Keysight Technologies N8241A, N8242A User Manual

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N8241A/N8242A

Arbitrary Waveform Generators

User’s Guide

NOTICE: In August 2014, Agilent Technologies’ former Test and Measurement business became Keysight Technologies. This document is provided as a courtesy but is no longer kept current and thus will contain historical references to Agilent. For more information, go to www.keysight.com.

Manufacturing Part Number: N8241-90001

Printed in USA

October 2015

Notices

Warranty

The material contained in this document is provided “as is,” and is subject to being changed, without notice, in future editions. Further, to the maximum extent permitted by applicable law, Agilent disclaims all warranties, either express or implied, with regard to this manual and any information contained herein, including but not limited to the implied warranties of merchantability and fitness for a particular purpose. Agilent shall not be liable for errors or fo r incidental or consequential damages in connection with the furnishing, use, or performance of this document or of any information contained herein. Should Agilent and the user have a separate written agreement with warranty terms covering the material in this document that conflict with these terms, the warranty terms in the separate agreement shall control.

Technology Licenses

The hardware and/or software described in this document are furnished under a license and may be used or copied only in accordance with the terms of such license.

Restricted Rights Legend

If software is for use in the performance of a U.S. Government prime contract or subcontract, Software is delivered and licensed as “Commercial computer software” as defined in DFAR 252.227-7014 (June 1995), or as a “commercial item” as defined in FAR 2.101(a) or as “Restricted computer software” as defined in FAR

52.227-19 (June 1987) or any equivalent agency regulation or contract clause. Use, duplication or disclosure of Software is subject to Agilent Technologies’ standard commercial license terms, and non-DOD Departments and Agencies of the U.S. Government will receive no greater than Restricted Rights as defined in FAR

52.227-19(c)(1-2) (June 1987). U.S. Government users will receive no greater than Limited Rights as defined in FAR 52.227-14 (June 1987) or DFAR 252.227-7015

(b)(2) (November 1995), as applicable in any technical data.

Safety Notices

The information contained in this document is subject to change without notice. Agilent Technologies makes no warranty of any kind with regard to this material,

including but not limited to, the implied warranties of merchantability and fitness for a particular purpose. Agilent Technologies shall not be liable for errors contained herein or for incidental or consequential damages in connection with the furnishing, performance, or use of this material.

The following safety symbols are used throughout this manual. Familiarize yourself with the symbols and their meaning before operating this instrument.

WARNING Warning denotes a hazard. It calls attention to a procedure which, if not

correctly performed or adhered to, could result in in ju ry or loss of life. Do not proceed beyond a warning note until the indicated conditions are fully understood and met.

CAUTION Caution denotes a hazard. It calls attention to a procedure that, if not correctly

performed or adhered to, could result in damage to or destruction of the instrument. Do not proceed beyond a caution sign until the indicated conditions are fully understood and met.

NOTE Note calls out special information for the user’s attention. It provides operational

information or additional instructions of which the user should be aware.

General Safety Information

The following general safety precautions must be observed during all phases of operation. Failure to comply with these precautions or with specific warnings elsewhere in this manual violates safety standards of design, manufacture, and intended use of the instrument. Agilent Technologies assumes no liability for the customer’s failure to comply with these requirements.

WARNING This is a Safety Class 1 Product (provided with a protective earthing ground

incorporated in the power cord). The mains plug shall only be inserted in a socket outlet provided with a protected earth contact. Any interruption of the protective conductor inside or outside of the product is likely to make the product dangerous. Intentional interruption is prohibited.

CAUTION This product is designed for use in Installation Category II and Pollution Degree 2

per IEC 61010 Second Edition and 664 respectively.

WARNING If this product is not used as specified, the protection provided by the

equipment could be impaired. This product must be used in a normal condition (in which all means for protection are intact) only.

WARNING No operator serviceable parts inside. Refer servicing to qualified personnel. to

prevent electrical shock do not remove covers.

CAUTION The Mains wiring and connectors shall be compatible with the connector used in the

premise electrical system. Failure to ensure adequate earth grounding by not using the correct components may cause product damage, and serious injury.

Safety Symbols

The following symbols on the instrument and in the manual indicate precautions which must be taken to maintain safe operation of the instrument.

The Instruction Documentation Symbol. The product is marked with this symbol when it is necessary for the user to refer to the instructions in the supplied documentation.

This symbol indicates the position of the operating switch for ‘On’ mode

This symbol indicates the position of the operating switch for ‘Stand-by’ mode. Note, the instrument is NOT isolated from the mains when the switch is in this position.

To isolate the instrument, the mains coupler (mains input cord) should be removed from the power supply.

This symbol indicates separate collection for electrical and electronic equipment, mandated under EU law as of August 13, 2005. All electric and electronic equipment are required to be separated from normal waste for disposal (Reference WEEE Directive, 200/96/EC).

The CE mark shows that the product complies with all relevant European Legal Directives.

The C-Tick mark is a registered trademark of the Australian Communications Authority. This signifies compliance with the Australian EMC Framework Regulations under the terms of the Radio communications Act of 1992.

ISM 1-A This is a symbol of an Industrial, Scientific, and

Medical Group 1 Class A product.

ICES/NMB-001 This ISM device complies with Canadian ICES-001.

Cet appareil ISM est conforme à la norme NMB-001 du Canada.

The CSA mark is a registered trademark of the Canadian Standards Association, and indicates compliance to the standards laid out by them.

Trademark Acknowledgement

Microsoft is a US registered trademark of Microsoft Corp. MATLAB is a U.S. registered trademark of The Math Works, Inc.

Updated Information

Where to Find the Latest Information Documentation is updated periodically. For the latest information about the N8241A

Arbitrary Waveform Generator, including firmware upgrades and application information, please visit the following Internet URL:

http://www.agilent.com/find/synthetic

Compliance

This product has been designed and tested in accordance with accepted industry standards, and has been supplied in a safe condition. The documentation contains information and warnings that must be followed by the user to ensure safe operation and to maintain the product in a safe condition.

Declaration of Conformity

The Declaration of Conformity (DOC) is on file. If a copy is required, please contact an Agilent Sales Representative or the closest Agilent Sales Office. Alternately, contact Agilent at:

http://www.agilent.com/find/

1. Introducing the N8241/2A AWGs

Front Panel Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16

Status Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

PWR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

LAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

1588 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20

Rear Panel Interface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

Graphical User Interface (GUI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23

Getting Started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24

System Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24

Hardware. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24

Supported Operating Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24

Required Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24

N8241/2A Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24

Installing the Instrument. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24

Installing the Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25

Connecting to the AWG over the LAN. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26

Verifying System Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29

System Set Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29

Waveform Generation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29

Shutting Down the System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Maintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33

Cleaning the Instrument . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Cleaning Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

2. Basic Operation

Using the Graphical User Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36

Generating a Single Tone Signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36

Generating a Multi-tone Signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40

Contents

Creating and Playing a Sequence. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43

Synchronizing Two N8241/2A Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47

Internal Clock Synchronization Using Continuous Mode . . . . . . . . . . . . . . . .47

Required Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47

Cables and Adapters required for 1.25 GHz external clock (Agilent N6030A K10 kit):47

Procedure Using a Software Marker . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47

Selecting the Master Unit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49

Selecting the Slave Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49

Initiating Synchronous Playback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50

Using Programmatic Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51

IVI-C Driver Functionality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 1

MATLAB Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51

MATLAB Example 1, Creating and Playing a Waveform. . . . . . . . . . . . . . . . . .52

MATLAB Example 2, Synchronizing Two N8241/2A AW Gs . . . . . . . . . . . . . .54

C/C++ Example Program. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61

3. Theory of Operation

N8241/2A Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .68

Clock I/O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .69

10 MHz In . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .69

Internal Clock Out . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .69

External Clock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .69

SYNC Clock In/SYNC Clock Out. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .69

Waveform Playback. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .70

Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .70

Waveform Sequencer Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .70

Sequence Play Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .70

Sequencer Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .70

Waveform Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .70

Contents

Basic Sequencing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .71

Playback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

Advanced Sequencing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .72

Scenario Pointer Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .72

Scenario Advance Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .73

Waveform Advancement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .75

Scenario Jump Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .75

Scenario Start/Jump Trigger Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .76

Markers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .79

Triggers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .80

Triggers 1,2,3,4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .81

LXI T1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .81

Synchronous Triggers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .82

Signal Conditioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .84

Single-Ended Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .84

Differential Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .85

Digital Predistortion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .86

Multiple Module Synchronization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .87

Synchronization Using an Internal Clock. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .87

Synchronization Using an External Clock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .88

Multiple Module Synchronous Trigger Timing . . . . . . . . . . . . . . . . . . . . . . . . . .91

Cable Length and Skew . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .92

4. Dynamic Sequencing Option 300

Dynamic Sequencing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .94

AUX PORT Connector. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .94

Signal Levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .96

Signal Descriptions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .96

Data Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .96

Data Valid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .96

Contents

Trigger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .96

5. Direct Digital Synthesis Option 330

Direct Digital Synthesis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9 8

Direct Digital Synthesis Using the Control Utility . . . . . . . . . . . . . . . . . . . . . . .99

Configuring the Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .99

Selecting the DDS Option . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .99

Configuring the Signal Conditioning Path . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

Configuring the Clock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .100

Configuring the Sequencer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .101

Out of Range Input Values. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .105

Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .108

6. Troubleshooting

Software. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112

Removing the Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .112

Moving the Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112

Updating the Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .112

Initializing the LAN Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .113

Contacting Agilent. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114

Returning the Instrument to Agilent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114

7. Technical Characteristics

1 Introducing the N8241/2A AWGs

The N8241A and N8242A are wideband arbitrary waveform generators (AWGs) capable of creating high-resolution waveforms for radar, satellite and frequency agile communication systems. Each channel of the AWGs operates at 1.25 GSa/s. The N8241A features 15 bits of vertical resolution and the N8242A 10 bits. Both AWGs offer dual differential output channels to drive both single-ended and balanced designs.

The AWGs include a complete software suite to speed waveform development and system integration supporting MATLAB

interfaces.

Front Panel Interface 16 Rear Panel Interface 21

Graphical User Interface (GUI) 23 Getting Started 24

System Requirements 24 N8241/2A Installation 24

Verifying System Operation 29

System Set Up 29

, LABVIEW, and IVI-C programmatic

Waveform Generation 29

Shutting Down the System 32 Maintenance 33

Introducing the N8241/2A AWGs

Status Indicators

Front Panel Interface

Figure 1-1 N8241/2A Front Panel

Item Description

# Name 1 EXT CLK IN Use this 50 ohm SMA connector to input an external sample

clock. It will accept clock rates in the range of 100 MS/s through 1.25 GS/s. Refer to “External Clock” on page 69 for more information.

2 INT CLK OUT Use this 50 ohm SMA connector to route the internal 1.25

GS/s clock to other test instrument or devices.

3 AUX 10 MHz REF IN This auxiliary 50 ohm SMA connector can be used to input

an external 10 MHz reference.

4 SYNC CLK IN /

SYNC CLK OUT

These connectors support synchronization of multiple modules. Refer to “Multiple Module Synchronization” on

page 87.

16 Chapter 1

Introducing the N8241/2A AWGs

Front Panel Interface

Item Description

# Name 5 CH 1/CH2 Out The CH 1 OUT and CH 2 OUT positive (+) connectors are

used for single-ended operation. Use both the positive (+) and negative (-) connectors for differential operation. Refer to “Signal Conditioning” on page 84 for more information.

6 AUX PORT The AUX port is reserved for future applications. 7DATA PORT The data port is reserved for future applications. 8

9 MARKERS 1/2/3/4 There are four SMB female marker output connectors that

10 Power Switch The power switch is toggled to either the ON or STANDBY

TRIGGERS 1/2/3/4

There are four SMB female trigger input connectors that are used to control the waveforms in the sequencer and create event-based signal simulation. The connectors support TTL/CMOS, ECL, and PECL logic levels.

can be used for triggering or system synchronization. The connectors are 3.3V TTL/CMOS 30 ohm series terminated. The output is capable of driving a 50 ohm load.

position.

Chapter 1 17

Introducing the N8241/2A AWGs

Front Panel Interface

Item Description

# Name 11 Reset The “RST” button enables you to put the LAN configuration

of the instrument into a known state. When you press this button the following settings are made

and the system reboots:

• IP Address is set to 192.168.EE.FF, where EE and FF are the last two parts of the MAC address (AA.BB.CC.DD.EE.FF). This is designed to prevent multiple instruments from using the same default IP address.

• Subnet Mask is set to 255.255.0.0

• DHCP is set to ON

• Auto IP is set to ON

• The instrument hostname is set to A-N82XXA-NNNNN, where N82XXA is the instrument model number (such as N8241A) and NNNNN represents the last five digits of the instrument serial number.

12 TRIGGER IN/OUT These SMB trigger input and output connectors are used to

control the waveforms and create event-based signal simulation. The connectors support LVTTL logic levels and are functionally equivalent to Triggers/Markers 1-4, but have additional latency.

13 10 MHz REF IN/OUT These SMB connectors can be used to input and output a

10 MHz reference.

18 Chapter 1

Introducing the N8241/2A AWGs

Front Panel Interface

Status Indicators

PWR

The power indicator has the following states:

State Power Status Illumination

OFF No Power None STANDBY Standby Power Solid Amber ON Power is on Solid Green

LAN

The LAN indicator has the following states:

State LAN Status Illumination

ON Normal Operation Solid Green ON Device Identity:

–Needs initialization, refer to

“Initializing the LAN Configuration” on page 93

OFF LAN Error/Fault:

–No valid or duplicate IPaddress –Unable to renew previously obtained DHCP lease –Disconnected LAN cable

OFF This is the state when:

–The system is initializing or –A LAN reset has been initialized

Chapter 1 19

Blinking Green

Solid Red

None

Introducing the N8241/2A AWGs

Front Panel Interface

1588

The IEEE 1588 Clock Status has the following states:

State Clock Status Illumination

OFF Not synchronized None ON Synchronized, clock is IEEE 1588

Slave

ON Synchronized, clock is IEEE 1588

Master

ON Synchronized, clock is IEEE 1588

Grand Master

OFF IEEE 1588 is in a fault state S olid Red

Solid Green

Blinking Green (once every second)

Blinking Green (once every two seconds)

20 Chapter 1

Rear Panel Interface

Figure 1-2 N8241A Rear Panel

Item Description

Introducing the N8241/2A AWGs

Rear Panel Interface

# Name 1LXI TRIG BUS This interface enables the instrument to detect any LXI

trigger bus events or LXI LAN-based events and can output such events.

Inbound events control the arming and triggering of the instrument subsystem for performi ng measu rements and other operations. Outbound events are used to notify other LXI devices of specific conditions.

2 AUX INTF This 9-pin serial interface connector is for factory-use only. 3 AC Power Receptacle The AC voltage is connected here. The power cord receptacle

Chapter 1 21

An LXI TRIG BUS cable and terminators will be available from Circuit Assembly in the near future.

accepts a three-prong power cable that is shipped with the instrument. The voltage range is 100/120/220/240 volts with a frequency range of 50 to 60 Hz and is automatically selected by the power supply.

Introducing the N8241/2A AWGs

Rear Panel Interface

Item Description

# Name 4LAN This local area network (LAN) interface allows

communication through a 100BaseT LAN cable.

5USB The USB port is reserved for future applications.

Electrostatic discharge (ESD) can damage the highly sensitive components in your instrument. ESD damage is most likely to occur as the instrument is being installed or when cables are connected or disconnected. Protect the circuits from ESD damage by wearing a grounding strap that provides a high resistance path to ground. Alternatively, ground yourself to discharge any static charge built-up by touching the outer shell of any grounded instrument chassis before touching the port connectors.

22 Chapter 1

Graphical User Interface (GUI)

The tab-based graphical interaction of the GUI gives instant access to the AWG parameters, making it easy to configure signal output. Each tab is labeled with its contents, enabling quick access to all functions. Figure 1-3 displays the first level of the GUI. For more information on the GUI, refer to the N8241A Online Help. Access this from the application Help menu, or in Windows:

Start > Programs > Agilent > N8241A > Help.

Figure 1-3 N8241A Control Utility

Introducing the N8241/2A AWGs

Graphical User Interface (GUI)

Chapter 1 23

Getting Started

Introducing the N8241/2A AWGs

Getting Started

System Requirements

Hardware

• Personal computer (PC) with LAN capability

• Agilent E4440A Spectrum Analyzer or equivalent (system verification)

Supported Operating Systems

• Windows

2000, Service Pack 4.0 or later

XP, Service Pack 2.0 or later

Required Software

• Windows.NET

Framework, Version 1.1 Redistributable Package, Service Pack

1 or later (included on the N8241A CD)

• IVI Compliance Package Version 2.3 or greater, which includes the IVI Shared Components (download from www.ni.com)

• Agilent IO Libraries Suite 14.1 or greater with Patch 2 (download from

www.agilent.com)

N8241/2A Installation

Installing the Instrument

1. Plug the AWG module into the mains power supply.

NOTE Install the instrument so that the detachable power cord is readily identifiable and is

easily reached by the operator. The detachable power cord is the instrument disconnecting device. It disconnects the mains circuits from the mains supply before other parts of the instrument. The front panel switch is only a standby switch and is not a LINE switch. Alternatively, an externally installed switch or circuit breaker (which is readily identifiable and is easily reached by the operator) may be used as a disconnecting device.

2. Connect the AWG module to a LAN line.

Installing the Software

Connect a LAN line to the PC and turn the PC on.

24 Chapter 1

Introducing the N8241/2A AWGs

Getting Started

3. Download the IVI Compliance Package, which contains the IVI Engine and the IVI Shared Components. Go to: http://www.ni.com/ Search on ivi compliance package version 2.3. Select IVI Compliance Package V ersion 2.3 for Windows 2000//NT/XP-HWDRIVER-Support-National

Follow the instructions for the Download Process at the bottom of the page.

4. Download the Agilent IO Libraries Suite 14.1 with Patch 2. Go to:http://www.agilent.com/find/iolib

5. Insert the N8241A CD into the CD drive on your PC and follow the instructions.

CAUTION Before switching on this instrument, make sure the supply voltage is in the specified

range.

6. Toggle the fron t panel switch to turn on the AWG module.

Chapter 1 25

Introducing the N8241/2A AWGs

Getting Started

Connecting to the AWG over the LAN

1. Open the Agilent Connection Expert (double-click the icon).

NOTE The Agilent Connection Expert will work only if Agilent VISA is operating as the

primary VISA driver. If it is operating as the secondary driver, and anoth er VISA such as NI VISA is the primary, you will need to add the N8241/2A using the tools of the primary VISA. The Agilent IO Libraries will alert you to this condition.

2. From the menu bar, select Add Instrument.

3. In the Add Instrument secondary window,

select LAN (TCPIP0) > OK.

26 Chapter 1

Introducing the N8241/2A AWGs

Getting Started

4. Enter the host name of the AWG in the LAN Instrument secondary window.

5. Click OK.

Chapter 1 27

Introducing the N8241/2A AWGs

Getting Started

6. The AWG is now configured to the PC.

28 Chapter 1

Introducing the N8241/2A AWGs

Verifying System Operation

Prior to verifying system operation, the N8241A software must be installed on the PC and the LAN line connected to the PC and AWG module. For more information

“Installing the Software” on page 25 and “Connecting to the A WG over the

refer to

LAN” on page 26

System Set Up

1. Connect the power cord to the AWG module and turn the power on.

CAUTION Before switching on this instrument, make sure the supply voltage is in the specified

range.

Waveform Generation

NOTE An Agilent E4440A Spectrum Analyzer or equivalent is required to view the

waveforms.

1. Connect the channel 1 positive (+) output to the spectrum analyzer RF input

connector.

2. Open the user interface by double-clicking the N8241A Control Utility icon

placed on the desktop during installation.

3. In the Output tab, configure the signal conditioning path to include the 500MHz

reconstruction filter through CH1 OUT (toggle the switches you want to connect) on channel 1 and CH2 OUT on channel 2. The connection will automatically

4. Click on the negative (-) node to enable single-ended mode. Notice that the

Chapter 1 29

enable differential mode.

Introducing the N8241/2A AWGs

Verifying System Operation

Output drops to 0.250 volts.

5. Select the Clock tab and confirm that the (AutoSense) 10MHz REF IN is

configured correctly. In the Quick Play section

and select the 400MHzTone.bin waveform file found on the CD for channel 1 and 2

of the user interface, browse

6. Click Play. The spectrum analyzer cabled to channel 1 should display a spurious

free dynamic range (SFDR) of at least -65 dBc for the N8241A as shown in

Figure 1-4, and a SFDR of at least -50 dBc for the N8242A, Figure 1-5.

30 Chapter 1

Figure 1-4 N8241A Playback of a 400 MHz Tone

Introducing the N8241/2A AWGs

Verifying System Operation

Figure 1-5 N8242A Playback of a 400 MHz Tone

7. You should get the same performance when you connect chan nel 2 positive (+)

to the spectrum analyzer RF input connector.

Chapter 1 31

Introducing the N8241/2A AWGs

Shutting Down the System

1. Close the N8241A Control Utility.

2. Toggle the front panel switch to place the AWG module in standby mode.

32 Chapter 1

Maintenance

Cleaning the Instrument

Cleaning Connectors

Introducing the N8241/2A AWGs

Maintenance

To prevent electrical shock, disconnect the instrument and/or system from mains before cleaning. Use a dry cloth or one slightly dampened with water to clean the external case parts. Do not attempt to clean internally.

Cleaning connectors with alcohol shall only be done with the instruments power cord removed, and in a well-ventilated area. Allow all residual alcohol moisture to evaporate, and the fumes to dissipate prior to energizing the instrument.

WARNING Keep isopropyl alcohol away from heat, sparks, and flame. Store in a tightly

closed container. It is extremely flammable. In case of fire, use alcohol foam, dry chemical, or carbon dioxide; water may be ineffective.

Use Isopropyl alcohol with adequate ventilation and avoid contact with eyes, skin, and clothing. It causes skin irritation, may cause eye damage, and is harmful if swallowed or inhaled. It may be harmful if absorbed through the skin. Wash thoroughly after handling.

In case of spill, soak up with sand or earth. Flush spill area with water. Dispose of isopropyl alcohol in accordance with all applicable federal, state,

and local environmental regulation.

Chapter 1 33

Introducing the N8241/2A AWGs

Maintenance

34 Chapter 1

2 Basic Operation

This chapter guides you through the basic operation of the AWG. Prior to following these procedures, the N8241A software must be installed on the PC. Refer to

“System Set Up” on page 29 for complete instructions on how to complete t his task .

Using the Graphical User Interface 36

Generating a Single Tone Signal 36 Generating a Multi-tone Signal 40 Creating and Playing a Sequence 43 Synchronizing Two N8241/2A Modules 47

Using Programmatic Interfaces 51

IVI-C Driver Functionality 51 MATLAB Interface 51 MATLAB Example 1, Creating and Playing a Waveform 52 MATLAB Example 2, Synchronizing Two N8241/2A AWGs 54

C/C++ Example Program 61

Basic Operation

Using the Graphical User Interface

Generating a Single Tone Signal

Use the following procedure as a guide to basic single-ended waveform playback with the N8241A or N8242A AWG. All waveform parameters need to be set prior to waveform playback

NOTE A spectrum analyzer is required to display the waveforms.

Connect the channel 1 positive (+) output to the spectrum analyzer RF input

connector.

2. Open the user interface by double-clicking the N8241A icon placed on the

desktop during installation.

NOTE If an icon was not placed on the desktop, go to:

Start > Programs > Agilent > N8241A > Control Utility

3. In the N8241A Open dialog, enter the VISA address and click OK.

36 Chapter 2

Basic Operation

Using the Graphical User Interface

4. To select the DDS opt ion 330 (lower-left corner of the display), refer to

“Selecting the DDS Option” on page 99

5. Select the Output tab and connect a single-ended signal conditioning path to CH1 OUT (+) (click on the node that you want to connect)

The connection will automatically enable differential mode. Click on the negative (-) node to enable single-ended mode. Notice that the default gain value was 0.500 volts. Once you select single-ended mode, the value drops to 0.250 volts. These are maximum values for the modes indicated.

6. Select the Clock tab and confirm that the (AutoSense) 10MHz REF IN is

Chapter 2 37

Basic Operation

Using the Graphical User Interface

configured correctly.

7. In the Quick Play section of the user interface, browse and select the desired single-tone waveform file for Channel 1 Waveform. The AWG accepts data formatted as 16-bit signed integers ignoring the LSB.

NOTE Different waveforms can be loaded into channel 1 and 2, but the length of the

waveforms must be the same.

8. Use the default setting for the play mode and predistortion.

9. Click Play.

Figure 2-1 and Figure 2-2 display a 100 MHz waveform played back on the

N8241A and N8242A respectively. The SFDR is greater than –70.0 dBc for the

38 Chapter 2

N8241A and greater than –50.0 dBc for the N8242A.

Figure 2-1 N8241A Playback of a 100 MHz Tone

Basic Operation

Using the Graphical User Interface

Figure 2-2 N8242A Playback of a 100 MHz Tone

Chapter 2 39

Basic Operation

Using the Graphical User Interface

Generating a Multi-tone Signal

1. Connect the channel 1 positive (+) output to the spectrum analyzer RF input

connector.

2. Open the user interface by double-clicking the N8241A icon placed on the

desktop during installation.

3. Select the Output tab and connect a single-ended signal conditioning path to

CH1 OUT (+) (click on the node that you want to connect).

4. Select the Clock tab and confirm that the (AutoSense) 10MHz REF IN is

configured correctly.

40 Chapter 2

Basic Operation

Using the Graphical User Interface

5. In the Quick Play section of the user interface, browse and select the desired

multi-tone waveform file for Channel 1 Waveform. The AW G accepts data formatted as 16-bit signed integers

NOTE Different waveforms can be loaded into channel 1 and 2, but the length of the

waveforms must be the same.

ignoring the LSB.

6. Use the default setting for the Play Mode and Predistortion.

7. Click Play.

For this example, a waveform with five tones was used. The intermodulation distortion produced by the five tones played back on the N8241A is less than –60.0 dBc, Figure 2-3, and less than –45.0 dBc on the N8242A, Figure 2-3.

Although the harmonic distortion for the N8241A and N8242A is specified to be <–65 dBc and <–50 dBc respectively below the total power, the tone power is determined by the following formula:

Tone Power = Total Power – 10 log 10 (1/N) where N= number of tones

Five tones reduces the tone power by approximately 7 dB.

Chapter 2 41

Basic Operation

Using the Graphical User Interface

Figure 2-3 N8241A Playback of Five Tones

Figure 2-4 N8241A Playback of Five Tones

42 Chapter 2

Basic Operation

Using the Graphical User Interface

Creating and Playing a Sequence

1. Connect the channel 1 positive (+) output to the spectrum analyzer RF input

connector.

2. Open the user interface by double-clicking the N8241A icon placed on the

desktop during installation.

3. Select the Output tab and connect a single-ended signal conditioning path to

CH1 OUT (+) (click on the node that you want to connect).

The connection will automatically enable differential mode. Click on the negative (-) node to enable single-ended mode. .Notice that the default gain value was 0.500 volts. Once you select single-ended mode, the value drops to 0.250 volts. These are maximum values for the modes indicated.

4. Select the Clock tab and confirm that the (AutoSense) 10MHz REF IN is

configured correctly .

Chapter 2 43

Basic Operation

Using the Graphical User Interface

5. Select the Sequencer tab.

6. From the Segment List select Add. This will bring up a Segment Information secondary window.

7. Browse and select the 500 MHz waveform, then click OK.

NOTE For dual channel sequencing, add the same waveform to both channel 1 and channel

2. Currently, the software does not support independent channel sequencing.

8. Repeat steps 6 and 7 twice, selecting the 100 MHz and two-tone waveforms.

9. In the Segment List, select the 500 MHz waveform.

10. In the Sequence Definition area, select Add. This will bring up the

44 Chapter 2

Enter Repetition Count secondary window.

11. Enter 5000 repetitions and click OK.

12. Repeat steps 9, 10, and 11 for the 100 MHz and two-tone waveforms.

13. In the Sequence Definition area, select segment ID 2 and move it below ID 3

using the down arrow.

14. Click Modify and change the count to 50000. The sequencer tab should look

like Figure 2-5.

Figure 2-5 Sequencer Tab

Basic Operation

Using the Graphical User Interface

15.Click Download & Play. The spectrum of the sequence should be similar to the

one shown in Figure 2-6

Chapter 2 45

Basic Operation

Using the Graphical User Interface

Figure 2-6 N8241A Playback of a Sequence

46 Chapter 2

Basic Operation

Using the Graphical User Interface

Synchronizing Two N8241/2A Modules

Internal Clock Synchronization Using Continuous Mode

When synchronizing two modules using the internal clock, one unit is designated as the Master and the other unit is designated as the Slave. The Master unit sources the sample clock and the sync clock signals. These signals are split and fed to the synchronized modules (the Master as well as the Slave).

The internal sample clock operates at 1.25 GHz and provides the final retiming of the analog output from each AWG. Any skew in the sample clock cable delays between the modules will result in the same skew in the analog outputs.The sample clock signal is split with a matched passive divider and the cable lengths are matched. The resulting skew is small and repeatable.

Required Equipment

Two N8241A or Two N8242A AWGs

•

• Personal Computer

• N8241A AWG Control Utility Software

Cables and Adapters required for 1.25 GHz external clock (Agilent N6030A K10 kit):

Power divider, 11636B (2 each) (11636B)

•

• SMB adapter Tee M-M-M (1 each) (1250-0670)

• SMA conformable cable assembly, 10 in (4 each) (5062-6685)

• SMB cable assembly, (3 each) (8120-5016)

• SMA adapter M-F (2 each) (1250-1788)

• SMA to BNC Cable (2 each, equal length), Customer furnished

Procedure Using a Software Marker

Start with the system turned off.

2. Cable the equipment as shown in Figure 2-7.

Chapter 2 47

Basic Operation

Using the Graphical User Interface

Figure 2-7 Cabling for Two AWG Synchr onization

3. Turn the system on.

48 Chapter 2

Selecting the Master Unit

1. Open an N8241A Control Utility session (double-click the Agilent N8241A icon on the desktop).

2. In the N8241A Open dialog, enter the VISA address for the master unit, then click OK.

Figure 2-8 N8241A Selection Window

Basic Operation

Using the Graphical User Interface

3. Select the desired signal conditioning path

4. Select the desired waveform file.

5. Select the Clock tab.

6. From the SYNC CLK IN drop-down list, select Master.

Notice the following changes to the graphical user interface that are automatically configured when the Master unit is assigned:

Clock Tab

• the internal clock is no longer driving the sample clock

• the sample clock and sync clock out are driven by the external clock in signal

• the sync clock in signal communicates with the sequencer

Chapter 2 49

Basic Operation

Using the Graphical User Interface

Markers Tab

• Marker 4 is assigned to a Software marker and is grayed out

Triggers Tab

• Start trigger is assigned to Trigger 4 and is grayed out

Selecting the Slave Unit

1. Open a second N8241A Control Utility session.

2. Highlight the unit designated as the Slave in the N8241A Selection window list and click OK.

3. Select the desired signal conditioning path.

4. Select the desired waveform file.

5. Select the Clock tab.

6. From the SYNC CLK IN drop-down list, select Slave.

Notice the following changes to the graphical user interface that are automatically configured when the Slave unit is assigned:

Clock Tab

• the internal clock is disabled

• the sample clock is driven by the external clock in signal

• the sync clock out is disabled

• the sync clock in signal communicates with the sequencer

Triggers Tab

• Start trigger is assigned to Trigger 4 and is grayed out

Initiating Synchronous Playback

1. In the Quick Play area of the Slave GUI, select Play. This arms the waveform playback.

2. In the Quick Play area of the Master GUI, select Play. This initiates synchronous waveform playback.

NOTE You can view the output on an oscilloscope by setting Marker 1 on the Master

module to Waveform Start and cabling th e ma rker output to trigger the oscilloscope.

50 Chapter 2

Using Programmatic Interfaces

IVI-C Driver Functionality

The IVI Foundation’s class driver specification for function generators has been the model for the features in the N8241A and N8242A AWGs. This includes the recommended method to incorporate attributes for instrument-specific functions.

Please refer to IVI-3.15 IviLxiSync Specification, IVI-4.3 IviFgen Class Specification, and IVI-3.1 Driver Architecture Specification for more information. These can be found at:

www.ivifoundation.org/Downloads/Specifications.htm A set of API Functions and Attributes can be found in the N8241A Help system. Go

to: Start > Programs > Agilent > N8241A > Help or from the application menu bar

Help > N8241A Online Help

Basic Operation

Using Programmatic Interfaces

MATLAB Interface

MATLAB is one of the programmatic interfaces supported by the N8241A and N8242A A WGs. Use the set of API functions to configure and play waveforms with the A WG. A complete list of the API functions can be found in the N8241A Control Utility in the Help menu. Go to: Help > N8241A Help > Programming > MATLAB API.

T o set up MATLAB for connectivity, while in the MATLAB environment, go to: File > Set Path > Add with Subfolders... navigate to your local drive and go to where your program files are stored. The

default is: Program Files > Agilent > N8241A AWG > Matlab click SAVE, then Close the Set Path window.

MATLAB can now execute all of the N8241A API functions.

Chapter 2 51

Basic Operation

Using Programmatic Interfaces

MATLAB Example 1, Creating and Playing a Waveform

% A simple example of how to create a waveform, open a % session to the Agilent N8241A AWG, play the waveform, % and close the session. % Note: the waveform must be configured before downloading. % If settings are changed after downloading the waveform, % the waveform must be re-downloaded.

% Create a waveform - a sine wave with 2000 pts

% Played at 1250 MHz, this will produce a tone of 1.250 MHz

numberOfSamples = 2000;

samples = 1:numberOfSamples;

ch1 = sin(2 * samples/numberOfSamples * 2*pi);

ch2 = cos(2 * samples/numberOfSamples * 2*pi);

waveform = [ch1; ch2];

% Open a session

disp('Opening a session to the instrument');

[instrumentHandle, errorN, errorMsg] = agt_awg_open('TCPIP','TCPIP0::A-N8241-90XXX::inst0::INST R');

if(errorN ~= 0)

% An error occurred while trying to open the session.

disp('Could not open a session to the instrument');

return;

end

52 Chapter 2

Basic Operation

Using Programmatic Interfaces

disp('Enabling the instrument output');

[errorN, errorMsg] = agt_awg_setstate(instrumentHandle, 'outputenabled', 'true');

if(errorN ~= 0)

% An error occurred while trying to enable the output.

disp('Could not enable the instrument output');

return;

end

disp('Setting the instrument to ARB mode');

[errorN, errorMsg] = agt_awg_setstate(instrumentHandle, 'outputmode', 'arb');

if(errorN ~= 0)

% An error occurred while trying to set the ARB mode.

disp('Could not set the instrument to ARB mode');

return;

end

disp('Transfering the waveform to the instrument');

[waveformHandle, errorN, errorMsg] = agt_awg_storewaveform(instrumentHandle, waveform);

if(errorN ~= 0)

% An error occurred while trying to transfer the waveform.

disp('Could not transfer the waveform to the instrument');

return;

end

disp('Initiating playback of the waveform on the instrument');

Chapter 2 53

Basic Operation

Using Programmatic Interfaces

[errorN, errorMsg] = agt_awg_playwaveform(instrumentHandle, waveformHandle);

if(errorN ~= 0)

% An error occurred while trying to playback the waveform.

disp('Could not initiate playback of the waveform on the instrument');

return;

end

disp('Press ENTER to close the instrument session and conclude this example.');

pause;

agt_awg_close(instrumentHandle);

disp('Session to the instrument closed successfully.');

MATLAB Example 2, Synchronizing Two N8241/2A AWGs

MATLAB Example 2, Synchronizing Two AWG Modules

% N6030 Matlab Interface, Version 1.12 % Copyright (C) 2005, 2006 Agilent Technologies, Inc. % % This example initiates dual module synchronized waveform % playback. % % Use agt_awg_browse to identify the modules. % % Create a waveform - a sine wave with 2000 pts % Played at 1250 MHz, this will produce a tone of 1.250 MHz numberOfSamples = 2000; samples = 1:numberOfSamples; ch1 = sin(2 * samples/numberOfSamples * 2*pi); ch2 = cos(2 * samples/numberOfSamples * 2*pi); waveform = [ch1; ch2];

54 Chapter 2

Basic Operation

Using Programmatic Interfaces

% Try to open a session

disp('Opening a session to the instrument');

[instrumentHandle2, errorN, errorMsg] = agt_awg_open('TCPIP','TCPIP0::A-N8241-90XXX::inst0::INST R');

if errorN ~= 0

disp(errorN);

disp(errorMsg);

disp('program stopped');

return;

else

disp('ok');

end

[instrumentHandle1, errorN, errorMsg] = agt_awg_open ('TCPIP','TCPIP0::A-N8241-90XXX::inst0::INSTR');

if errorN ~= 0

disp(errorN);

disp(errorMsg);

disp('program stopped');

return;

else

disp('ok');

end

disp('Enabling the instrument output');

[errorN, errorMsg] = agt_awg_setstate(instrumentHandle1, 'outputenabled', 'true');

if errorN ~= 0

disp(errorN);

Chapter 2 55

Basic Operation

Using Programmatic Interfaces

disp(errorMsg);

disp('program stopped');

return;

else

disp('ok');

end

[errorN, errorMsg] = agt_awg_setstate(instrumentHandle2, 'outputenabled', 'true');

if errorN ~= 0

disp(errorN);

disp(errorMsg);

disp('program stopped');

return;

else

disp('ok');

end

disp('Setting the instrument to ARB mode');

[errorN, errorMsg] = agt_awg_setstate(instrumentHandle1, 'outputmode', 'arb');

if errorN ~= 0

disp(errorN);

disp(errorMsg);

disp('program stopped');

return;

else

disp('ok');

end

56 Chapter 2

Basic Operation

Using Programmatic Interfaces

[errorN, errorMsg] = agt_awg_setstate(instrumentHandle2, 'outputmode', 'arb');

if errorN ~= 0

disp(errorN);

disp(errorMsg);

disp('program stopped');

return

else

disp('ok');

end

disp('Setup the Master');

[errorN, errorMsg] = agt_awg_setstate(instrumentHandle1, 'syncmode', 'master');

if errorN ~= 0

disp(errorN);

disp(errorMsg);

disp('program stopped');

return

else

disp('ok');

end

disp('Setup the Slave');

[errorN, errorMsg] = agt_awg_setstate(instrumentHandle2, 'syncmode', 'slave');

if errorN ~= 0

disp(errorN);

Chapter 2 57

Basic Operation

Using Programmatic Interfaces

disp(errorMsg);

disp('proram stopped');

return

else

disp('ok');

end

disp('Transfering the waveform to the instrument');

[waveformHandle, errorN, errorMsg] = agt_awg_storewaveform(instrumentHandle1, waveform);

if errorN ~= 0

disp(errorN);

disp(errorMsg);

disp('program stopped');

return

else

disp('ok');

end

[waveformHandle, errorN, errorMsg] = agt_awg_storewaveform(instrumentHandle2, waveform);

if errorN ~= 0

disp(errorN);

disp(errorMsg);

disp('program stopped');

return

else

disp('ok');

end

disp('Initiating playback of the waveform on the

58 Chapter 2

Basic Operation

Using Programmatic Interfaces

instrument');

[errorN, errorMsg] = agt_awg_playwaveform(instrumentHandle2, waveformHandle);

if errorN ~= 0

disp(errorN);

disp(errorMsg);

disp('program stopped');

return

else

disp('ok');

end

[errorN, errorMsg] = agt_awg_playwaveform(instrumentHandle1, waveformHandle);

if errorN ~= 0

disp(errorN);

disp(errorMsg);

disp('program stopped');

return

else

disp('ok');

end

disp('Init Generation');

[errorN, errorMsg] = agt_awg_initiategeneration(instrumentHandle2);

if errorN ~= 0

disp(errorN);

disp(errorMsg);

disp('program stopped');

return

Chapter 2 59

Basic Operation

Using Programmatic Interfaces

else

disp('ok');

end

[errorN, errorMsg] = agt_awg_initiategeneration(instrumentHandle1);

if errorN ~= 0

disp(errorN);

disp(errorMsg);

disp('program stopped');

return

else

disp('ok');

end

disp('Press ENTER to close the instrument session and conclude this example.');

60 Chapter 2

Basic Operation

Using Programmatic Interfaces

C/C++ Example Program

This will compile and link into a working.EXE file.

For Compile: Add include path = C:\Program Files\IVI\include,

C:\vxipnp\winnt\include

For Link: Add libpath = C:\Program Files\IVI\Lib\msc, Add lib = AGN6030A.lib

Opening a session with predistortion enabled (default) creates a discrepancy for the waveform in ch2 since predistortion is applied twice; once when it was downloaded to ch1 and again when it is downloaded to ch2.

You can eliminate this problem by turning off the predistortion before downloading the waveform to ch2. An alternative is to clone the waveform to another file name. For example, clone Wfm_ch1 to Wfm_ch2.

#include <math.h>

#include <windows.h>

#include <winbase.h>

#include <AGN6030A.h>

// #include "stdafx.h" // if you use Microsoft // Visual Studio you might use this

#define WFM_LENGTH 800 //should be integer divisible by 16

int main(int argc, char* argv[])

{

ViStatus rc;

ViRsrc resourceName = "TCPIP0::A-N8241-90XXX::inst0::INSTR"; // Set // this to match your hardware

ViBoolean IDQuery = VI_FALSE;

Chapter 2 61

Basic Operation

Using Programmatic Interfaces

ViBoolean resetDevice = VI_TRUE;

ViSession session = 0;

ViInt32 wfmHandle1;

ViInt32 wfmHandle2;

int i;

double twopi;

double ifWfm[WFM_LENGTH];

double Fsig = 500e6; // Set this to a CW frequency // <= 500 MHz

double Fs = 1.25e9; // Sample Clock Frequency

// Initialize N8241A and setup session handle

rc = AGN6030A_init(resourceName, IDQuery, resetDevice, &session);

if (rc != VI_SUCCESS)

return -1;

// Setup some Channel 1 states

// Set to single-ended operation, filter on, // 500 MHz filter selected

rc = AGN6030A_ConfigureOutputConfiguration(session, "1", AGN6030A_VAL_CONFIGURATION_SINGLE_ENDED,

VI_TRUE, 500e6);

if (rc != VI_SUCCESS)

return -1;

// Set output to ON

rc = AGN6030A_ConfigureOutputEnabled(session, "1", VI_TRUE);

if (rc != VI_SUCCESS)

return -1;

// Do the same for Channel 2

rc = AGN6030A_ConfigureOutputConfiguration(session, "2", AGN6030A_VAL_CONFIGURATION_SINGLE_ENDED,

VI_TRUE, 500e6);

62 Chapter 2

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Using Programmatic Interfaces

if (rc != VI_SUCCESS)

return -1;

rc = AGN6030A_ConfigureOutputEnabled(session, "2", VI_TRUE);

if (rc != VI_SUCCESS)

return -1;

// Select the Internal Sample Clock and an //External Reference Clock

rc = AGN6030A_ConfigureSampleClock(session, AGN6030A_VAL_CLOCK_INTERNAL, Fs);

if (rc != VI_SUCCESS)

return -1;

// This uses the front panel 10MHz REF IN

// connection. To use the PCI backplane clock, // substitute AGN6030A_VAL_REF_CLOCK_PXI

rc = AGN6030A_ConfigureRefClockSource(session, AGN6030A_VAL_REF_CLOCK_EXTERNAL);

if (rc != VI_SUCCESS)

return -1;

// Enable or disable built-in corrections. // Default is enabled. This attribute is not // available in release 1.00.

/* rc = AGN6030A_SetAttributeViBoolean(session, NULL, AGN6030A_ATTR_PREDISTORTION_ENABLED,

VI_TRUE);

if (rc != VI_SUCCESS)

return -1;

// Build a sample waveform for testing. // This produces a CW tone at Fsig Hz.

twopi = 8.0 * atan(1.0);

for (i = 0; i < WFM_LENGTH; i++)

{

Chapter 2 63

Basic Operation

Using Programmatic Interfaces

ifWfm[i] = sin(twopi * (Fsig/Fs) * (double)i);

}

// Set N8241A output mode to ARB in preparation of // downloading and playing our waveform.

rc = AGN6030A_ConfigureOutputMode(session, AGN6030A_VAL_OUTPUT_ARB);

if (rc != VI_SUCCESS) return -1;

// Download the waveform to both channels 1 and 2 // even if 2is not used. This is a requirement at // this time and must be followed!! To do this, // call the function twice and discard the second // waveform handle if Channel 2 is not used.

rc = AGN6030A_CreateArbWaveform(session, WFM_LENGTH, ifWfm, &wfmHandle1);

if (rc != VI_SUCCESS)

return -1;

rc = AGN6030A_CreateArbWaveform(session, WFM_LENGTH, ifWfm, &wfmHandle2);

if (rc != VI_SUCCESS)

return -1;

// Configure N8241A to play downloaded waveforms.

// Set to 250 mV gain and 0V offset.

rc = AGN6030A_ConfigureArbWaveform(session, "1", wfmHandle1, 0.250, 0.0);

if (rc != VI_SUCCESS) return -1;

rc = AGN6030A_ConfigureArbWaveform(session, "2", wfmHandle2, 0.250, 0.0);

if (rc != VI_SUCCESS)

return -1; // Close the open session

rc = AGN6030A_close(session);

return 0;

64 Chapter 2

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}

Chapter 2 65

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Using Programmatic Interfaces

66 Chapter 2

3 Theory of Operation

This chapter includes the following topics that explain the theory behind the functionality of the N8241A and N8242A Arbitrary Waveform Generators.

N8241/2A Block Diagram 68 Clock I/O 69 Waveform Playback 70

Basic Sequencing 71 Advanced Sequencing 72 Markers 79 Triggers 80 Synchronous Triggers 82 Signal Conditioning 84 Digital Predistortion 86

Multiple Module Synchronization 87

Theory of Operation

N is the Sync clock prescaler divide ratio. Refer to “Synchronous Triggers”.

N8241/2A Block Diagram

The N8241A and N8242A Arbitrary Waveform Generators (AWGs) are dual channel AWGs that offer wide bandwidth as well as excellent signal fidelity. The AWG was developed incorporating a high performance Agilent digital-to-analog converter (DAC) designed to clock up to 1.25 GHz. The N8241A has 15 bits of vertical resolution and the N8242A 10 bits. The DACs are fully differential and the AWGs support both single-ended and differential outputs through the analog signal conditioning path.

The AWGs support advanced sequencing and triggering modes that enable event-based signal simulations. The DSP forms the heart of the sequencer storing the information used to define the order that stored waveforms are played.

The AWGs are also designed to enable synchronization of multiple units.

68 Chapter 3

Clock I/O

Theory of Operation

Clock I/O

10 MHz In

A 10 MHz reference is required when using the internal clock. You can use either the (AutoSense) 10 MHz REF IN (the default) or the AUX 10 MHz REF IN connector to supply the 10 MHz reference.

The high-performance 1.25 GHz oscillator provides the internal sample clock for the module.

Internal Clock Out

The 1.25 GS/s low noise internal sample clock is output through the INT CLK OUT connector and can be routed to other AWGs or test equipment. The internal clock output is available even when an external clock is used.

External Clock

An external sample clock can be input through the EXT CLK IN connector. The external sample rate must be within the range of 100 MS/s and 1.25 GS/s. To achieve the optimal signal performance on the AWG analog output, use an external clock with a phase noise floor below -155 dBc/Hz and a power setting of approximately 0 dBm.

NOTE An error message will appear if the clock rate does not match the hardware setting,

or an external clock is not present.

SYNC Clock In/SYNC Clock Out

The SYNC CLOCK IN and SYNC CLOCK OUT are used for the synchronization of multiple modules. Refer to

page 87

Chapter 3 69

and “Synchronization Using an External Clock” on page 88.

“Synchronization Using an Internal Clock” on

Theory of Operation

Waveform Playback

Waveforms

Single waveforms are played back in one of two modes:

• Continuous The waveform repeats indefinitely.

• Burst Once a trigger is received, the waveform repeats a specified number of times.

Waveform Sequencer Function

Sequencing provides a method of waveform memory compression using a play table, sequencer memory, and waveform memory. The sequencer controls how waveforms are accessed and performs the following functions:

• determines the order of play for waveforms stored in memory

• enables the construction of long waveforms from shorter or repeated segments

• responds to external triggers

• offers several modes of segment advance

• outputs markers

Sequence Play Table

The play table contains entries that point to sequences in the sequencer memory. Within the play table you can have up to 16384 sequence pointers.

Sequencer Memory

The sequencer memory contains instructions on how to play through the waveform memory. It can hold up to 32768 segments (waveforms with a specified loop count).

Waveform Memory

The waveform memory contains Channel 1 and Channel 2, and output marker data.

NOTE The N8241A Control Utility GUI only supports basic sequencing. Advanced

sequencing features can only be accessed through the programmatic interfaces.

70 Chapter 3

Basic Sequencing

A sequence is a sequential list of segments and may occur anywhere in the sequence memory. A sequence may have a preamble of one or more segments that is played once at the start of the sequence, but not repeated until the sequence is started again.

Waveforms are stored in dedicated banks of memory for channel 1 and channel 2. The waveform playback of each channel is directly controlled by the sequencer. The sequencer supplies the memory pointers necessary to create analog signals from the digital data stored in memory. In addition, the sequencer provides the capability to create sequences made of multiple waveform segments. This is helpful when constructing long waveforms with repeating segments. A long waveform might consist of repetitive data that can be stored as single segments and repeated in the sequencer. This extends the waveform play time achievable with the available memory.

Basic sequencing can be done using the software N8241A Control Utility GUI or through the programmatic interfaces.

Figure 3-1 Example Sequence

Theory of Operation

Waveform Playback

Playback

There are two playback modes for basic sequencing:

• Continuous

The sequence repeats indefinitely or until an event trigger is received.

• Burst

The sequence is repeated a predefined number of times. This mode requires a start trigger.

A total of 16,000 unique waveform sequences can be defined. Segments have a minimum length of 128 samples and a granularity of 8 samples. A sequence must contain at least two segments and can have up to the maximum number of 32768

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segments. Each waveform segment is played out according to its segment and sequence definition. A total of 1 million (220) loops can be defined for each segment. After the last segment loop is executed, the entire sequence can repeat continuously or for the predefined number of times.

Advanced Sequencing

NOTE Advanced sequencing is only available through the programatic interfaces.

Advanced sequencing enables the grouping of sequences into scenarios in a way that is similar to how segments are grouped in sequencing. With scenarios you gain more control of waveform playback.

Scenario Pointer Source

There are two ways to choose which sequence to play.

• Index A register is written to by the host processor that addresses entries in the sequence play table. This register can be written to at any time including while a sequence is playing. A valid Start trigger or Jump trigger starts the sequence specified by the index in the register. The valid sequence index range is 0-16383. Selecting invalid sequence indexes causes indeterminate behavior.

• Direct

The user can directly address waveforms in the sequencer memory completely bypassing the play table. The next sequence pointer can be written to while a sequence is being played. A valid Start trigger or Jump trigger starts the sequence specified by the new pointer in the register. Addressing undefined sequences causes indeterminate behavior.

72 Chapter 3

Theory of Operation

Waveform Playback

Scenario Advance Mode

The play table can be configured to play a scenario once or continuously after starting.

• Single

The scenario plays once and then waits for a trigger. While waiting for a trigger, the value of the last waveform continues to play. If the scenario pointer does not change, a Start trigger or Jump trigger causes the scenario to play again. If the scenario pointer changes, the next Start trigger or Jump trigger will start the new scenario. The effect of a scenario jump trigger received before the end of the scenario is determined by the scenario jump mode.

• Continuous

The scenario repeats indefinitely until it is stopped or a scenario jump trigger is received. The scenario exit is dependent on the scenario jump mode.

Refer to

“Advanced Sequencer Flow Chart” on page 74.

Chapter 3 73

Theory of Operation

Figure 3-3

Waveform Playback

Figure 3-2 Advanced Sequencer Flow Chart

74 Chapter 3

Theory of Operation

Waveform Playback

Wa veform Ad van cement

In basic sequencing, waveforms always advance to the next waveform automatically after the specified number of repetitions. With advanced sequencing, waveforms can be configured to advance in one of four ways:

• Automatic

The waveform automatically advances to the next waveform after completing the specified number of loop repetitions.

• Continuous

The waveform loop is repeated continuously until a trigger is received. The current loop is finished before advancing to the next waveform. The waveform loop repetition count is ignored.

• Single

The waveform loop plays once and waits at the end of the loop for a trigger. The waveform loop is repeated for each trigger until the number of waveform loop repetitions is met. The next trigger will advance to the next waveform. When the waveform loop repetition count is one, a single trigger will advance to the next waveform. While waiting for a trigger, the last value of the waveform loop continues to play.

• Repeat

The waveform loop repeats until the number of waveform loop repetitions is met.

Scenario Jump Mode

The scenario jump mode determines how the play table responds to a scenario jump input. There are no discontinuities in a scenario jump, other than those imposed by the waveform data. A scenario jump has very predictable behavior. For scenario jumping to be valid, the scenario length must be equal to or greater than the jump immediate latency.

There are three types of jump modes:

• Immediate

The scenario starts or jumps immediately with latency.

• End of Waveform

The current waveform, including repeats, is completed before jumping to the new scenario.The jump latency is the longer of either the jump immediate latency or the length of the remaining part of the current waveform. If the remaining part of the scenario is less than the jump immediate latency, the scenario is repeated one more time before jumping.

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Waveform Playback

• End of Scenario

The current scenario is completed before jumping to the new scenario. The jump latency is the longer of either the jump immediate latency or the length of the remaining part of the current waveform. If the remaining part of the scenario is less than the jump immediate latency, the scenario is repeated one more time before jumping.

Scenario Start/Jump Trigger Source

It is possible to start a scenario, or to jump to a new scenario using one of five inputs. There are four external trigger inputs and a host trigger source. The host trigger source is a register in the play table that can be written to by the host processor. The host processor provides the user a way to start the scenario, or create a jump event. The latency for a scenario jump is established by the jump mode.

Refer to

Sequence Play Flow Charts” on page 78

The Jump Trigger condition is satisfied either by a waveform jump event, or by a scenario jump trigger event when the scenario jump mode is set to “End of Waveform.”

“Waveform Play Flow Chart” on page 77 and “Scenario and

76 Chapter 3

Figure 3-3 Waveform Play Flow Chart

Theory of Operation

Waveform Playback

Chapter 3 77

Theory of Operation

Waveform Playback

Figure 3-4 Scenario and Sequence Play Flow Charts

78 Chapter 3

Markers

The N8241/2A AWG provides four front panel marker output connectors that can be used for system synchronization and triggering. The following markers can be enabled:

• Ch 1 Memory Marker 1 and Memory Marker 2

• Ch 2 Memory Marker 1 and Memory Marker 2

• Waveform Start, Repeat, and Gate

• Sequence Start, Repeat, and Gate

• Scenario Repeat

•Software Marker outputs are aligned with the analog output of the AWG.

Figure 3-5 Marker Block Diagram

Theory of Operation

Waveform Playback

In addition, two LXI markers are available for routing to the LXI Trigger Bus or the

Chapter 3 79

Theory of Operation

Waveform Playback

front panel trigger out connector. There are 16 marker output selections for the LXI trigger bus; LAN 0–7 and LXI 0–7.

Markers can be set in the sequencer to be at any point in the data with a positive or negative polarity. Marker widths, except those derived from waveform memory , can be set in increments of the SYNC clock (-8 to 247 clocks). The marker delay function uses the input value to calculate the delay to the nearest 1/4 SYNC clock cycle. The sequencer is capable of outputting nine markers, which can be multiplexed to the four marker outputs. The Sequence Start, Sequence Gate, Scenario Repeat, and three software markers are only available through the programmatic interfaces.

Triggers

The AWG module has five front panel trigger input connector, a rear panel LXI trigger bus, and triggering through the LAN line. All triggers passing through the LXI trigger bus and the LAN line are executed through the LXI T1 trigger.

Figure 3-6 Trigger Block Diagram

80 Chapter 3

Theory of Operation

Waveform Playback

Triggers 1,2,3,4

These four trigger inputs can be used to control waveforms in the sequencer. Hardware trigger inputs may be configured to generate events on the rising or falling SYNC clock edges, but not both at the same time. The trigger threshold can be set between –4.5 and +4.5V. Ports 1 and 2 have a common threshold, and ports 3 an 4 have a common threshold. These two common thresholds are not shared and can be set independently.

Trigger delays can be set in increments of the SYNC clock (0-255 clocks). These trigger inputs can be configured to initiate the following events through the

software Control Utility: Start starts playback at the beginning of the waveform Hold holds at the end of the waveform Stop stops playback Resume resumes playback at the point in the waveform that play was

held or stopped

The Waveform Advance, Scenario Advance, Waveform Jump, and Scenario Jump triggers are only available through the programatic interfaces.

LXI T1

These trigger inputs can be configured to the following: LAN 0-7 provides a way to trigger programmatically over a LAN line LXI 0-7 the LXI Trigger Bus enables event driven functionality over an

eight channel multipoint LVDS system that can simultaneously transmit and receive signals

Trigger In direct trigger

NOTE T o achieve the specified performance, use front panel triggers 1, 2, 3, or 4. Triggers

over the Trigger In and LXI Trigger Bus will have more latency than what is specified for Triggers 1-4. Triggers over the LAN will experience the most latency.

Chapter 3 81

Theory of Operation

Waveform Playback

Synchronous Triggers

Triggers are registered into the AWG using the SYNC clock. The SYNC clock is nominally at the sample clock frequency divided by 8. However, at lower sample rates an internal variable modulus prescaler selects other binary divide ratios: 4, 2, and 1. In general, the SYNC clock frequency is always in the range of 78.13 MHz to

156.25 MHz. The input clock frequency ranges and prescaler divide ratios are as

specified in

Table 3-1 Synchronous Triggers

Sample Clock Frequency SYNC Clock Prescaler Divide Ratio

625 MHz - 1.25 GHz 8

312.5 MHz – 625 MHz 4

156.25 MHz – 312.5MHz 2 100 MHz – 156.25 MHz 1

It is necessary to insure that the correct timing relationships are achieved to guarantee consistent synchronous trigger operation. The trigger input must occur within a valid window with respect to the SYNC clock. The window is specified by two times: Twin_low —the minimum trigger delay after the prior SYNC clock edge; and Twin_up — the minimum trigger setup before the next SYNC clock edge. These are specified for the trigger input relative to the SYNC clock output. The trigger must be a minimum of two SYNC clock cycles long. The trigger timing is specified relative to the rising edge of the SYNC clock. The analog output from the AWG is then produced a fixed number of sample clock cycles (plus a small fixed propagation delay) after the first rising edge of the SYNC clock after the trigger goes active. Since the analog output is retimed by the sample clock, the reference for jitter measurements is the sample clock, as shown in the input trigger to generate an output marker to synchronize triggers since marker outputs are aligned with the analog output of the AWG.

Table 3-1:

Figure 3-7. Y ou can use an

Figure 3-7 Synchronous Trigger Timing Diagram

82 Chapter 3

Signal Conditioning

Single-Ended Mode

Single-ended mode has two modes of operation with signal output through the positive (+) port. The negative port (-) is reserved for differential mode.

Passive mode has an adjustable output level of up to 0.5Vp-p This mode gives the greatest single-ended signal fidelity because there is a balun in the path that suppresses the second order harmonic.

Active mode has an output level of up to 1.0Vp-p and ±0.2Vp-p offset range when the amplifier is activated. The active mode trades off signal fidelity for an increase in signal power.

Theory of Operation

Signal Conditioning

There are two internal reconstruction filters, 250 MHz and 500 MHz, that can be inserted in the signal path of either mode.

Chapter 3 83

Theory of Operation

Signal Conditioning

Differential Mode

The differential mode has an output level of up to 0.5Vp-p. This mode provides exceptional signal fidelity into true differential inputs (which provide common mode rejection). A larger differential output voltage is also obtained without the use of the amplifier. To preserve signal purity, the active amplifier cannot be used in differential mode. Differential mode is not recommended when driving single-ended loads since the second order distortion is degraded. If you choose to drive single-ended loads, you must terminate the negative (-) port of the channel with a 50 ohm load.

Adjustable output voltage and offsets as well as reconstruction filters can be used in differential mode

84 Chapter 3

Digital Predistortion

The predistortion function compensates for the variation in the magnitude of the output response as a function of frequency. This variation is the result of the sin x/x (sinc) roll-off of the internal DAC and the frequency response of the reconstruction filter. The correction method uses filters to level the amplitude response and to create a linear phase response at the front panel of the A WG. This process attenuates the signal as a function of frequency, but cannot increase the signal above the maximum output voltage. Therefore, it is necessary to attenuate the lower frequency signals. This results in a reduced output voltage and dynamic range at all frequencies, but with uniform response across the full frequency range.

Theory of Operation

Digital Predistortion

Chapter 3 85

Theory of Operation

Multiple Module Synchronization

Within each AWG, the two channels are synchronized by design. Some systems, such as phased array radar, require more than two synchronized channels. The A WG is designed to support the synchronization of up to 16 channels through the use of eight AWGs. Synchronization of multiple AWGs can be achieved using either the internal clock or an external clock.

Synchronization Using an Internal Clock

In synchronizing multiple modules using the internal clock, one unit is designated as the Master and the other units are designated as Slave units. The Master unit sources the following signals: Sample clock, SYNC clock, and the Sync Marker. These signals are all split and fed to each of the synchronized modules (the Master as well as the Slaves).The internal sample clock is at 1.25 GHz. The sample clock provides the final retiming of the analog output from each AWG. Any skew in the sample clock cable delays between the multiple modules will result in the same skew in the analog outputs.

Typically, the sample clock signal is split with a matched passive splitter and the cable lengths are matched to better than 5 mm. The resulting skew is small and repeatable. If desired, the skew can be measured and calibrated (along with any phase shifts in cables on the AWG outputs) by adding fixed delay offsets to the waveforms.

The SYNC clock is used internal to the AWG to clock the internal data generator and to clock in the synchronous triggers. When using the internal clock, the SYNC clock has a frequency of 1/8th the sample clock rate (156.25 MHz). When synchronizing multiple units, the SYNC clock output must be enabled in software (in the Master) and the external SYNC clock input selected in all the modules. The SYNC clock signal is split passively and distributed with low skew. The SYNC clock output level and the input sensitivity support up to a 1 to 8 split (fan-out) using matched 50 Ohm splitters (6 dB loss per 1 to 2 splitter). There is a specific SYNC cable length that is required as a function of the sample clock frequency. Several different lengths can be used, provided they are integer multiples of one half of a SYNC clock period.

86 Chapter 3

Figure 3-8 Cabling for Internal Clock Synchronization

Theory of Operation

Multiple Module Synchronization

The trigger cables should all be the same length. The trigger inputs are high impedance and several inputs can be driven in parallel without matched passive splitters. The synchronous trigger timing can be determined in the same way as any synchronous trigger into the AWG. The timing is specified relative to the SYNC clock out. This is easily observed on the slave modules, where the SYNC clock out is unconnected.

The multiple AWGs are configured to have an internal start trigger to begin play. A software start marker event is used to initiate the synchronized play. Marker 4 and Trigger 4 are used for this purpose.

Synchronization Using an External Clock

In synchronizing multiple modules using an external clock, one unit is designated as the Master and the other units are designated as Slave units. The external clock is split with low skew and distributed to all units. The Master unit sources the following signals: SYNC clock, and the Sync Marker. These signals are all split and fed to each of the synchronized modules (the Master as well as the Slaves). The

Chapter 3 87

Theory of Operation

Multiple Module Synchronization

external Sample clock can be in the range of 625 MHz to 1.25 GHz. The Sample clock provides the final retiming of the analog output from each A WG. Any skew in the Sample clock cable delays between the multiple modules will result in the same skew in the analog outputs. Typically, the sample clock signal is split with a matched passive splitter and the cable lengths are matched to better than 5 mm. The resulting skew is small and repeatable. The skew can be measured and calibrated, along with any phase shifts in cables on the ARB outputs, by adding fixed delay offsets to the AWG waveforms. The SYNC clock is used internal to the AWG to clock the internal data generator and to clock in the synchronous triggers. When using the internal clock, the SYNC clock has a frequency of 1/8 of the sample clock rate (156.25 MHz). When synchronizing multiple units, the SYNC clock output must be enabled in software (in the Master) and the external SYNC clock input selected in all the modules. The SYNC clock signal is split passively and distributed with low skew. The SYNC clock output level and the input sensitivity support up to a 1 to 8 split (fan-out) using matched 50 Ohm splitters (6 dB loss per 1 to 2 splitter). There is a specific SYNC cable length that is required as a function of the Sample clock frequency. Several different lengths can be used, provided they are integer multiples of one half of a SYNC clock period.

88 Chapter 3

Figure 3-9 Cabling Using and External Clock

Theory of Operation

Multiple Module Synchronization

Chapter 3 89

Theory of Operation

Multiple Module Synchronization

Multiple Module Synchronous Trigger Timing

Triggers are registered into the AWG using the SYNC clock. The SYNC clock is nominally at the sample clock frequency divided by 8. However at lower sample rates an internal variable modulus prescaler selects other binary divide ratios: 8, 4, 2, and 1. Multiple AWG synchronization is only supported in the 625 MHz to 1.25 GHz frequency range. The input clock frequency ranges and prescaler divide ratios are as specified in

Table 3-2 SYNC Clock Frequency Ranges

Frequency Range SYNC Clock Prescaler Divide Ratio

625 MHz-1.25 GHz 8

“SYNC Clock Frequency Ranges” on page 91.

312.5 MHz-625 MHz

156.25 MHz-312.5 MHz 100 MHz-156.25 MHz

Multi-Module Synchronization Not Supported

Figure 3-10. To guarantee proper synchronous trigger operation with arbitrary

length cables, it is possible to configure the trigger inputs to register the trigger event with respect to the falling edge of the SYNC clock, under software control. In this way there is always a setting for the trigger input timing which will operate reliably for any chosen cable. The typical specifications for the trigger window using the internal clock at 1.25 GS/s is (these values will vary at other clock frequencies): Twin_high > 3.4 ns

Twin_low > -2.8 ns (the trigger can occur slightly before the prior SYNC clock edge)

90 Chapter 3

Theory of Operation

Length n( 686 1250MHz()f )⁄×× 394–[]=

Cabledelay n 3.29 1250MHz()f⁄××()1.89–=

Multiple Module Synchronization

Figure 3-10 Multiple Module Synchronous Trigger Timing Diagram

Cable Length and Skew

The cabling requirements are as follows:

Sample Clock

Skew less than 10 mm between modules. The absolute SYNC cable length is given by the

Sample Clock Skew Formula

Equation as a function of the Sample clock frequency:

Expressed in mm, where n is an arbitrary integer and f is the sample clock frequency in MHz.

It should be noted that n is the number of 1/2 SYNC clock cycles of total delay between the modules.

This can also be expressed in terms of delay:

Expressed in nanoseconds, where n is an arbitrary integer and f is the sample clock frequency in MHz.

For the external Sample clock the formulas apply over the frequency range of 625 MHz to 1.25 GHz

Marker and Trigger Cables

The Marker Out to Trigger In cable should be less than 305 mm (12 in). With the

1.25 GHz internal clock, the trigger is falling edge triggered.

Chapter 3 91

Theory of Operation

Multiple Module Synchronization

92 Chapter 3

4 Dynamic Sequencing

Option 300

The dynamic sequencing option enables you to access up to eight thousand previously stored scenarios through a 16-bit interface. This functionality gives you the ability to build custom signal scenarios to simulate dynamically changing environments.

Dynamic Sequencing 94 AUX PORT Connector 94 Signal Levels 96 Signal Descriptions 96

Dynamic Sequencing Option 300

Dynamic Sequencing

Dynamic sequencing is a mode where the AWG scenario handle memory is bypassed and scenarios are selectedfrom an external source. You must first load the data into the N8241A LXI-AWG memory, then, in real-time, provide the scenario handles through the AUX PORT input connector.

NOTE The dynamic sequencing option is only available through the programmatic

interfaces since it operates in the advanced sequencing mode that is not available through the Control Utility. Refer to “Advanced Sequencing” on

page 72.

Figure 4-1 Dynamic Sequencing Block Diagram

AUX PORT Connector

Description: Receptacle , Mini D Number of Contacts: 20 Manufacturer: 3M Part Number: 10220-0210EC

94 Chapter 4

Figure 4-2 AUX PORT Pin Outs

Table 4-1 Pin Assignment

Pin No. Signal Assignment

1 Trigger 2 Ground 3 Data Valid 4 CH 1/CH 2 (Reserved, set low) 5 D0 6D1 7 Ground 8D2 9 D3 10 D4 11 D5 12 D6 13 D7 14 Ground 15 D8 16 D9 17 D10 18 D11 19 Ground 20 D12

Dynamic Sequencing Option 300

Dynamic Sequencing

Chapter 4 95

Dynamic Sequencing Option 300

Dynamic Sequencing

Signal Levels

All pins are configured as 2.5 V, LVCMOS inputs. The logic levels must be within the following ranges:

Low −0.2 to +0.5 V High +2.0 to +2.8 V

Signal Descriptions

Data Input

The input data represents a handle to the next scenario to be played by the AWG module. Only the first 8,192 scenarios are available. The scenario handle must be divided by 2 before being written to the AUX port. For example, to play the scenario with a handle of 72, write the value 36 to the AUX port. All scenario handles are even numbers.

Data Valid

When Data Valid is asserted high, it indicates that the data present on the Data pins is valid and can be latched into the channel 1 and channel 2 next sequence register.

Trigger

Trigger input can be configured to be either rising-or falling-edge, with a programmable delay. Refer to “Triggers” on page 80.

NOTE The latency between trigger assertion and sequence playback is the same as

that for the front panel trigger inputs, a resolution of one SYNC clock.

96 Chapter 4

5 Direct Digital Synthesis

Option 330

The direct digital synthesis (DDS) architecture in the N8241A Series A WGs enables you to create basic waveforms in the AWG memory and then modify the behavior of the waveforms with profiles for amplitude, phase and frequency modulations.

Direct Digital Synthesis Using the Control Utility 99

Configuring the Equipment 99 Selecting the DDS Option 99 Configuring the Clock 100 Configuring the Sequencer 101

Out of Range Input Values 105

Theory of Operation 108

Direct Digital Synthesis Option 330

Direct Digital Synthesis

The N8241A direct digital synthesis application can be managed through the Control Utility graphical user interface (GUI) or one of the supported programmatic interfaces. Accessing DDS through the GUI is the easiest way to view the functionality as many details are handled by the software in the background.

As an introduction, we will step through using DDS with the Control Utility.

Figure 5-1 displays a high level DDS block diagram.

Figure 5-1 DDS Block Diagram

98 Chapter 5

Direct Digital Synthesis Option 330

Direct Digital Synthesis

Direct Digital Synthesis Using the Control Utility

NOTE A spectrum analyzer is required to display the waveform.

Configuring the Equipment

1. Connect a 10 MHz reference from the spectrum analyzer to the AWG front panel connector. If you are using a PXI chassis, use the backplane 10MHz reference.

2. Connect the channel 1 positive (+) output to the spectrum analyzer RF input connector.

Selecting the DDS Option

1. Open the Control Utility by double-clicking the icon on the desktop.

2. In the Open Dialog box, check Load DDS (if present).

Configuring the Signal Conditioning Path

1. Select the Output tab and connect a single-ended signal conditioning

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Direct Digital Synthesis Option 330

Direct Digital Synthesis

path to CH1 OUT (+) (click on the node that you want to connect).

The connection will automatically enable differential mode. Click on the negative (-) node to open this path and enable single-ended mode.

Configuring the Clock

1. Select the Clock tab and configure the 10MHz REF IN. For this

example, we utilized the 10 MHz reference from the E4440 Spectrum Analyzer in step 1. If you are using a PXI chassis, leave the clock set to the default Backplane 10MHz.

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Direct Digital Synthesis Option 330

Direct Digital Synthesis

2. Use the default setting for the Interpolation Ratio.

Configuring the Sequencer

1. Select the DDS Sequencer tab.

2. From the Segment List select Add. This brings up a Segment Information window.

3. Browse and select the DDS_All_Ones waveform from the Demo Waveform DDS folder included on the N8241A Series CD or the memory stick, then click OK.

NOTE For dual channel sequencing, add waveforms of the same length to both

channel 1 and channel 2. Currently, the software does not support independent channel sequencing.

Chapter 5 101

Keysight Technologies N8241A, N8242A User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Contents

1 Introducing the N8241/2A AWGs

Front Panel Interface

Status Indicators

Rear Panel Interface

Graphical User Interface (GUI)

Getting Started

System Requirements

N8241/2A Installation

Verifying System Operation

System Set Up

Waveform Generation

Shutting Down the System

Maintenance

Cleaning the Instrument

Cleaning Connectors

2 Basic Operation

Using the Graphical User Interface

Generating a Single Tone Signal

Generating a Multi-tone Signal

Creating and Playing a Sequence

Synchronizing Two N8241/2A Modules

Using Programmatic Interfaces

IVI-C Driver Functionality

MATLAB Interface

MATLAB Example 1, Creating and Playing a Waveform

MATLAB Example 2, Synchronizing Two N8241/2A AWGs

C/C++ Example Program

3 Theory of Operation

N8241/2A Block Diagram

Clock I/O

10 MHz In

Internal Clock Out

External Clock

SYNC Clock In/SYNC Clock Out

Waveform Playback

Waveforms

Waveform Sequencer Function

Sequence Play Table

Sequencer Memory

Waveform Memory

Basic Sequencing

Advanced Sequencing

Markers

Triggers

Synchronous Triggers

Signal Conditioning

Single-Ended Mode

Differential Mode

Digital Predistortion

Multiple Module Synchronization

Synchronization Using an Internal Clock

Synchronization Using an External Clock

Multiple Module Synchronous Trigger Timing

Cable Length and Skew

Dynamic Sequencing

AUX PORT Connector

Signal Levels

Signal Descriptions

Direct Digital Synthesis

Direct Digital Synthesis Using the Control Utility