Used Agilent Agilent Used 33250A Manual

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Page 1

User’s Guide

Publication Number 33250-90001 April 2000

Test Equipment Depot - 800.517.8431 - 99 Washington Street Melrose, MA 02176 - TestEquipmentDepot.com

Agilent 33250A 80 MHz Function / Arbitrary Waveform Generator

Page 2

Agilent 33250A at a Glance

The Agilent Technologies 33250A is a high-performance 80 MHz synthesized function generator with built-in arbitrary waveform and pulse capabilities. Its combination of bench-top and system features makes this function generator a versatile solution for your testing requirements now and in the future.

Convenient bench-top features

• 10 standard waveforms

• Built-in 12-bit 200 MSa/s arbitrary waveform capability

• Precise pulse waveform capabilities with adjustable edge time

• LCD color display provides numeric and graphical views

• Easy-to-use knob and numeric keypad

• Instrument state storage with user-defined names

• Portable, ruggedized case with non-skid feet

Flexible system features

• Four downloadable 64K-point arbitrary waveform memories

• GPIB (IEEE-488) interface and RS-232 interface are standard

• SCPI (Standard Commands for Programmable Instruments) compatibility

Note:

Unless otherwise indicated, this manual applies to all Serial

Numbers.

Page 3

The Front Panel at a Glance

1 Graph Mode/Local Key 2 Menu Operation Softkeys 3 Waveform Selection Keys 4 Knob 5 Modulation/Sweep/Burst Menus 6 State Storage Menu

Note: To get context-sensitive help on any front-panel key or menu softkey, press and hold down that key.

7 Utility Menu 8 Instrument Help Topic Menu 9 Output Enable/Disable Key

10 Manual Trigger Key (

Sweep and Burst only

Navigation Arrow Keys

used for

)

Page 4

The Front-Panel Display at a Glance

Menu Mode

Numeric Readout

Mode

Information

Trigger

Information

Softkey Labels

Units

Output

Status

Graph Mode

To enter the Graph Mode, press the key.

Parameter

Name

Parameter

Valu e

Display Icon

Signal Ground

The softkey colors correspond

to the waveform parameters.

Page 5

Front-Panel Number Entry

You can enter numbers from the front-panel using one of two methods.

Use the knob and arrow keys to modify the displayed number.

Use the numeric keypad and menu softkeys to select the units.

Page 6

The Rear Panel at a Glance

External 10 MHz Reference Input Terminal

Internal 10 MHz Reference Output Terminal

3 RS-232 Interface Connector 4 External Modulation Input Terminal

Use the menu to:

• Select the GPIB or RS-232 interface (see chapter 2).

• Select the GPIB address (see chapter 2).

• Set the RS-232 baud rate, parity, and handshake mode (see chapter 2).

Input: External Trig/FSK/ Burst Gate Output: Trigger Output

6 GPIB Interface Connector 7 Chassis Ground

WARNING For protection from electrical shock, the power cord ground must not be

defeated. If only a two-contact electrical outlet is available, connect the

instrument’s chassis ground screw (see above) to a good earth ground.

Page 7

In This Book

Quick Start Chapter 1 prepares the function generator for use and helps you get familiar with a few of its front-panel features.

Front-Panel Menu Operation Chapter 2 introduces you to the front-

panel menu and describes some of the function generator’s menu features.

Features and Functions Chapter 3 gives a detailed description of the

function generator’s capabilities and operation. You will find this chapter useful whether you are operating the function generator from the front panel or over the remote interface.

Remote Interface Reference

to help you program the function generator over the remote interface.

Error Messages Chapter 5 lists the error messages that may appear as you are working with the function generator. Each listing contains enough information to help you diagnose and solve the problem.

Application Programs Chapter 6 contains several remote interface application programs to help you develop programs for your application.

Tutorial Chapter 7 discusses the fundamentals of signal generation and modulation techniques.

Specifications Chapter 8 lists the function generator’s specifications.

If you have questions relating to the operation of the Agilent 33250A, call 1-800-452-4844 in the United States, or contact your nearest Agilent Technologies Office.

Chapter 4 contains reference information

If your 33250A fails within three years of purchase, Agilent will either repair or replace it free of charge. Call 1-877-447-7278 in the United States (and ask for “Agilent Express”) or contact your local Agilent Technologies Office.

Page 8

Page 9

Chapter 1 Quick Start

To Prepare the Function Generator for Use 15 To Adjust the Carrying Handle 16 To Set the Output Frequency 17 To Set the Output Amplitude 18 To Set a DC Offset Voltage 20 To Set the Duty Cycle 21 To Configure a Pulse Waveform 22 To View a Waveform Graph 23 To Output a Stored Arbitrary Waveform 24 To Use the Built-In Help System 25 To Rack Mount the Function Generator 27

Chapter 2 Front-Panel Menu Operation

Front-Panel Menu Reference 31 To Select the Output Termination 33 To Reset the Function Generator 33 To Output a Modulated Waveform 34 To Output an FSK Waveform 36 To Output a Frequency Sweep 38 To Output a Burst Waveform 40 To Trigger a Sweep or Burst 42 To Store the Instrument State 43 To Configure the Remote Interface 44

Chapter 3 Features and Functions

Output Configuration 49 Pulse Waveforms 64 Amplitude Modulation (AM) 67 Frequency Modulation (FM) 72 Frequency-Shift Keying (FSK) Modulation 78 Frequency Sweep 82 Burst Mode 89 Triggering 98 Arbitrary Waveforms 103 System-Related Operations 109 Remote Interface Configuration 118 Calibration Overview 123 Factory Default Settings 127

Contents

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Contents

Chapter 4 Remote Interface Reference

SCPI Command Summary 131 Simplified Programming Overview 142 Using the APPLy Command 144 Output Configuration Commands 153 Pulse Configuration Commands 166 Amplitude Modulation (AM) Commands 169 Frequency Modulation (FM) Commands 172 Frequency-Shift Keying (FSK) Commands 176 Frequency Sweep Commands 179 Burst Mode Commands 187 Triggering Commands 195 Arbitrary Waveform Commands 198 State Storage Commands 209 System-Related Commands 213 Interface Configuration Commands 218 RS-232 Interface Configuration 219

Phase-Lock Commands 223 The SCPI Status System 225 Status Reporting Commands 235 Calibration Commands 239 An Introduction to the SCPI Language 241 Using Device Clear 246

Chapter 5 Error Messages

Command Errors 249 Execution Errors 252 Query Errors 267 Instrument Errors 268 Self-Test Errors 269 Calibration Errors 271 Arbitrary Waveform Errors 272

Chapter 6 Application Programs

Introduction 276 Example: BASIC for Windows 278 Example: Microsoft Visual Basic for Windows 282 Example: Microsoft Visual C++ for Windows 287

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Contents

Chapter 7 Tutorial

Direct Digital Synthesis 295 Creating Arbitrary Waveforms 298 Square Waveform Generation 300 Pulse Waveform Generation 300 Signal Imperfections 302 Output Amplitude Control 304 Ground Loops 305 Attributes of AC Signals 307 Modulation 309 Frequency Sweep 312 Burst 315

Chapter 8 Specifications

Frequency Characteristics 320 Sinewave Spectral Purity 320 Signal Characteristics 320 Output Characteristics 321 Modulation Characteristics 321 Burst 321 Sweep 321 System Characteristics 322 Trigger Characteristics 322 Clock Reference 322 Sync Output 322 General Specifications 323 Product Dimensions 324

Index 325

Contents

Page 12

Contents

Page 13

Quick Start

Page 14

Quick Start

One of the first things you will want to do with your function generator is to become acquainted with the front panel. We have written the exercises in this chapter to prepare the instrument for use and help you get familiar with some of its front-panel operations. This chapter is divided into the following sections:

• To Prepare the Function Generator for Use, on page 15

• To Adjust the Carrying Handle, on page 16

• To Set the Output Frequency, on page 17

• To Set the Output Amplitude, on page 18

• To Set a DC Offset Voltage, on page 20

• To Set the Duty Cycle, on page 21

• To Configure a Pulse Waveform, on page 22

• To View a Waveform Graph, on page 23

• To Output a Stored Arbitrary Waveform, on page 24

• To Use the Built-In Help System, on page 25

• To Rack Mount the Function Generator, on page 27

Page 15

Chapter 1 Quick Start

Power Switch

To Prepare the Function Generator for Use

1 Check the list of supplied items.

Verify that you have received the following items with your instrument. If anything is missing, please contact your nearest Agilent Sales Office.

❑ One power cord. ❑ This User’s Guide. ❑ One Service Guide. ❑ One folded Quick Reference Guide. ❑ Certificate of Calibration. ❑ Connectivity software on CD-ROM. ❑ One RS-232 cable.

2 Connect the power cord and turn on the function generator.

Several power-on information messages are displayed after the function generator performs its power-on self-test. The GPIB address is displayed. The function generator powers up in the sine wave function at 1 kHz

with an amplitude of 100 mV peak-to-peak (into a 50Ω termination).

At power-on, the connector, press the key

If the function generator does not turn on, verify that the power cord is firmly connected to the power receptacle on the rear panel (the power-line voltage is automatically sensed at power-on). You should also make sure that the function generator is connected to a power source that is energized Then, verify that the function generator is turned on.

Output

connector

is disabled. To enable the Output

f you need further assistance, refer to the Agilent 33250A

for instructions on returning the function generator to Agilent for service.

Service Guide

Page 16

Chapter 1 Quick Start

To Adjust the Carrying Handle

To adjust the position, grasp the handle by the sides and pull outward. Then, rotate the handle to the desired position.

Bench-top viewing positions Carrying position

Page 17

Chapter 1 Quick Start

To Set the Output Frequency

At power-on, the function generator outputs a sine wave at 1 kHz with

an amplitude of 100 mV peak-to-peak (into a 50Ω termination).

The following steps show you how to change the frequency to 1.2 MHz.

1Press the “Freq” softkey.

The displayed frequency is either the power-on value or the frequency previously selected. When you change functions, the same frequency is used if the present value is valid for the new function. To set the waveform period instead, press the Freq softkey again to toggle to the Period softkey (the current selection is highlighted).

2 Enter the magnitude of the desired frequency.

Using the numeric keypad, enter the value “1.2”.

3 Select the desired units.

Press the softkey that corresponds to the desired units. When you select the units, the function generator outputs a waveform with the displayed frequency (if the output is enabled). For this example, press MHz

Note: Y

ou can also enter the desired value using the knob and arrow keys.

Page 18

Chapter 1 Quick Start

To Set the Output Amplitude

At power-on, the function generator outputs a sine wave with an

amplitude of 100 mV peak-to-peak (into a 50Ω termination).

The following steps show you how to change the amplitude to 50 mVrms.

1Press the “Ampl” softkey.

The displayed amplitude is either the power-on value or the amplitude previously selected. When you change functions, the same amplitude is

used if the present value is valid for the new function. To set the amplitude

using a high level and low level, press the Ampl softkey again to toggle to the HiLevel and LoLevel softkeys (the current selection is highlighted).

2 Enter the magnitude of the desired amplitude.

Using the numeric keypad, enter the value “50”.

3 Select the desired units.

Press the softkey that corresponds to the desired units. When you select

the units, the function generator outputs the waveform with the displayed

amplitude (if the output is enabled). For this example, press mV

Note: Y

ou can also enter the desired value using the knob and arrow keys.

RMS

Page 19

Chapter 1 Quick Start

To Set the Output Amplitude

You can easily convert the displayed amplitude from one unit to another. For example, the following steps show you how to convert the amplitude from Vrms to Vpp.

4 Enter the numeric entry mode.

Press the key to enter the numeric entry mode.

5 Select the new units.

Press the softkey that corresponds to the desired units. The displayed value is converted to the new units. For this example, press the Vpp softkey to convert 50 mVrms to its equivalent in volts peak-to-peak.

To change the displayed amplitude by decades, press the right-arrow key to move the cursor to the units on the right side of the display. Then, rotate the knob to increase or decrease the displayed amplitude by decades.

Page 20

Chapter 1 Quick Start

To Set a DC Offset Voltage

At power-on, the function generator outputs a sine wave with a dc offset

of 0 volts (into a 50Ω termination). The following steps show you how to

change the offset to –1.5 mVdc.

1Press the “Offset” softkey.

The displayed offset voltage is either the power-on value or the offset previously selected. When you change functions, the same offset is used if the present value is valid for the new function.

2 Enter the magnitude of the desired offset.

Using the numeric keypad, enter the value “–1.5”.

3 Select the desired units.

Press the softkey that corresponds to the desired units. When you select

the units, the function generator outputs the waveform with the displayed

offset (if the output is enabled). For this example, press mV

Note: Y

Note: To select dc volts from the front panel, press and then select

the DC On softkey. Press the

ou can also enter the desired value using the knob and arrow keys.

Offset softkey to enter the desired voltage level.

Page 21

Chapter 1 Quick Start

To Set the Duty Cycle

Applies only to square waves. At power-on, the duty cycle for square waves is 50%. You can adjust the duty cycle from 20% to 80% for output frequencies up to 25 MHz. The following steps show you how to change

the duty cycle to 30%.

1 Select the square wave function.

Press the key and then set the desired output frequency to any value less than 25 MHz.

2Press the “Duty Cycle” softkey.

The displayed duty cycle is either the power-on value or the percentage previously selected. The duty cycle represents the amount of time per cycle that the square wave is at a high level (note the icon on the right side of the display).

3 Enter the desired duty cycle.

Using the numeric keypad or the knob, select a duty cycle value of “30”. The function generator adjusts the duty cycle immediately and outputs a square wave with the specified value (if the output is enabled).

Page 22

Chapter 1 Quick Start

To Configure a Pulse Waveform

You can configure the function generator to output a pulse waveform with variable pulse width and edge time. The following steps show you

how to configure a 500 ms pulse waveform with a pulse width of 10 ms

and edge times of 50 µs.

1 Select the pulse function.

Press the key to select the pulse function and output a pulse waveform with the default parameters.

2 Set the pulse period.

Press the Period softkey and then set the pulse period to 500 ms.

3 Set the pulse width.

Press the Pulse Width softkey and then set the pulse width to 10 ms. The pulse width represents the time from the 50% threshold of the rising edge to the 50% threshold of the next falling edge (note the display icon).

4 Set the edge time for both edges.

Press the Edge Time softkey and then set the edge time for both the

rising and falling edges to 50 µs. The edge time represents the time from

the 10% threshold to the 90% threshold of each edge (note the display icon

Page 23

Chapter 1 Quick Start

To View a Waveform Graph

In the Graph Mode, you can view a graphical representation of the current waveform parameters. Each softkey parameter is shown in a different color corresponding to the lines above the softkeys at the bottom of the display. Note that the softkeys are listed in the same order as in the normal display mode.

1 Enable the Graph Mode.

Press the key to enable the Graph Mode. The name of the parameter currently selected is shown in the upper-left corner of the display and the numeric value is highlighted.

2 Select the desired parameter.

To select a specific parameter, note the colored bars above the softkeys at the bottom of the display and select the corresponding color. For example to select amplitude, press the softkey below the magenta-colored bar.

• As in the normal display mode, you can edit numbers using either the numeric keypad or the knob and arrow keys.

Parameters which normally toggle when you press a key a second time

• (e.g., Freq /Period) also toggle in the Graph Mode.

• To exit the Graph Mode, press again.

The key also serves as a key to restore front-panel control after remote interface operations.

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Chapter 1 Quick Start

To Output a Stored Arbitrary Waveform

There are five built-in arbitrary waveforms stored in non-volatile memory

The following steps show you how to output the built-in “exponential fall” waveform

For information on creating a custom arbitrary waveform, refer to “To Create and Store an Arbitrary Waveform” on page 109.

1 Select the arbitrary waveform function.

When you press the key to select the arbitrary waveform function, a temporary message is displayed indicating which waveform is currently

selected (the default is “exponential rise”).

2 Select the active waveform.

Press the Select Wform softkey and then press the Built-In softkey to select from the five built-in waveforms. Then press the Exp Fall softkey. The waveform is output using the present settings for frequency, amplitude, and offset unless you change them.

from the front panel.

The selected waveform is now assigned to the key. Whenever you press this key, the selected arbitrary waveform is output. To quickly determine which arbitrary waveform is currently selected, press .

Page 25

Chapter 1 Quick Start

To Use the Built-In Help System

The built-in help system is designed to provide context-sensitive assistance on any front-panel key or menu softkey. A list of help topics is also available to assist you with several front-panel operations.

1 View the help information for a function key.

Press and hold down the key. If the message contains

information than will fit on the display, press the ↓ softkey or turn the

knob clockwise to view the remaining information.

Press DONE to exit the help menu.

2 View the help information for a menu softkey.

Press and hold down the Freq softkey.

information than will fit on the display, press the ↓ softkey or rotate the

knob clockwise to view the remaining information.

Press DONE to exit the help menu.

If the message contains

Page 26

Chapter 1 Quick Start

To Use the Built-In Help System

3 View the list of help topics.

Press the key to view the list of available help topics. To scroll

through the list, press the ↑ or ↓ softkey or rotate the knob. Select the

third topic “Get HELP on any key” and then press SELECT.

Press DONE to exit the help menu.

4 View the help information for displayed messages.

Whenever a limit is exceeded or any other invalid configuration is found, the function generator will display a message. For example, if you enter a value that exceeds the frequency limit for the selected function, a message will be displayed. The built-in help system provides additional information on the most recent message to be displayed.

Press the key, select the first topic “

and then press SELECT.

Local Language Help: The built-in help system in available in multiple

languages. All messages, context-sensitive help, and help topics appear in the selected language. The menu softkey labels and status line messages are not translated.

To select the local language, press the key, press the System softkey, and then press the Help In softkey. Select the desired language.

View the last message displayed”,

Page 27

Chapter 1 Quick Start

To Rack Mount the Function Generator

You can mount the Agilent 33250A in a standard 19-inch rack cabinet using one of two optional kits available. Instructions and mounting hardware are included with each rack-mounting kit. Any Agilent System II instrument of the same size can be rack-mounted beside the Agilent 33250A.

Note:

before rack-mounting the instrument.

Remove the carrying handle, and the front and rear rubber bumpers

To remove the handle, rotate it to vertical and pull the ends outward.

Front Rear (bottom view)

To remove the rubber bumper, stretch a corner and then slide it off.

Page 28

Chapter 1 Quick Start

To Rack Mount the Function Generator

To rack mount a single instrument, order adapter kit 5063-9240.

To rack mount two instruments side-by-side, order lock-link kit 5061-9694 and flange kit 5063-9212. Be sure to use the support rails in the rack cabinet.

In order to prevent overheating, do not block the flow of air into or out of the instrument. Be sure to allow enough clearance at the rear, sides, and bottom of the instrument to permit adequate internal air flow.

Page 29

Front-Panel Menu Operation

Page 30

Front-Panel Menu Operation

This chapter introduces you to the front-panel keys and menu operation. This chapter does not give a detailed description of every front-panel key or menu operation. It does, however, give you an overview of the front-

panel menus and many front-panel operations. See chapter 3 “Features and Functions,” starting on page 53, for a complete discussion of the function generator’s capabilities and operation.

• Front-Panel Menu Reference, on page 31

• To Select the Output Termination, on page 33

• To Reset the Function Generator, on page 33

• To Output a Modulated Waveform, on page 34

• To Output an FSK Waveform, on page 36

• To Output a Frequency Sweep, on page 38

• To Output a Burst Waveform, on page 40

• To Trigger a Sweep or Burst, on page 42

• To Store the Instrument State, on page 43

• To Configure the Remote Interface, on page 44

Page 31

Chapter 2 Front-Panel Menu Operation

Front-Panel Menu Reference

This section gives an overview of the front-panel menus. The remainder of this chapter contains examples of using the front-panel menus.

Configure the modulation parameters for AM, FM, and FSK.

• Select the modulation type.

• Select an internal or external modulation source.

• Specify the AM modulation depth, modulating frequency, and modulation shape. Specify the FM frequency deviation, modulating frequency, and modulation shape.

•

• Specify the FSK “hop” frequency and FSK rate.

Configure the parameters for frequency sweep.

• Select linear or logarithmic sweeping.

• Select the start/ stop frequencies or

• Select the time in seconds required to complete a sweep.

• Specify a marker frequency.

• Specify an internal or external trigger source for the sweep.

• Specify the slope (rising or falling edge) for an external trigger source.

• Specify the slope (rising or falling edge) of the “Trig Out” signal.

Configure the parameters for burst.

• Select the triggered (N Cycle) or externally-gated burst mode.

• Select the number of cycles per burst (1 to 1,000,000, or Infinite).

• Select the starting phase angle of the burst (-360° to +360°).

• Specify the time from the start of one burst to the start of the next burst.

• Specify a delay between the trigger and the start of the burst.

• Specify an internal or external trigger source for the burst.

• Specify the slope (rising or falling edge) for an external trigger source.

• Specify the slope (rising or falling edge) of the “Trig Out” signal.

center/ span frequencies.

Page 32

Chapter 2 Front-Panel Menu Operation

Front-Panel Menu Reference

Store and recall instrument states.

• Store up to four instrument states in non-volatile memory.

• Assign a custom name to each storage location.

• Recall stored instrument states.

• Restore all instrument settings to their factory default values.

• Select the instrument’s power-on configuration (last or factory default).

Configure system-related parameters.

• Generate a dc-only voltage level.

• Enable/disable the Sync signal which is output from the “Sync” connector.

• Select the output termination (1Ω to 10 kΩ, or Infinite).

• Enable/disable amplitude autoranging.

• Select the waveform polarity (normal or inverted).

• Select the GPIB address.

• Configure the RS-232 interface (baud rate, parity, and handshake mode). Select how periods and commas are used in numbers displayed on the front panel.

•

• Select the local language for front-panel messages and help text.

• Enable/disable the tone heard when an error is generated.

• Enable/disable the display bulb-saver mode.

• Adjust the contrast setting of the front-panel display.

• Perform an instrument self-test.

• Secure/unsecure the instrument for calibration and perform manual calibrations.

• Query the instrument’s firmware revision codes.

View the list of Help topics.

• View the last message displayed.

• View the remote command error queue.

• Get HELP on any key.

• How to generate a dc-only voltage level.

• How to generate a modulated waveform.

• How to create an arbitrary waveform.

• How to reset the instrument to its default state.

• How to view a waveform in the Graph Mode.

• How to synchronize multiple instruments.

• How to obtain Agilent Technical Support.

Page 33

Chapter 2 Front-Panel Menu Operation

To Select the Output Termination

The Agilent 33250A has a fixed series output impedance of 50 ohms to the front-panel Output connector. If the actual load impedance is different than the value specified, the displayed amplitude and offset levels will be incorrect. The load impedance setting is simply provided as a convenience to ensure that the displayed voltage matches the expected load.

1Press .

2 Navigate the menu to set the output termination.

Press the Output Setup softkey and then select the Load softkey.

3 Select the desired output termination.

Use the knob or numeric keypad to select the desired load impedance or press the Load softkey again to choose “High Z”.

To Reset the Function Generator

To reset the instrument to its factory default state, press and then select the Set to Defaults softkey. Press YES to confirm the operation.

For a complete listing of the instrument’s power-on and reset conditions, see “Factory Default Settings” on page 133.

Page 34

Chapter 2 Front-Panel Menu Operation

To Output a Modulated Waveform

A modulated waveform consists of a carrier and a modulating waveform. In AM (amplitude modulation), the amplitude of the carrier is varied by the amplitude of the modulating waveform. For this example, you will output an AM waveform with 80% modulation depth. The carrier will be a 5 kHz sine wave and the modulating waveform will be a 200 Hz sine wave.

1 Select the function, frequency, and amplitude of the carrier.

Press and then press the Freq, Ampl, and Offset softkeys to configure the carrier waveform.

with an amplitude of 5 Vpp.

2 Select AM.

Press and then select “AM” using the Type softkey. Notice that a status message “AM by Sine” is shown in the upper-left corner of the display.

3 Set the modulation depth.

Press the AM Depth softkey and then set the value to 80% using the numeric keypad or the knob and arrow keys.

For this example, select a 5 kHz sine wave

Page 35

Chapter 2 Front-Panel Menu Operation

To Output a Modulated Waveform

4 Set the modulating frequency.

Press the AM Freq softkey and then set the value to 200 Hz using the numeric keypad or the knob and arrow keys.

5 Select the modulating waveform shape.

Press the Shape softkey to select the shape of the modulating waveform. For this example, select a sine wave.

At this point, the function generator outputs an AM waveform with the specified modulation parameters (if the output is enabled).

6 View the waveform.

Press t

To turn off the Graph Mode, press

o view the waveform parameters.

again

Page 36

Chapter 2 Front-Panel Menu Operation

To Output an FSK Waveform

You can configure the function generator to “shift” its output frequency between two preset values using FSK modulation. The rate at which the output shifts between the two frequencies (called the “carrier frequency” and the “hop frequency”) is determined by the internal rate generator or the signal level on the rear-panel Trig In connector. For this example,

you will set the “carrier” frequency to 3 kHz and the “hop” frequency to 500 Hz, with an FSK rate of 100 Hz.

1 Select the function, frequency, and amplitude of the carrier.

Press and then press the Freq, Ampl, and Offset softkeys to configure the carrier waveform.

with an amplitude of 5 Vpp.

2 Select FSK.

Press and then select “FSK” using the Typ e softkey. Notice that a status message “FSK” is shown in the upper-left corner of the display.

For this example, select a 3 kHz sine wave

Page 37

Chapter 2 Front-Panel Menu Operation

To Output an FSK Waveform

3 Set the “hop” frequency.

Press the Hop Freq softkey and then set the value to 500 Hz using the numeric keypad or the knob and arrow keys.

4 Set the FSK “shift” rate.

Press the FSK Rate softkey and then set the value to 100 Hz using the numeric keypad or the knob and arrow keys.

At this point, the function generator outputs an FSK waveform (if the output is enabled).

5 View the waveform.

Press t

To turn off the Graph Mode, press

o view the waveform parameters.

again

Page 38

Chapter 2 Front-Panel Menu Operation

To Output a Frequency Sweep

from 50 Hz to 5 kHz. You will not change the other parameters from their default settings: internal sweep trigger, linear spacing, and 1 second sweep time.

1 Select the function and amplitude for the sweep.

For sweeps, you can select sine, square, ramp, or arbitrary waveforms (pulse, noise, and dc are not allowed). For this example, select a sine wave

with an amplitude of 5 Vpp.

2 Select the sweep mode.

Press and then verify that the linear sweep mode is currently selected. Notice that a status message “Linear Sweep” is shown in the upper-left corner of the display.

3 Set the start frequency.

Press the Start softkey and then set the value to 50 Hz using the numeric keypad or the knob and arrow keys.

Page 39

Chapter 2 Front-Panel Menu Operation

To Output a Frequency Sweep

4 Set the stop frequency.

Press the Stop softkey and then set the value to 5 kHz using the numeric keypad or the knob and arrow keys.

At this point, the function generator outputs a continuous sweep from 50 Hz to 5 kHz (if the output is enabled).

Note: If desired, you can set the frequency boundaries of the sweep using a center frequency and frequency span. These parameters are similar to the start frequency and stop frequency and are included to give you added flexibility. To achieve the same results, set the center frequency to 2.525 kHz and the frequency span to 4.950 kHz.

5 View the waveform.

Press t

To turn off the Graph Mode, press

You can generate a single frequency sweep by pressing the key. For more information, see “To Trigger a Sweep or Burst” on page 42.

o view the waveform parameters.

again

Page 40

Chapter 2 Front-Panel Menu Operation

To Output a Burst Waveform

You can configure the function generator to output a waveform with a specified number of cycles, called a burst. You can output the burst at a rate determined by the internal rate generator or the signal level on the rear-panel Trig In connector. For this example, you will output a

three-cycle sine wave with a 20 ms burst period. You will not change the other parameters from their default settings: internal burst source and 0 degree starting phase.

1 Select the function and amplitude for the burst.

For burst waveforms, you can select sine, square, ramp, pulse, or

arbitrary waveforms (noise is allowed only in the “gated” burst mode and dc is not allowed). For this example, select a sine wave with an

amplitude of 5 Vpp.

2 Select the burst mode.

Press and then verify that the “N Cycle” (internally-triggered) mode is currently selected. Notice that a status message “N Cycle Burst” is shown in the upper-left corner of the display.

Page 41

Chapter 2 Front-Panel Menu Operation

To Output a Burst Waveform

3 Set the burst count.

Press the # Cycles softkey and then set the count to “3” using the numeric keypad or knob.

4 Set the burst period.

Press the Burst Period softkey and then set the period to 20 ms using the numeric keypad or the knob and arrow keys. The burst period sets the time from the start of one burst to the start of the next burst (note the display icon).

At this point, the function generator outputs a continuous three-cycle burst (if the output is enabled).

5 View the waveform.

Press t

To turn off the Graph Mode, press

You can generate a single burst (with the specified count) by pressing the key. For more information, see “To Trigger a Sweep or Burst” on page 42.

You can also use an external gate signal to either turn the output signal “on” or “off” based on the external signal applied to the rear-panel

Tri g In

o view the waveform parameters.

again

connector. For more information, see “Burst Mode” on page 95.

Page 42

Chapter 2 Front-Panel Menu Operation

To Trigger a Sweep or Burst

You can issue triggers from the front panel for sweeps and bursts using a manual trigger or an internal trigger.

• Internal or “automatic” triggering is enabled with the default settings of the function generator. In this mode, the function generator outputs continuously when the sweep or burst mode is selected.

• Manual triggering initiates one sweep or outputs one burst each time you press the key from the front-panel. Continue pressing this key to re-trigger the function generator.

• The key is disabled when in remote (the remote icon turns on while in remote) and when a function other than sweep or burst is currently selected (or when the output is disabled). The key flashes off momentarily when using a manual trigger.

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Chapter 2 Front-Panel Menu Operation

To Store the Instrument State

You can store the instrument state in one of four non-volatile storage locations. A fifth storage location automatically holds the power-down configuration of the instrument. When power is restored, the instrument can automatically return to its state before power-down.

1 Select the desired storage location.

Press and then select the Store State softkey.

2 Select a custom name for the selected location.

If desired, you can assign a custom name to each of the four locations.

• The name can contain up to 12 characters. The first character

be a letter but the remaining characters can be letters, numbers

the underscore character (“_”).

• To add additional characters, press the right-arrow key until the cursor is to the right of the existing name and then turn the knob.

• To delete all characters to the right of the cursor position, press .

• To use numbers in the name, you can enter them directly from the numeric keypad. Use the decimal point from the numeric keypad to add the underscore character (“_” ) to the name.

must

, or

3 Store the instrument state.

Press the STORE STATE softkey. The instrument stores the selected function, frequency, amplitude, dc offset, duty cycle, symmetry, as well as any modulation parameters in use. The instrument does not store volatile waveforms created in the arbitrary waveform function.

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Chapter 2 Front-Panel Menu Operation

To Configure the Remote Interface

The instrument is shipped with both a GPIB (IEEE-488) interface and an RS-232 interface. Only one interface can be enabled at a time. The GPIB interface is selected when the instrument is shipped from the factory.

GPIB Configuration

1 Select the GPIB interface.

Press and then select the

2 Select the GPIB address.

Press the

numeric keypad or knob. The factory setting is “10”.

The GPIB address is shown on the front-panel display at power-on.

3 Exit the menu.

GPIB Address

GPIB softkey from the “I/O” menu.

softkey

and enter the desired address using the

Press the DONE softkey.

Page 45

RS-232 Configuration

Chapter 2 Front-Panel Menu Operation

To Configure the Remote Interface

1 Select the RS-232 interface.

Press and then select the

2 Set the baud rate.

Press the Baud Rate softkey and select one of the following: 300, 600, 1200, 2400, 4800, 9600, 19200, 38400, 57600 (factory setting), or 115200 baud.

3 Select the parity and number of data bits.

Press the Parity / # Bits softkey and select one of the following: None (8 data bits, factory setting), Even (7 data bits), or Odd (7 data bits). When you set the parity, you are also setting the number of data bits.

4 Select the handshake mode.

Press the Handshake softkey and select one of the following: None, DTR / DSR (factory setting), Modem, RTS/ CTS, or XON / XOFF.

5 Exit the menu.

RS-232 softkey from the “I/O” menu.

Press the DONE softkey.

Page 46

Page 47

Features and Functions

Page 48

Features and Functions

You will find that this chapter makes it easy to look up all the details about a particular feature of the function generator. Whether you are operating the function generator from the front panel or over the remote interface, this chapter will be useful. This chapter is divided into the following sections:

• Output Configuration, on page 49

• Pulse Waveforms, on page 64

• Amplitude Modulation (AM), on page 67

• Frequency Modulation (FM), on page 72

• Frequency-Shift Keying (FSK) Modulation, on page 78

• Frequency Sweep, on page 82

•Burst Mode, on page 89

•Triggering, on page 98

• Arbitrary Waveforms, on page 103

• System-Related Operations, on page 109

• Remote Interface Configuration, on page 118

• Calibration Overview, on page 123

• Factory Default Settings, on page 127

Some knowledge of the front-panel menus will be helpful before you read this chapter. If you have not already read chapter 2, “Front-Panel Menu Operation,” starting on page 29, you may want to read it now. Chapter 4, “Remote Interface Reference,” starting on page 129, lists the syntax for the SCPI commands available to program the function generator.

Throughout this manual, the following conventions are used for SCPI command syntax for remote interface programming:

• Square brackets ( [ ] ) indicate optional keywords or parameters.

• Braces ( { } ) enclose parameters within a command string.

• Triangle brackets ( < > ) enclose parameters for which you must substitute a value.

• A vertical bar ( | ) separates multiple parameter choices.

Page 49

Chapter 3 Features and Functions

Output Configuration

This section contains information to help you configure the function generator for outputting waveforms. You may never have to change some of the parameters discussed here, but they are provided to give you the flexibility you might need.

Output Function

The function generator can output five standard waveforms including sine, square, ramp, pulse, and noise. You can also select one of five built-in arbitrary waveforms or create your own custom waveforms. You can internally modulate any of the standard waveforms (except pulse and noise) and also arbitrary waveforms using AM, FM, or FSK. Linear or logarithmic frequency sweeping is available for any of the standard waveforms (except pulse and noise) and also arbitrary waveforms. You can generate a burst waveform using any of the standard waveforms and also arbitrary waveforms. The default function is sine wave.

• The table below shows which output functions are allowed with modulation, sweep, and burst. Each “ • ” indicates a valid combination

If you change to a function that is not allowed with modulation, sweep, or burst, then the modulation or mode is turned off.

Sine Square Ramp Pulse Noise DC Arb

AM, FM Carrier •• • • FSK Carrier •• • • Sweep Mode •• • • Burst Mode •• •• •

Allowed in the External Gated burst mode only.

•

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Chapter 3 Features and Functions

Output Configuration

• Function Limitations: If you change to a function whose maximum frequency is less than that of the current function, the frequency is adjusted to the maximum value for the new function. For example, if you are currently outputting an 80 MHz sine wave and then change to the ramp function, the function generator will automatically the output frequency to 1 MHz (the upper limit for ramps).

• Amplitude Limitations: If you change to a function whose maximum amplitude is less than that of the current function, the amplitude is automatically adjusted to the maximum value for the new function. This may occur when the output units are Vrms or dBm due to the differences in crest factor for the various output functions.

For example, if you output a 5 Vrms square wave (into 50 ohms) and then change to the sine wave function, the function generator will automatically adjust the output amplitude to 3.536 Vrms (the upper limit for sine in Vrms).

• Front-Panel Operation: To select a function, press any key in the top row of function keys. Press to output the arbitrary waveform currently selected. To view the other arbitrary waveform choices, press the Select Wform softkey.

adjust

To select dc volts from the front panel, press and then select the DC On softkey. Press the Offset softkey to enter the desired offset voltage level.

• Remote Interface Operation:

FUNCtion:SHAPe {SINusoid|SQUare|RAMP|PULSe|NOISe|DC|USER}

You can also use the

amplitude, and offset with a single command.

APPLy

command to select the function, frequency

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Chapter 3 Features and Functions

Output Configuration

Output Frequency

As shown below, the output frequency range depends on the function currently selected. The default frequency is 1 kHz for all functions.

Function Minimum Frequency Maximum Frequency

Sine

Square

Ramp

Pulse

Noise, DC

Arbs

1 µHz 1 µHz 1 µHz

500 µHz

Not Applicable

1 µHz

80 MHz 80 MHz

1 MHz

50 MHz

Not Applicable

25 MHz

adjust

the output frequency to 1 MHz (the upper limit for ramps).

• Burst Limitation: For internally-triggered bursts, the minimum frequency is 2 mHz. For sine and square waveforms, frequencies above 25 MHz are allowed only with an “infinite” burst count.

Duty Cycle Limitations

•

: For square waveforms, the function generato may not be able to use the full range of duty cycle values at higher frequencies as shown below.

20% to 80% (frequency < 40% to 60% (25 MHz < frequency <

25 MHz)

50 MHz)

50% (frequency > 50 MHz)

If you change to a frequency that cannot produce the current duty cycle the duty cycle is automatically adjusted to the maximum value for the new frequency. For example, if you currently have the duty cycle set to 70% and then change the frequency to 60 MHz, the function generator will automatically adjust the duty cycle to 50% (the upper limit for this frequency).

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Chapter 3 Features and Functions

Output Configuration

• Front-Panel Operation: To set the output frequency, press the Freq softkey for the selected function. Then use the knob or numeric keypad to enter the desired frequency. To set the waveform period instead, press the Freq softkey again to toggle to the Period softkey.

• Remote Interface Operation:

FREQuency {<frequency>|MINimum|MAXimum}

You can also use the amplitude, and offset with a single command.

APPLy

command to select the function, frequency

Output Amplitude

The default amplitude is 100 mVpp (into 50 ohms) for all functions.

• Offset Voltage Limitations: The relationship between output amplitude and offset voltage is shown below. Vmax is the maximum

peak voltage for the selected output termination (5 volts for a 50Ω

load or 10 volts for a high-impedance load).

Vpp <

• Limits Due to Output Termination: If you change the output termination setting, the displayed output amplitude will be adjusted

(and no error will be generated). For example, if you set the amplitude

to 10 Vpp and then change the output termination from 50 ohms to “high impedance”, the amplitude displayed on the function generator’s front-panel will double to 20 Vpp. If you change from “high impedance” to 50 ohms, the displayed amplitude will drop in half. For more information, see “Output Termination” on page 57.

• Limits Due to Units Selection: In some cases, the amplitude limits are determined by the output units selected. This may occur when the units are Vrms or dBm due to the differences in crest factor for the various output functions. For example, if you output a 5 Vrms square wave (into 50 ohms) and then change to the sine wave function, the function generator will automatically adjust the output amplitude to 3.536 Vrms (the upper limit for sine waves in Vrms).

2 X (Vmax –|Voffset|)

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Chapter 3 Features and Functions

Output Configuration

• You can set the output amplitude in Vpp, Vrms, or dBm. For more

information, see “Output Units” on page 56.

• You cannot specify the output amplitude in dBm if the output termination is currently set to “high impedance”. The units are automatically converted to Vpp. For more information, see “Output

Units” on page 56.

• Arbitrary Waveform Limitations: For arbitrary waveforms, the maximum amplitude will be limited if the waveform data points do not span the

For example

of values between ±1 and therefore its maximum amplitude is limited to 6.087 Vpp (into 50 ohms).

• While changing amplitude, you may notice a momentary disruption in the output waveform at certain voltages due to switching of the output attenuators. The amplitude is controlled, however, so the output voltage will never exceed the current setting while switching ranges. To prevent this disruption in the output, you can disable the voltage autoranging feature as described on page 60.

full range of the output DAC (Digital- to-Analog Converter).

, the built-in “Sinc” waveform does not use the full range

• You can also set the amplitude (with an associated offset voltage) by specifying a high level and low level. For example, if you set the high level to +2 volts and the low level to -3 volts, the resulting amplitude is 5 Vpp (with an offset voltage of -500 mV).

• For dc volts, the output level is actually controlled by setting the offset voltage. You can set the dc level to any value between ±5 Vdc into 50 ohms or ±10 Vdc into an open circuit. See “DC Offset Voltage”

on the following page for more information.

To select dc volts from the front panel, press and then select the

DC On softkey. Press the Offset softkey to set the desired offset voltage level.

• Front-Panel Operation: softkey for the selected function. Then use the knob or numeric keypad to enter the desired amplitude. To set the amplitude using a high level and low level, press the Ampl softkey again to toggle to the HiLevel and LoLevel softkeys.

To set the output amplitude, press the

Ampl

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Chapter 3 Features and Functions

Output Configuration

• Remote Interface Operation:

VOLTage {<amplitude>|MINimum|MAXimum}

Or, you can set the amplitude by specifying a high level and low level using the following commands.

VOLTage:HIGH {<voltage>|MINimum|MAXimum} VOLTage:LOW {<voltage>|MINimum|MAXimum}

You can also use the

amplitude, and offset with a single command.

APPLy

command to select the function, frequency

DC Offset Voltage

The default offset is 0 volts for all functions.

Limits Due to Amplitude

• output amplitude is shown below. Vmax is the maximum peak voltage

for the selected output termination (5 volts for a 50Ω load or 10 volts

for a high-impedance load).

|Voffset| <

If the specified offset voltage is not valid, the function generator will automatically adjust it to the maximum dc voltage allowed with the amplitude specified.

• Limits Due to Output Termination: The offset limits are determined by the current output termination setting. For example, if you set the offset to 100 mVdc and then change the output termination from 50 ohms to “high impedance”, the offset voltage displayed on the function generator’s front-panel will double to 200 mVdc (and no error will be generated). If you change from “high impedance” to 50 ohms, the displayed offset will drop in half. See “Output Termination” on

page 57 for more information.

Vmax –

: The relationship between offset voltage and

Vpp

----------2

Page 55

Chapter 3 Features and Functions

Output Configuration

• Arbitrary Waveform Limitations: For arbitrary waveforms, the maximum

points do not Converter).

the full range of values between ±1 and therefore its maximum offset is limited to 4.95 volts (into 50 ohms).

• You can also set the offset by specifying a high level and low level. For example, if you set the high level to +2 volts and the low level to

-3 volts, the resulting amplitude is 5 Vpp (with an offset voltage of

-500 mV).

offset and amplitude will be limited if the waveform data

span the

For example, the built-in “Sinc” waveform does not use

full range of the output DAC (Digital-to-Analog

• For dc volts, the output level is actually controlled by setting the offset voltage. You can set the dc level to any value between ±5 Vdc into 50 ohms or ±10 Vdc into an open circuit.

To select dc volts from the front panel, press and then select the DC On softkey. Press the Offset softkey to set the desired offset voltage level.

• Front-Panel Operation: for the selected function. Then use the knob or numeric keypad to enter the desired offset. To set the offset using a high level and low level, press the Offset softkey again to toggle to the HiLevel and LoLevel softkeys.

• Remote Interface Operation:

VOLTage:OFFSet {<offset>|MINimum|MAXimum}

Or, you can set the offset by specifying a high level and low level using the following commands.

VOLTage:HIGH {<voltage>|MINimum|MAXimum} VOLTage:LOW {<voltage>|MINimum|MAXimum}

You can also use the

amplitude, and offset with a single command.

To set the dc offset, press the

APPLy

command to select the function, frequency

Offset

softkey

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Chapter 3 Features and Functions

Output Configuration

Output Units

Applies to output amplitude only

amplitude are volts peak-to-peak.

• Output units: Vpp, Vrms, or dBm. The default is Vpp.

• The unit setting is stored in volatile memory; the units are set to “Vpp” when power has been off or after a remote interface reset.

• The function generator uses the current units selection for both front panel and remote interface operations. For example, if you select “VRMS” from the remote interface, the units are displayed as “VRMS” on the front panel.

• The output units for amplitude cannot be set to dBm if the output termination is currently set to “high impedance”. The units are automatically converted to Vpp.

• Front-Panel Operation: Use the numeric keypad to enter the desired magnitude and then press the appropriate softkey to select the units. You can also convert from one unit to another from the front panel. For example, to convert 2 Vpp to its equivalent value in Vrms, press and then press the V

707.1 mVrms for a sine wave.

• Remote Interface Operation:

VOLTage:UNIT {VPP|VRMS|DBM}

. At power-on, the units for output

softkey. The converted value is

RMS

Page 57

Chapter 3 Features and Functions

Output Configuration

Output Termination

Applies to output amplitude and offset voltage only. The Agilent 33250A has a fixed series output impedance of 50 ohms to the front-panel Output connector. If the actual load impedance is different than the value specified, the displayed amplitude and offset levels will be incorrect.

• Output termination: 1Ω to 10 kΩ, or Infinite. The default is 50Ω.

• The output termination setting is stored in non-volatile memory and does not change when power has been off or after a remote

interface reset. When shipped from the factory, 50Ω is selected.

• If you specify a 50-ohm termination but are actually terminating into an open circuit, the actual output will be twice the value specified. For example, if you set the offset to 100 mVdc (and specify a 50-ohm load) but are terminating the output into an open circuit, the actual offset will be 200 mVdc.

• If you change the output termination setting, the displayed output amplitude and offset levels are automatically adjusted (no error will be generated). For example, if you set the amplitude to 10 Vpp and then change the output termination from 50 ohms to “high impedance”, the amplitude displayed on the function generator’s

front-panel will to 50 ohms, the displayed amplitude will drop in half.

• You cannot specify the output amplitude in dBm if the output termination is currently set to “high impedance”. The units are automatically converted to Vpp.

• Front-Panel Operation: Press and select the Output Setup softkey. Then use the knob or numeric keypad to select the desired load impedance or press the Load softkey again to choose “High Z”.

• Remote Interface Operation:

OUTPut:LOAD {<ohms>|INFinity|MINimum|MAXimum}

double

to 20 Vpp. If you change from “high impedance”

Page 58

Chapter 3 Features and Functions

Output Configuration

Duty Cycle

Applies to square waves only. Duty cycle represents the amount of time per cycle that the square wave is at a high level (assuming that the

waveform polarity is not reversed).

20% Duty Cycle 80% Duty Cycle

• Duty Cycle: 20% to 80% (frequency < 40% to 60% (25 MHz < frequency < 50% (frequency > 50 MHz)

• The duty cycle is stored in volatile memory; the duty cycle is set to

50% when power has been off or after a remote interface reset.

• The duty cycle setting is remembered when you change from square

wave to another function. When you return to the square function, the previous duty cycle is used.

• Limits Due to Frequency: If the square wave function is selected and

you change to a frequency that cannot produce the current duty cycle, the duty cycle is automatically adjusted to the maximum value for the new frequency. For example, if you currently have the duty cycle set to 70% and then change the frequency to 60 MHz, the function generator will automatically adjust the duty cycle to 50% (the upper limit for this frequency).

• If you select a square waveform as the modulating waveform for

AM or FM, the duty cycle setting does not apply. The function generator always uses a square waveform with a 50% duty cycle.

• Front-Panel Operation: After selecting the square wave function,

press the Duty Cycle softkey. Then use the knob or numeric keypad to enter the desired duty cycle.

25 MHz)

50 MHz)

• Remote Interface Operation:

FUNCtion:SQUare:DCYCle {<percent>|MINimum|MAXimum}

The APPLy command automatically sets the duty cycle to 50%.

Page 59

Chapter 3 Features and Functions

Output Configuration

Symmetry

Applies to ramp waves only. Symmetry represents the amount of time per cycle that the ramp wave is rising (assuming that the waveform polarity is not reversed).

0% Symmetry 100% Symmetry

• The symmetry is stored in volatile memory; the symmetry is set to 100% when power has been off or after a remote interface reset.

• The symmetry setting is remembered when you change from ramp wave to another function. When you return to the ramp function, the previous symmetry is used.

• If you select a ramp waveform as the modulating waveform for AM or FM, the symmetry setting does not apply.

• Front-Panel Operation: After selecting the ramp function, press the Symmetry softkey. Then use the knob or numeric keypad to enter the desired symmetry.

• Remote Interface Operation:

FUNCtion:RAMP:SYMMetry {<percent>|MINimum|MAXimum}

The APPLy command automatically sets the symmetry to 100%.

Page 60

Chapter 3 Features and Functions

Output Configuration

Voltage Autoranging

In the default mode, autoranging is automatically selects the optimal settings for the output amplifier and attenuators. With autoranging disabled, the function generator uses the current

• One advantage of disabling autoranging is to eliminate momentary

• Front-Panel Operation: Press and select the Output Setup

• Remote Interface Operation:

amplifier and attenuator settings.

disruptions caused by switching of the attenuators while changing amplitude. However, the amplitude and offset accuracy and resolution (as well as waveform fidelity) may be adversely affected when reducing the amplitude below the expected range change.

softkey. Then press the Range softkey again to toggle between the “Auto” and “Hold” selections.

VOLTage:RANGe:AUTO {OFF|ON|ONCE}

The APPLy command automatically enables autoranging.

overrides the voltage autorange setting

enabled and the function generator

and

Output Control

You can disable or enable the front-panel Output connector. At power-on, the output is disabled. When enabled, the key is illuminated.

• If an excessive external voltage is applied to the front-panel Output connector, an error message will be displayed and the output will be disabled.

Output

• Front-Panel Operation: Press to enable or disable the output.

• Remote Interface Operation:

OUTPut {OFF|ON}

The APPLy command overrides the current setting and automatically enables the Output connector.

To re-enable the output, remove the overload from the

connector

and press to enable the output.

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Chapter 3 Features and Functions

Output Configuration

Waveform Polarity

In the normal mode (default), the waveform goes positive during the first part of the cycle. In the inverted mode, the waveform goes negative during the first part of the cycle.

• As shown in the examples below, the waveform is inverted relative to the offset voltage. Any offset voltage present will remain unchanged when the waveform is inverted.

nverte

Offset

Normal

No Offset Voltage

Inverted

Normal

With Offset Voltage

• When a waveform is inverted, the Sync signal associated with the waveform is not inverted.

• Front-Panel Operation: Press and select the Output Setup softkey. Then press the Normal softkey again to toggle between the “Normal” and “Invert” selections.

• Remote Interface Operation:

OUTPut:POLarity {NORMal|INVerted}

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Chapter 3 Features and Functions

Output Configuration

Sync Output Signal

A sync output is provided on the front-panel Sync connector. All of the standard output functions (except dc and noise) have an associated Sync signal. For certain applications where you may not want to output the Sync signal, you can disable the Sync connector.

• By default, the Sync signal is routed to the Sync connector (enabled). When the Sync signal is disabled, the output level on the Sync connector is at a logic “low” level.

When a waveform is inverted (see “Waveform Polarity” on the previous

•

page), the Sync signal associated with the waveform is not inverted.

• The Sync signal setting is overridden by the setting of the Marker frequency used with the sweep mode (see page 86). Therefore, when

the marker frequency is enabled (and the sweep mode is also enabled

the Sync signal setting is ignored.

•For sine, ramp, and pulse waveforms, the Sync signal is a square waveform with a 50% duty cycle. The Sync signal is a TTL “high” when the waveform’s output is positive, relative to zero volts (or the dc offset value). The Sync signal is a TTL “low” when the output is negative, relative to zero volts (or the dc offset value).

•For square waveforms, the Sync signal is a square waveform with the same duty cycle as the main output. The Sync signal is a TTL “high” when the waveform’s output is positive, relative to zero volts (or the dc offset value). The Sync signal is a TTL “low” when the output is negative, relative to zero volts (or the dc offset value).

•For arbitrary waveforms, the Sync signal is a square waveform with a 50% duty cycle. The Sync signal is a TTL “high” when the first downloaded waveform point is output.

• For internally-modulated AM and FM, the Sync signal is referenced to the modulating waveform (not the carrier) and is a square waveform with a 50% duty cycle. The Sync signal is a TTL “high” during the first half of the modulating waveform.

• For externally-modulated AM and FM, the Sync signal is referenced to the carrier waveform (not the modulating waveform) and is a square waveform with a 50% duty cycle.

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Chapter 3 Features and Functions

Output Configuration

•For FSK, the Sync signal is referenced to the “hop” frequency and is a

square waveform with a 50% duty cycle. The Sync signal is a TTL

on the transition to the “hop” frequency.

“high”

•For frequency sweeps with Marker Off, the Sync signal is a square waveform with a 50% duty cycle. The Sync signal is a TTL “high” at the beginning of the sweep and goes “low” at the midpoint of the sweep

The frequency of the sync waveform equals the specified sweep time.

•For frequency sweeps with Marker On, the Sync signal is a TTL “high” at the beginning of the sweep and goes “low” at the marker frequency.

•For a triggered burst, the Sync signal is a TTL “high” when the burst

. The Sync signal

begins number of cycles (may not be

has an associated start phase). For an signal is the same as for a continuous waveform.

•For an externally-gated burst, the Sync signal follows the external gate signal. However, note that the signal will not go to a TTL “low” until the end of the last cycle (may not be the zero-crossing point if the waveform has an associated start phase).

• Front-Panel Operation: Press and select the Sync softkey again to toggle between “off” and “on”.

• Remote Interface Operation:

OUTPut:SYNC {OFF|ON}

is a TTL “low” at the end of the specified

the zero-crossing point if the waveform

infinite count burst

Setting is stored in non-volatile memory

, the Sync

Page 64

Chapter 3 Features and Functions

Pulse Waveforms

A shown below, a pulse waveform consists of a period, a pulse width, a rising edge, and a falling edge.

90%

50%

Pulse Width

10%

Rise Time

Period

90%

50%

10%

Fall Time

Pulse Period

• Pulse period: 20 ns to 2000 seconds. The default is 1 ms.

• The specified period must be greater than the sum of the pulse width and the edge time as shown below. The function generator will adjust the pulse width and edge time as needed to accommodate the specified period.

Period >

• Function Limitations: If you change to a function whose minimum period is greater than that for a pulse waveform, the period is adjusted to the minimum value allowed for the new function. For example, if you output a pulse waveform with a period of 50 ns and then change to the ramp function, the function generator will

automatically adjust the period to 1 µs (the lower limit for ramps).

Pulse Width + (1.6 X Edge Time)

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Chapter 3 Features and Functions

Pulse Waveforms

• Front-Panel Operation: After selecting the pulse function, press the Freq softkey again to toggle to the Period softkey. Then use the knob or numeric keypad to enter the desired pulse period.

• Remote Interface Operation:

PULSe:PERiod {<seconds>|MINimum|MAXimum}

Pulse Width

The pulse width represents the time from the 50% threshold of the rising edge of the pulse to the 50% threshold of the next falling edge.

Pulse width: 8 ns to 2000 seconds (see restrictions below).

• pulse width is 100 µs.

• The specified pulse width must be less than the difference between the period and the edge time as shown below. The function generator

automatically adjust the pulse width as needed to accommodate

will

the specified period.

Pulse Width < Period – (1.6 X Edge Time)

• The pulse width must also be greater than the total time of one edge as shown below.

Pulse Width >

• Front-Panel Operation: After selecting the pulse function, press the Pulse Width softkey. Then use the knob or numeric keypad to enter the desired pulse width.

• Remote Interface Operation:

PULSe:WIDTh {<seconds>|MINimum|MAXimum}

1.6 X Edge Time

The default

Page 66

Chapter 3 Features and Functions

Pulse Waveforms

Edge Time

The edge time represents the time from the 10% threshold to the 90% threshold of both the rising and falling edges.

• Edge time: 5 ns to 1 ms (see restrictions below). The default edge time is 5 ns.

• The specified edge time must fit within the specified pulse width as shown below. The function generator will adjust the edge time as needed to accommodate the specified pulse width.

Edge Time <

• Front-Panel Operation: After selecting the pulse function, press the Edge Time softkey. Then use the knob or numeric keypad to enter the desired edge time.

• Remote Interface Operation:

PULSe:TRANsition {<seconds>|MINimum|MAXimum}

0.625 X Pulse Width

Page 67

Chapter 3 Features and Functions

Amplitude Modulation (AM)

A modulated waveform consists of a carrier waveform and a modulating waveform. In AM, the amplitude of the carrier is varied by the instantaneous voltage of the modulating waveform. The function generator will accept an internal or external modulation source.

For more information on the fundamentals of Amplitude Modulation,

refer to chapter 7, “Tutorial”.

To Select AM Modulation

• The function generator will allow only one modulation mode to be enabled at a time. For example, you cannot enable AM and FM at the same time. When you enable AM, the previous modulation mode is turned off.

• The function generator will not allow AM to be enabled at the same time that sweep or burst is enabled. When you enable AM, the sweep or burst mode is turned off.

• Front-Panel Operation: You must enable AM before setting up any of the other modulation parameters. Press and then select “AM” using the Typ e softkey. The AM waveform is output using the present settings for the carrier frequency, modulating frequency, output amplitude, and offset voltage.

• Remote Interface Operation: To avoid multiple waveform changes, enable AM after you have set up the other modulation parameters.

AM:STATe {OFF|ON}

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Chapter 3 Features and Functions

Amplitude Modulation (AM)

Carrier Waveform Shape

• AM carrier shape: Sine, Square, Ramp, or Arbitrary waveform.

The default is Sine. You cannot use pulse, noise, or dc as the carrier waveform.

• Front-Panel Operation: Press any of the front-panel function keys except or . For arbitrary waveforms, press and then choose the Select Wform softkey to select the active waveform.

• Remote Interface Operation:

FUNCtion:SHAPe {SINusoid|SQUare|RAMP|USER}

You can also use the

APPLy

command to select the function, frequency

amplitude, and offset with a single command.

Carrier Frequency

The maximum carrier frequency depends on the function selected as shown below. The default is 1 kHz for all functions.

Function Minimum Frequency Maximum Frequency

Sine

Square

Ramp

Arbs

• Front-Panel Operation: To set the carrier frequency, press the Freq softkey for the selected function. Then use the knob or numeric keypad to enter the desired frequency.

• Remote Interface Operation:

FREQuency {<frequency>|MINimum|MAXimum}

1 µHz 1 µHz 1 µHz 1 µHz

80 MHz 80 MHz

1 MHz

25 MHz

You can also use the

APPLy

command to select the function, frequency

amplitude, and offset with a single command.

Page 69

Chapter 3 Features and Functions

Amplitude Modulation (AM)

Modulating Waveform Shape

The function generator will accept an internal or external modulation source for AM.

• Modulating waveform shape (internal source): Sine, Square, Ramp,

Negative Ramp, Triangle, Noise, or Arb waveform.

• Square has 50% duty cycle.

• Ramp has 100% symmetry.

• Triangle has 50% symmetry.

• Negative ramp has 0% symmetry.

• You can use noise as the modulating waveshape, but you cannot use noise, pulse, or dc as the carrier waveform.

The default is Sine.

If you select an arbitrary waveform as the

• the waveform is automatically limited to 8K points. Extra waveform points are removed using decimation.

• Front-Panel Operation: After enabling AM, press the Shape softkey.

• Remote Interface Operation:

AM:INTernal:FUNCtion {SINusoid|SQUare|RAMP|NRAMp|

TRIangle|NOISe|USER}

modulating

waveshape

Modulating Waveform Frequency

The function generator will accept an internal or external modulation source for AM.

• Modulating frequency (internal source): 2 mHz to 20 kHz.

The default is 100 Hz

•

Front-Panel Operation

• Remote Interface Operation:

AM:INTernal:FREQuency {<frequency>|MINimum|MAXimum}

: After enabling AM, press the

AM Freq

softkey.

Page 70

Chapter 3 Features and Functions

Amplitude Modulation (AM)

Modulation Depth

The modulation depth is expressed as a percentage and represents the extent of the amplitude variation. At 0% depth, the output amplitude is half of the selected value. At 100% depth, the output amplitude equals the selected value.

• Modulation depth: 0% to 120%. The default is 100%.

• Note that even at greater than 100% depth, the function generator

will not exceed ±5V peak on the output (into a 50Ω load).

•If you select the External modulating source, the carrier waveform is modulated with an external waveform. The modulation depth is controlled by the ±5V signal level present on the rear-panel Modulation In connector. For example, if you have set the modulation depth to 100%, then when the modulating signal is at +5 volts, the output will be at the maximum amplitude. When the modulating

signal is at -5 volts, then the output will be at the

• Front-Panel Operation: After enabling AM, press the AM Depth softkey.Then use the knob or numeric keypad to enter the depth.

minimum

amplitude

• Remote Interface Operation:

AM:DEPTh {<depth in percent>|MINimum|MAXimum}

Page 71

Chapter 3 Features and Functions

Amplitude Modulation (AM)

Modulating Source

The function generator will accept an internal or external modulation source for AM.

• Modulating source: Internal or External. The default is Internal.

•

If you select the External source, the carrier waveform is modulated with an external waveform. The modulation depth is controlled by the

±5V signal level present on the rear-panel Modulation In connector. For example, if you have set the modulation depth to 100%

when the modulating signal is at +5 volts, the output will be at the

maximum

the output will be at the

Modulation

amplitude. When the modulating signal is at -5 volts, then

minimum

+5 V

amplitude.

, then

Front-Panel Operation

•

Remote Interface Operation

AM:SOURce {INTernal|EXTernal}

: After enabling AM, press the

-5 V

Source

softkey.

Page 72

Chapter 3 Features and Functions

Frequency Modulation (FM)

A modulated waveform consists of a carrier waveform and a modulating waveform. In FM, the frequency of the carrier is varied by the instantaneous voltage of the modulating waveform.

For more information on the fundamentals of Frequency Modulation,

refer to chapter 7, “Tutorial”.

To Select FM Modulation

• The function generator will allow only one modulation mode to be enabled at a time. For example, you cannot enable FM and AM at the same time. When you enable FM, the previous modulation mode is turned off.

• The function generator will not allow FM to be enabled at the same time that sweep or burst is enabled. When you enable FM, the sweep or burst mode is turned off.

• Front-Panel Operation: You must enable FM before setting up any of the other modulation parameters. Press and then select “FM” using the Typ e softkey. The FM waveform is output using the present settings for the carrier frequency, modulating frequency, output amplitude, and offset voltage.

• Remote Interface Operation: To avoid multiple waveform changes, enable FM after you have set up the other modulation parameters.

FM:STATe {OFF|ON}

Page 73

Chapter 3 Features and Functions

Frequency Modulation (FM)