the pivot out until it stops.

s

Agilent

54622D
MIXED SIGNAL OSCILLOSCOPE

CHANN EL
Select

Time/Div

0

15

1s

5 ns

INPUTS

2 Without releasing the pivots, swivel the handle to the desired position. Then release the pivots. Continue pivoting the handle until it clicks into a set position.

1- 11

Getting Started To power-on the oscilloscope

To power-on the oscilloscope
1 Connect the power cord to the rear of the oscilloscope, then to a suitable ac voltage source.

The oscilloscope power supply automatically adjusts for input line voltages in the range 100 to 240 VAC. Therefore, you do not need to adjust the input line voltage setting. The line cord provided is matched to the country of origin. Ensure that you have the correct line cord. See table 1-3

2 Press the power switch.

T rigger out

~5V

Some front panel key light will come on and the oscilloscope will be operational in about 5 seconds.

1- 12

Getting Started To adjust the display intensity

To adjust the display intensity
The Intensity control is at the lower left corner of the front panel.

· To decrease display intensity, rotate the Intensity control counterclockwise. · To increase display intensity, rotate the Intensity control clockwise.
Figure 1-1

Dim Intensity control

Bright

The grid or graticule intensity on the display can be adjusted by pressing the Display key, then turn the Entry knob (labeled on the front panel) to adjust the Grid control.

1- 13

Getting Started To connect the oscilloscope probes

To connect the oscilloscope probes
1 Connect the 10074C 1.5-meter, 10:1 oscilloscope probe to the analog channel 1 or 2 BNC connector input on the oscilloscope, or channel 1 through channel 4 on the 54624A.
Maximum input voltage for analog inputs: CAT I 300 Vrms, 400 Vpk CAT II 100 Vrms, 400 Vpk with 10074C 10:1 probe: CAT I 500 Vpk, CAT II 400 Vpk

2 Connect the retractable hook tip on the probe tip to the circuit point of interest. Be sure to connect the probe ground lead to a ground point on the circuit.
The probe ground lead is connected to the oscilloscope chassis and the ground wire in the power cord. If you need to connect the ground lead to a point in the circuit that cannot be grounded to power ground, consider using a differential probe.

1- 14

Getting Started To use the digital probes (mixed-signal oscilloscope only)

To use the digital probes (mixed-signal oscilloscope only)
1 If you feel it's necessary, turn off the power supply to the circuit under test.

Off

Turning off power to the circuit under test would only prevent damage that might occur if you accidentally short two lines together while connecting probes. You can leave the oscilloscope powered on because no voltage appears at the probes.

2 Connect the digital probe cable to D15 - D0 connector on the front panel of the mixed-signal oscilloscope. The digital probe cable is indexed so you can connect it only one way. You do not need to power-off the oscilloscope.

Use only the Agilent part number 54620-68701 digital probe kit supplied with the mixed-signal oscilloscope. Additional probe kits may be ordered by specifying Agilent part number 10089A.

1- 15

Getting Started To use the digital probes (mixed-signal oscilloscope only)

3 Connect a clip to one of the probe leads. Be sure to connect the ground lead. (Other probe leads are omitted from the figure for clarity.)

Clip

4 Connect the clip to a node in the circuit you want to test.

1- 16

Getting Started To use the digital probes (mixed-signal oscilloscope only)

5 For high-speed signals, connect a ground lead to the probe lead, connect a clip to the ground lead, and attach the clip to ground in the circuit under test.

Signal Lead

Ground Lead

Clip

6 Connect the ground lead on each set of channels, using a probe clip. The ground lead improves signal fidelity to the instrument, ensuring accurate measurements.

Channel Pod Ground

Circuit Ground

1- 17

Getting Started To use the digital probes (mixed-signal oscilloscope only)

7 Repeat steps 3 through 6 until you have connected all points of interest.
Signals

Ground

8 If you need to remove a probe lead from the cable, insert a paper clip or other small pointed object into the side of the cable assembly, and push to release the latch while pulling out the probe lead.

Replacement parts are available. See the Replaceable Parts chapter in the Service Guide for details.

1- 18

Getting Started To connect a printer

To connect a printer
The oscilloscope connects to a parallel printer through the Parallel output connector on the rear of the oscilloscope. You will need a parallel printer cable to connect to the printer.

1 Attach the 25-pin small "D" connector to the Parallel output connector on the rear of the oscilloscope. Tighten the thumbscrews on the cable connector to secure the cable. 2 Attach the larger 36-pin "D" connector to the printer. 3 Set up the printer configuration on the oscilloscope.
a Press the Utility key, then press the Print Confg softkey. b Press the Print to: softkey and set the interface to Parallel. c Press the Format softkey and select your printer format from the list. For more information on printer configuration, refer to the "Utilities" chapter.

To connect an RS-232 cable
The oscilloscope can be connected to a controller or a pc through the RS-232 connector on the rear of the oscilloscope. An RS-232 cable is shipped with each 54622A/22D/24A oscilloscope and may be purchased for the 54621A/21D oscilloscopes.

1 Attach the 9-pin "D" connector on the RS-232 cable to the RS-232 connector on the rear of the oscilloscope. Tighten the thumbscrews on the cable connector to secure the cable 2 Attach the other end of the cable to your controller or pc. 3 Set up the RS-232 configuration on the oscilloscope.
a b c d Press the Utility key, then press the I/O softkey. Press the Controller softkey and select RS-232. Press the Baud softkey and set the baud rate to match your controller or pc. Press the XON DTR softkey and set the handshake to match your controller or pc. For more information on RS-232 configuration, refer to the "Utilities" chapter.

1- 19

Getting Started To verify basic oscilloscope operation

To verify basic oscilloscope operation
1 Connect an oscilloscope probe to channel 1. 2 Attach the probe to the Probe Comp output on the lower-right side of the front panel of the oscilloscope.
Use a probe retractable hook tip so you do not need to hold the probe.

3 Press the Save/Recall key on the front panel, then press the Default Setup softkey under the display.
The oscilloscope is now configured to its default settings.

4 Press the Autoscale key on the front panel.
You should then see a square wave with peak-to-peak amplitude of about 5 divisions and a period of about 4 divisions as shown below. If you do not see the waveform, ensure your power source is adequate, the oscilloscope is properly powered-on, and the probe is connected securely to the front-panel channel input BNC and to the Probe Comp calibration output.

Verifying Basic Oscilloscope Operation

1- 20

Getting started using the oscilloscope interface

When the oscilloscope is first turned on, it performs a self-test, then momentarily shows a startup screen as shown below.

This menu is only accessible when the oscilloscope first starts up.

1- 21

Getting Started To verify basic oscilloscope operation

· Press the Getting Started softkey to view the symbols used in the oscilloscope softkey menus.

Use the Entry knob labeled

to adjust the parameter.

Press the softkey to display a pop up with a list of choices. Repeatedly press the softkey until your choice is selected. Use the Entry knob labeled or press the softkey to adjust the parameter. Option is selected and operational. Feature is on. Press the softkey again to turn the feature off. Feature is off. Press the softkey again to turn the feature on. Press the softkey to view the menu. Press the softkey to return to the previous menu. Press the softkey to view additional selections. Links you to another menu.



1- 22

Using Quick Help

The oscilloscope has a Quick Help system that provides user help for each front-panel key and softkey on the oscilloscope. To view Quick Help information: 1 Press and hold down the key for which you would like to view help. 2 Release the key after reading the message. Releasing the key returns the oscilloscope to the previous state.

Selecting a language for Quick Help when the oscilloscope starts up
When the oscilloscope first powers up, you can press the Language softkey to select a language for viewing Quick Help. Successive press the Language softkey until the desired language in the list selected.

You can also select and load a language later from the Utility Language menu.

1- 23

Getting Started Selecting a language for Quick Help after you have been operating the oscilloscope

Selecting a language for Quick Help after you have been operating the oscilloscope
1 Press the Utility key, then press the Language softkey to display the Language menu. 2 Press the Language softkey until the desired language in the list selected.

If the language you want to load is grayed-out in the list, you will need to load the language from floppy disk. The language file can be downloaded from www.agilent.com/find/5462xsw or call an Agilent center and request a language disk for your instrument

1- 24

Getting Started Loading a language from floppy disk

Loading a language from floppy disk
Language files can be downloaded from www.agilent.com/find/5462xsw or call an Agilent center and request a language disk for your instrument.

1 Insert the floppy disk with a language file into the floppy disk drive on the oscilloscope. 2 Press the Utility key, then press the Language softkey to display the Language menu. 3 Press the Load/Del softkey to select the language to be loaded. 4 Press the Load Language softkey to load the selected language into the oscilloscope.
For more information about loading and deleting languages, refer to the "Utilities" chapter.

1- 25

1- 26

2

Front-Panel Overview

Front-Panel Overview

Before you make measurements using the Agilent 54600-series Oscilloscopes, you must first set up the instrument using front-panel controls. Then, make the measurement and read the display results. These oscilloscopes operate much like an analog scope, but it can do much more. Spending a few minutes to learn some of this capability will take you a long way toward more productive troubleshooting. The "MegaZoom Concepts and Oscilloscope Operation" chapter has more detail on the things to consider while operating your oscilloscope. The keys on the front panel bring up softkey menus on the display that allow access to oscilloscope features. Many softkeys use the Entry knob to select values. Throughout this book, the front-panel keys and softkeys are denoted by a change in the text type. For example, the Cursors key is on the front panel and the Normal softkey is appears at the bottom of the display directly above its corresponding key. Other softkey graphic conventions used on the oscilloscope and throughout this guide are shown in the "Getting started using the oscilloscope interface" topic in chapter 1.

2- 2

Front-Panel Overview Important Oscilloscope Considerations

Important Oscilloscope Considerations
Using Single versus Run/Stop The oscilloscopes have a Single key and a Run/Stop key. When you press Run (key is illuminated in green), the trigger processing and screen update rate are optimized over the memory depth. Single acquisitions always use the maximum memory available--at least twice as much memory as acquisitions captured in Run mode--and the scope stores at least twice as many samples. At slow sweep speeds, the oscilloscope operates at a higher sample rate when Single is used to capture an acquisition, as opposed to running, due to the increased memory available. Viewing signal detail with acquire mode Remember how you had to constantly adjust the brightness on old analog scopes to see a desired level of detail in a signal, or to see the signal at all? With the Agilent 54600-series oscilloscopes, this is not necessary. The Intensity knob operates much like the brightness knob on your computer screen, so you should set it to a level that makes for comfortable viewing, given the room lighting, and leave it there. Then you can control the detail by selecting an Acquire mode: Normal, Peak Detect, Average, or Realtime as described in the following paragraphs. Normal acquire mode Normal mode is the acquisition mode that you will probably use for acquiring samples most of the time. It compresses up to 2 million acquisition points per channel into a 1,000-point display record. The scope's 200 MSa/s sampling speed specification means that samples are taken every 5 ns. At the faster sweep speeds, the running display is built from many individual triggers. If you press the Stop key, and pan and zoom through the waveform by using the Horizontal and Vertical knobs, only the last trigger's acquisition will be displayed. Whether the oscilloscope is stopped or running, you see more detail as you zoom in, and less as you zoom out. To keep from losing detail as you zoom out, switch to the Peak Detect acquisition mode. Zoom means you expand the waveform using either the main or delayed sweep window. Panning the waveform means you use the Horizontal Delay time knob( )to move it horizontally.

2-3

Front-Panel Overview Important Oscilloscope Considerations

Peak Detect acquire mode In Peak Detect acquisition mode, any noise, peak, or signal wider than 5 ns will be displayed, regardless of sweep speed. In Normal acquisition mode, at sweep speeds faster than 2 µs/div, you would see a 5-ns peak, so peak detect has no effect at sweep speeds faster than 2 µs/div. Using Peak Detect and infinite persistence together is a powerful way to find spurious signals and glitches. Average acquire mode Averaging is a way to pull a repetitive signal out of noise. Averaging works better than either a bandwidth limit or a brightness control because the bandwidth is not reduced. The simplest averaging is smoothing (number of averages = 1). For example, the sample rate at a Time/Div setting of 2 ms/div allows the extra 5-ns samples to be smoothed together, smoothing the data into one sample, which is then displayed. As with Peak Detect, smoothing has no effect at less than 2 µs/div. Smoothing works on a single acquisition (even untriggered and single-shot). Averaging (number of averages > 1) needs a stable trigger, because in this mode multiple acquisitions are averaged together. See the "MegaZoom Concepts and Oscilloscope Operation" chapter for more information about smoothing. Realtime acquire mode In Realtime mode, the oscilloscope acquires all of the waveform samples during one trigger event. To accurately reproduce a sampled waveform, the sample rate (200 MSa/s for single channel or 100 MSa/s with channel pairs 1 and 2, 3 and 4, or pod 1 and pod 2 running) should be at least four times the highest frequency component of the waveform. If not, it is possible for the reconstructed waveform to be distorted or aliased. Aliasing is most commonly seen as jitter on fast digital edges. Use Realtime to capture infrequent triggers, unstable triggers, or complex changing waveforms, such as eye diagrams. Realtime mode is only necessary at sweep speeds of 200 ns/div and faster.

2- 4

Front-Panel Overview Important Oscilloscope Considerations

Auto-Single mode In Normal trigger mode, the oscilloscope will not trigger or display a waveform unless a trigger signal is present and trigger conditions are met. In this trigger mode, each time Single is pressed, the oscilloscope will wait for a valid trigger. In Auto or Auto Lvl trigger mode, the oscilloscope will generate a trigger for you if one is not found in the predetermined time from when the trigger system is armed. To take a single-shot acquisition, if you are not particularly interested in triggering the acquisition (for example, if you are probing a known signal), use this auto-trigger mode (auto-signal mode). If a trigger exists, it will be used; if a trigger does not exist, an untriggered or auto-triggered acquisition will be taken for later analysis. Using Vectors (Display menu) One of the most fundamental choices you must make about your display is whether to draw vectors (connect the dots) between the samples, or simply let the samples fill in the waveform. To some degree, this is a matter of personal preference, but it also depends on the waveform. · You will probably operate the oscilloscope most often with vectors on. Having vectors on slows the display of the oscilloscope, thus works better for slower sweep speeds, peak detect, or average displays, and signals with stable triggers. · Having vectors off works better for fast sweep speeds, normal displays, or unstable triggers. Complex analog signals like video and eye diagrams show more intensity information with vectors off. Turn vectors off when the maximum display rate is required, or when highly complex or multi-valued waveforms are displayed. Delayed Sweep Delayed sweep is a simultaneous display of the waveform at two different sweep speeds. Because of the deep memory in the MegaZoom technology, it is possible to capture the main display at 1 ms/div, and redisplay the same trigger in the delayed display at any desired faster time base. There is no limit imposed on the zoom ratio between the main and delayed displays. There is, however, a useful limit when the samples are spaced so far apart that they are of little value. See the "MegaZoom Concepts and Oscilloscope Operation" chapter for more information about delayed sweep and time reference.

2-5

Front-Panel Overview Important Oscilloscope Considerations

Post Acquisition Processing In addition to changing display parameters after the acquisition, you can do all of the measurements and math functions after the acquisition. Measurements and math functions will be recalculated as you pan and zoom and turn channels on and off. As you zoom in and out on a signal using the horizontal sweep speed knob and vertical volts/division knob, you affect the resolution of the display. Because measurements and math functions are performed on displayed data, you affect the resolution of functions and measurements.

2- 6

Front-Panel Overview 54600-series Oscilloscope1 Front Panels

54600-series Oscilloscope1 Front Panels
Figure 2-1
Display Measure keys Horizontal controls Waveform keys Run controls

Entry knob Autoscale key Softkeys

Trigger controls

Utility key Probe comp output

Intensity control

Floppy disk

Power switch

Vertical inputs/ controls

File keys

External Trigger input

54621A and 54622A 2-Channel Oscilloscopes Front Panel

2-7

Front-Panel Overview 54600-series Oscilloscope1 Front Panels

Figure 2-2
Display Measure keys Horizontal controls Waveform keys Run controls

Entry knob Autoscale key Softkeys

Trigger controls

Utility key Probe comp output

Intensity control

Floppy disk

Power switch

Vertical inputs/ controls

File keys

54624A 4-Channel Oscilloscope Front Panel

2- 8

Front-Panel Overview 54600-series Oscilloscope1 Front Panels

Figure 2-3
Display Measure keys Horizontal controls Waveform keys Run controls

Entry knob Autoscale key Softkeys

Trigger controls

Utility key Probe Comp output

Intensity control

Floppy disk

Power switch

Analog Channel inputs/ controls

File keys

Digital Channel inputs/ controls

54621D and 54622D Mixed-Signal Oscilloscopes Front Panel

2-9

Front-Panel Operation

This chapter provides a brief overview of interpreting information on the display and an introduction to operating the front-panel controls. Detailed oscilloscope operating instructions are provided in later chapters.
54621D and 54622D digital channels Because all of the oscilloscopes in the 54600-series have analog channels, the analog channel topics in this chapter apply to all instruments. Whenever a topic discusses the digital channels, that information applies only to the 54621D or 54622D Mixed-Signal Oscilloscopes.

2- 10

Front-Panel Overview Interpreting the display

Interpreting the display
The oscilloscope display contains channel acquisitions, setup information, measurement results, and softkeys for setting up parameters.
Analog channels sensitivity Digital channel activity Trigger point, time reference Delay time Sweep speed Trigger mode Trigger type Trigger source

Analog channels and ground levels

Trigger level or digital threshold Cursor markers defining measurement

Digital channels Measurement line Softkeys Interpreting the display

Status line The top line of the display contains vertical, horizontal, and trigger setup information. Display area The display area contains the waveform acquisitions, channel identifiers, and analog trigger and ground level indicators. Measurement line This line normally contains automatic measurement and cursor results, but can also display advanced trigger setup data and menu information. Softkeys The softkeys allow you to set up additional parameters for front-panel keys.

2- 11

Front-Panel Overview To use analog channels to view a signal

To use analog channels to view a signal
· To configure the oscilloscope quickly, press the Autoscale key to display the connect signal. · To undo the effects of Autoscale, press the Undo Autoscale softkey before pressing any other key. · To set the instrument to the factory-default configuration, press the Save/Recall key, then press the Default Setup softkey.
Example Connect the oscilloscope probes for channels 1 and 2 to the Probe Comp output on the front panel of the instrument. Set the instrument to the factory default configuration by pressing the Save/Recall key, then the Default Setup softkey. Then press the Autoscale key. You should see a display similar to the following.

Autoscale with analog channels

2- 12

Front-Panel Overview To use digital channels to view a signal

To use digital channels to view a signal
· To configure the instrument quickly, press the Autoscale key. · To undo the effects of Autoscale, press the Undo Autoscale softkey before pressing any other key. · To set the instrument to the factory-default configuration, press the Save/Recall key, then press the Default Setup softkey.
Example Install probe clips on channels 0 and 1 on the digital probe cable. Connect the probes for digital channels 0 and 1 to the Probe Comp output on the front panel of the instrument. Be sure to connect the ground lead. Set the instrument to the factory default configuration by pressing the Save/Recall key, then the Default Setup softkey. Then press the Autoscale key. You should see a display similar to the following.

Autoscale with digital channels (54621D and 54622D)

2- 13

Front-Panel Overview To display signals automatically using Autoscale

To display signals automatically using Autoscale
· To configure the instrument quickly, press the Autoscale key.
Autoscale displays all connected signals that have activity. To undo the effects of Autoscale, press the Undo Autoscale softkey before pressing any other key. How Autoscale Works Autoscale automatically configures the oscilloscope to best display the input signal by analyzing any waveforms connected to the external trigger and channel inputs. Autoscale finds, turns on, and scales any channel with a repetitive waveform with a frequency of at least 50 Hz, a duty cycle greater than 0.5%, and an amplitude of at least 10 mV peak-to-peak. Any channels that do not meet these requirements are turned off. The trigger source is selected by looking for the first valid waveform starting with external trigger, then continuing with the highest number analog channel down to the lowest number analog channel, and finally (if applicable) the highest number digital channel. During Autoscale, the delay is set to 0.0 seconds, the sweep speed setting is a function of the input signal (about 2 periods of the triggered signal on the screen), and the triggering mode is set to edge. Vectors remain in the state they were before the Autoscale. Undo Autoscale Press the Undo Autoscale softkey to return the oscilloscope to the settings that existed before you pressed the Autoscale key. This is useful if you have unintentionally pressed the Autoscale key or do not like the settings Autoscale has selected and want to return to your previous settings.

2- 14

Front-Panel Overview To apply the default factory configuration

To apply the default factory configuration
· To set the instrument to the factory-default configuration, press the Save/Recall key, then press the Default Setup softkey.
The default configuration returns the oscilloscope to its default settings. This places the oscilloscope in a known operating condition. The major default settings are: Horizontal main mode, 100 us/div scale, 0 s delay, center time reference Vertical (Analog) Channel 1 on, 5 V/div scale, dc coupling, 0 V position, probe factor to 1.0 if an AutoProbe probe is not connected to the channel Trigger Edge trigger, Auto level sweep mode, 0 V level, channel 1 source, dc coupling, rising edge slope, 60 ns holdoff time Display Vectors on, 20% grid intensity, infinite persistence off Other Acquire mode normal, Run/Stop to Run, cursor measurements off

2- 15

Front-Panel Overview To adjust analog channel vertical scaling and position

To adjust analog channel vertical scaling and position
This exercise guides you through the vertical keys, knobs, and status line.

1 Center the signal on the display using the position knob.
The position knob ( ) moves the signal vertically; the signal 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 reference symbol at the left edge of the display moves 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.

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 large volts/division knob in the Vertical (Analog) section of the front panel and notice that it causes the status line to change. · Press the 1 key. If channel 1 was not turned on, a softkey menu appears on the display, and the channel turns on (the 1 key will be illuminated). If channel 1 was already turned on, but another menu was being displayed, the softkeys will now display the channel 1 menu. When Vernier is turned off, the volts/div knob can change the channel sensitivity in a 1-2-5 step sequence. When Vernier is selected, you can change the channel sensitivity in smaller increments with the volts/division knob. The channel sensitivity remains fully calibrated when Vernier is on. The sensitivity value is displayed in the status line at the top of the display. · To turn the channel off, press the channel 1 key until the key is not illuminated.

2- 16

Front-Panel Overview To set the vertical expand reference for the analog signal

To set the vertical expand reference for the analog signal
When changing the volts/division for analog channels, you can have the signal expand (or compress) about the signal ground point or about the center graticule on the display. This works well with two signals displayed, because you can position and see them both on the screen while you change the amplitude. · To expand the signal about the center graticule of the display, press the Utility key, press the Options softkey, then press the Expand softkey and select Expand About Center. With Expand About Center selected, when you turn the volts/division, the waveform with expand or contract about the center graticule of the display. · To expand the signal about the position of the channel's ground, press the Utility key, press the Options softkey. Then press the Expand softkey and select Expand About Ground. With Expand About Ground selected, when you turn the volts/division knob, the ground level of the waveform remains at the same point on the display, while the non-ground portions of the waveform expand or contract.

To set analog channel probe attenuation factor
If you have an AutoProbe self-sensing probe (such as the 10074C) connected to the analog channel, the oscilloscope will automatically configure your probe to the correct attenuation factor. In the previous figure, the oscilloscope has sensed an AutoProbe 10:1 probe. If you do not have an AutoProbe probe connected, you can turn the Entry knob to set the attenuation factor for the connected probe. The attenuation factor can be set from 0.1:1 to 1000:1 in a 1-2-5 sequence. The probe correction factor must be set properly for measurements to be made correctly.

2- 17

Front-Panel Overview To display and rearrange the digital channels

To display and rearrange the digital channels
1 Press the D15 Thru D8 key or D7 Thru D0 key to turn the display of the digital channels on or off.
The digital channels are displayed when these keys are illuminated.

2 Turn the Digital Channel Select knob to select a single digital channel.
The selected channel number is highlighted on the left side of the display.

3 Turn the Digital position knob ( ) to reposition the selected channel on the display.
If two or more channels are displayed at the same position, a pop up will appear showing the overlaid channels. Continue turning the Channel Select knob until the desired channel within the pop up is selected.

2- 18

Front-Panel Overview To operate the time base controls

To operate the time base controls
The following exercise guides you through the time base keys, knobs, and status line.

· Turn the Horizontal sweep speed (time/division) knob and notice the change it makes to the status line.
The sweep speed knob changes the sweep speed from 5 ns/div to 50 s/div in a 1-2-5 step sequence, and the value of the sweep speed is displayed in the status line at the top of the display.

· Press the Main/Delayed, then press the Vernier softkey.
The Vernier softkey allows you to change the sweep speed in smaller increments with the time/div knob. These smaller increments are calibrated, which result in accurate measurements, even with the vernier turned on.

· Turn the delay time knob ( the status line.

) and notice that its value is displayed in

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 with the Delay time knob. The symbol indicates the time reference point. If the Time Ref softkey is set to Left, the is located one graticule in from the left side of the display. If the Time Ref softkey is set to Center, the is located at the center of the display. If the Time Ref softkey is set to Right, the is located one graticule in from the right side of the display. The delay number tells you how far the time 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 pre-trigger information. 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 post-trigger information. The amount of delay range (pre-trigger and post-trigger information) available depends on the sweep speed selected.

2- 19

Front-Panel Overview To start and stop an acquisition

To start and stop an acquisition
· When the Run/Stop key is illuminated in green, the oscilloscope is in continuous running mode.
You are viewing multiple acquisitions of the same signal similar to the way an analog oscilloscope displays waveforms.

· When the Run/Stop key is illuminated in red, the oscilloscope is stopped.
"Stop" is displayed in the trigger mode position in status line at the top of the display. You may now pan and zoom the stored waveform by turning the Horizontal and Vertical knobs. The stopped display may contain several triggers worth of information, but only the last trigger acquisition is available for pan and zoom. To ensure the display does not change, use the Single key to be sure you have acquired only one trigger.

To make a single acquisition
The Single run control key lets you view single-shot events without subsequent waveform data overwriting the display. Use Single when you want maximum memory depth for pan and zoom.

1 First set trigger Mode/Coupling Mode softkey to Normal.
This keeps the oscilloscope from autotriggering immediately.

2 If you are using the analog channels to capture the event, turn the Trigger Level knob to the trigger threshold where you think the trigger should work. 3 To begin a single acquisition, press the Single key.
When you press Single, the display is cleared, the trigger circuitry is armed, the Single key is illuminated, and the oscilloscope will wait until a trigger condition occurs before it displays a waveform. When the oscilloscope triggers, the single acquisition is displayed and the oscilloscope is stopped (Run/Stop key is illuminated in red). Press Single again to acquire another waveform.

2- 20

Front-Panel Overview To use delayed sweep

To use delayed sweep
Delayed sweep is an expanded version of main sweep. When Delayed mode is selected, the display divides in half and the delayed sweep icon displays in the middle of the line at the top of the display. The top half displays the main sweep and the bottom half displays the delayed sweep. 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.
To change the sweep speed for the delayed sweep window, turn the sweep speed knob. As you turn the knob, the sweep speed is highlighted in the status line above the waveform display area. The area of the main display that is expanded is intensified and marked on each end with a vertical marker. These markers show what portion of the main sweep is expanded in the lower half. The Horizontal knobs control the size and position of the delayed sweep. The delay value is momentarily displayed in the upper-right portion of the display when the delay time ( ) knob is turned. 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 (higher-resolution) analysis of signals. The point about which the delayed sweep window is expanded is referenced to the delay time and is dependent on the time reference setting: · When Time Ref is set to Left, the delayed sweep expands to the right starting from the delay time setting (one graticule from the left side of the display when delay time = 0). · When Time Ref is set to Center, the delayed sweep expands equally left and right) from the delay time setting (center of the display when delay time = 0). · When Time Ref is set to Right, the delayed sweep expands to the left starting from the delay time setting (one graticule from the right side of the display when delay time = 0). To change the sweep speed for the main sweep window, press the Main softkey, then turn the sweep speed knob.

2- 21

Front-Panel Overview To make cursor measurements

To make cursor measurements
You can use the cursors to make custom voltage or time measurements on scope signals, and timing measurements on digital channels.

1 Connect a signal to the oscilloscope and obtain a stable display. 2 Press the Cursors key. View the cursor functions in the softkey menu:
Mode Set the cursors results to measure voltage and time (Normal), or display the binary or hexadecimal logic value of the displayed waveforms. Source selects a channel or math function for the cursor measurements. X Y Select either the X cursors or the Y cursors for adjustment with the Entry knob. X1 and X2 adjust horizontally and normally measure time. Y1 and Y2 adjust vertically and normally measure voltage. X1 X2 and Y1 Y2 move the cursors together when turning the Entry knob. For more information about using cursors for measurements, refer to the "Making Measurements" chapter.

2- 22

Front-Panel Overview To make automatic measurements

To make automatic measurements
You can use automatic measurements on any channel source or any running math function. Cursors are turned on to focus on the most recently selected measurement (right-most on the measurement line above the softkeys on the display).

1 Press the Quick Meas key to display the automatic measurement menu. 2 Press the Source softkey to select the channel or running math function on which the quick measurements will be made.
Only channels or math functions that are displayed are available for measurements. If a portion of the waveform required for a measurement is not displayed or does not display enough resolution to make the measurement, the result will be displayed with a message such as greater than a value, less than a value, not enough edges, not enough amplitude, incomplete, or waveform is clipped to indicate that the measurement may not be reliable.

3 Press the Clear Meas softkey to stop making measurements and to erase the measurement results from the measurement line above the softkeys.
When Quick Meas is pressed again, the default measurements on an analog channel will be will be Frequency and Peak-Peak.

4 Choose what measurements you want on that source by pressing the softkey. 5 To turn off Quick Meas, press the Quick Meas key again until it is not illuminated.
For detailed information about making automatic measurements, refer to the "Making Measurements" chapter.

2- 23

Front-Panel Overview To modify the display grid

To modify the display grid
1 Press the Display key. 2 Turn the Entry knob to change the intensity of the displayed grid. The intensity level is shown in the Grid softkey and is adjustable from 0 to 100%.
Each major division in the grid (also know as graticule) corresponds to the sweep speed time shown in the status line on the top of the display.

· To change waveform intensity, turn the INTENSITY knob on the lower-left corner of the front panel.

To print the display
You can print the complete display, including the status line and softkeys, to a parallel printer or to the floppy disk by pressing the Quick Print key. You can stop printing by pressing the Cancel Print softkey. To set up your printer, press the Utility key, then press the Print Confg softkey. For more information on printing and floppy disk operation, refer to the "Utilities" chapter.

2- 24

3

Triggering the Oscilloscope

Triggering the Oscilloscope

The Agilent 54600-series Oscilloscopes provide a full set of features to help automate your measurement tasks, including MegaZoom technology to help you capture and examine the stored waveforms of interest, even untriggered waveforms. With these oscilloscopes you can: · modify the way the oscilloscope acquires data. · set up simple or complex trigger conditions, as needed, to capture only the sequence of events you want to examine. The oscilloscopes all have common triggering functionality: · Trigger modes (Auto Level, Auto, Normal) · Trigger types (slope/edge, pulse width, pattern, duration, sequence, I2C, and TV triggering) · Mode/Coupling (including high frequency and noise rejection) · Holdoff and Trigger Level

3- 2

Selecting Trigger Modes and Conditions

The trigger mode affects the way in which the oscilloscope searches for the trigger. The figure below shows the conceptual representation of acquisition memory. Think of the trigger event as dividing acquisition memory into a pre-trigger and post-trigger buffer. The position of the trigger event in acquisition memory is defined by the time reference point and the delay setting.
Trigger Event

Pre-Trigger Buffer

Post-Trigger Buffer

Acquisition Memory Acquisition Memory

To select the Mode and Coupling menu
· Press the Mode/Coupling key in the Trigger section of the front panel.

3-3

Triggering the Oscilloscope To select a trigger mode: Auto Level, Auto, Normal

To select a trigger mode: Auto Level, Auto, Normal
1 Press the Mode/Coupling key. 2 Press the Mode softkey, then select Auto Level, Auto, or Normal trigger.
· Normal mode displays a waveform the trigger conditions are met, otherwise the oscilloscope does not trigger and the display is not updated. · Auto mode is the same as Normal mode, except it forces the oscilloscope to trigger if the trigger conditions are not met. · Auto Level mode works only when edge triggering on analog channels or external trigger. The oscilloscope first tries to Normal trigger. If no trigger is found, it searches for a signal at least 10% of full scale on the trigger source and sets the trigger level to the 50% amplitude point. If there is still no signal present, the oscilloscope auto triggers. This mode is useful when moving a probe from point to point on a circuit board. Auto Level and Auto modes Use the auto trigger modes for signals other than low-repetitive-rate signals. To display a dc signal, you must use one of these two auto trigger modes since there are no edges on which to trigger. Auto Level mode is the same as Auto mode with an automatic trigger level adjustment. The oscilloscope looks at the level on the signals, and if the trigger level is out-of-range with respect to the signal, the scope adjusts the trigger level back to the middle of the signal. When you select Run, the oscilloscope operates by first filling the pre-trigger buffer. It continues to flow data through this buffer while it searches for the trigger. While searching for the trigger, the oscilloscope overflows the pre-trigger buffer; the first data put into the buffer is the first pushed out (FIFO). When a trigger is found, the pre-trigger buffer will contain the events that occurred just before the trigger. If no trigger is found, the oscilloscope generates a trigger and displays the data as though a trigger had occurred. When you select Single, the oscilloscope will fill pre-trigger buffer memory, and continue flowing data through the pre-trigger buffer until the auto trigger overrides the searching and commands a trigger. At the end of the trace, the scope will stop and display the results.

3- 4

Triggering the Oscilloscope To select a trigger mode: Auto Level, Auto, Normal

Normal mode Use Normal trigger mode for low repetitive-rate signals. In this mode, the oscilloscope has the same behavior whether the acquisition was initiated by pressing Run/Stop or Single. When the trigger event is found, the oscilloscope will fill the post-trigger buffer and display the acquisition memory. If the acquisition was initiated by Run/Stop, the process repeats. The waveform data will be scrolled onto the display as it is being acquired. In Normal mode the oscilloscope must fill the pre-trigger buffer with data before it will begin searching for a trigger event. The trigger mode indicator on the status line flashes to indicate the oscilloscope is filling the pre-trigger buffer. While searching for the trigger, the oscilloscope overflows the pre-trigger buffer; the first data put into the buffer is the first pushed out (FIFO). In either Auto or Normal mode, the trigger may be missed completely under certain conditions. This is because the oscilloscope will not recognize a trigger event until the pre-trigger buffer is full. Suppose you set the Time/Div knob to a slow sweep speed, such as 500 ms/div. If the trigger condition occurs before the oscilloscope has filled the pre-trigger buffer, the trigger will not be found. If you use Normal mode and wait for the trigger condition indicator to flash before causing the action in the circuit, the oscilloscope will always find the trigger condition correctly. Some measurements you want to make will require you to take some action in the circuit under test to cause the trigger event. Usually, these are single-shot acquisitions, where you will use the Single key.

3-5

Triggering the Oscilloscope To select trigger Coupling

To select trigger Coupling
1 Press the Mode/Coupling key. 2 Press the Coupling softkey, then select DC, AC, or LF Reject coupling.
· DC coupling allows dc and ac signals into the trigger path. · AC coupling places a 3.5 Hz high-pass filter in the trigger path removing any DC offset voltage from the trigger waveform. Use AC coupling to get a stable edge trigger when your waveform has a large DC offset. · LF (low frequency) Reject coupling places a 50-kHz high-pass filter in series with the trigger waveform. Low frequency reject removes any unwanted low frequency components from a trigger waveform, such as power line frequencies, that can interfere with proper triggering. Use this coupling to get a stable edge trigger when your waveform has low frequency noise. · TV coupling is normally grayed-out, but is automatically selected when TV trigger is enabled in the Trigger More menu.

To select Noise Reject and HF Reject
1 Press the Mode/Coupling key. 2 Press the Noise Rej softkey to select noise reject or press the HF Reject softkey to select high frequency reject.
· Noise Rej adds additional hysteresis to the trigger circuitry. When noise reject is on, the trigger circuitry is less sensitive to noise but may require a greater amplitude waveform to trigger the oscilloscope. · HF Reject adds a 50 kHz low-pass filter in the trigger path to remove high frequency components from the trigger waveform. You can use HF Reject to remove high-frequency noise, such as AM or FM broadcast stations, from the trigger path.

3- 6

Triggering the Oscilloscope To set holdoff

To set holdoff
1 Press the Mode/Coupling key. 2 Turn the Entry knob to increase or decrease the trigger holdoff time shown in the Holdoff softkey.
Holdoff sets the amount of time that the oscilloscope waits before re-arming the trigger circuitry. Use Holdoff to stabilize the display of complex waveforms. To get a stable trigger on the pulse burst shown below, set the holdoff time to be >200 ns but <600 ns.
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By setting the Holdoff, you can synchronize triggers. The oscilloscope will trigger on one edge of the waveform, and ignore further edges until the holdoff time expires. The oscilloscope will then re-arm the trigger circuit to search for the next edge trigger. This allows the oscilloscope to trigger on a repeating pattern in a waveform.

3-7

Triggering the Oscilloscope To set holdoff

Holdoff Operating Hints Holdoff keeps a trigger from occurring until after a certain amount of time has passed since the last trigger. This feature is valuable when a waveform crosses the trigger level multiple times during one period of the waveform. Without holdoff, the scope could trigger on each of the crossings, producing a confusing waveform. With holdoff set correctly, the scope always triggers on the same crossing. The correct holdoff setting is typically slightly less than one period. Set the holdoff to this time to generate a unique trigger point. This action works even though many waveform periods pass between triggers, because the holdoff circuit operates on the input signal continuously. Changing the time base settings does not affect the holdoff number. In contrast, the holdoff in analog oscilloscopes is a function of the time base setting, making it necessary to re-adjust the holdoff each time you change the time base setting. With Agilent's MegaZoom technology, you can press Stop, then pan and zoom through the data to find where it repeats. Measure this time using the cursors, then set holdoff to this number.

3- 8

Trigger Types

The oscilloscope allows you to synchronize the display to the actions of the circuit under test by defining a trigger condition. The triggering modes include Auto Level, Auto, and Normal. Triggering types include edge, pulse width, pattern, duration, sequence, I2C, and TV trigger. You can use any input channel, line, or the Ext Trigger BNC for the source.
MegaZoom Technology Simplifies Triggering With the built-in MegaZoom technology, you can simply Autoscale the wav