Keysight N4903A User guide

Getting Started

with the

Agilent J-BERT N4903A

High-Performance Serial BERT

You only need a few minutes to get started with the J-BERT.

This Getting Started Brochure helps you to quickly understand the operating principles and set up your first BER test.

If you need more detailed information on the J-BERT, check out the Online Help.

The Help also offers printable versions of the

User Guide and the Programming Guide.

2

Notice

Copyright

© Agilent Technologies, Inc. 2006.

Revision

Revision 2.0, January 2006

Manual Part Number

N4903-91010

Printed in Germany

Agilent Technologies, Deutschland GmbH

Herrenberger Str. 130

71034 Boeblingen, Germany

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 terms of such license.

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 for 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.

Restricted Rights Legend

U.S. Government Restricted Rights.

Software and technical data rights granted to the federal government include only those rights customarily provided to end user customers.

Agilent provides this customary commercial license in Software and technical data pursuant to FAR 12.211

(Technical Data) and 12.212 (Computer Software) and, for the Department of Defense, DFARS 252.227-7015

(Technical Data - Commercial Items) and

DFARS 227.7202-3 (Rights in Commercial Computer

Software or Computer Software Documentation).

Safety Summary

General Safety Precautions

The following general safety precautions must be observed during all phases of operation of this instrument. 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 Inc. assumes no liability for the customer's failure to comply with these requirements.

Before operation, review the instrument and manual for safety markings and instructions. You must follow these to ensure safe operation and to maintain the instrument in safe condition.

General

This product is a Safety Class 1 instrument

(provided with a protective earth terminal).

The protective features of this product may be impaired if it is used in a manner not specified in the operation instructions.

All Light Emitting Diodes (LEDs) used in this product are Class 1 LEDs as per IEC 60825-1.

Environmental Conditions

This instrument is intended for indoor use in an installation category II, pollution degree

2 environment. It is designed to operate within a temperature range of 5 – 40 °C (40 – 105 °F) at a maximum relative humidity of 95% and at altitudes of up to 2000 meters.

Refer to the specifications tables for the ac mains voltage requirements and ambient operating temperature range.

Before Applying Power

Verify that all safety precautions are taken.

The power cable inlet of the instrument serves as a device to disconnect from the mains in case of hazard.

The instrument must be positioned so that the operator can easily access the power cable inlet. When the instrument is rackmounted the rack must be provided with an easily accessible mains switch.

Ground the Instrument

To minimize shock hazard, the instrument chassis and cover must be connected to an electrical protective earth ground. The instrument must be connected to the ac power mains through a grounded power cable, with the ground wire firmly connected to an electrical ground (safety ground) at the power outlet. Any interruption of the protective (grounding) conductor or disconnection of the protective earth terminal will cause a potential shock hazard that could result in personal injury.

Do Not Operate in an Explosive Atmosphere

Do not operate the instrument in the presence of flammable gases or fumes.

Do Not Remove the Instrument Cover

Operating personnel must not remove instrument covers. Component replacement and internal adjustments must be made only by qualified personnel.

Instruments that appear damaged or defective should be made inoperative and secured against unintended operation until they can be repaired by qualified service personnel.

Services and Support

Any adjustment, maintenance, or repair of this product must be performed by qualified personnel.

Contact your customer engineer through your local

Agilent Technologies Service Center. You can find a list of local service representatives on the Web at:

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

Installing the Agilent J-BERT

Inspect Shipment

Check if the J-BERT shipping container contains the following standard deliverables:

Agilent J-BERT N4903A

High-Performance Serial BERT

Power Cable

If the contents are incomplete, if there is mechanical damage, or if the instrument does not work within its specifications, notify the nearest Agilent office. The

Agilent office will arrange for repair or replacement without awaiting settlement.

For the complete content of your delivery please refer to the Box Contents List.

Agilent Pulse Genarator

Box Contents List Contents

Box Contents List Contents

Box Contents List Contents

Box Contents List Contents

Box Contents List Contents

Box Contents List Contents

Box Contents List Contents

Box Contents List Contents

Box Contents List

This Getting Started Brochure

Agilent I/O Libraries Suite CDs

USB Cable

Power Requirements

When the front panel switch is off, the instrument is in standby mode. The instrument can only be disconnected from the AC line power by disconnecting the power cord. The instrument must be positioned so that the operator can easily access the power cable inlet.

The instrument can operate from any single-phase

AC power source supplying 100 – 240 V in the frequency range from 47 – 63 Hz. The maximum power consumption is 450 VA with all options installed. The power supply automatically adapts to the applied AC power (Auto Selection) and monitors the AC power range.

The mains plug can only be inserted in a socket outlet that provides protective earth contact. Any interruption of the protective earth contact inside or outside the instrument makes any operation of the instrument dangerous. Intentional interruption is prohibited.

Connect the Instrument

1

If desired, connect a keyboard and mouse.

This is optional, the instrument can be operated without external input devices. Mouse and keyboard are not included in the shipment. You can use standard USB or PS/2 devices.

2

Connect the line cord.

3

Turn on the instrument.

If condensation has collected, it might be required to turn on the instrument several times until fully operational.

All data and clock input and output connectors of the instrument that are not used in your test setup should be terminated with 50 Ohm.

Please refer to the Online Help for detailed information about working with the instrument.

Ventilation Requirements

Make sure that there is adequate clearance of 50 mm (2 in) at the top and right side of the instrument to ensure adequate air flow. If the air flow is restricted, the internal operating temperature will be higher, reducing the instrument's reliability.

Do not cover the ventilation holes.

3

4

Operating the Agilent J-BERT

Now that the instrument is running, let’s take a look at its front panel elements:

Instrument Setup Controls

Accumulation Controls

Power Switch and

Earth Terminal

Preset

Local

USB

PG Controls ED Controls ED Connectors

The Agilent J-BERT is available in different versions.

Depending on your version, some of the hardware and functionality described in this brochure may not be available.

Keypad and

Front Panel Knob

PG Connectors

Power

Supply

The rear panel of the instrument provides the following connectors:

GPIB Port USB 2.0 VISA Port

10 MHz REF IN

10 MHz REF OUT

PS/2 Mouse

(green)

Parallel Port Ethernet Port 1/2

PS/2 Keyboard

(purple)

Serial Port 1

VGA Monitor

Audio Line

Output Jack

Diagnostic

LED Stack

USB 2.0

Channel 0-3

Audio Microphone

Input Jack

To avoid damage to the J-BERT and your devices under test, always use an ESD strap that is connected to the earth terminal.

Operating the Agilent J-BERT

Changing Parameters

With the touchscreen, your finger is the mouse. Tipping an item with your finger is like clicking it with the mouse.

Analysis Results

You can use the numeric keypad to enter values by hand, or the large knob to adjust values.

You can also use the knobs at the bottom of the instrument to change certain frequently used values in run-time.

Navigating the GUI

The menu buttons allow you to quickly navigate through the instrument's software sections:

Pattern Setup

Toggle between pattern generator and error detector setup

Pattern

Generator Setup

Error Detector Setup

5

6

Preparing the Test

What Are We Testing?

The quickest way to familiarize yourself with the instrument is to set up a short test. You can test the BER on a cable. All you need for this test is an

APC/RPC cable for the data port connection and an APC/RPC-SMA adapter cable to connect the PG clock output to the ED clock input.

Setting up the Pattern Generator

First we need to set up the pattern generator.

To keep things simple, let's set up LVDS logic levels for both the data and clock output.

1

Reset the instrument.

Preset

Local

USB

This sets all voltages and parameters to default values.

2

Switch to the

PG Setup.

The pattern generator's output ports are always active.

Therefore, you must be sure that your device can handle these ranges before you connect it.

3

Now select the logic family LVDS for the data and clock port.

Check the values to make sure you can’t damage your device.

You can change the output signal parameters according to the needs of your device.

4

Let's increase the signal's data offset by 100 mV. Just tip the offset field,

Use the Up and Down buttons below the knob to position the cursor.

5

and turn the fine-tuning knob until you have the desired value.

Setting Up the Instrument

Set the Bit Rate

Now we want to set the pattern generator's bit rate. For now, we will use the instrument's internal clock:

1

Switch to the

Bit Rate Setup.

2

Keep the Internal

Clock Source.

Select the Pattern

Now select the data pattern to be used for the test:

1

Press the

Pattern Setup

button to switch to the pattern editor.

2

Open the

Select

Pattern

dialog box.

3

Select

1.06250 Gb/s

Ethernet

from the list.

You can easily add your favorite frequencies to the list.

3

Select the pattern type 2^n-1 PRBS.

4

Select the pattern size 2^31-1.

3

4

5

The cable does not convert any data.

Therefore, we use the same pattern for the pattern generator and the error detector.

5

Besides generated patterns like PRBS, you can also use memory-based patterns. A large variety of useful test patterns is already provided, but you can also set up your own custom patterns. See the Help for details.

7

Setting up the Instrument

Setting up the Error Detector

The next step is to set up the error detector’s inputs.

1

Press the

PG/ED Setup

button twice to switch to the error detector setup.

2

Click the

Edit

button.

8

3

Set the Input to

Normal

.

This means, we need only one cable that will be connected between the pattern generator and the data input port.

4

Enter the termination voltage that matches the output termination of the DUT, in our case equal to the pattern generator’s data output.

5

Set the

Input Range

so that it covers both the high and low voltage levels of the data signal.

Connecting the DUT

You can now connect the DUT. In our case you just have to connect the following ports:

PG Clock Out

ED Clock In

PG Data Out

ED Data In

1

Defining the Clock

We have to make sure that the error detector uses the clock from the pattern generator:

Switch to the

Clock Setup.

2

2

Select

External Clock

Source

as the source for the clock signal.

Setting Up the Instrument

Synchronizing the Pattern

Now make sure that the error detector automatically syncs to the data pattern:

1

Open the

Setup

Pattern Sync

dialog box.

2

Make sure that

Normal Sync Mode

and

Automatic Sync

are selected.

With this setting, the error detector starts synchronizing when the BER exceeds a certain threshold value. You can see when it has synchronized when the

Sync Loss

indicator goes off.

If sync fails, the sampling point is probably outside of the eye. You should proceed with setting the sampling point anyway. As soon as the instrument finds the eye, with the settings we just made, it will automatically synchronize the patterns.

Setting the Sampling Point

Now set the optimum sampling point:

1

Switch to the

Sampling Point Setup.

2

Press the

Auto Align

button to measure the eye diagram and to position the sampling point at the center of the eye.

This usually takes about 10 seconds.

The BER indicator in the top left corner displays the current BER at this sampling point which should be 0 for this test.

9

Modifying the Test Setup

Adjusting the Sampling Point

You can adjust the sampling point manually, for example, to test the performance of your DUT closer to the edge of the eye:

1

Use the

Decision Threshold

knob to move the sampling point vertically.

2

Use the

Data In Delay

knob to move the sampling point horizontally.

Viewing Eye Results

Now let’s check the resulting eye:

1

Press the

Analysis Results

button twice to switch to the

Results

tab.

2

Switch to the

Eye Results.

You can see how the BER increases when measuring at the edge of the eye.

10

Here you can see the measured eye diagram along with all the important eye parameters. If you have done a measurement previously, these results are listed here too, for comparison.

Modifying the Test Setup

Inserting Errors

You can add a single bit error to the data stream by pressing the

Error Add

button.

The pattern generator can also be set up to insert a specified BER in the data stream. This can, for example, be used for testing error correction algorithms.

You could also loosen the data cable and wiggle it carefully.

Watch how the BER changes.

Setting up Error Accumulation

To provide comparable results, you can run tests over a longer time and collect the measured data:

1

Press the

PG/ED Setup

button twice to switch to the error detector setup.

3

5

2

Open the

Setup

Accumulation

dialog box.

3

Select the activation mode

Repeat

to run repeated tests.

4

6

4

Select

No Logging

because we do not

, need a measurement log file now.

7

Press the

Accum

Start

button to start accumulating.

6

Press

OK

.

5

Select a

Time

of

10 seconds as the measurement period.

Accumulation Results

View the accumulated results:

1

Press the

Analysis Results

button twice to switch to the

Results

tab.

2

Switch to the

Accumulated Results.

Here you can view all statistics measured during the current and the previous measurement.

To stop the J-BERT from collecting any more data, press the

Stop Accum

button.

11

Installing Hardware Options

Installing the J20 Option

To install the J20 Interference Channel:

1

Perform the regular shutdown procedure provided by the operating system.

2

Disconnect the instrument from mains.

6

Insert and tighten the fixing screw.

5

Press the lever until the module rests firmly in place, the front plate aligned with the Error Detector’s front panel.

Caution

Never plug in or remove a module while the instrument is connected to mains power.

3

Unscrew and remove the slot cover.

4

Insert the module into the slot.

7

Power up the instrument.

The software will automatically recognize the new component and provide the Interface Channel

Icon and according setup functions in the

Jitter

window.

Connecting the J20 Option

The J20 Interface Channel has two ports,

P1 and P2. They can be connected single-ended or differentially.

If you connect P1 to the Data Out of the

Pattern Generator, P2 provides the output that is meant to be connected to the DUT.

If you connect P2 to the Data Out of the

Pattern Generator, P1 provides the output.

Caution

The module has golden 2.4 mm connectors.

Be sure to use the specific cables for the connection. Improper connection can damage the module.

How to Get Help

The J-BERT is equipped with a context-sensitive Online Help. There you will find comprehensive information on the basic concepts of the J-BERT, detailed procedures for operating it, and reference information on all elements of the GUI and the programming interface.

Agilent Corporate Information

For further product information, ordering information, and related literature, please refer to the website:

12 www.agilent.com/find/N4900_Series

N4903-91010