Lecroy 9300C User Manual

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Operator’s Manual

LeCroy 9300C Series Digital Oscilloscopes

Revision A — January 1998

LeCroy Corporation

700 Chestnut Ridge Road Chestnut Ridge, NY 10977–6499 Tel: (845) 578 6020, Fax: (845) 578 5985

LeCroy SA

2, rue du Pré-de-la-Fontaine 1217 Meyrin 1/Geneva, Switzerland Tel: (41) 22 719 21 11, Fax: (41) 22 782 39 15

Internet: www.lecroy.com

LeCroy, ProBus and SMART Trigger are registered trademarks of LeCroy Corporation. MathCad is a registered trademark of MATHSOFT Inc. Centronics is a registered trademark of Data Computer Corp. Epson is a registered trademark of Epson America Inc. PowerPC is a registered trademark of IBM Microelectronics. MATLAB is a registered trademark of The MathWorks, Inc. DeskJet, ThinkJet, QuietJet, LaserJet, PaintJet, HP 7470 and HP 7550 are registered trademarks of HewlettPackard Company. I

Manufactured under an ISO 9000 Registered Quality Management System Visit www.lecroy.com to view the certificate.

C is a trademark of Philips.

This electronic product is subject to disposal and recycling regulations that vary by country and region. Many countries prohibit the disposal of waste electronic equipment in standard waste receptacles. For more information about proper disposal and recycling of your LeCroy product, please visit www.lecroy.com/recycle.

93XXC-OM-E Rev A 0198

Chapter 1 — Read This First!

Product and Client Care..............................................................1–1

Chapter 2 — Instrument Architecture

General Designed Capabilities................................................2–1

Block Diagrams.................................................................................2–4

Chapter 3 — Installation and Safety

Installation for Safe and Efficient Operation...................3–1

Chapter 4 — Introduction to the Controls

The Front Panel.................................................................................4–1

The Main Controls.......................................................................... 4–3

Choosing and Navigating in Menus.......................................4–4

System Setup and Menu Controls..........................................4–6

Screen Topography ........................................................................4–8

Contents

Chapter 5 — CHANNELS, Coupling and Probes

Channel Controls..................................................................... 5–1

Coupling...............................................................................................5–3

Probes and Probe Calibration ..................................................5–4

Chapter 6 — TIMEBASE + TRIGGER

TIMEBASE + TRIGGER Controls..............................................6–1

Chapter 7 — Timebase Modes and Setup

Timebase Sampling Modes........................................................7–1

Timebase Setup ...............................................................................7–5

iii

Chapter 8 — Triggers and When to Use Them

Choosing the Right Trigger .......................................................8–1

Edge or SMART? ..............................................................................8–2

Edge Trigger ......................................................................................8–3

TRIGGER SETUP: Edge................................................................8–9

SMART Triggers.............................................................................8–10

TRIGGER SETUP: SMART ........................................................ 8–29

Chapter 9 — ZOOM + MATH

Zoom and Math Controls............................................................. .9–1

Chapter 10 — Zoom, Mathematics and Math Setup

Zooming for Precise Waveform Measurements...........10–1

Math Functions and Options ..............................................10–2

Using Waveform Mathematics...........................................10–5

Configuring for Zoom and Math.........................................10–6

Setting Up FFT Span and Resolution .............................10–17

Contents

Chapter 11 — Display

Chapter 12 — UTILITIES

Setting Up the Display........................................................ 11–1

Printing, Storing, Using Special Modes ........................... 12–1

Hardcopy Setup............................................................................12–2

Time/Date Setup...........................................................................12–4

GPIB/RS232 Setup.......................................................................12–5

Mass Storage Utilities .............................................................. 12–7

Special Modes ........................................................................ 12–19

CAL BNC Setup.............................................................................12–21

Chapter 13 — WAVEFORM STORE & RECALL

Waveform Store......................................................................13–1

Waveform Recall....................................................................13–4

Chapter 14 — CURSORS/MEASURE & Parameters

Cursors: Tools for Measuring Signal Values.................14–1

Parameters: Automatic Measurements ..........................14–4

Pass/Fail Testing...................................................................14–13

Chapter 15 — PANEL SETUPS

Saving and Recalling Panel Setups...............................15–1

Chapter 16 — SHOW STATUS

The Complete Picture — Summarized............................ 16–1

Appendix A — Specifications Appendix B — Enhanced Resolution Appendix C — Fast Fourier Analysis (FFT) Appendix D — Parameter Measurement Appendix E — ASCII-Stored Files

Read This First!

Product and Client Care

We recommend you thoroughly inspect the contents of the scope packaging at once. Check all the contents against the packing list/invoice copy shipped with the instrument and the list on page 1–3 of this manual. Unless LeCroy is notified promptly of a missing or damaged item, we cannot accept responsibility for its replacement. Contact your national LeCroy Customer Service Department or local office immediately (contact numbers follow index).

Warranty LeCroy warrants its oscilloscope products for normal use and

operation within specifications for a period of three years from the date of shipment. Calibration each year is recommended to ensure in-spec performance. Spares, replacement parts and repairs are warranted for 90 days. The instrument's firmware has been thoroughly tested and is thought to be functional, but is supplied without warranty of any kind covering detailed performance. Products not made by LeCroy are covered solely by the warranty of the original equipment manufacturer.

In exercising its warranty, LeCroy will repair or, at its option, replace any product returned within the warranty period to the Customer Service Department or an authorized service center. However, this will be done only if the product is determined by LeCroy’s examination to be defective due to workmanship or materials, and the defect has not been caused by misuse, neglect or accident, or by abnormal conditions or operation.

Note: This warranty replaces all other warranties, expressed or implied, including but not limited to any implied warranty of merchantability, fitness, or adequacy for any particular purpose or use. LeCroy shall not be liable for any special, incidental, or consequential damages, whether in contract or otherwise. The client will be responsible for the transportation and insurance charges for the return of products to the service facility. LeCroy will return all products under warranty with transport prepaid.

1–1

Read This First!

Product Assistance Help on installation, calibration, and the use of LeCroy

equipment is available from the LeCroy Customer Service Department in your country (see contact numbers following the index).

Maintenance Agreements We provide a variety of customer support services. Maintenance

agreements give extended warranty and allow our clients to budget maintenance costs after the initial three-year warranty has expired. Other services such as installation, training, enhancements and on-site repairs are available through special Supplemental Support Agreements.

Staying Up to Date LeCroy is dedicated to offering state-of-the-art instruments,

continually refining and improving the performance of our products. Because of the speed with which physical modifications may be implemented, this manual and related documentation may not agree in every detail with the products they describe. For example, there might be small discrepancies in the values of components affecting pulse shape, timing or offset, and — infrequently — minor logic changes.

However, be assured the scope itself is in full order and incorporates the most up-to-date circuitry.

We frequently update firmware or software during servicing to improve scope performance, free of charge during warranty. We will keep you up to date with such changes, through new or revised manuals and other publications.

But you should retain this, the original manual, for future reference to your scope’s unchanged hardware specifications.

Service and Repair Please return products requiring maintenance to the Customer

Service Department in your country or to an authorized service facility. LeCroy will repair or replace any product under warranty free of charge. The customer is responsible for transportation charges to the factory, whereas all in-warranty products will be returned to you with transportation prepaid. Outside the warranty period, you will need to provide us with a purchase order number before we can repair your LeCroy product. You will be

1–2

billed for parts and labor related to the repair work, and for shipping.

1–3

Read This First!

How to Return a ProductContact your country’s Customer Service Department or local

field office to find out where to return the product. All returned products should be identified by model and serial number. You should describe the defect or failure, and provide your name and contact number. And in the case of products returned to the factory, a Return Authorization Number (RAN) should be used. The RAN can be obtained by contacting the Customer Service Department.

Return shipments should be made prepaid. We cannot accept COD (Cash On Delivery) or Collect Return shipments. We recommend air-freighting.

It is important that the RAN be clearly shown on the outside of the shipping package for prompt redirection to the appropriate LeCroy department.

What Comes with Your Scope The following items are shipped

together with the standard configuration of this oscilloscope:

Ø Front Scope Cover Ø 10:1 10 MΩ Passive Probe — one per channel Ø ProBus Single-Channel Adapter (9354C, 9374C, 9384C

SERIES ONLY)

Ø Two 250 V T-rated Fuses (5 A or 6.3 A depending on model

— see Chapter 3)

Ø AC Power Cord and Plug Ø Operator’s Manual (this manual) Ø Remote Control Manual Ø Hands-On Guide Ø Performance Certificate Ø Declaration of Conformity Ø Warranty

Note: Wherever possible, please use the original shipping carton. If a substitute carton is used, it should be rigid and packed so that that the product is surrounded by a minimum of four inches or 10 cm of shock-absorbent material.

1–4

Instrument

Architecture

General Designed Capabilities

Your oscilloscope is the newest version of a series that set the standard for monochrome DSOs (Digital Storage Oscilloscopes). Each of the scope’s channels has an 8-bit ADC (Analog–to–Digital Converter). On the higher-range models, combining two channels doubles the scope’s sampling rate. While on high-range, four-channel models, combining all channels increases the original rate by four times.

Processors The central microprocessor performs the scope’s computations and

controls its operation. A wide range of peripheral interfaces allow remote control, storage and printing. A support processor constantly monitors the front-panel controls, rapidly reconfiguring setups. Data processing is also rapid, with data being transferred to the display memory for direct waveform display or stored in the reference memories (see below).

Note: Wherever a feature is specific to a particular model, or not included with a model, it is indicated thus: 9314C ONLY, for example. For the complete list of specifications for each model, see the section on that model or its series in Appendix A.

ADCs The instrument’s multiple-ADC architecture ensures absolute

amplitude and phase correlation, maximum ADC performance for multi-channel acquisitions, large record lengths and excellent time resolution.

Memories The copious acquisition memories simplify transient capture by

producing long waveform records that capture even when triggertiming or signal-speed is uncertain. Combining channels also increases the acquisition memory length. There are four memories for temporary storage, and four more for waveform zooming and processing.

2–1

Instrument

Architecture

RIS Repetitive signals can be acquired and stored at a Random

Interleaved Sampling (RIS) rate of 10 GS/s. RIS is a highprecision digitizing technique that enables measurement of repetitive signals to the instrument's full bandwidth, with an effective sampling interval of 100 ps and measurement resolution of 10 ps. (See Chapter 7).

Trigger System The Trigger System offers an extensive range of capabilities,

selected according to the character of the signal, using onscreen menus and front-panel controls. In standard trigger mode these menus and controls enable the selection and setting of parameters such as pre- and post-trigger recording, as well as special modes. The trigger source can be any of the input channels, line (synchronized to the scope’s main input supply) or external. The coupling is selected from AC, LF REJect, HF REJect, HF, and DC; the slope from positive and negative. (See Chapter 8.)

Automatic Calibration The oscilloscope’s automatic calibration ensures an overall

vertical accuracy of typically 1% of full scale. Vertical gain and offset calibration take place each time the volts/div setting is modified. In addition, periodic calibration is performed to ensure long-term stability at the current setting.

Display System The display’s interactive, user-friendly interface is controlled by

push-buttons and knobs (see Chapter 4). The large, 12.5 × 17.5 cm (nine-inch diagonal) screen shows

waveforms and data with enhanced resolution on a variety of grid styles (see Chapter 11). Up to four waveforms can be displayed at once, while the parameters controlling signal acquisition are simultaneously reported. The screen presents internal status and measurement results, as well as operational, measurement, and waveform-analysis menus.

Printing or copying the screen on plotter, printer or to a recording medium is done by pressing the front-panel SCREENDUMP button(See Chapter 12).

2–2

Manual or Remote Control

Despite being a truly digital instrument, the scope has a frontpanel layout and controls that will be familiar to users of analog oscilloscopes. Rapid instrument response and instant representation of waveforms on the high-resolution screen add to this impression.

Four front-panel setups can be stored internally and recalled either manually or by remote control, thus ensuring rapid frontpanel configuration. When the power is switched off, the current front-panel settings are automatically stored for subsequent recall at the next power-on.

The oscilloscope has also been designed for remote control operation in automated testing and computer-aided measurement applications — operations described in the Remote Control Manual. The entire measurement process, including cursor and pulse-parameter settings, dynamic modification of front-panel settings, and display organization, is controlled through the rear-panel GPIB (IEEE-488) and RS-232-C ports (see Chapter 12).

2–3

Block Diagrams

Program memory

Microprocessor

Storage devices

Ø 9304C, 9310C, 9314C

Instrument

Architecture

Series

Hi-Z, 50 Amplifiers + Attenuators

CH1

CH2

External

trigger

CH3

CH4

Sample

& Hold

Sample

& Hold

Sample

& Hold

Sample

& Hold

Trigger

logic

8-bit

Flash ADC

8-bit

Flash ADC

Timebase

8-bit

Flash ADC

8-bit

Flash ADC

Fast

memory

Fast

memory

Fast

memory

Fast

memory

processor

Display

Centronics

RS-232-C

GPIB

Coprocessor

Front-panel

processor

Real-time

clock

Data memories

2–4

Ø 9344C, 9350C, 9354C

Program memory

Microprocessor

Series

Ø 9370C, 9374C Series Ø 9384C Series

Hi-Z, 50 Amplifiers + Attenuators

CH1

CH2

External

trigger

CH3

CH4

Sample

& Hold

Sample

& Hold

Sample

& Hold

Sample

& Hold

8-bit ADC

Trigger

logic

8-bit ADC

Peak

detect

Peak

detect

Timebase

Peak

detect

Peak

detect

Fast

memory

Fast

memory

Fast

memory

Fast

memory

Display

processor

Storage devices

Centronics

RS-232-C

GPIB

Coprocessor

Front-panel

processor

Real-time

clock

Data memories

2–5

Installation and Safety

Installation for Safe and Efficient Operation

The oscilloscope will operate to its specifications if the operating environment is maintained within the following parameters:

Operating Environment

Safety Symbols Where the following symbols or indications appear on the

Symbol Meaning

Ø Temperature..........................5 to 40 °C (41 to 104 °F) rated.

Ø Humidity................................Maximum relative humidity 80 % RH

(non-condensing) for temperatures up to 31 °C decreasing linearly to 50 % relative humidity at 40 °C

Ø Altitude ..................................< 2000 m (6560 ft)

The oscilloscope has been qualified to the following EN61010-1 category:

Ø Protection Class.........................................I

Ø Installation (Overvoltage) Category...........II

Ø Pollution Degree.........................................2

instrument’s front or rear panels, or elsewhere in this manual, they alert the user to an aspect of safety.

CAUTION: Refer to accompanying documents (for Safetyrelated information).

See elsewhere in this manual wherever the symbol is present, as indicated in the Table of Contents.

CAUTION: Risk of electric shock.

On (Supply).

3–1

Installation and Safety

Symbol Meaning

Off (Supply)

Earth (Ground) Terminal

Protective Conductor Terminal

Chassis Terminal

Earth (Ground) Terminal on BNC Connectors

Denotes a hazard. If a WARNING is indicated on the

WARNING

WARNING Any use of this instrument in a manner not specified by the

Power RequirementsThe oscilloscope operates from a 115 V (90 to 132 V) or 220 V (180

instrument, do not proceed until its conditions are understood and met.

manufacturer may impair the instrument’s safety protection. The oscilloscope has not been designed to make direct measurements on the human body. Users who connect a LeCroy oscilloscope directly to a person do so at their own risk. Use only indoors.

to 250 V) AC power source at 45 Hz to 66 Hz.

3–2

No voltage selection is required, since the instrument automatically adapts to the line voltage present.

Fuses The oscilloscope’s power supply is protected against short-circuit and

overload by means of two “T”-rated fuses of type according to scope model:

Ø 6.3 A/250 V AC 9344C, 9350C, 9354C, 9370C, 9374C, 9384C Series Ø 5 A/250 V AC 9304C, 9310C, 9314C Series.

The fuses are located above the mains plug. Disconnect the power cord before inspecting or replacing a fuse. Open the fuse box by inserting a small screwdriver under the plastic cover and prying it open. For continued fire protection at all line voltages, replace only with fuses of the specified type and rating (see above).

Ground The oscilloscope has been designed to operate from a single-phase

power source, with one of the current-carrying conductors (neutral conductor) at ground (earth) potential. Maintain the ground line to avoid an electric shock. None of the current-carrying conductors may exceed 250 V rms with respect to ground potential. The oscilloscope is provided with a three-wire electrical cord containing a three-terminal polarized plug for mains voltage and safety ground connection. The plug's ground terminal is connected directly to the frame of the unit. For adequate protection against electrical hazard, this plug must be inserted into a mating outlet containing a safety ground contact.

Cleaning and Maintenance Maintenance and repairs should be carried out exclusively by a LeCroy

technician (see Chapter 1). Cleaning should be limited to the exterior of the instrument only, using a damp, soft cloth. Do not use chemicals or abrasive elements. Under no circumstances should moisture be allowed to penetrate the oscilloscope. To avoid electric shocks, disconnect the instrument from the power supply before cleaning.

CAUTION Risk of electrical shock: No user-serviceable parts inside. Leave

repair to qualified personnel.

Power On Connect the oscilloscope to the power outlet and switch it on by pressing

the power switch located on the rear panel. After the instrument is switched on, auto-calibration is performed and a test of the oscilloscope's ADCs and memories is carried out. The full testing procedure takes approximately 10 seconds, after which time a display will appear on the screen.

3–3

Two-Channel Front Panel

Introduction to the

Controls

4–1

Four-Channel Front Panel

Introduction to the

Controls

4–2

The Main Controls

The front panel controls are divided into four main groups of buttons and knobs: the System Setup and menu controls, CHANNELS, TIMEBASE + TRIGGER and ZOOM + MATH.

System Setup Dark-gray, menu-entry buttons, also represented in the other

groups of controls, provide access to the main on-screen menus and the acquisition, processing and display modes of the instrument.

The SCREEN DUMP, SHOW STATUS and CLEAR SWEEPS buttons, respectively: copy or print the screen display, show onscreen summaries of the scope’s status, and restart operations that require several acquisitions. See page 4–6.

Menu Buttons & Knobs The seven untitled buttons vertically aligned beside the screen,

RETURN and the two linked rotary knobs enable on-screen menu selection. See following pages.

CHANNELS This group offers selection of displayed traces and adjustment of

vertical sensitivity and offset. See Chapter 5.

AUTO SETUP This singular blue button automatically adjusts the scope to acquire

and display signals on the input channels. See Chapter 6.

TIMEBASE + TRIGGER These controls allow direct adjustment of time/division, trigger level

and delay, as well as access to the “TIMEBASE” and “TRIGGER” menu groups. See Chapters 6, 7 and 8.

ZOOM + MATH And this group controls trace selection, movement, definition, and

expansion with Zoom and Math functions. See Chapters 9 and 10.

See also “ Getting Started”, Part 2 of the Hands-On Guide , for more on the front-panel and a complete run-through of the controls…

4–3

Introduction to the

entry

Choosing and Navigating in Menus

On-screen menus — the panels running down the righthand side of the screen — are used to select specific scope actions and settings. All other on-screen text is for information only. The menus are broadly grouped according to function. The name of each menu group is shown at the top of the column of menus. Individual menus also have names in the top of their frames.

Each menu either contains a list of items or options — functions to be selected or variables modified — or when selected performs a specific action. Menus that perform certain actions are indicated by capitalized text, as in the example shown at left.

Controls

Going to Menus and Selecting from them

When a menuconfiguration for its particular group of functions is immediately displayed on-screen as a menu group. Once accessed, these menus are controlled using the menu buttons and the two menu knobs (illustrated at left).

A menu button is active and can be pressed to make selections whenever a menu is visible beside it on-screen.

The two menu knobs work together with the two menu buttons to which they are joined by lines. Both control the menus currently shown beside them. Buttons and knobs are used either for selecting entire menus, particular items from menus, for moving up or down through menu lists, or for changing the values listed in menus.

Some menus, referred to as primary, have secondary menus beneath them whose existence is indicated by a heavy outline or shadow, as illustrated at left. Pressing the corresponding menu button reveals and activates these ‘hidden’ menus. Pressing the RETURN button again displays the top, or primary, menu.

Changing a menu value normally changes the screen, because the new value is immediately used in acquisition settings, processing or display.

button is pressed, the set-up

4–4

Setting Menu Options The activated selection is highlighted in the menu. Press the

corresponding menu button and the field will advance to highlight and select the next item on the menu. However, if there is only one item on a menu, pressing its button will have no effect.

Where a menu is associated with one of the two menu knobs, turning this knob in one direction or the other will cause the selection to move either up or down the list in the menu.

Menus that extend along the length of two menu buttons can be operated using both buttons. Pressing the lower of the two will move the highlighting forward — down the list — while pushing the upper will move the selector back up the list.

An arrow on the side of a menu frame indicates that by pressing the button beside this arrow, the selection can be moved further up or down the list. The arrow’s direction shows whether the highlighting selector will move up or down. Arrows may also indicate items that are not visible, either above or below on the list. The respective arrow will disappear when the selection is at the very beginning or end of the list.

As in the examples at left, some menu button and knob combinations control the value of a continuously adjustable variable. The knob is then used to set its value, while the button either selects a value or makes a simple change in it.

Still other menu button and knob combinations control the value of several continuously adjustable variables, with the knob used to set the value and the button to highlight it.

Note: When the oscilloscope is placed in a remote state, the REMOTE ENABLE menu will be displayed. It will contain the command “GO TO LOCAL”, activated by menu button if the action is possible. This is the only manual way to turn off the REMOTE ENABLE menu. The scope need not be in remote state to accept remote commands.

4–5

Introduction to the

System Setup and Menu Controls

As well as the menu buttons and knobs described on the previous pages, the System Setup controls include the menuentry buttons and others for copying displays, reporting instrument status and restarting multiple-acquisition operations.

The RETURN button is used to go back to the preceding displayed menu group. Or it returns the display to a higher-level, or primary menu. But when the display is at the highest possible menu level, the button switches off that menu.

Each of the dark-gray menu-entry buttons activates a major set of on-screen menus (those represented in the other control groups are

described in the following chapters, along with the other elements in the groups).

The DISPLAY button provides entry to the “DISPLAY SETUP” group of menus, controlling display mode, grids, intensities, Dot Join and Persistence menus. See Chapter 11.

Controls

The UTILITIES button gives access to the “UTILITIES” menus, controlling hardcopy setups, GPIB addresses and special modes of operation. Chapter 12.

The WAVEFORM STORE button “STORE W’FORM” menus, used for storing waveforms to internal or external memory. Chapter 13.

Whereas, WAVEFORM RECALL “RECALL W’FORM”: menus for retrieving waveforms stored in internal or external memory. Chapter 13.

CURSORS/MEASURE menus, used for making precise cursor measurements on traces, and “MEASURE”, for precise parameter measurements. Chapter

14.

4–6

offers up the “CURSORS” Setup

accesses the

calls up

And PANEL SETUPS gives access to the “PANEL SETUPS” menus for saving and recalling a configuration of the instrument.

See Chapter 13.

SCREEN DUMP — prints or plots the screen display to an on-line hardcopy device,

via the GPIB, RS-232-C or Centronics interface ports, or directly to an external thermal graphics printer. Hardcopies can also be generated as data files onto floppy, memory card or portable hard disk.

Once SCREEN DUMP is pressed, all displayed information will be copied. However, it is possible to copy the waveforms without the grid by turning the grid intensity to 0 with the “Display Setup” menu.

While a screen dump is taking place — indicated by the on-screen “PRINTING” or “PLOTTING” message — it can be aborted by pressing SCREEN DUMP a second time. It will take a certain amount of time for the buffer to empty before copying stops.

CLEAR SWEEPS — restarts operations requiring several acquisitions, or sweeps,

including averaging, extrema, persistence and pass/fail testing, by resetting the sweep counter(s) to zero.

SHOW STATUS — menu entry to “STATUS”, which shows summaries of the

instrument’s status for acquisition, system and other aspects. See

Chapter 16.

4–7

Screen Topography

Introduction to the

Controls

The sections of the screen shown here and described below, which surround the grid, contain a variety of useful information as well as accessing specific commands and functions.

4–8

Real-Time Clock field: powered by a battery-backed real-time clock, it displays the current date and time.

Displayed Trace Label indicates each channel or channel displayed, the time/div and volts/div settings, and cursor readings where appropriate. It indicates the acquisition parameters set when the trace was captured or processed, while the Acquisition Summary field (below) indicates the present setting.

Acquisition Summary field: timebase, volts/div, probe attenuation and coupling for each channel, with the selected channel highlighted. It indicates the present setting, while the acquisition parameters set when the trace was captured or processed are indicated in the Displayed Trace label (above).

Trigger Level arrows on both sides of the grid that mark the trigger voltage level relative to ground level.

Trigger Delay: an arrow indicating the trigger time relative to the trace. The delay can be adjusted from zero to ten grid divisions (pre-trigger), or zero to −10 000 (post-trigger) offscreen. Pre-trigger delay appears as the upward-pointing arrow, while post-trigger is given as a delay in seconds.

Trigger Status field shows sample rate and trigger re-arming status (AUTO, NORMAL, SINGLE, STOPPED). The small square icon flashes to indicate that an acquisition has been made.

Trigger Configuration field: icon indicating type of trigger, and information on the trigger’s source, slope, level and coupling, and other information when appropriate.

Trace and Ground Level: trace number and ground-level marker.

4–9

Introduction to the

AUTO

SETUP

Controls

Other Fields

(not illustrated here)

Time and Frequency field: displays time and frequency relative to cursors beneath the grid. For example, when the absolute time cursor (the cross-hair) is activated by selection from the “MEASURE” menu group, this field displays the time between the cursor and the trigger point.

Message field: used to display a variety of messages, above the grid, including warnings, indications and titles showing the instrument’s current status.

General Instrument Reset: Simultaneously press the AUTO SETUP button, the top menu button, and the RETURN button. The scope will revert to its default power-up settings.

Press:

+ +

4–10

Channel Controls

These enable selection of displayed traces and adjustment of vertical sensitivity and offset.

TRACE ON/OFF Pressing these buttons either

displays or switches off the corresponding channel trace. When a channel is switched on, the OFFSET and VOLTS/DIV controls will then be attributed to this, the active channel. On twochannel models (right), each channel has its own set of unique, dedicated controls.

CHANNELS, Coupling & Probes

SELECT CHANNEL On four-channel models

(right), these buttons are used to attribute all the vertical controls to one channel, independent of whether or not it is the channel displayed. The selected channel number is highlighted in the Acquisition Summary field (see previous chapter).

OFFSET — vertically positions the

active channel.

5–1

CHANNELS, Coupling & Probes

FIND — automatically adjusts offset and volts/div to match the active

channel’s input signal.

VOLTS/DIV — selects the vertical sensitivity factor either in a 1–2–5 sequence

or continuously (see VAR, below ). The effect of gain changes on the acquisition offset can be chosen from the “SPECIAL MODES” menu.

VAR — allows the user to determine whether the VOLTS/DIV knob will

modify the vertical sensitivity in a continuous manner or in discrete 1–2–5 steps.

The format of the vertical sensitivity in the Acquisition Summary field (bottom left of screen) shows whether the VOLTS/DIV knob is operating in continuous or stepping mode.

COUPLING — menu-entry button that accesses the “Coupling” menus (see next

section).

5–2

Coupling

Coupling Menus Press for access to selection of:

Ø Coupling and grounding of each input channel Ø ECL or TTL gain, offset and coupling preset for the

channel shown

Ø Bandwidth limiter for all channels Ø Probe attenuation of each input channel.

Coupling

Used to select the input channel’s coupling. If an overload is detected, the instrument will automatically set the channel to the grounded state: the menu can then be reset to the desired coupling.

V/div Offset

When NORMAL is highlighted, pressing the corresponding menu button sets the offset, Volts/div, and input coupling to display ECL signals. Press the button a second time and the settings for TTL signals are given. And a third time returns the settings to those used at the last manual setup of the channel.

Global BWL

To turn the bandwidth limit “OFF” or “ON”. The bandwidth can be reduced from 500 MHz or 1 GHz, to either 200 MHz or 25 MHz, or 30 MHz (–3dB), depending on the model (see Appendix A). Bandwidth limiting can be useful in reducing signal and system noise or preventing high-frequency aliasing, reducing — for example — any high-frequency signals that may cause aliasing in single-shot applications.

Note: This command is global and affects all input channels.

Probe Atten

Sets the probe attenuation factor related to the input channel (see following for probe details).

5–3

CHANNELS, Coupling & Probes

In the AC position, signals are coupled capacitively, thus

blocking the input signal’s DC component and limiting the

In the DC position, all signal frequency components are

allowed to pass through, and 1

MΩ or 50

Ω may be chosen as

The maximum dissipation into 50

Ω is 0.5

W and inputs will

automatically be grounded whenever this is attained. An

overload message will be displayed in the Acquisition

Summary Field and “Grounded” will be indicated in the

the signal from the input and again selecting the 50

Ω input

Probes and Probe Calibration

Probe Calibration To calibrate the probe supplied, connect it to one of the input

channels’ BNC connectors. Connect the probe’s grounding alligator clip to the CAL BNC ground and touch the tip to the inner conductor of the CAL BNC. The CAL signal is a 1 kHz square wave, 1 V p-p.

Set the channel coupling to DC 1 MΩ, turn the trace ON and push AUTO SETUP to set up the oscilloscope. If over- or undershoot of the displayed signal occurs, the probe can be adjusted by inserting the small screwdriver, supplied with the probe package, into the trimmer on the probe’s barrel and turning it clockwise or counter-clockwise to achieve the optimal square-wave contour.

More On Coupling

signal frequencies below 10 Hz.

the input impedance.

“Coupling” menu. The overload condition is reset by removing impedance from the menu.

5–4

ProBus System LeCroy’s ProBus system provides a complete measurement

solution from probe tip to oscilloscope display. This intelligent interconnection between LeCroy oscilloscopes and a growing range of accessories is achieved via a six-wire bus following Philips’ I2C protocol. It provides major benefits over standard BNC or even probe-ring connections:

Ø Autosensing the probe type, eliminating all the guesswork —

and the errors — from manually setting attenuation or amplification factors, and ensuring proper input coupling.

Ø Transparent gain and offset control right from the front panel

— particularly useful for FET (FET menus shown here) and current probes.

Ø Gain and offset correction factors are uploaded from the

ProBus EPROMS on FET probes and automatically compensated to achieve fully calibrated measurements.

Coupling

Used to select the input channel’s coupling. If an overload is detected, the instrument will automatically set the channel to the grounded state: the menu can then be reset to the desired coupling.

V/div Offset

Global BWL

When a FET probe is used, “Probe sensed…”, automatically appears to indicate settings. When other ProBus probes are used, this is redefined.

5–5

TIMEBASE + TRIGGER

TIMEBASE + TRIGGER Controls

These controls allow direct adjustment of time/division, trigger level and delay, and access the “TIMEBASE” and “TRIGGER” menu groups.

AUTO SETUP The blue button

automatically scales the timebase, trigger level, offset, and volts/div to provide a stable display of repetitive signals.

AUTO SETUP operates only on channels which are active. If no channels are on, then AUTO SETUP will operate on all channels, switching them all on.

Signals detected must have an amplitude between 5 mV and 40 V, a frequency greater than 50 Hz, and a duty cycle greater than 0.1 %.

If signals are detected on several channels, the channel with the lowest number will determine the selection of the timebase and trigger source.

STOP This button halts the acquisition in any of the three re-arming

modes: Auto, Normal or Single. Pressing the STOP button prevents the oscilloscope acquiring a

new signal. Press STOP while a single-shot (see next chapter) acquisition is

under way and the last acquired signal will be kept.

6–1

TIMEBASE + TRIGGER

Press STOP after an RIS acquisition has been started (next chapter) and the acquisition will be halted and a partial

waveform reconstruction will be performed. Press STOP when the acquisition is in Roll Mode (see next

chapter) and the incomplete acquisition data will be shown as if a trigger had occurred.

In Sequence Mode (next chapter), the action will stop the timebase and show all new segments.

AUTO Pressing this button places the instrument in Auto Mode: the

scope automatically displays the signal if no trigger occurs within 60 ms.

If a trigger does occur within this time, the oscilloscope behaves as in Normal Mode.

Press AUTO in RIS Mode and the acquisition will be terminated and shown each second (some required segments may be missing).

Press the button in Roll Mode and the oscilloscope will sample the input signals continuously and indefinitely. The acquisition will have no trigger condition but can be stopped as desired.

Press AUTO in Sequence Mode and the acquisition will be terminated if the time between two consecutive triggers exceeds a timeout that can be selected. The next acquisition is then started from Segment 1.

NORM Pressing this button will continuously update the screen as long

as a valid trigger is present. If not, the last signal is preserved and the warning “SLOW TRIGGER” is displayed in the Trigger Status Field.

Press NORM in Roll Mode and the acquisition will be terminated when the last needed data after a trigger have been taken. The display will pause to show the entire waveform. It then goes back into Roll Mode while it waits for the next trigger.

Press this button in Sequence Mode and the acquisition will be terminated after the last segment is acquired. The next acquisition will start immediately. Sequence WRAP in Normal is the same as in Single-Shot Mode.

6–2

SNGL Pressing this button places the scope in Single-Shot Mode,

where it waits for a single trigger to occur, then displays the signal and stops acquiring. If no signal occurs, the button can be pressed again to show the signal being observed without a trigger.

Press SNGL when in RIS Mode and the instrument will wait for all the trigger events required to build up one signal on screen before it stops. This may require as many as 4000 trigger events.

Single-Shot Roll Mode behavior is the same as standard SingleShot but without the need to press the button a second time to show the signal.

DELAY — is used to adjust the pre- or post-trigger delay. Pre-trigger

adjustment is available from zero to 100 % of the full time-scale in steps of 1 %. The pre-trigger delay is illustrated by the vertical arrow symbol at the bottom of the grid. Post-trigger adjustment is available from 0 to 10 000 divisions in increments of 0.1 of a division. The post-trigger-delay value is labeled in seconds and is located in the on-screen Trigger Delay field.

ZERO — sets the trigger delay at zero, the trigger instant at the left-

hand edge of the grid.

TIME/DIV — selects the time per division in a 1–2–5 sequence. The

time/div setting is displayed in the Acquisition Summary field.

LEVEL — adjusts the trigger threshold. The amplitude of trigger signals

and the range of trigger levels is limited: ± 5 screen divisions with a channel as trigger source; ± 0.5 V with EXT as trigger source; ± 5 V with EXT/10 as trigger source; and Inactive with Line as trigger source. The trigger sensitivity is better than a third-of-a-screen division.

6–3

TIMEBASE + TRIGGER

TIMEBASE SETUP — menu-entry button that calls up the “TIMEBASE” menus

described in the next chapter.

TRIGGER SETUP — menu-entry button that calls up “TRIGGER SETUP” detailed

in Chapter 8.

6–4

Timebase Modes and Setup

Timebase Sampling Modes

Depending on the timebase, any of three sampling modes can be chosen: Single-Shot, Random Interleaved Sampling (RIS) or Roll Mode. Furthermore, for timebases suitable for either Single-Shot or Roll Mode, the acquisition memory can be subdivided into user-defined segments to give Sequence Mode. Channels can also be combined to boost sample rate and record length.

Single-Shot Single-Shot is the digital oscilloscope’s basic acquisition

technique and other timebase modes make use it. An acquired waveform consists of a series of measured voltage

values sampled at a uniform rate on the input signal. The acquisition, a single series of measured data values associated with one trigger event, is typically stopped at a fixed time after the arrival of the event, this being determined by the trigger delay. The time of the trigger event is measured using the timebase clock. The horizontal position of a waveform is determined using the trigger event as the definition of time zero. Waveform display is also carried out using this definition.

Because each channel has its own ADC, the voltage on each input channel is sampled and measured at the same instant. This allows very reliable time measurements between different channels.

Trigger delay can be selected anywhere within a range that allows the waveform to be sampled from well before the trigger event up to the moment it occurs (100 % pre-trigger), or at the equivalent of 10 000 divisions (at the current time/div) after the trigger.

For fast timebase settings the ADCs’ maximum single-shot sampling rate is used (on one and each channel, with higher sampling rates achieved by combining channels — see page 7–4). For slower timebases, the sampling rate is decreased and the number of data samples maintained. (See Appendix A for details).

7–1

Timebase Modes and Setup

Peak Detect

NOT AVAILABLE WITH 9304C, 9310C, 9314C SERIES

RIS: Random Interleaved Sampling

When using slow timebases, sample-rate decreases and very short events such as glitches can be missed if they occur between two samples. To prevent this, a special circuitry called the Peak Detect system can be switched on (see “Channel Use” menu, page 7–5) to capture the signal envelope with a resolution of 2.5 ns. This is done without destroying the underlying, simultaneously captured data, on which a wide range of advanced processing can be performed.

RIS is an acquisition technique that allows effective sampling rates higher than the maximum single-shot sampling rate. It is used on repetitive waveforms with a stable trigger.

The maximum effective sampling rate of 10 GS/s can be achieved by acquiring 100 single-shot acquisitions, or bins, at 100 MS/s using the 9304C, 9310C, 9314C Series oscilloscopes; 20 bins at 500 MS/s when using the other models. These bins are positioned approximately 0.1 ns apart. The process of acquiring this number of bins and satisfying the time constraint is random. The relative time between ADC sampling instants and the event trigger provides the necessary variation, measured by the timebase to 10 ps accuracy.

7–2

On average, 104 trigger events are needed to complete an acquisition. But sometimes many more are needed. These segments are interleaved to provide a waveform covering a time interval that is a multiple of the maximum single-shot sampling rate. However, the real-time interval over which the waveform data are collected is orders of magnitude longer and depends on the trigger rate and the desired level of interleaving. The oscilloscope is capable of acquiring approximately 40 000 RIS segments per second.

Roll Single-shot acquisitions at timebase settings slower than

0.5 s/div (10 s/div for traces with more than 50 000 points) have a sufficiently low data rate to allow the display of the incoming points in real time. The oscilloscope shows the incoming data continuously, “rolling” it across the screen, until a trigger event is detected and the acquisition completed. The latest data is used to update the trace display in the same manner as a strip-chart recorder. Waveform Math and Parameter calculations are done on the completed waveforms.

Note: The behavior of , ,

and

is modified in Roll Mode and Sequence Modes (refer to previous chapter and pages 7–8 and 7– 9).

Sequence Sequence Mode is an alternative to single-shot acquisition that

offers many unique features. The complete waveform consists of a number of fixed-size segments acquired in Single-Shot Mode (see Appendix A for the limits), which are able to be selected. .

The dead time between the trigger events for consecutive segments can be kept to under 50 µs — in contrast to the hundreds of milliseconds normally found between consecutive single-shot waveforms. Complicated sequences of events covering a large time interval can be captured in fine detail,

Note: to ensure low deadtime between segments, button-pushing and knob-turning is to be avoided during sequence acquisition.

ignoring uninteresting periods between events. And time measurements can be made between events on different

7–3

Timebase Modes and Setup

segments of a sequence waveform using the full precision of the acquisition timebase.

Trigger-time stamps are given for each of the segments in the “Text & Times Status” menu. Each individual segment can be displayed by Zoom, or used as input to the MATH functions. Sequence Mode can be used in remote operation to take full advantage of the scope’s high data-transmission capability: overlapping transmission of one waveform with its successor’s acquisition (see the Remote Control Manual for details).

The timebase setting in Sequence Mode is used to determine the acquisition duration of each segment, which will be 10 x TIME/DIV.

Timebase setting, desired number of segments, maximum segment length and total available memory are used to determine the actual number of samples/segment and time/point. The display of the complete waveform with all its segments may not entirely fill the screen.

Sequence Mode is normally for acquiring the desired number of segments and terminating the waveform acquisition. It can also be used to acquire the segments continuously, overwriting the oldest ones as needed, with a manual STOP order or timeout condition being used to terminate the waveform acquisition.

Combining Channels

NOT AVAILABLE WITH 9304C, 9310C, 9314C SERIES

The ADCs can be interleaved to boost standard sampling rate and record length considerably.

When channels are combined on two-channel models, both channels are paired on Channel 2, while Channel 1 is disabled. On four-channel models, the two pairs of channels are enabled on Channels 2 and 3, while Channels 1 and 4 are disabled. Both maximum sampling rate and record length are doubled using this function, activated by menu selection (see page 7–9).

On fast timebases it is even possible to again double the sampling rate by means of a special adapter. With this adapter in place, the oscilloscope interleaves the four ADCs and the acquisition memory to achieve the maximum sampling rate and up to four times the initial record length (see Appendix A for details).

7–4

Timebase Setup

TIMEBASE Press

Ø Single-Shot or Interleaved (RIS) sampling Ø External clock Ø Channel pairing (combining) and Peak Detect .. Ø Sequence Mode Ø Number of segments in Sequence Mode Ø Maximum record length.

The “TIMEBASE” menus also show the number of points acquired, the sampling rate and the total time span.

Sampling

For selecting either of the two principal modes of acquisition: Ø “Single Shot” — displays data collected during successive

single-shot acquisitions from the input channels. This mode allows the capture of non-recurring or very low repetition-rate events simultaneously on all input channels.

Ø “RIS” (Random Interleaved Sampling) — achieves a higher

effective sampling rate than Single-Shot, provided the input signal is repetitive and the trigger stable.

Sample Clock

To select “Internal” or External (“ECL”, “OV ”, “TTL”) clock modes (see next page).

Channel Use (NOT AVAILABLE WITH 9304C, 9310C, 9314C SERIES)

To select for channel pairing and, on models with this feature, to control Peak Detect Mode (refer page 7–2).

Sequence

For turning “Off” or selecting “Sequence” or “Wrap ” Mode. See page 7–10.

Record up to

to access and choose:

7–5

Timebase Modes and Setup

For selecting the maximum number of samples to be acquired, using the associated menu knob. See Appendix A for model

maximums.

7–6

TIMEBASE EXTERNAL — appears when an External clock mode is chosen.

Sampling

This menu is inactive when the external sample clock is being used. Only single-shot acquisition is available (see below ).

Sample Clock

For selecting a description of the signal applied to the EXT BNC connector for the sample clock up to 100 MHz. The rising edge of the signal is used to clock the ADCs of the oscilloscope. The effective thresholds for sampling the input are*:

ECL..................................... −1.3 V

0V ....................................... 0.0 V

TTL................................ ...... +1.5 V

(With CKTRIG Option ONLY) RP (Rear Panel) specifies that the 50–500 MHz external clock connected to the rear panel be used as the sample clock (see CKTRIG Manual for details).

External

To select the input coupling for the external clock signal.

Sequence

Offers Sequence Mode. The corresponding knob is used to adjust the number of segments. Neither the trigger time stamps nor the AUTO sequence time-out feature are available when the external clock is in use. Nor is the inter-segment dead time guaranteed.

Record

To select the desired number of samples for the single-shot acquisition. See Appendix A for model maximums.

External clock modes are available only if the EXT trigger is not

the trigger source.

7–7

Timebase Modes and Setup

ger and the external

Notes for using External Clock

Ø The time/div is expressed in s/div, to be understood to be samples/div. Ø The trigger delay is also expressed in samples and can be adjusted as normal. Ø No attempt is made to measure the time difference between the trig

clock. Therefore, successive acquisitions of the same signal can appear to jitter on the screen.

Ø The oscilloscope will require a number of pulses (typically 50) before it recognizes the

external clock signal. The acquisition is halted only when the trigger conditions have been satisfied and the appropriate number of data points have been accumulated.

Ø Any adjustment to the time/division knob automatically returns the oscilloscope to

normal (internal) clock operation.

7–8

TIMEBASE — Sequence — for operating in Sequence Mode

Sampling

This menu is inactive when the external sample clock is being used. Only single-shot acquisition is available (see pages 7–7, 7– 1).

Sample Clock

For selecting a description of the signal applied to the EXT BNC connector for the sample clock (7–7).

Channel Use (NOT AVAILABLE WITH 9304C, 9310C, 9314C SERIES)

For combining or pairing channels to achieve more memory and a greater sampling rate by interleaving the ADCs in time. When “2” is selected on two-channel models both channels are combined, or paired. While when the same selection is made on four-channel models either Channels 1 and 2 or 3 and 4 may be combined. But when “1” on two-channel models or “4” on four-channel scopes is selected, none of the channels is combined.

Sequence

When either “On” or “Wrap” are activated, the menu changes to the one shown here. The associated menu knob is used to choose the desired number of segments, here given in example as “100 segments”..

Also, when “Sequence“ is “On”: If the trigger mode is Single

the oscilloscope fills the segments

and stops.

But it will wait until is pressed if there are not enough trigger events to fill the segments.

If the trigger mode is Normal the oscilloscope fills the segments and then, if more trigger events occur, the acquisition is restarted from Segment 1.

7–9

Timebase Modes and Setup

If the trigger mode is Auto and if the time between two consecutive triggers exceeds a time-out that can be selected, the acquisition is restarted from Segment 1. The time-out is selected in “SPECIAL MODES” “UTILITIES”.

However, when “Wrap” is selected, the segments are filled continuously until the STOP button is pressed. The last n segments will be displayed. An alterna tive way to stop the WRAP sequence is through AUTO mode; if the time between two consecutive triggers exceeds a time-out that can be selected, the acquisition will stop.

Max. segment

To select using the corresponding button or associated knob the maximum record length for each segment. See Appendix A for

model maximums.

Note: A summary of the acquisition conditions is displayed above the “TIMEBASE” menus, indicating number of segments, available record length per segment, sampling rate, and timebase setting.

7–10

Triggers and When to Use Them

Choosing the Right Trigger

Your oscilloscope offers many distinctive and useful techniques for triggering on and capturing data. These range from the simple Edge triggers to the advanced SMART Trigger types, which trigger on multiple inputs.

Three triggering modes are available: AUTO, NORM and SNGL. Additionally, STOP enables the acquisition process to be aborted. All are directly accessible by pressing the respective front-panel buttons. (See Chapter 6.)

Modifying Trigger Settings Trigger adjustments are made directly using the front-panel controls

and with the trigger menus.

Rotating — for example — causes the scope to adjust the trigger level of the highlighted trace.

Pressing accesses advanced trigger operations, such as changing the glitch width or the hold-off timeout, which are changed via the TRIGGER SETUP menu group (Fig. 8–1). Once the trigger configuration has been modified, changes are stored internally in a non-volatile memory.

This chapter describes the triggering operations and offers hints on how to perform them. Along with the standard menu descriptions, schematics show the trigger-menu structure, and diagrams explain how the main triggers work.

TRIGGER SETUP

Edge

SMART

Figure 8–1. Main Trigger Menu.

8–1

Triggers and When to Use Them

Edge or SMART

A variety of triggers for different applications can be chosen from the two main trigger groups, the Edge and SMART trigger types.

Edge Triggers In the Edge group of menus trigger conditions are defined by the

vertical trigger level, coupling, and slope. Edge triggers use simple selection criteria to characterize a signal. They are most useful for triggering on simple signals (see page 8–3).

SMART Trigger The SMART Trigger types allow additional qualifications to be

set before a trigger is generated. These qualifications can be used to capture rare phenomena such as glitches or spikes, specific logic states, or missing bits. A qualification might include trigger generation only on a pulse wider or narrower than a user-specified limit. Or it might require — to take but another example — three trigger sources exceeding specific levels for a minimum time.

Generally speaking, SMART Trigger offers various trigger qualifications based on three basic abilities:

1. To count a specified number of events

2. To measure time intervals

3. To recognize a pattern input.

SMART explanations start on page 8–10 and on page menus 8–

29.

Trigger Symbols, illustrated throughout this chapter, allow immediate on-screen recognition of the current trigger conditions. There is a symbol for each Edge and SMART Trigger type, with the more heavily-marked transitions on the symbols indicating where a trigger will be generated.

8–2

Edge Trigger

Selecting Edge and its menus (Fig. 8–2) causes the scope to trigger whenever the selected signal source meets the trigger conditions. The trigger source is defined by the trigger level, coupling, slope or hold-off.

Edge

Trigger on

Coupling

Slope Pos|Neg|Window

Holdoff

Figure 8–2. Edge Trigger Menu (see page 8–9).

1|2|3|4|Ext|Ext10|Line

DC|AC|LFREJ|HFREJ|HF

Off|Time (10 ns to 20 s)

|Events (1to 99 999 999)

8–3

Triggers and When to Use Them

Trigger Source The trigger source may be:

Ø The acquisition channel signal (CH 1, CH 2 or CH 3, CH 4

on four-channel models) conditioned for the overall voltage gain, coupling, and bandwidth.

Ø The line voltage that powers the oscilloscope (LINE). This

can be used to provide a stable display of signals synchronous with the power line. Coupling and level are not relevant for this selection.

Ø The signal applied to the EXT BNC connector (EXT). This

can be used to trigger the oscilloscope within a range of ± 0.5 V, or ± 5 V with EXT/10 as trigger source.

Level Level defines the source voltage at which the trigger circuit will

generate an event (a change in the input signal that satisfies the trigger conditions). The selected trigger level is associated with the chosen trigger source. Note that the trigger level is specified in volts and is normally unchanged when the vertical gain or offset is modified.

The Amplitude and Range of the trigger level are limited as follows:

Ø ± 5 screen divisions with a channel as trigger source Ø ± 0.5 V with EXT as trigger source Ø ± 5 V with EXT/10 as trigger source Ø None with LINE as trigger source (zero crossing is used).

Note: Once specified, Trigger Level and Coupling are the only parameters that pass unchanged from mode to mode for each trigger source.

Coupling This is the particular type of signal coupling at the input of the

trigger circuit. As with the trigger level, the coupling can be independently selected for each source. Thus changing the trigger source can change the coupling. The types of coupling able to be selected are:

8–4

Ø DC: All the signal's frequency components are coupled to

the trigger circuit. This is used in the case of high-frequency bursts, or where the use of AC coupling would shift the effective trigger level.

Ø AC: Here the signal is capacitively coupled. DC levels are

rejected and frequencies below 50 Hz attenuated.

Ø LF REJ: The signal is coupled via a capacitive high-pass

filter network. DC is rejected and signal frequencies below 50 kHz attenuated. This mode is used when stable triggering on medium- to high-frequency signals is desired.

Ø HF REJ: Signals are DC-coupled to the trigger circuit and a

low-pass filter network attenuates frequencies above 50 kHz. The HF REJ trigger mode is used to trigger on low frequencies.

Ø HF: Used for triggering on high-frequency repetitive signals

in excess of 300 MHz. Maximum trigger rates greater than 500 MHz are possible. HF triggering should be used only when needed. It will be automatically overridden and set to AC when incompatible with other trigger characteristics — as is also the case for SMART Trigger. Only one slope is available, indicated by the trigger symbol.

Slope Slope determines the direction of the trigger voltage transition

used for generating a particular trigger event. Like coupling, the selected slope is associated with the chosen trigger source.

Hold-off Hold-off disables the trigger circuit for a given period of time or

a number of events after a trigger event occurs. It is used to obtain a stable trigger for repetitive, composite waveforms. For example, if the number or duration of sub-signals is known they can be disabled by choosing an appropriate hold-off value.

Without Hold-off, the time between each successive trigger event would be limited only by the input signal, the coupling, and the oscilloscope's bandwidth. Sometimes a stable display of complex repetitive waveforms can be achieved by placing a condition on this time. This hold-off is expressed either as a time or an event count, described on the following pages.

8–5

Triggers and When to Use Them

Hold-off by Time This is the selection of a minimum time for triggers (Fig. 8–

3). A trigger is generated when the trigger condition is met after the selected delay from the last trigger. The timing for the delay is initialized and started on each trigger. The holdoff timeout should exceed the duration of the signal displayed on screen. For instance, at a timebase setting of 1 ms/div, the time-out hold-off should at least exceed 10 ms.

Trigger Source: Positive Slope

Trigger

Event

Trigger can occur

Hold-off time Hold-off time

Generated Trigger

Trigger

Event

Trigger initiates hold-off timer

Figure 8–3. Edge Trigger with Hold-off by Time.

Trigger

Event

Trigger initiates hold-off timer

8–6

Hold-off by Events Hold-off by events is initialized and started on each trigger

(Fig. 8–4 ). A trigger is generated when the trigger condition is met after the selected number of events from the last trigger. Event here refers to the number of times the trigger condition is met after the last trigger. For example, if the number selected is two, the trigger will occur on the third event.

Trigger Source: Positive Slope

Trigger

Event

Trigger

Event

Trigger can occur

Holdoff by 2 events Holdoff by 2 events

Generated Trigger

Trigger initiates hold-off timer

Figure 8–4. Edge Trigger with Hold-off by Events.

Event

Trigger initiates hold-off timer

Trigger

Event

8–7

Triggers and When to Use Them

Window Trigger

AVAILABLE ONLY WITH 9304C, 9310C, 9314C SERIES

Trigger Level

On some scope models a “Window” Edge Trigger is also available (Fig. 8–5). Two trigger levels are defined and a trigger event occurs when the signal leaves the window region in either direction.

Upper Region

WINDOW REGION

Lower Region

Time

Triggers

Figure 8–5. Edge Window Trigger.

8–8

TRIGGER SETUP: Edge

Press to access menu selection of:

Ø Trigger source Ø Coupling for each source Ø Slope (positive or negative), and Ø Hold-off by time or events.

Edge/SMART To select “Edge”

trigger on

For selecting the Edge trigger source (four-channel menu shown).

coupling

To select the trigger coupling for the current source.

slope

To place the trigger point on either the “Pos ”-itive or “Neg”-ative slope of the selected source. On those models featuring Window Trigger (9304C, 9310C, 9314C SERIES), this menu will also include a “Window” option, which allows triggering whenever the input signal leaves a specified voltage window, defined in the “window size” menu. The “window size” menu becomes available on models featuring Window Trigger. It allows adjustment of the window around a level defined using the Trigger LEVEL knob.

holdoff

To allow the disabling of the oscilloscope's trigger circuit for a definable period of time or number of events after a trigger event occurs. When activated, “holdoff” can be defined as: a period of “Time”, or a number of “Evts ” (an event being a change in the input signal that satisfies the trigger conditions). The menu knob is used to vary the “holdoff” value. Time hold-off values in the range 10 ns–20 s may be entered. Event counts in the range 1–109 are allowed.

8–9

Triggers and When to Use Them

SMART Trigger

SMART Trigger allows the setting of additional qualifications before a trigger is generated. Depending on the oscilloscope model, this can include triggers adapted for glitches, intervals, abnormal signals, TV signals, state- or edge-qualified events, dropouts and patterns.

Glitch Trigger Glitch Trigger (Fig. 8–6) is used to capture narrow pulses

inferior to or exceeding a given time limit. In addition, a width range can be defined to capture any pulse that is comprised within or outside the specified range — an Exclusion Trigger.

Glitch

Trigger on

Coupling

At end of Neg|Pos|Pulse

Width: l

than or equal

greater than

or equal to

Figure 8–6. Glitch Trigger Menu (see page 8–30).

ess

Width:

1|2|3|4|Ext|Ext10|Pattern

DC|AC|LFREJ|HFREJ|HF

Off|Time (2.5 ns to 20 s)

8–10

Applications In digital electronics circuits normally use an internal clock, and for

testing purposes a glitch can be defined as any pulse of width smaller than the clock- or half-period. But generally speaking a glitch is a pulse much faster than the waveform under observation. Glitch Trigger thus has a broad range of applications in digital and analog electronic development, ATE, EMI, telecommunications, and magnetic media studies.

Pulse Smaller than Selected Pulse Width

This Glitch Trigger selects a maximum pulse width (Fig. 8–7). It is generated on the selected edge when the pulse width is less than the selected width. The timing for the width is initialized and restarted on the slope opposite to the edge selected. Widths of between 2.5 ns and 20 s can be selected, but typically triggering will occur on glitches 1 ns wide.

Trigger Source

Glitch

Glitch width

width

Trigger can occur

Selected width

Generated Trigger

Figure 8–7. Glitch Trigger on pulse width < selected width.

8–11

Triggers and When to Use Them

Exclusion Trigger Exclusion Trigger enables the exclusion of events over a

determined time interval. Exclusion Trigger is generated on the selected edge when the pulse width is within or outside the selected width range. For example (Fig. 8–8), only pulses smaller than 25 ns or longer than 27.5 ns will generate the trigger. The timing for the width is initialized and restarted on the slope opposite to the edge selected. Widths of between 2.5 ns and 20 s can be selected.

Figure 8–8. Exclusion Trigger. Only pulses within or outside the boundaries of the width range are captured.

Applications Exclusion Triggers allow a signal’s normal width or period to be

specified, with the scope instructed to ignore the normally shaped signals and trigger only on abnormal ones. Circuit failures, for instance, can be looked for all the time.

8–12

Interval Trigger Whereas Glitch Trigger performs over the width of a pulse,

Interval Trigger (Fig. 8–9) performs over the width of an interval. An interval corresponds to the signal duration separating two consecutive edges of the same polarity. Interval Trigger is used to capture intervals that are inferior to or exceeding a given time limit. In addition, a width range can be defined to capture any interval that is comprised within or outside the specified range — an Exclusion Trigger by Interval.

Interval

Trigger on

Coupling

Between

Interval: l

than or equal

greater than

or equal to

Figure 8–9. Interval Trigger Menu (see page 8–32).

ess

Interval:

1|2|3|4|Ext|Ext10|Pattern

DC|AC|LFREJ|HFREJ|HF

Pos|Neg

edges

Off|Time (10 ns to 20 s)

Applications Interval Trigger is helpful for determining missing cycles or

transitions, and for ignoring unwanted signal reflections.

8–13

Triggers and When to Use Them

Interval Smaller For this Interval Trigger, generated on a time interval smaller than

the one selected, a maximum interval between the two edges of the same slope is chosen (Fig. 8–10). The trigger is generated on the second edge if it occurs within the selected interval. The timing for the interval is initialized and restarted whenever the selected edge occurs. Intervals of between 10 ns and 20 s can be selected.

Trigger Source: Positive Slope

Interval width

Interval

width

Trigger can occur

Selected interval

Generated Trigger

Figure 8–10. Interval Trigger: Trigger if the interval is smaller than the

selected interval.

8–14

Interval Larger For this Interval Trigger, generated on an interval larger than the

one selected, a minimum interval between the two edges of the same slope is chosen (Fig. 8–11). The trigger is generated on the second edge if it occurs after the selected interval. The timing for the interval is initialized and restarted whenever the selected edge occurs. Intervals of between 10 ns and 20 s can be selected.

Trigger Source: Positive Slope

Interval width

Interval

width

Trigger can occur

Selected interval

Generated Trigger

Figure 8–11. Interval Trigger: Trigger if the interval is greater than

the selected width.

8–15

Triggers and When to Use Them

Interval Between Range This Interval Trigger selects a maximum interval between the

two edges of the same slope (Fig. 8–12). The trigger is generated on the second edge if it occurs within the selected interval range. The timing for the interval is initialized and restarted whenever the selected edge occurs. Intervals of between 10 ns and 20 s can be selected.

Trigger Source: Positive Slope

Interval width

Interval

width

Trigger can occur

Selected ranges

Generated Trigger

Figure 8–12. Interval Trigger: Trigger if the interval is between the

selected ranges.

8–16

Interval Outside Range This Interval Trigger selects a minimum interval between the

two edges of the same slope (Fig. 8–13). The trigger is generated on the second edge if it occurs after the selected interval range. The timing for the interval is initialized and restarted whenever the selected edge occurs. Intervals of between 10 ns and 20 s can be selected.

Trigger Source: Positive Slope

Interval width

Interval

width

Trigger can occur

Selected ranges

Generated Trigger

Figure 8–13. Interval Trigger: Trigger if the interval is outside the

selected ranges.

8–17

Triggers and When to Use Them

Pattern Trigger Pattern Trigger (Fig. 8–14) enables triggering on a logical

NOT AVAILABLE ON 9304C, 9310C, 9314C SERIES

combination of the inputs CH 1, CH 2 (plus CH 3 and CH 4 on fourchannels models) and EXT. This combination, called a pattern, is defined as the logical AND of trigger states. A trigger state is either high or low: high when a trigger source is greater than the trigger level (threshold); low when less than this threshold (Fig. 8–15). For example, the pattern could be defined as present when the trigger state for CH 1 is high, CH 2 is low, and EXT is irrelevant (X or don’t care). If any of these conditions are not met, the pattern state is considered absent. Limits can be selected from 10 ns to 20 s.

Pattern

Trigger on

Pattern

with

Coupling DC|AC|LFREJ|HFREJ

Level L|H|X|(Level value)

Holdoff

Figure 8–14. Pattern Trigger Menu (see page 8–33).

1|2|3|4|Ext (according to model)

Exiting|Entering

Off| Time (10 ns to 20 s)

|Evs (1 to 99 999 999)

8–18

Applications Pattern Trigger is useful in digital design for the testing of complex

logic inputs or data transmission buses.

Threshold

CH 1

Threshold

CH 2

High Low

Pattern 1H*2L

Generated Trigger (Pattern Entering)

Generated Trigger (Pattern Exiting)

Figure 8–15. Pattern Trigger: Trigger when pattern conditions met.

8–19

Triggers and When to Use Them

More About Pattern Trigger Once the pattern is defined, one of two transitions can be used to

generate the trigger. When the pattern begins, called entering the pattern, a trigger can be generated. Alternatively, a trigger can be generated when the pattern ends, exiting the pattern.

With pattern triggering, as in single source, either of these qualifications can be selected: Hold-off for 10 ns up to 20 s, or Hold-off for 1 to 99 999 999 events.

Set to Pattern Trigger, the oscilloscope always checks the logic AND of the defined input logic states. However, with the help of de Morgan's laws, the pattern becomes far more generalized.

Consider the important example of the Bi-level or Window Pattern Trigger. Bi-level implies the expectation of a single-shot signal on which the amplitude will go in either direction outside a known range. To set up a Bi-level Pattern trigger, connect the signal to two inputs: Channels 1 and 2 or any other pair that can be triggered on. For example, the threshold of CH 1 could be set to +100 mV and that of CH 2 at −200 mV. The Bi-level Trigger will occur if the oscilloscope triggers on CH 1 for any pulse greater than +100 mV, or on CH 2 for any pulse less than –200 mV. For improved precision, the gains of the two channels should be at the same setting.

In Boolean notation we can write:

Trigger CH 1 CH 2= + ,

i.e. trigger when entering the pattern CH 1 = high OR CH 2 = low. By de Morgan's laws this is equivalent to:

Trigger CH 1 CH 2= ⋅ ,

i.e. trigger when exiting the pattern CH 1 = low AND CH 2 = high. This configuration can be easily programmed.

The possibility of setting the threshold individually for each channel extends this method so that it becomes a more general Window Trigger: in order to trigger the input pulse amplitude must lie within or outside a given arbitrary window.

Pattern Trigger has been designed to allow a choice of the trigger point. By choosing 1L*2H entering, the trigger will occur at the moment the pattern 1L*2H becomes true.

8–20

Qualified Triggers In the case of Qualified Triggers (Fig. 8–16), a signal’s transition

above or below a given level, the validation, serves as an enabling, or qualifying, condition for a second signal that is the source of the trigger.

Two Qualified Triggers are available: State-Qualified, where the amplitude of the first signal must remain in the desired state until the trigger occurs, and Edge-Qualified, for which the validation is sufficient and no additional requirement is placed on the first signal.

A Qualified Trigger can occur immediately after the validation or within a set time after it. Or it can occur following a predetermined time delay or number of potential trigger events. The time delay or trigger count is restarted with every validation.

Qualified

Trigger on

Only after 1|2|3|4|Ext|Ext10|Pattern

Goes and

stays

Wait

Edge|State qualifier

1|2|3|4|Ext|Ext10

Above|Below|Value

Off|Time <| Time> (10 ns to 20 s)| Evs (1 to 99 999 999)

Trigger on

After 1|2|3|4|Ext|Ext10|Pattern

Has gone Above|Below|Value

Wait

Edge|State qualifier

1|2|3|4|Ext|Ext10

Off|Time <| Time> (10 ns to 20 s)| Evs (1 to 99 999 999)

Figure 8–16. State- and Edge-Qualified Trigger Menus (see pages 8–35 and 8–36).

8–21

Triggers and When to Use Them

Qualified Triggers offer the choice of generating a trigger either when the selected pattern is present or absent. As with Pattern Trigger, the pattern is defined as a logical AND combination of trigger states that are either high or low: high when a trigger source is greater than the selected trigger level, and low when it is less than. For example, a pattern might be defined as present when the trigger states for Channels 1 and 2 are high and EXT is low. If any of these conditions is not met, the pattern state is considered absent.

Qualified Triggers allow an additional qualification once the selected pattern state occurs. For example: “wait for 10 ns up to 20 s, trigger on CH 1 to the 99 999 999th event”. The pattern is used to qualify the trigger without actually generating it. Triggering will occur when another signal, the trigger source, meets its trigger condition while the pattern is present. The trigger source itself is not allowed in the pattern.

Applications Typical applications can be found wherever time violations

occur, such as in micro-processor debugging or telecommunications.

State-Qualified with Wait State-Qualified Trigger with Wait (Fig. 8–17) is determined by

the parameters of Time and number of Events: Ø Time selects a delay from the start of the desired pattern.

After the delay (timeout) and while the pattern is present, a trigger can occur. The timing for the delay is restarted when the selected pattern begins

Ø Events selects a minimum number of events of the trigger

source. An event is generated when a trigger source meets its trigger conditions. On the selected event of the trigger source and while the pattern is present, a trigger can occur. The count is initialized and started whenever the selected pattern begins, and continues while the pattern remains. When the selected count is reached, the trigger occurs.

8–22

Trigger Source: Positive Slope

Qualifier: Pattern Present

Trigger can occur

Generated Trigger

Figure 8–17. State-Qualified by Wait: Trigger after timeout.

Selected wait

As Figure 8–17 illustrates, a trigger is generated on a rising edge whenever the pattern is asserted (pattern present) and the wait timeout has expired. The timeout is, respectively, activated or disabled once the pattern is asserted or absent.

8–23

Triggers and When to Use Them

Edge-Qualified with Wait Like its State-Qualified equivalent, Edge-Qualified with Wait

(Fig. 8–18) is conditioned by Time and Events: Ø Time Selects a delay from the start of the desired pattern.

After the delay (timeout) and before the end of the pattern, a trigger can occur. The timing for the delay is restarted when the selected pattern begins.

Ø Events selects a minimum number of events of the trigger

source. An event is generated when a trigger source meets its trigger conditions. On the selected event of the trigger source and before the end of the pattern, a trigger can occur. The count is initialized and started whenever the selected pattern begins. It continues while the pattern remains. When the selected count is reached, the trigger occurs.

Trigger Source: Positive Slope

Qualifier: Pattern Present

Trigger can occur

Selected time

Generated Trigger

Figure 8–18. Edge-Qualified by Wait: Trigger after timeout.

8–24

TV Trigger A special kind of Edge-Qualified Trigger, TV Trigger allows

stable triggering on standard or user-defined composite video signals, on a specific line of a given field. Applications can be found wherever TV signals are present. And TV Trigger can be used on PAL, SECAM or NTSC systems.

A composite video signal on the trigger input is analyzed to provide a signal for the beginning of the chosen field — “any”, “odd” or “even” — and for a signal at the beginning of each line. The field signal provides the starting transition, and the beginnings of line pulses are counted to allow the final trigger on the chosen line.

Each field, the number of fields, the field rate, interlace factor, and number of lines per picture must be specified — although there are standard settings for the most common types of TV signals. TV Trigger can also function in a simple any-line mode.

TV signal on

# of fields

TV type Standard | Custom

Trigger on Line | Field

1|2|3|4|Ext|Ext 10

1|2|4|8

as: 625/50/2:1| 525/60/2:1

(Standard)

as: Line| Hz | Interlacing

1 to 1500| 50/60 | 1:1/2:1/

4:1/8:1/

(Custom)

Figure 8–19. TV Trigger Menus (see page 8–34 )

8–25

Triggers and When to Use Them

Notes for TV Trigger

Ø Because most TV systems have more than two fields, the enhanced field-counting

capability (FIELDLOCK) allows the oscilloscope to trigger consistently on a chosen line within a chosen field of the signal. The field-numbering system is relative, in that the oscilloscope cannot distinguish between lines 1, 3, 5, and 7 (or 2, 4, 6, and 8) in an absolute way.

Ø For each of the characteristics the following remarks apply:

Ø 625/50/2:1 (PAL and SECAM systems)

This setting should be used for most of the standard 50-field signals. The lines may be selected in the range 1 to 626 where line 626 is identical to line 1.

Number of fields: eight is most useful for color PAL signals; four for SECAM signals.

Ø 525/60/2:1 (NTSC systems)

This setting should be used for standard 60-field NTSC signals. The lines can be selected in the range 1 to 1051, where line 1051 is identical to line 1.

Number of fields: four is most useful for US-type NTSC systems.

Ø ?/50/?, ?/60/?

In order to allow maximum flexibility, no line-counting convention is used. The line count should be thought of as a line-synchronizing pulse count. It includes the transitions of the equalizing pulses. For certain extreme cases, the field transition recognition will no longer work, and only the “any line” mode will be available.

Ø The enhanced field-counting capability cannot be used for RIS acquisitions. Ø Composite video signals must have negative-going synch to be decoded correctly.

8–26

Dropout Trigger Dropout Trigger (Fig. 8–20) provides triggering whenever the

signal disappears for a selectable period of time. The trigger is generated at the end of the time-out period following the “last” trigger source transition. Time-outs of between 25 ns and 20 s can be selected.

Dropout

Trigger after

timeout if no edge

occurs on

1|2|3|4|Ext|Ext10

With

slope

Within Time (25 ns to 20 s)

Figure 8–20. Dropout Trigger Menu (see page 8– 37)

Positive|Negative

Applications Dropout Trigger is useful for detecting interruptions in data

streams such as network hang-ups and microprocessor crashes. A typical application is on the last ‘normal’ interval of a signal

that has disappeared completely. This is essentially a singleshot application, usually with a pre-trigger delay. RIS acquisition is not useful here because the timing of the trigger timeout is insufficiently correlated with the input channel signals.

8–27

Trigger Source

Trigger can occur

Generated Trigger

Triggers and When to Use Them

Wait timeout

Figure 8–21. Dropout Trigger: A trigger occurs when the timeout has expired.

8–28

TRIGGER SETUP: SMART

Press to access, too, the various SMART Trigger types, to trigger on:

Ø Glitches Ø Intervals Ø Abnormal signals (Exclusion Trigger) Ø Patterns (NOT AVAILABLE ON 9304C, 9310C, 9314C SERIES) Ø State- or edge-qualified events Ø TV signals Ø Dropouts.

Edge/SMART To select “SMART

SETUP SMART TRIGGER

This is primary menu that accesses the “SMART TRIGGER” menu group, for choosing the type of SMART Trigger required from the “type” secondary menu. This and the other SMART

menus are described starting page 8–30.

8–29

SMART TRIGGER — Glitch

type

trigger on

coupling

at end of

Triggers and When to Use Them

To select “Glitch”.

For selecting the trigger source (four-channel menu shown).

To select the trigger coupling.

To define the test on either “Pos”-itive or “Neg”-ative pulses.

width ≤

When “On” instructs the instrument to trigger if the pulse is smaller than the value defined in this field. The value can be adjusted with the associated menu knob, while the test can be turned on or off by pressing the menu button, and used in combination with the “width ≥” test. Width values in the range 2.5 ns to 20 s can be entered.

& width ≥

“On” instructs the instrument to trigger if the pulse is greater than the value defined in that field. The value can be adjusted using the associated menu knob, and the test turned on or off with the menu button in combination with the “width ≤” test menu selection. The two width limits are combined to select glitches within (“&”) a certain range if the “width ≤” value is greater than the “width ≥” value. Otherwise, they are combined to select glitches outside this range.

8–30

SMART TRIGGER — Glitch — Pattern (NOT ON 9304C, 9310C, 9314C SERIES)

When “Pattern” is selected in Glitch mode, the instrument triggers on the logic AND of up to five sources.

type

To select “Glitch”.

trigger on

To select “Pattern” (four-channel menu shown).

for pattern

For selecting pattern “Present” or “Absent”.

width ≤

To trigger if the pattern is present or absent for less than the time value defined in that field. The value can be adjusted with the associated menu knob and the test commuted to “≥” by pressing the corresponding menu button.

& width ≥

To trigger if the pattern is present or absent for more than the time value defined in that field. The value can be adjusted and the test commuted to “≤ ” as per “width ≤ ”.

8–31

SMART TRIGGER — Interval

type

To select “Interval”.

trigger on

For selecting the trigger source (four-channel menu shown).

coupling

For selecting the trigger coupling.

between

To define the interval between two adjacent “Pos”-itive or “Neg”

-ative edges.

Triggers and When to Use Them

interval ≤

To trigger if the interval is smaller than the value defined here, which can be adjusted using the associated knob. The test can be turned on or off with the corresponding menu button, and can be used in combination with the “interval ≥” test. Interval values in the range 10 ns to 20 s may be entered.

OR interval ≥

To trigger if the interval is greater than the value defined here, which can be adjusted using the associated menu knob The test can be turned on or off using the corresponding menu button, and can be used in combination with the “interval ≤” test. The two interval limits are combined to select intervals within (“&”) a range if the “interval ≤” value is greater than the “interval ≥” value. Otherwise they are combined to select intervals outside (“OR”) the range.

8–32

SMART TRIGGER — Pattern (NOT ON 9304C, 9310C, 9314C SERIES)

type

To select “Pattern”.

trigger on

To select “Entering” for the scope to trigger when the pattern starts being true, and “Exiting” for triggering when it stops being true .

Pattern with

For selecting the channel to be modified using the lower menus’ corresponding menu buttons (four-channel menu shown).

coupling

To select the desired coupling. HF coupling is not available for Pattern Trigger.

level

For modifying these values using the associated knob — adjusts the level — and the corresponding menu button, which chooses “L” (low), “H” (high), or “X” (Don't care).

holdoff

To disable the trigger circuit for a definable period of time or number of events after a trigger event (a change in the input signal that satisfies the trigger conditions). When not turned off, holdoff can be defined as a period of “Time” or a number of “Evts” (events). Use the associated menu knob to vary the “holdoff” value. Time holdoff values in the range 10 ns–20 s may be entered. Event counts in the range 1–109 are allowed.

8–33

SMART TRIGGER — TV

Triggers and When to Use Them

type

To select “TV” .

TV signal on

For selecting the trigger source (four-channel menu shown).

# of fields

To define the number of fields — up to eight.

TV type

For selecting either “Standard” or “Custom” TV decoding.

When “Standard” is chosen, for selecting either “625/50/2:1” (PAL SECAM) or “525/60/2:1” (NTSC) standards.

When “Custom” is selected, for specifying the number of lines and cycles, and setting the interlacing factor for non-standard TV signals.

trigger on

For selecting the line and field number on which to trigger.

8–34

SMART TRIGGER — Qualified — State

type

To select “Qualified”.

To select “State”.

trigger on

For selecting the trigger source — the other conditions for this source can be set up using Edge Trigger (four-channel menu shown).

only after

To select the qualifier source — the other conditions can be set up using Edge Trigger.

goes & stays

For selecting the qualifier threshold using the associated knob, and using the menu button to select whether the qualifier signal will be valid either “Above” or “Below” that threshold.

When “Pattern” is selected as the qualifier source, this menu is used to determine whether the pattern should be present or absent.

wait/within

To specify the time limit (“T<”) for accepting the trigger event. And alternatively, to specify how much time (“T>”) or how many trigger events (“Evs”) should be allowed before the acquisition is taken on the next trigger event. The qualifier signal must remain valid until the final trigger has been received. The time value can be chosen in the range 10 ns–20 s. The trigger event count can be chosen in the range 1–109.

8–35

Triggers and When to Use Them

SMART TRIGGER — Qualified — Edge

type

To select “Qualified”.

To select “Edge”.

trigger on

For selecting the trigger source — the other conditions for this source are set up using Edge Trigger (four-channel menu shown).

after

For selecting the qualifier source — other setup conditions use Edge Trigger (four-channel menu shown).

has gone

To adjust the qualifier threshold and determine whether the qualifier signal is valid once it “has gone” above or below that threshold. “Pattern” selected as the qualifier source determines whether the pattern should be present or absent.

wait/within

To specify the time limit (“T<”) for accepting the trigger event. Or, to specify the delay in time (“T>”) or number of trigger events (“Evs”) after a valid transition has occurred. A trigger can only be accepted after this delay. Any subsequent qualifier event restarts this count. The time value can be chosen in the range 10 ns–20 s. The trigger event count can be chosen in the range 1–109.

8–36

SMART TRIGGER — Dropout

type

To select “Dropout”.

trigger after timeout, if NO edge occurs on

For selecting the trigger source (four-channel menu shown).

with slope

To define whether the measurement starts on a “Positive” or “Negative” slope of the trigger signal.

Within… of previous edge

For defining the time-out value in the range 25 ns–20 s.

8–37

ZOOM + MATH Controls

A wide range of Zoom and Mathematical processing functions (detailed in the next chapter) can be performed on acquired waveforms with the controls described here.

Four processed traces are available for straight-forward zooming or for waveform mathematics. Any one of these traces, A, B, C or D, can be set up to zoom a trace acquired on any channel or stored in any of the four reference memories M1–4. Or zoom any of the other three original traces. Thus Trace A, for example, could be set up to zoom Trace B, C, or D, but not itself. The Displayed Trace label at left of screen indicates the source.

ZOOM + MATH

The corresponding trace A, B, C or D. When a trace is switched on, the POSITION and ZOOM knobs and the RESET button will then be attributed to this, the active trace.

The SELECT ABCD button assigns the controls to the active trace for adjustment, as only one trace can be modified at a time. Pressing this button activates the next trace, in A–D sequence.

The four ZOOM + MATH knobs adjust the horizontal and vertical positions and expansion factors of the zoomed trace…

9–1

TRACE ON/OFF buttons display the

ZOOM + MATH

The POSITION knob repositions zoomed traces horizontally. If the source of the expanded waveform is displayed, an intensified region corresponding to the area of expansion is shown.

Whereas the vertically repositions the active trace.

The ZOOM knob horizontally expands or contracts the active trace. If the source of the zoomed trace is also displayed, it will show an intensified region corresponding to the area of expansion.

While the vertically expands or contracts the active trace.

The RESET button resets the vertical and horizontal POSITION and ZOOM.

Finally, the menu-entry button accesses the zoom, math and sequence segment features. See next chapter for details.

9–2

Zoom, Mathematics and Math Setup

Zooming for Precise Waveform

Measurements

Several traces can be zoomed from a single waveform to obtain precise timing measurements.

For instance, on a waveform composed of two pulses separated by a long delay, Trace A could be made a zoom of the first pulse, and Trace B a zoom of the second.

The combination of long memory and zooming allows extremely accurate time interval measurements. And the time resolution on the viewed trace can be significantly improved.

For example, choosing 50 000 points per channel on a timebase of 0.1 ms/div, traces can be expanded to as much as 50 ns/div — a factor of 2000. Using Relative Time cursors (see Chapter

14), a delay of, say, 500 µs could be measured with resolution as high as 0.5 ns. Even with as many as eight million points acquired, zooming can be done until there are only a few points on the screen.

Using Multi-Zoom With Multi-Zoom, the zoomed region of the waveform can be

moved simultaneously along two or more different traces, or two or more regions of the same trace.

When “Multi-Zoom” “On” is selected from the “ZOOM – MATH” menu (see page 10–8), the horizontal zoom and position controls apply simultaneously to all displayed traces — A, B, C and D — allowing similar sections of different traces to be viewed at the same time. The vertical controls still act individually on the traces: switching from one trace to another is done using the TRACE ON/OFF buttons. The highlighting of trace titles in the Displayed Trace label indicates an active MultiZoom.

Zooming Math Functions When Trace A, B, C or D is defined as a mathematical function

rather than as a simple zoom (see next section), the zoom controls remain operative and defining another trace as a zoom of the math function becomes unnecessary. In order to view the entire

10–1

Zoom, Mathematics and Math Setup

mathematical function, simply cancel any expansion or position change by pressing RESET.

10–2

Math Functions and Options

Coverage of the Setup menus for configuring zoom, math and waveform processing functions starts page 10–6. Averaging and Extrema are outlined on this and the following pages. For details on Enhanced Resolution filtering, see Appendix B. How to Set Up for FFT (Fast Fourier Transform) is explained at the conclusion of this chapter, while a complete description of FFT practice and theory is presented in Appendix C. Information on each of the Waveform Processing packages on option is to found in

A wide range of standard or optional mathematical and waveform processing functions are available.

The scope’s standard waveform mathematics functions consist of waveform negation, identity, addition, subtraction, multiplication and division, summed averaging of up to 1000 waveforms and the (sin x)/x interpolation function.

Advanced waveform processing features, depending on the options installed, include:

Ø Continuous Averaging (menus page 10–11); Ø Summed Averaging of up to 1 000 000 waveforms (menus

10–11);

Ø Enhanced Resolution by up to 3 bits with filtering (menus

10–12);

Ø Extrema — envelope of many waveforms (menus 10–13); Ø Fast Fourier Transform, including FFT averaging (menus

10–14 and 10–15);

Ø Mathematical Functions such as Integral, Derivative,

Logarithm, Exponential, Square, and Square Root (menus 10–16);

Ø Parameter Analysis, histogramming, trending and statistical

analysis (menus page 10–17).

Continuous Averaging This is the repeated addition, with unequal weight, of successive

source waveforms. It is particularly useful for reducing noise on signals that drift very slowly in time or amplitude.

However, the statistics of a continuous average tend to be worse than those from a summed average (see next page) on the same number of sweeps. This is because the most recently acquired waveform has more weight than all previously acquired ones: the continuous average is dominated by the statistical fluctuations of the most recently acquired.

10–3

Zoom, Mathematics and Math Setup

The weight of ‘old’ waveforms in the continuous average gradually tends to zero (following an exponential rule) at a rate that decreases as the weight increases.

Summed Averaging Summed Averaging is the repeated addition, with equal weight,

of successive source waveform records. If a stable trigger is available, the resulting average has a random noise component lower than that of a single-shot record.

Whenever the maximum number of sweeps is reached, the averaging process stops. An even larger number can be accumulated simply by changing the number in the “SETUP” “for” menu. However, the other parameters must be left unchanged or a new averaging calculation will be started.

The process may be interrupted by changing the trigger mode from NORM to STOP or by turning off the active trace using the respective buttons. Averaging will be resumed when the inverse is done. The accumulated average is reset by pushing the CLEAR SWEEPS button or changing an acquisition parameter such as input gain, offset, coupling, trigger condition, timebase or bandwidth limit. The number of current averaged waveforms of the function or its expansion is shown in the Displayed Trace label.

When summed averaging is selected, the display is updated at a reduced rate — about once every 1.5 s — in order to increase the averaging speed (points and events per second).

Summed averaging can also be done on sequence waveforms to give the average of the segments. And it can be applied to an expansion of a sequence segment, giving the segment’s average waveform over many sequence acquisitions.

Extrema Waveforms These are computed by a repeated comparison of successive

source waveform records with the already-accumulated extrema waveform, which consists of a maxima (roof) and a minima (floor) record. Whenever a given data point of the new waveform is greater than the corresponding maximum roofrecord value, or less than the corresponding floor value, it replaces it. Thus the maximum and the minimum envelope of all waveform records is accumulated.

Roof and Floor records can be displayed individually or together.

10–4

Whenever the selected maximum number of sweeps is reached, the accumulation stops. The same process may be interrupted by changing the trigger mode from Normal to Stopped or by turning off the function trace. Accumulation will continue when these actions are reversed.

The currently accumulated extrema waveform may be reset by either pushing the CLEAR SWEEPS button or by changing an acquisition parameter such as input gain, offset, coupling, trigger condition, or the timebase- or bandwidth-limit. The number of currently accumulated waveforms is displayed in the function’s Displayed Trace Label of that of its zoom expansion.

Whenever the maximum number of sweeps is reached, an even larger number can be accumulated simply by changing the number in the “SETUP” “for” menu. However, the other parameters must be left unchanged or the extrema calculation will be restarted.

10–5

Zoom, Mathematics and Math Setup

Using Waveform Mathematics

Waveform mathematics can be applied to any channel or reference memory. And any trace of A, B, C or D can be set up as a math function, allowing several computations to be made in sequence.

For example: Trace A could be set up as the difference between Channels 1 and 2; Trace B defined as the average of A, and Trace C made the integral of B — thus displaying the integral of the averaged difference between Channels 1 and 2.

In order to avoid slowing down the instrument with unwanted computations, a particular mathematical function is only computed when its display is turned on. However, using the same example as above, it would be sufficient to display Trace C alone, as the instrument knows it must compute A and B as intermediate steps to C.

Waveform processing can also take time when many data points are involved. This delay can be cut by limiting the number of data points used in the computation. To do this, the instrument will process the entire waveform by taking every Nth point, where N depends on the timebase and the desired maximum number of points, and the first point taken is always the data value at the left-hand edge of the screen.

Combining Channels Zoom and math functions on Traces A, B, C, D and Reference

Memories M1, M2, M3, M4 use the instrument’s system memory, which is dynamically allocated to each trace as required. When more acquisition memory is achieved by combining channels, a single long trace can consume all the reference memory or zoom and math trace capacity in the instrument. When this happens, an on-screen warning message will avert accidental storing of a new trace to a reference memory already in use.

Note: A processing title for each displayed trace will be shown in the Displayed Trace Label. If the title is missing, the desired processing cannot be done and the contents of the trace remain unchanged.

10–6

Zoom, Mathematics and Math Setup

Configuring for Zoom and Math

Press traces and execute any zoom, math function using the “ZOOM + MATH” menus.

Any trace and function can be chained to another trace and function (not all functions shown are necessarily available). Trace A, for example,

could be configured to average Channel 1, Trace B could be made a Fourier Transform (FFT) of A, and Trace C a zoom of B. All traces can be viewed simultaneously on-screen using the ZOOM + MATH TRACE ON/OFF buttons. Any function can be zoomed directly.

REDEFINE A, B, C, or D

To select the trace to be redefined and accesses the “SETUP” menus (described in the remainder of this chapter, using A as an

example).

Multi-Zoom

For switching Multi-Zoom “On” or “Off”. When “On”, all displayed traces (A,B,C,D) are simultaneously controlled by the horizontal POSITION and ZOOM knobs. When “OFF”, only the active trace, chosen using the SELECT ABCD button, is controlled by POSITION and ZOOM.

to enable the configuration of any of the four

Selected (NOT SHOWN)

When a trace with a zoom of a sequence-mode waveform is selected, the “Selected” menu — not shown here — becomes accessible. Pressing the corresponding menu button toggles the selection between display of a single, specific “Segment” and “All Segments”. With the former selected, the associated knob can be used to step through the segments and choose one.

for Math use max points…

For selecting the maximum number of points for all math operations — a low number increases computation speed.

10–8

Zoom

Zoom and Math Setup Menus

use Math?

For toggling between “No” (Zoom only) and “Yes” (Math functions) SETUP.

Trace A, B, C or D is ZOOM of

To select the source trace to be zoomed (four-channel menu shown).

10–9

Zoom, Mathematics and Math Setup

Arithmetic — allows addition, subtraction, multiplication and division, as well as

choice of the two operands and the operator. The example on this page shows a setup of trace A as the sum of Channels 1 and 2.

use Math?

To choose a math function.

Math Type

To select “Arithmetic”.

Sum Difference Product Ratio

For selecting the operator.

1 2 3 4 B C D

M1 M2 M3 M4

To select one of two operand source traces (four-channel menu shown).

plus 1 2 3 4 B C D

M1 M2 M3 M4

To select the other operand source trace (four-channel menu shown).

10–10

Zoom and Math Setup Menus

Average — offers Summed (Linear) or Continuous (Exponential) Averaging.

Shown here is an example setup of trace A as a Summed Average (over 1000 sweeps) of Channel 1. See also page 10–3.

use Math?

To choose a math function.

Math Type

To select, in this case, “Average” (other choices in the example menu shown here include options not available on the standard scope).

Avg Type

To select “Summed” or “Continuous Average ”.

for / weight

When “Summed” is selected, this menu (“for”) is used to define the number of sweeps. When “Continuous Average” is chosen, the same menu becomes “weight” and is used to define the weight, similar to number of sweeps.

In “for” the first n sweeps will be taken into account, whereas in “weight” the last sweep will be given a weight of 1 and the previous result a weight of n in calculating the new average.

For selecting the source trace for averaging (four-channel menu shown).

10–11

Zoom, Mathematics and Math Setup

Enhanced Resolution

— allows the selection of low-pass digital filters that increase the resolution of the displayed signal at the expense of its bandwidth. Appendix B gives a detailed explanation.

These digital filters work very much like analog bandwidth-limit ones. In Single-Shot mode, they and the sampling speed affect bandwidth. If high bandwidth is needed at slow timebases, averaging and repetitive sampling should be considered.

use Math?

To choose a math function.

Math Type

To select “Enhanced Resolution”.

enhance by

For selecting the filter that will enhance resolution of the displayed signal from one to three bits in 0.5-bit steps.

1 2 3 4 B C D

M1 M2 M3 M4

To select the source trace for filtering (four-channel menu shown).

Only with WP01 Advanced Math package. See “Signal

Analysis” in Appendix A for specifications.

10–12

Zoom and Math Setup Menus

SETUP Extrema

†

— used for acquiring a trace envelope over many acquisitions (see also page 10–4).

use Math?

To choose a math function.

Math Type

To select “Extrema”.

limits

To select either “Envelope”, “Floor” or “Roof ”. Floor shows only the lower, and Roof only the upper part of the envelope. Changing the limits does not force the analysis to start again.

for

For selecting the number of sweeps.

To select the source trace (four-channel menu shown).

†

Only with WP01 Math package. See “Signal Analysis” in

Appendix A for specifications.

10–13

Zoom, Mathematics and Math Setup

SETUP — FFT

‡

— used to display the Fast Fourier Transform (FFT) of a signal and visualize it in the frequency domain. See the final section of this

chapter, and Appendix C, for when and how to use FFT.

use Math?

To choose a math function.

Math Type

For selecting “FFT”.

FFT result

To select the FFT’s output format: “Imaginary”, “Magnitude”, “Phase”, “Power Dens”-ity, “Power Spect”-rum, “Real ” or “Real + Imag”.

with window

Using the corresponding menu button to select the FFT window type from “Rectangular”, “Hanning”, “Hamming ”, “Blackman-Harris”, and “Flat-top”. And the associated knob to select “AC” or “DC ”.

For selecting the source trace (four-channel menu shown).

Note: During Fast Fourier Transform computation the FFT sign is displayed in the lower right-hand corner of the screen. The computation of FFT on long time-domain records can take time. The computation can be interrupted or aborted at any time using any front-panel control.

‡

Only with WP02 Spectral Analysis package. See “Signal

Analysis” in Appendix A for specifications.

10–14

Zoom and Math Setup Menus

SETUP — FFT Average§— used for displaying the FFT power averaging of an FFT source

trace, power averaging being useful for characterizing broadband noise or periodic signals without a stable trigger signal. Total power — signal and noise — is measured at each frequency. The source trace must be an FFT function. See the final section of this chapter,

and Appendix C, for when and how to use FFT.

use Math?

To choose a math function.

Math Type

To select “FFT AVG”.

FFT result

To select the output format of the FFT Average: “Magnitude”, “Power Density”, “Power Spectrum”.

for

For selecting the number of sweeps.

To select the FFT source.

Note: FFT Average can be reset by pressing CLEAR SWEEPS. The number of currently accumulated waveforms is then shown in the Displayed Trace field of the function or its expansion.

Only with WP02 Spectral Analysis package. See “Signal

Analysis” in Appendix A for specifications.

10–15

Lecroy 9300C User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual