EXFO PSO-100 User Manual

PSO-100

Optical Sampling Oscilloscope Series

User Guide

Copyright © 2007–2010 EXFO Inc. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form, be it electronically, mechanically, or by any other means such as photocopying, recording or otherwise, without the prior written permission of EXFO Inc. (EXFO).

Information provided by EXFO is believed to be accurate and reliable. However, no responsibility is assumed by EXFO for its use nor for any infringements of patents or other rights of third parties that may result from its use. No license is granted by implication or otherwise under any patent rights of EXFO.

EXFO’s Commerce And Government Entities (CAGE) code under the North Atlantic Treaty Organization (NATO) is 0L8C3.

The information contained in this publication is subject to change without notice.

Trademarks

EXFO’s trademarks have been identified as such. However, the presence or absence of such identification does not affect the legal status of any trademark.

Units of Measurement

Units of measurement in this publication conform to SI standards and practices.

Version number: 1.0.0

ii PSO-100

Contents

Certification Information ....................................................................................................... vi

1 Introducing the PSO-100 Optical Sampling Oscilloscope Series ................ 1

PSO-100 Optical Sampling Oscilloscope Series Basic Theory ...................................................3

Typical Applications ................................................................................................................4

Conventions ............................................................................................................................6

2 Safety Information ....................................................................................... 7

Laser Safety Information .........................................................................................................7

Electrical Safety Information ...................................................................................................8

3 Getting Started with Your Optical Sampling Oscilloscope ...................... 11

Host Computer Minimum Requirements ..............................................................................11

Installing the Matlab Runtime, USB Drivers and Optical Sampling Oscilloscope Software ....12

Installing and Starting the Optical Sampling Oscilloscope ....................................................20

Turning off the Optical Sampling Oscilloscope ......................................................................24

Cleaning and Connecting Optical Fibers ...............................................................................25

Installing the EXFO Universal Interface (EUI) .........................................................................27

Optical Sampling Oscilloscope iii

Contents

4 Setting up and Using the Optical Sampling Oscilloscope ........................29

Adjusting the Zero Level (Nulling Offsets) .............................................................................32

Managing SoftSync Input .....................................................................................................33

Scaling Channel 1 to Channel 2 (PSO-102 Models) ...............................................................35

Finding a Pattern in a Sampling ............................................................................................36

Using the Zoom Functions ....................................................................................................37

Synchronizing the Input to a Specific Channel ......................................................................38

Selecting Sync Format ...........................................................................................................38

Selecting the Channels (PSO-102 Only) .................................................................................40

Selecting Trace and Background Colors ................................................................................41

Using the Dual Window View ...............................................................................................42

Using the Clock Input ...........................................................................................................44

Selecting the Number of Samples per Layer of Display .........................................................48

Changing the Persistence Time .............................................................................................49

Changing the Averaging Value .............................................................................................50

Displaying Histograms ..........................................................................................................52

Managing Filters ...................................................................................................................55

Using Colorgrade ..................................................................................................................58

Using Markers .......................................................................................................................59

Using the Eyeline Mode ........................................................................................................61

Using Masks .........................................................................................................................63

Displaying the FFT Spectrum of a Sampled Signal ................................................................66

Displaying a Reference Trace for your Measurements ...........................................................68

Managing Measurement Parameters ....................................................................................69

Managing Synchronization ...................................................................................................75

Setting the Data Phase Tracking Algorithm ...........................................................................76

Filter-Based Phase Tracking ...................................................................................................77

Saving Sample Files ...............................................................................................................79

5 Maintenance ................................................................................................81

Cleaning EUI Connectors ......................................................................................................82

Replacing Fuses ....................................................................................................................84

Recycling and Disposal (Applies to European Union Only) ....................................................85

6 Troubleshooting ..........................................................................................87

Solving Common Problems ...................................................................................................87

Contacting the Technical Support Group ..............................................................................95

Transportation ......................................................................................................................96

iv PSO-100

Contents

7 Warranty ..................................................................................................... 97

General Information .............................................................................................................97

Liability .................................................................................................................................98

Exclusions .............................................................................................................................99

Certification ..........................................................................................................................99

Service and Repairs .............................................................................................................100

EXFO Service Centers Worldwide ........................................................................................101

A Technical Specifications ........................................................................... 103

B Burst Mode Measurements ..................................................................... 105

C Measurement Definitions ........................................................................ 109

One Level ............................................................................................................................110

Zero Level ...........................................................................................................................110

Signal-to-Noise Ratio ..........................................................................................................111

Crossing ..............................................................................................................................111

Timing Jitter ........................................................................................................................112

Rise Time and Fall Time .......................................................................................................113

Extinction Ratio ..................................................................................................................113

Eye Height ..........................................................................................................................114

Eye Amplitude ....................................................................................................................114

Eye Opening Factor .............................................................................................................114

Eye Width ...........................................................................................................................115

Duty Cycle Distortion ..........................................................................................................116

Pulse Width ........................................................................................................................117

Contrast Ratio .....................................................................................................................117

Duty Cycle ...........................................................................................................................118

D Asynchronous Sampling Principle ........................................................... 119

Trigger-Free Synchronization ...............................................................................................119

Frequency Holes ..................................................................................................................120

Pattern Effects ....................................................................................................................123

Index .............................................................................................................. 125

Optical Sampling Oscilloscope v

Certification Information

FCC Information

Electronic test equipment is exempt from Part 15 compliance (FCC) in the United States. However, compliance verification tests are systematically performed on most EXFO equipment.

 Information

Electronic test equipment is subject to the EMC Directive in the European Union. The EN61326 standard prescribes both emission and immunity requirements for laboratory, measurement, and control equipment. This unit has undergone extensive testing according to the European Union Directive and Standards.

vi PSO-100

Certification Information

Application of Council Directives: 2006/95/EC - The Low Voltage Directive 2004/108/EC - The EMC Directive 2006/66/EC - The Battery Directive

93/68/EEC - CE Marking and their amendments Manufacturer’s Name: EXFO Inc. Manufacturer’s Address: 400 Godin Avenue Quebec, Quebec Canada, G1M 2K2

Equipment Type/Environment: Electrical Equipment for Measurement / Control and

Laboratory

Trade Name/Model No.: Optical Sampling Oscilloscopes / PSO-100 Series

Standard(s) to which Conformity is Declared:

EN 61010-1:2001 Edition 2.0 Safety Requirements for Electrical Equipment for Measurement,

Control, and Laboratory Use, Part 1: General Requirements.

EN 61326-1:2006 Electrical Equipment for Measurement, Control and Laboratory

Use - EMC Requirements – Part 1: General requirements

EN 60825-1:2007 Edition 2.0 Safety of laser products – Part 1: Equipment classification,

requirements, and user’s guide

EN 55022: 2006 + A1: 2007 Information technology equipment - Radio disturbance

characteristics - Limits and methods of measurement

I, the undersigned, hereby declare that the equipment specified above conforms to the above Directives and Standards.

Manufacturer

Signature:

Full Name: Stephen Bull, E. Eng

Position: Vice-President Research and

Development

Address: 400 Godin Avenue, Quebec (Quebec),

Canada, G1M 2K2

Date: August 11, 2010

DECLARATION OF CONFORMITY

Optical Sampling Oscilloscope vii

1 Introducing the PSO-100

Front View (PSO-101)

LED ON/OFF

indicator

External clock input

(optional)

Optical fiber input, FC/PC connection

Optical Sampling Oscilloscope Series

Based on a unique optical sampling approach, the PSO-100 Optical Sampling Oscilloscope Series eliminates almost all the limitations typically found in electrical sampling oscilloscopes. This is done when narrow sampling pulses open a sampling gate that generates a time-stretched version of the measured signal. The optical samples are then converted to electrical signals, which can be easily detected by low-speed electronics and digitally processed.

The figures below show the front and rear panels for both models.

Optical Sampling Oscilloscope 1

Introducing the PSO-100 Optical Sampling Oscilloscope Series

Front View (PSO-102)

External clock input (optional)

Optical fiber input B, FC/PC connection

Optical fiber input A, FC/PC connection

Delay adjustment for

Input B (optional)

LED ON/OFF

indicator

Rear View

USB 2.0 connection

to the host computer

Power switch

110-240 V AC

voltage supply input

Fan

2 PSO-100

All instruction or information in this user documentation pertain to both models, unless specified otherwise. The image you see on-screen may be slightly different depending on which model you are using.

IMPORTANT

Introducing the PSO-100 Optical Sampling Oscilloscope Series

Signal

Sampling Pulses

Sampling Gate

Time-Stretched Copy

Generated Samples

Detection, A/D

Conversion,

Visualization

PSO-100 Optical Sampling Oscilloscope Series Basic Theory

The theory behind the Optical Sampling Oscilloscope is that the input optical signal is repeatedly sampled in an all-optical gate with high resolution.

The optical samples are detected and then A/D converted and buffered in a data acquisition board. The data is transferred via USB 2.0 to a host computer, where it is processed. An internal software synchronization algorithm calculates the frequency offset between the signal and the sampling frequency. As a result, you can view synchronized eye diagrams, patterns, or pulses without the need for external triggering.

Optical Sampling Oscilloscope 3

Introducing the PSO-100 Optical Sampling Oscilloscope Series

Typi c a l A pp licat i o ns

Typical Applications

The Optical Sampling Oscilloscope displays eye-diagrams, patterns, or pulses with very high temporal resolution. It is therefore a useful tool for studying and characterizing very high bit-rate systems or very fast events like short pulses, where the bandwidth of ordinary electrical sampling oscilloscopes is not sufficient.

The instrument can measure a number of amplitude modulation formats, such as:

³ non-return-to-zero (NRZ)

³ different kinds of return-to-zero (RZ) formats (for example chirped RZ

(CRZ) and carrier suppressed RZ (CSRZ))

³ other formats, such as duo-binary transmission (DBT).

Since only the amplitude of the signal is measured, the system cannot directly measure the optical phase. By placing a delay interferometer before the scope, you can also handle phase modulated formats like differential phase shift keying (DPSK).

A number of measurement tools are included in the software for characterizing eye-diagrams and waveforms, such as:

³ ultra-low timing jitter

³ rise and fall times

³ extinction ratio (ER)

³ and signal-to-noise ratio (SNR), etc.

Functions for waveform averaging, histograms and color grade, are also included.

4 PSO-100

Introducing the PSO-100 Optical Sampling Oscilloscope Series

Typical Applications

If the optional external clock input is installed, the internal software synchronization can be performed on the clock signal instead and thereby relaxes the requirements on the signal quality. The external clock is useful in a number of measurement situations where the internal synchronization may fail, such as:

³ very noisy or distorted signals

³ unconventional modulation formats

³ low duty cycle RZ pulses

³ sub-optimally multiplexed signals.

If the gated clock mode is installed, the PSO-100 can be used for measuring gated data that come in bursts (for example, circulating loop experiments and optical packet switching).

Optical Sampling Oscilloscope 5

Introducing the PSO-100 Optical Sampling Oscilloscope Series

Conventions

Before using the product described in this manual, you should understand the following conventions:

WARNING

Indicates a potentially hazardous situation which, if not avoided, could result in death or serious injury. Do not proceed unless you understand and meet the required conditions.

CAUTION

Indicates a potentially hazardous situation which, if not avoided, may result in minor or moderate injury. Do not proceed unless you understand and meet the required conditions.

CAUTION

Indicates a potentially hazardous situation which, if not avoided, may result in component damage. Do not proceed unless you understand and meet the required conditions.

IMPORTANT

Refers to information about this product you should not overlook.

6 PSO-100

2 Safety Information

CAUTION

Do not open the unit. It contains fragile fiber-optic components, which can be damaged if the unit is opened. There is also a risk for exposure of laser light if the unit is opened. EXFO shall not be liable for any damages resulting from opening the unit.

Laser Safety Information

WARNING

Do not install or terminate fibers while a light source is active. Never look directly into a live fiber and ensure that your eyes are protected at all times.

WARNING

Use of controls, adjustments and procedures for operation and maintenance other than those specified herein may result in hazardous radiation exposure or impair the protection provided by this unit.

Your instrument is a Class 1 laser product in compliance with standards IEC 60825-1 and 21 CFR 1040.10. Laser radiation may be encountered at the output port.

The following label indicates that a product contains a Class 1 source:

Note: The label is located at the back of the unit.

Optical Sampling Oscilloscope 7

Safety Information

Electrical Safety Information

This unit uses an international safety standard three-wire power cable. This cable serves as a ground when connected to an appropriate AC power outlet.

Note: If you need to ensure that the unit is completely turned off, disconnect the

power cable.

WARNING

³ Insert the power cable plug into a power outlet with a

protective ground contact. Do not use an extension cord without a protective conductor.

³ Before turning on the unit, connect all grounding terminals,

extension cords and devices to a protective ground via a ground socket. Any interruption of the protective grounding is a potential shock hazard and may cause personal injury. Whenever the ground protection is impaired, do not use the unit and secure it against any accidental operation.

³ Do not tamper with the protective ground terminal.

8 PSO-100

Safety Information

Electrical Safety Information

The color coding used in the electric cable depends on the cable. New plugs should meet the local safety requirements and include:

³ adequate load-carrying capacity

³ ground connection

³ cable clamp

WARNING

³ Use this unit indoors only.

³ Position the unit so that the air can circulate freely around it.

³ Do not remove unit covers during operation.

³ Operation of any electrical instrument around flammable gases

or fumes constitutes a major safety hazard.

³ To avoid electrical shock, do not operate the unit if any part of

the outer surface (covers, panels, etc.) is damaged.

³ Only authorized personnel should carry out adjustments,

maintenance or repair of opened units under voltage. A person qualified in first aid must also be present. Do not replace any components while power cable is connected.

³ Capacitors inside the unit may be charged even if the unit has

been disconnected from its electrical supply.

Optical Sampling Oscilloscope 9

Safety Information

Electrical Safety Information

Temp er at ur e

³ Operation

³ Storage

Relative humidity

Equipment Ratings

18 °C to 30 °C (64 °F to 86 °F)

0 °C to 50 °C (32 °F to 122 °F)

80 % non-condensing

Maximum operation

3000 m (9843 ft)

altitude

Pollution degree 2

Installation category II

Power supply rating

100 V to 240 V (50 Hz/60 Hz)

maximum input power 20 VA

a. Measured in 0 °C to 31 °C (32 °F to 87.8 °F) range, decreasing linearly to 50 % at 40 °C (104 °F). b. Not exceeding ± 10 % of the nominal voltage.

The following label is located on the back panel of the unit:

10 PSO-100

3 Getting Started with Your

Optical Sampling Oscilloscope

Host Computer Minimum Requirements

Your host computer must meet the minimum requirements below to display the values properly:

³ Microsoft Windows XP, Vista (32 bits), or Windows 7 (32 bits)

³ USB 2.0 connection

³ CPU: 2 GHz or faster recommended

³ 2Gb of RAM

³ 600 Mb of disk space on the host computer

You can use either a desktop or a laptop computer, as long as it meets the requirements.

Note: The faster the computer, the higher the refresh rate will be on-screen.

Optical Sampling Oscilloscope 11

Getting Started with Your Optical Sampling Oscilloscope

Installing the Matlab Runtime, USB Drivers and Optical Sampling Oscilloscope Software

Before using your application, you must install the corresponding Matlab Runtime and USB drivers.

The user software is created in Matlab code, which has been compiled into an executable file. To be able to run this software on your computer, you must install the Matlab Component Runtime software. Afterwards, the installation for the Optical Sampling Oscilloscope application will start by itself.

To install Matlab Runtime and Optical Sampling Oscilloscope software:

1. Make sure that you have Administrator privileges on your computer.

2. Put your CD in the CD ROM drive. If the installation does not start

automatically, locate Setup.exe, and double-click it.

A list of the components to install appears.

3. Click Install to start the process.

12 PSO-100

Getting Started with Your Optical Sampling Oscilloscope

Installing the Matlab Runtime, USB Drivers and Optical Sampling Oscilloscope Software

4. Select the language to use for the installation, then click OK.

Note: This setting is for the installation only. The applications themselves are in

English only.

5. When the list of Matlab components appears, click Install again, then Next to start the installation.

6. Enter your user name and organization information, then click Next.

Optical Sampling Oscilloscope 13

Getting Started with Your Optical Sampling Oscilloscope

Installing the Matlab Runtime, USB Drivers and Optical Sampling Oscilloscope Software

7. Select a destination folder, then click Next.

8. You are now ready to install the program. Click Install.

9. The installation of the Matlab Compiler Runtime is now complete, click

Finish.

14 PSO-100

Getting Started with Your Optical Sampling Oscilloscope

Installing the Matlab Runtime, USB Drivers and Optical Sampling Oscilloscope Software

10. When the Optical Sampling Oscilloscope wizard appears, click Next to start the installation.

11. Read and accept the licence agreement, then click Next.

Optical Sampling Oscilloscope 15

Getting Started with Your Optical Sampling Oscilloscope

Installing the Matlab Runtime, USB Drivers and Optical Sampling Oscilloscope Software

12. Enter your user name and organization information, then click Next.

13. You are now ready to install the program. Click Install.

16 PSO-100

Getting Started with Your Optical Sampling Oscilloscope

Installing the Matlab Runtime, USB Drivers and Optical Sampling Oscilloscope Software

14. The installation of the Optical Sampling Oscilloscope is now complete, click Finish.

If any version of Matlab is installed on your computer, the system path must be adjusted to prioritize the Runtime over the Matlab software.

Note: If you have an old version of the Optical Sampling Oscilloscope application

that was compiled with an old version of Matlab, and you want to update to the EXFO application, you need to uninstall the older versions first, then install a new version of MCR (follow the procedure above).

IMPORTANT

You must remove the HKEY_LOCAL_MACHINE\SOFTWARE\MATLAB registry key after uninstalling the older versions to make sure that the new version is installed correctly.

Optical Sampling Oscilloscope 17

Getting Started with Your Optical Sampling Oscilloscope

Installing the Matlab Runtime, USB Drivers and Optical Sampling Oscilloscope Software

To install the USB driver on your computer:

1. Connect the unit using a USB connection. When the instrument is

connected to a USB port of the computer for the first time, Windows will find the new hardware and ask you to install the USB driver.

IMPORTANT

Make sure that you use a USB 2.0 port and not a USB 1.1, since this will affect the refresh rate.

2. Windows Update should not search for updates. Select No, not this time, and then click Next (Windows XP installation only).

18 PSO-100

Getting Started with Your Optical Sampling Oscilloscope

Installing the Matlab Runtime, USB Drivers and Optical Sampling Oscilloscope Software

3. Select Install from a specific location, and then click Next.

The USB driver is found in your folder under "…\drivers"; indicate it in the corresponding box. The installation will not pass Windows Logo testing to verify compatibility with Windows XP.

4. Click Continue anyway to install the driver and complete the process.

5. Click Finish. Windows indicates that it has found new hardware but

recognizes the USB device. A loader was installed at step 2. In a second step, the real driver is installed by following step 2 and on once more.

Note: The exact appearance of the windows differ slightly depending on which

version of Windows you are using.

Optical Sampling Oscilloscope 19

Getting Started with Your Optical Sampling Oscilloscope

Installing and Starting the Optical Sampling Oscilloscope

Before you turn on the instrument, follow the procedure below.

To install and start the instrument:

1. Connect the included AC adapter to the input on the rear panel and to

the wall socket.

2. If you have not already done so, link the unit and the host computer together using a USB cable.

Note: The first time you do this you are asked to install the USB driver on your

computer. Follow the instructions in Installing the Matlab Runtime, USB Drivers and Optical Sampling Oscilloscope Software on page 12. If you are working in Windows XP, make sure that you use the same USB port every time afterwards. If not, you will have to install the USB driver again.

3. Turn on the instrument using the control on the rear panel. The blue LED indicator on the front panel should be on. Wait 5 minutes and let the instrument warm up.

IMPORTANT

Do not turn off the instrument unnecessarily, for example if you change the host computer. If the instrument is turned off, it may need to cool down for five minutes before it can be started again.

20 PSO-100

Getting Started with Your Optical Sampling Oscilloscope

Installing and Starting the Optical Sampling Oscilloscope

4. Start the application on your computer by selectin the start menu, then Programs > EXFO > Optical Sampling Oscilloscope.

IMPORTANT

The Optical Sampling Oscilloscope must be turned on before starting the application.

IMPORTANT

EXFO recommends that you put the synchronization type to Freerun before starting your tests. This ensures that you have an adequate signal with an appropriate amplitude.

First a DOS window opens where the version number is shown. Then the USB connection OK message should appear. If it does not, the USB communication with the instrument is not functioning properly. If the initial test is passed the application appears on-screen.

Optical Sampling Oscilloscope 21

Getting Started with Your Optical Sampling Oscilloscope

Installing and Starting the Optical Sampling Oscilloscope

The first time you start the application, the screen will show the default setting. However, if you make changes to these settings while working, the unit will retain those changes and display them again the next time you start the application.

22 PSO-100

Getting Started with Your Optical Sampling Oscilloscope

Installing and Starting the Optical Sampling Oscilloscope

5. From the Setup menu, select Sync Format, then Freerun, and click the Start button at the left bottom corner to check for the signal quality.

The instrument should now start to measure and samples should appear at the zero level. The instrument will need some time to warm up before the samples attain the correct DC level. The DC level is somewhat temperature dependent.

Optical Sampling Oscilloscope 23

Getting Started with Your Optical Sampling Oscilloscope

Turning off the Optical Sampling Oscilloscope

To turn off the instrument:

1. Stop the sampling with the Stop button in the application.

2. Turn off the instrument using the control on the rear panel.

Note: If you do the opposite, the application may freeze.

IMPORTANT

Do not turn off the instrument unnecessarily, for example if you change the host computer. If the instrument is turned off, it may need to cool down for five minutes before it can be started again.

24 PSO-100

Getting Started with Your Optical Sampling Oscilloscope

Cleaning and Connecting Optical Fibers

IMPORTANT

To ensure maximum power and to avoid erroneous readings:

³ Always inspect fiber ends and make sure that they are clean as

explained below before inserting them into the port. EXFO is not responsible for damage or errors caused by bad fiber cleaning or handling.

³ Ensure that your patchcord has appropriate connectors. Joining

mismatched connectors will damage the ferrules.

To connect the fiber-optic cable to the port:

1. Inspect the fiber using a fiber inspection microscope. If the fiber is

clean, proceed to connecting it to the port. If the fiber is dirty, clean it as explained below.

2. Clean the fiber ends as follows:

2a. Gently wipe the fiber end with a lint-free swab dipped in isopropyl

alcohol.

2b. Use compressed air to dry completely.

2c. Visually inspect the fiber end to ensure its cleanliness.

Optical Sampling Oscilloscope 25

Getting Started with Your Optical Sampling Oscilloscope

Cleaning and Connecting Optical Fibers

3. Carefully align the connector and port to prevent the fiber end from touching the outside of the port or rubbing against other surfaces.

If your connector features a key, ensure that it is fully fitted into the port’s corresponding notch.

4. Push the connector in so that the fiber-optic cable is firmly in place, thus ensuring adequate contact.

If your connector features a screwsleeve, tighten the connector enough to firmly maintain the fiber in place. Do not overtighten, as this will damage the fiber and the port.

Note: If your fiber-optic cable is not properly aligned and/or connected, you will

notice heavy loss and reflection.

26 PSO-100

Getting Started with Your Optical Sampling Oscilloscope

Bare metal

(or blue border)

indicates UPC

option

Green border indicates APC

option

2 3 4

Installing the EXFO Universal Interface (EUI)

The EUI fixed baseplate is available for connectors with angled (APC) or non-angled (UPC) polishing. A green border around the baseplate indicates that it is for APC-type connectors.

To install an EUI connector adapter onto the EUI baseplate:

1. Hold the EUI connector adapter so the dust cap opens downwards.

2. Close the dust cap in order to hold the connector adapter more firmly.

3. Insert the connector adapter into the baseplate.

4. While pushing firmly, turn the connector adapter clockwise on the

baseplate to lock it in place.

Optical Sampling Oscilloscope 27

bar

Sample screen

Input

controls

Zoom controls

Starts/Stops

sampling

Switches between eye diagram view and pattern view (you can also select the display mode in the

Setup > Display Mode menu.

Clears sample screen

4 Setting up and Using the

Optical Sampling Oscilloscope

Once the unit and application are started, you can begin using the Optical Sampling Oscilloscope.

Optical Sampling Oscilloscope 29

Setting up and Using the Optical Sampling Oscilloscope

³ From the menu bar you can select different functions, for example to

save samples, to select the waveform format, and clock settings.

³ From the Setup menu, you can select the method used to synchronize

the channel(s), the synchronization format, as well as the color settings and the display modes. This is also where you will set the dual window settings.

³ The Clock menu allows you to enable the optional external and gated

clocks.

³ From the Display menu you can select the number of samples,

persistence layers, averaging, histograms, and color grade, etc.

³ In the Measure menu, you can select a number of parameters to

measure in eye diagrams or waveforms.

³ In the Utilities menu, you can perform actions such as synchronizing

the signals, adjusting the zero level (nulling the signal) or find a pattern for your sampling.

³ Under SoftSync inputs you can insert the signal frequency, how many

periods/eye-diagrams to visualize on the sample screen, pattern length, and clock sub rate if the external clock option is used.

³ The zoom controls feature functions for zooming in x- or y directions.

You can also use the pan function to view a particular part of the time or power scales.

³ At the bottom there are three buttons: Start/Stop, a switch button

between eye-diagram and pattern, and a Clear button for clearing measurements, histograms, averaging and color grades.

By clicking the right mouse button you can place markers and introduce a time delay between the data and the external clock.

Note: The controls for the dual window display function exactly in the same way

as their single-window counterparts. For details on the features you can use in the dual display, please see the corresponding section for single display.

30 PSO-100

Setting up and Using the Optical Sampling Oscilloscope

Optional 10 GHz clock

Pattern Generator

Laser 1550 nm

Driver Amplifier

EDFA

Mach-Zender Modulator

Optical Bandpass Filter

10 GHz clock

40 Gb/s Output

10log10P2σ2⁄()=()

For the examples in this documentation, we have tested an optical 40 Gb/s NRZ transmitter, which consists of a laser source modulated by a pattern generator and a Mach-Zender modulator according to the figure below.

The average input power to the sampling oscilloscope was approximately 15 mW after amplification and filtering. Since the signal sensitivity that is the peak power required to get 20 dB SNR , is approximately 1 mW, you may need to amplify an NRZ signal to measure a clear eye diagram. Short RZ pulses on the other hand, for example from a ring laser with comparable average power, and hence high peak power, do not need amplification. An optical band-pass filter is recommended to filter out ASE noise from the EDFA. The input signal could, of course, be of various types of optical amplitude modulated signals at any bit rate from DC to 1.28 Tb/s or short pulses without data.

Optical Sampling Oscilloscope 31

Setting up and Using the Optical Sampling Oscilloscope

Adjusting the Zero Level (Nulling Offsets)

Temperature and humidity variations affect the performance of electronic circuits and optical detectors, which can offset measurement results. To compensate for this offset, the PSO-100 is equipped with an offset nulling function.

EXFO recommends performing a nulling of the electrical offsets whenever environmental conditions change.

IMPORTANT

Light must not reach the detector when nulling offsets.

To adjust the zero level:

1. From the main window, select the Utilities menu, then Adjust Zero

Level.

2. Remove the input signals from the unit, then click on the screen to start the process.

The unit will set the average level to zero, then continue to measure.

Once the process is complete, you can turn on the input signal again and continue the measurements.

32 PSO-100

Setting up and Using the Optical Sampling Oscilloscope

Signal

frequency

Number of eye periods to display

on-screen (available in eye diagram mode)

Data symbol rate (for example,

1/4 for a signal frequency of

40 GHz and a clock frequency of

10 GHz).

Pattern length of the input signal (available in pattern mode)

...

Signal frequency

8 MHz

Even Intervals

Odd intervals

Correct interval

Managing SoftSync Input

The SoftSync inputs section the bottom left is used for input of parameters important for the software synchronization algorithm to correctly synchronize the data.

In order to obtain the correct time scale, an estimate of the signal frequency should be inserted since there is no other way for the software to know the bit rate. The signal frequency should be accurate within the correct 8 MHz (sampling frequency divided by two) interval, according to the figure below.

Optical Sampling Oscilloscope 33

Ensuring that the correct values are entered ensures appropriate measurements.

Setting up and Using the Optical Sampling Oscilloscope

Managing SoftSync Input

³ If you select an incorrect interval, you will still see an eye-diagram, but

with an incorrect time scale; it will actually show a reversed time scale for odd intervals.

³ If you select an incorrect interval in pattern mode, you will notice that

you see numerous eye diagrams instead of a pattern. Although this is not the expected result, this can be used to determine the correct interval or signal frequency by selecting a value untils you see a pattern.

IMPORTANT

Different signal generators may have different calibrations. The sampling frequency also drifts slightly with temperature. Therefore, a 40 GHz setting in SoftSync inputs is not guaranteed to fully match a signal generator set to 40.000 GHz. You may have to tune the signal frequency in SoftSync to find the correct interval.

You can also calibrate the sampling frequency in the Utilities menu,, using the Find pattern feature.

³ When the external clock (option) is selected from the Clock menu,

Clock subrate becomes active. You can then select the correct clock sub rate from the list. For example, if a 10 GHz clock and 40 Gb/s data is used, a ¼ sub rate clock should be used. If an incorrect value is chosen from the list, the time scale will be incorrect.

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Setting up and Using the Optical Sampling Oscilloscope

Scaling Channel 1 to Channel 2 (PSO-102 Models)

If, for some reason, the power calibration has shifted (the signal is not of the same value on both channels), you can re-calibrate this ratio. for the two channels.

To enter a ratio for channel 1 vs. channel 2:

1. From the main window, select the Utilities menu.

2. Select Ch A / Ch B scaling.

3. Enter the ratio you want to use for channel A compared to channel B.

4. Click OK to close the window.

Optical Sampling Oscilloscope 35

Setting up and Using the Optical Sampling Oscilloscope

Finding a Pattern in a Sampling

If for some reason the pattern does not show up in your measurement, but numerous eye diagrams instead, you can find the pattern using your unit.

Note: It will only work if you have a repetitive pattern, not random data or

SONET/SDH framed data.

Before you do this, make sure that you have inserted the correct pattern length. Also insert the approximate signal frequency (and clock subrate if using the external clock). For example you may not know the signal frequency exactly, which results in incorrect time scale. But if you still want to see the pattern use the find pattern function.

To find the pattern in your sampling:

1. Make sure that you are in pattern display mode, and that the sampling

is running.

2. From the main window, select the Utilities menu, then Find pattern.

The pattern is displayed automatically.

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Setting up and Using the Optical Sampling Oscilloscope

Reverts to default zoom values

Zooms according to the time or power axis (the upper part of the zoom tools is updated accordingly)

Closes zoom tool menu

Lets you select a specific

area where to zoom

In dual- window mode, to use

the zoom tool on both windows

Time or power unit settings (automatically updated on-screen)

Time or power units

Moves to other sections of the window when zoom is applied

Zooms in/out automatically

Focuses the zoom function

on top or bottom window

Focal point for zoom function. The reference is on the horizontal axis for time, and vertical axis for power

Using the Zoom Functions

The zoom functions are located on the right hand side of the window. You can decide to show or hide the zoom menu at any time.

To display the zoom controls:

Click at the top right hand corner of the window.

To use the zoom controls:

Once you have activated the zoom tools, use the feature that suits your situation best:

Note: The blue portion of the button indicates which option is currently selected.

Note: Each time that you change the view type for a window, the zoom factor

Optical Sampling Oscilloscope 37

reverts to the default value.

Setting up and Using the Optical Sampling Oscilloscope

Synchronizing the Input to a Specific Channel

You might want to synchronize your input signal with a specific channel (A or B), or let the Optical Sampling Oscilloscope pick the best signal automatically.

To select a channel for input synchronization:

1. From the main window, select the Setup menu, then Sync. Channel.

2. Select which channel you want to use, or select the automatic mode.

Your choice will be indicated on the top lefthand part of the screen.

Selecting Sync Format

The Optical Sampling Oscilloscope features several synchronization formats so that the software and data are correctly matched. If you use an unconventional data format, the existing format selections may fail to provide you with an accurate measurement. For testing unconventional data formats, EXFO recommends using the optional external clock.

³ In Freerun mode, the raw data is shown without synchronization.

³ The NRZ mode is optimized for NRZ, but can also be used, for

example, in duo-binary transmission.

³ The RZ mode is preferable for all RZ formats (for example RZ, chirped

RZ (CRZ), carrier suppressed RZ (CSRZ), etc.). It also works for RZ pulses (no data). There is also a selection for inverse RZ data, which can be used for example in NRZ-DPSK or NRZ-DQPSK data, before demodulation..

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Setting up and Using the Optical Sampling Oscilloscope

Selecting Sync Format

³ The DPSK (differential phase-shift keying) formats selection (PSO-102

model only) allow you to measure either RZ-DPSK or NRZ-DPSK formats after a delay interferometer that is used to demodulate the phase encoded data.

You can also select the balanced detection type for the two outputs from the delay interferometer, with a manual delay on channel B to make sure that the sampling occurs simultaneously on both channels. This selection also applies to NRZ-DQPSK and RZ-DQPSK.

Note: In the case of the PSO-101, it is of course possible to look at a single-ended

detection of DPSK and DQPSK by measuring one output from the demodulator, and then use the NRZ format for NRZ-DPSK (and NRZ-DQPSK) and the RZ format for RZ-DPSK (and RZ-DQPSK).

To select a data format:

1. From the main window, select the Setup menu, then Sync Format.

2. From the list, select the desired format.

Optical Sampling Oscilloscope 39

Setting up and Using the Optical Sampling Oscilloscope

Selecting the Channels (PSO-102 Only)

You can view either channel A, B, or both in either the top or bottom window. You can also set your Optical Sampling Oscilloscope to automatically detect which channel is active and display it accordingly.

To select the channel to display:

1. From the main window, select the Setup menu, then View.

2. Select which channel configuration you want to view.

You can also display a balanced signal, A-B or B-A. It is almost mandatory in DPSK and DQPSK receivers to perform balanced detection. Here we can do the balanced detection in software and visualize a balanced detected eye diagram with very high bandwidth.

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Setting up and Using the Optical Sampling Oscilloscope

Selecting Trace and Background Colors

Depending on your work environment, you may find that some display colors are better to view the samplings. You can change the background color, and the sampling trace color for each viewing window.

To change the background color:

From the Setup menu, select Background Color, then select either black or white.

To select a trace color:

1. From the Setup menu, select Trace Color.

2. Select the channel for which you want to change the color, then select

a color in the list.

Optical Sampling Oscilloscope 41

Setting up and Using the Optical Sampling Oscilloscope

Using the Dual Window View

The dual window view allows you to open a second window to simultaneously visualize the eye, the pattern, or the Freerun trace.

Note: The controls for the dual window display function exactly in the same way

as their single-window counterparts. For details on the features you can use in the dual display, please see the corresponding section for single display.

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Setting up and Using the Optical Sampling Oscilloscope

Using the Dual Window View

To select the dual view and its options:

1. From the main window, select the Setup menu, then Dual Window.

2. Select the channel to display in the window under View, and the type

of display (eye diagram or pattern) for it.

3. From the main window select the Display menu.

4. Select Dual window, then select which option you wish to view.

Optical Sampling Oscilloscope 43

Setting up and Using the Optical Sampling Oscilloscope

Using the Clock Input

In some situations, you cannot fully rely on the software synchronization of the input signal alone, for example when sampling very noisy or distorted signals, or when using unconventional data formats or setting up OTDM data. In such situations, the external clock option is very useful.

You can work using different types of clocks for your testing.

³ Internal clock (default): the signal is software synchronized without an

external clock.

³ External clock (optional): the clock signal determines the time scale,

which should be synchronous with the signal.

The external clock is useful in a number of measurement situations where the internal synchronization may fail, for example with very noisy or distorted signals, unconventional modulation formats, and sub-optimally multiplexed signals. In the external clock selection you can select either an absolute or adaptive time scale, where the absolute time scale is the standard selection and the adaptive is recommended for an external clock with large timing jitter.

³ Gated clock (optional): for burst measurements, for example in

circulating loop- or packet- switching experiments, you can use the gated clock mode. A window then opens where you can customize parameters such as the burst period and duty cycle.

Note: The external clock option must be installed for the gated clock to be

available.

To activate the internal clock:

1. From the main window, select the Clock menu.

2. Select Internal.

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Setting up and Using the Optical Sampling Oscilloscope

Using the Clock Input

To activate the external clock:

1. From the main window, select the Clock menu.

2. Select External, then select either the absolute or adaptive time scale.

To activate the gated clock:

1. From the main window, select the Clock menu.

2. Select Gated.

3. Enter the settings for using the gated clock in the corresponding boxes.

4. Click OK to confirm your choice and close the window.

Optical Sampling Oscilloscope 45

Setting up and Using the Optical Sampling Oscilloscope

Using the Clock Input

To use the external clock input:

1. Connect an external electrical clock to the front panel.

The clock should have a peak-to-peak voltage between 0.8 and 2 volts for clock frequencies up to 12.5 GHz. It will work also for lower voltages, but with a slightly worse timing jitter. For clock frequencies up to 25 GHz, higher voltages are required, between 1.5 and 3 V.

2. Select External from the Clock menu (constant time scale is recommended for a high quality clock with low timing jitter). The figure below shows an example using a 10 GHz sub-rate clock and a 40 Gb/s NRZ data signal, that is a ¼ clock sub-rate.

The clock signal itself is shown above the data signal.

Note: If the clock signal on the sample screen turns red, this indicates that the

clock signal is too low, and should be increased; or it may happen in a measurement situation with frequency holes. It goes away after a while (read more about frequency holes in Frequency Holes on page 120).

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Setting up and Using the Optical Sampling Oscilloscope

Using the Clock Input

In this example, we have chosen to view two clock periods at 10 GHz, which makes eight eyes at 40 Gb/s. You can also view patterns in external clock mode, just switch to Pattern. Again, make sure that the pattern length, the signal frequency, and also the sub-rate clock are correct. By clicking the right button and select Signal/clock delay, you can introduce a delay between the data and the clock, which is useful for centering eye diagrams on the screen and perform measurements on a specific eye diagram, since all measurements are performed on the first eye diagram as shown in Eye Mode Measurement Example on page 73.

To display the clock trace on-screen:

1. From the main window, select the Setup menu, then View.

2. Select Clock trace.

To introduce a time delay between the data and the external clock:

Right-click when in the main window, then select Signal/Clock delay.

Optical Sampling Oscilloscope 47

Setting up and Using the Optical Sampling Oscilloscope

Selecting the Number of Samples per Layer of Display

You can choose to have more or less samples per layer of display. More samples will make a more precise measurement, but it takes longer to achieve. The refresh rate will change depending on the number of samples selected.

To select the number of samples:

1. From the main window, select the Display menu, then Samples /

Layer.

2. Select the number of samples to use.

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Setting up and Using the Optical Sampling Oscilloscope

Changing the Persistence Time

In the Display menu you can change the persistence time by choosing a number of layers and the number of samples per layer. In this way you can determine the total number of samples on the screen. Since the persistence time depends on the speed of the host computer, this allows for a selection better adapted for each user.

To change the persistence time:

1. From the main window, select the Display menu.

2. Select Persistence, then select the number of layers to use.

Optical Sampling Oscilloscope 49

Setting up and Using the Optical Sampling Oscilloscope

Changing the Averaging Value

The averaging value is where noise can be averaged out from a waveform, pulse or pattern. The number of averages can be between 1 and 64, and infinite.

In the figure below, the 127-bit pattern is averaged and the noise is removed. Note that this works for patterns, pulses and waveforms, not eye-diagrams, since it does not represent a continuous curve. The number of averages can be set from 1 to 64 and infinite.

The averaging function uses the pixel information to calculate the average. This means that a higher resolution in pixels/ps is achieved in a zoomed window compared to the default window.

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Setting up and Using the Optical Sampling Oscilloscope

Changing the Averaging Value

To change the averaging value:

1. From the main window, select the Display menu.

2. Select Averaging, then select the number of averages to use.

To average from the beginning:

From the main window, click Clear.

Optical Sampling Oscilloscope 51

Setting up and Using the Optical Sampling Oscilloscope

10*log10mean2std2⁄()=()

Displaying Histograms

You can view either a horizontal or a vertical histogram of the data to help you better see the distributions in the time or power direction. For example, you can select a vertical histogram to measure the SNR, or a horizontal histogram to measure the RMS timing jitter.

In the figure below, we have selected a vertical histogram, and selected a window using the mouse. A red square shows the histogram window. The histogram is shown to the left and the mean, the standard deviation, the SNR values, and the number of histogram hits are shown in the measurement box at the bottom of the application.

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Setting up and Using the Optical Sampling Oscilloscope

Displaying Histograms

In the figure below, we have instead selected a horizontal histogram at a rising slope in the pattern. The histogram is shown at the bottom of the sample screen. The mean time in the histogram window, the standard deviation, and the number of histogram hits are shown under Histogram results.

Optical Sampling Oscilloscope 53

Setting up and Using the Optical Sampling Oscilloscope

Displaying Histograms

To display a histogram of the data:

1. From the main window, select the Display menu, then Histogram.

2. Select the type of histogram to view (horizontal or vertical).

3. Select a histogram window using the mouse by clicking-dragging the

mouse cursor to select the desired area.

Note: You can clear the histogram by clicking the Clear button at the bottom of

the application.

If you want to select a new histogram window, first deselect the present window in the histogram menu.

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Setting up and Using the Optical Sampling Oscilloscope

Managing Filters

Software defined filters can be applied to emulate a measurement situation with lower bandwidth, or to obtain filter characteristics that are theoretically perfect instead of hardware filters that change with time and from unit to unit. On the Optical Sampling Oscilloscope, you can use the following filters:

³ Bessel

³ Butterworth

³ Chebychev

You can set the order of the filter, and customize a bandwith over which the filter is applied.

Note: The Chebychev filter is of Type 1, with a 1-dB ripple in the passband.

Note: You must be in pattern mode and use a repetitive sequence to use filters.

To add a filter to the sampling:

1. From the main window, select the Display menu, then Filtering.

2. Select the type of filter to apply. You can select only one type at a time.

Optical Sampling Oscilloscope 55

Setting up and Using the Optical Sampling Oscilloscope

Managing Filters

To set the order for the filter:

1. From the main window, select the Display menu, then Filtering.

2. Under Filter order, select the rank for your filter.

To set the bandwidth for the filter:

1. From the main window, select the Display menu, then Filtering.

2. Select Filter bandwidth.

3. Enter a value in GHz for the bandwidth.

4. Click OK to confirm your choice.

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Setting up and Using the Optical Sampling Oscilloscope

Managing Filters

The figure below shows an example of a filtered 127-bit, 40 Gb/s, NRZ signal with a 40 GHz, 5

order Butterworth filter.

Optical Sampling Oscilloscope 57

Setting up and Using the Optical Sampling Oscilloscope

Using Colorgrade

Colorgrading the sampling can let you see which parts of the graph are displayed more often and which are displayed less often. The more often the parts are displayed, the brighter the corresponding color will be. The longer you let the sampling run, the more data is accumulated and the more precise the results.

The color grade function uses the pixel information to calculate the 2-D histogram. This means that a higher resolution in pixels/ps is achieved in a zoomed window compared to the default window.

In the figure below you can see colorgrade in eye-mode.

To activate the color grade mode:

In the Display menu, select Colorgrade.

To restart the color grade accumulation:

Click Clear.

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Setting up and Using the Optical Sampling Oscilloscope

Using Markers

Markers are quick and easy ways to take precise measurements.

To place markers:

1. Make sure that the sampling is running.

2. Right-click on the sample screen, then select Marker 1.

3. Click on the location where you want to put the marker.

4. Repeat steps 2 and 3 for the other marker.

Note: You can also select the markers from the Display menu.

The figure below shows an example where we have placed two markers in a 160 Gb/s pattern to measure the spacing between two slopes. The difference in time and power is shown at the top right corner of the sample screen. The red and blue indicators will give you the power and time values for each marker.

Using Markers

Optical Sampling Oscilloscope 59

Setting up and Using the Optical Sampling Oscilloscope

Using Markers

To move markers:

When the appropriate marker is selected, click on the screen where you want to put it.

To switch between the markers:

Right-click on the screen and select Toggle marker.

Select the Display menu, then Markers.

To remove the markers:

Right-click on the screen, then click on the marker to remove the check mark.

Select the Display menu, then Markers to select the marker and remove the check mark.

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Setting up and Using the Optical Sampling Oscilloscope

Using the Eyeline Mode

The eyeline mode is mainly used for noise reduction in eye diagrams. When a periodic pattern is sampled it is possible to average over several patterns in a similar way as in normal averaging mode. An eyeline trace is obtained when the averaged pattern is folded back into an eye diagram. In order to produce a full eyeline trace several samples must be recorded from all bits in the pattern. Hence, the longer the pattern the more time it will take to acquire all samples.

To use the eyeline mode:

1. Select the pattern view mode using the button at the bottom of the

screen.

Optical Sampling Oscilloscope 61

Setting up and Using the Optical Sampling Oscilloscope

Using the Eyeline Mode

2. In the Display menu, select Eyeline mode.

The figure below shows an eyeline trace from a normal 40 Gb/s, NRZ 127, bit pattern. Before the eyeline trace appears all bins (separated with 1 ps) must be filled with at least one sample. During this process, the maximum number of samples in any bin, the average number of samples per bin, and the minimum number of samples in any bin are shown in the sample window. This will be noticed first when the pattern is relatively long.

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Setting up and Using the Optical Sampling Oscilloscope

Using Masks

Mask testing is a procedure commonly used to verify that a transmitter complies with certain standards. The test is done in an eye diagram, where masks are placed in three regions: in the center of the eye, above the logic one, and below the logic zero level. Samples in these regions are unacceptable and referred to as mask hits or mask violations.

You can also activate a mask margin, which is slightly larger (a certain percentage) than the original mask to see the tolerance area within the eye diagram.

You can see at the bottom of the application the results from the mask test, including the total number of samples, the number of hits in the mask and in the margin, etc.

The mask is only placed in one eye period, so if for example four eyes periods are shown in the application, it will take longer time to acquire a certain number of samples in the mask test. Therefore, EXFO recommends to visualize one eye period.

Optical Sampling Oscilloscope 63

Setting up and Using the Optical Sampling Oscilloscope

Mask

Margin

Using Masks

The figure below shows the result from a mask test on 40 Gb/s NRZ data. The mask that is centered to the eye diagram is a standard square shaped mask with a height of 50 % of the eye amplitude (P of 20 % of the eye period.

one-Pzero

), and a width

To set up the mask parameters:

1. From the main window, select the Display menu.

2. Select Mask test, then Settings.

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Setting up and Using the Optical Sampling Oscilloscope

Using Masks

3. Enter values for the width, the height and the margin value of the mask.

4. Click OK to close the window.

To activate the mask testing option:

From the main window, select the Display menu, then Mask test and On.

The mask is automatically aligned and shown as grey areas that appear in the eye diagram.

To view the margins of the mask:

When the mask mode is activated, go in the Display menu, then select Mask test and Margins.

The margin will appear as a red outline arount the mask.

Optical Sampling Oscilloscope 65

Setting up and Using the Optical Sampling Oscilloscope

Displaying the FFT Spectrum of a Sampled Signal

Your Optical Sampling Oscilloscope can be used as an FFT spectrum viewer as well.

To look at the spectral content of a signal is useful in many situations. For example, you might want to see the bandwidth of the signal, or look at specific frequency harmonics that you want to maximize or minimize.

You can choose between two spectrum types:

³ Batch: The FFT of each batch is taken separately.

³ Averaged: Several batches are taken together to accumulate an

averaged FFT.

To display an FFT spectrum:

1. From the main window, select the Display menu, then Spectrum

(FFT).

2. Select which type of spectrum to view.

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Setting up and Using the Optical Sampling Oscilloscope

Displaying the FFT Spectrum of a Sampled Signal

3. Start the sampling session.

Here is an example of a spectrum of an NRZ 40Gb/s signal. You can see the characteristic dips in the spectrum at 40 GHz, 80 GHz, and so forth.

Optical Sampling Oscilloscope 67

Setting up and Using the Optical Sampling Oscilloscope

Displaying a Reference Trace for your Measurements

You can display a reference trace for your sampling to better see how your sampling relates to the desired result. The reference trace will appear in white on the display as you activate the sampling.

To display the reference trace:

From the main window, select the Display menu, then Reference Trace.

To save the reference trace and display it on-screen for the current session:

While the reference trace is activated, select the File menu, then Save data > Save setup > Bottom, then select the reference trace.

The reference trace appears in the background of the window in white.

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Setting up and Using the Optical Sampling Oscilloscope

Managing Measurement Parameters

In the Measurement menu you can select one or more parameters to measure from an eye diagram, pattern or waveform.

You can display up to three measured parameters simultaneously in the sample screen. When a fourth parameter is selected, the first one is automatically deselected. The indicators on-screen always pertain to the most recent measurement type you have selected.

The measurements are based on a number of histograms, so the longer time you wait, the more accurate the parameters will become. As long as at least one parameter is selected, all histograms are accumulated and all parameters are measured even though not shown. By removing all measurements, the histograms are cleared.

If you want to clear the histograms without removing the measurements, use the Clear button in the main window.

Optical Sampling Oscilloscope 69

Setting up and Using the Optical Sampling Oscilloscope

Managing Measurement Parameters

To select a measurement type:

From the main window, select the Measure menu, then the measurement type you want.

Note: For more details, see Measurement Definitions on page 109.

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Setting up and Using the Optical Sampling Oscilloscope

Managing Measurement Parameters

To set the thresholds for rise and fall times:

1. From the main window, select the Measure menu.

2. Select Thresholds, then the desired value (10-90 % or 20-80 %).

Optical Sampling Oscilloscope 71

Setting up and Using the Optical Sampling Oscilloscope

Managing Measurement Parameters

To set the histogram window width for NRZ and RZ formats:

1. From the main window, select the Measure menu.

2. Select Window width.

3. Enter the desired values for the window.

Note: In the case of short RZ pulses with a low duty cycle, you must decrease the

RZ window width to a small value. For example, if the duty cycle is only 10%, EXFO recommends that the window width is set to 1 %; if the duty cycle is only 1 %, the window width should be set to 0.1%.

4. Click OK to close the window.

To remove all measurements from the window:

From the main window, select the Measure menu, then Remove all.

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Setting up and Using the Optical Sampling Oscilloscope

Managing Measurement Parameters

Eye Mode Measurement Example

In the figure below, we have selected to show the measures of fall time, crossing and extinction ratio, which are shown under Measurement results at the bottom of the application. Markers associated with the parameter that was chosen last (here the 3rd in the list - the ER) indicate where the measurement was taken and what were the one and zero levels from which the ER was calculated.

Note: You can also use the dual window function in the display menu to view

both the eye and pattern simultaneously.

Optical Sampling Oscilloscope 73

Setting up and Using the Optical Sampling Oscilloscope

Managing Measurement Parameters

Pattern Measurement Example

Instead of an eye diagram you can choose to visualize the pattern procedure. Switch from Eye to Pattern at the bottom left. The figure below shows a part of a 127 bit, 40 Gb/s, NRZ pattern with measurements of ER, fall time and rise time..

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Setting up and Using the Optical Sampling Oscilloscope

Managing Synchronization

There are two synchronization methods used for measurements:

³ The fast sync, which implies that only a fine-tuning is done from the

last measurement. This is the default method.

³ If the fast sync is switched off, the software performs a coarse sync

every time, which takes more time, but is convenient when tuning the signal frequency continuously during the measurement, for example when optimizing the signal frequency of a ring laser.

To activate the fast sync option:

1. From the main window, select the Utilities menu.

2. Select Synchronization options.

3. Specify whether you want fast or slow sync.

Optical Sampling Oscilloscope 75

Setting up and Using the Optical Sampling Oscilloscope

Setting the Data Phase Tracking Algorithm

Data phase noise lead to timing jitter. To counter this, you can optimize the phase tracking algorithm settings. There are two different algorithms; piece wise constant, or filter-based. In the piece wise constant setting, you can shorten the batch length from the default value of 16000 to a smaller value. This will divide the whole batch into smaller subbatches, and since the synchronization is performed on each of the batches, the data phase is tracked in a faster manner.

For high performance signal generators, there is usually no need to reduce the batch length at all. For line card transmitters however, there is sometimes needed to reduce the batch length. Use the highest batch length possible, since a short batch length normally leads to larger problems with frequency holes.

In some cases, there may be even more phase noise and the algorithm must be faster. If the eye diagram looks jittery even with a batch length of 1000, EXFO recommends to select the filter-based phase tracking algorithm.

To set the phase tracking value:

1. From the main window, select the Utilities menu, then Advanced >

Phase tracking.

2. Under Piecewise constant, select the value you want to use.

The rate is updated automatically.

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Setting up and Using the Optical Sampling Oscilloscope

Filter-Based Phase Tracking

If the piecewise constant algorithm cannot handle the timing jitter, and a faster algorithm is required in order to track the phase, use the Filter based phase tracking algorithm. It is typically needed in some transponder line cards with relatively large phase noise.

You can set a software-defined filter bandwidth, which corresponds to a hardware clock recovery circuit with the same bandwidth.

To activate the filter-based phase tracking:

1. From the main window, select the Utilities menu, then Advanced >

Phase tracking.

2. Select Filter based, then On.

Optical Sampling Oscilloscope 77

Setting up and Using the Optical Sampling Oscilloscope

Filter-Based Phase Tracking

To set the filter bandwidth:

1. From the main window, select the Utilities menu, then Advanced >

Phase tracking.

2. In Filter based, select Filter bandwidth.

3. Enter the bandwidth value to use, in kHz.

4. Click OK to validate your choice.

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Setting up and Using the Optical Sampling Oscilloscope

Saving Sample Files

You can save the samples on the screen in a number of different formats, as a picture or as data samples. The saved pictures only show the sample screen with the same axis proportions as in the application.

To save or print a sample as a graph:

1. From the main window, select the File menu, then Save / Print

graphics.

2. In the Windows submenu, select whether you want to save or print the top or the bottom window.

3. In the Info messages submenu, select whether you want the messages displayed in the graph or not.

Note: These settings will remain as you have selected them until you change

them again.

Optical Sampling Oscilloscope 79

Setting up and Using the Optical Sampling Oscilloscope

Saving Sample Files

4. Click Save / print.

5. Select to save the file to the desired folder, or to print it.

To save the sample as data:

1. From the main window, select File, then Save data.

2. Under the Save setup menu, select if you want to include the

waveform samples for channel A and/or B for the top and bottom window

Note: If you are not using the dual window setting, or if only channel A or B are

active, you will have fewer choices.

3. Click Save. Confirm the location and format for the resulting file (.csv for Excel format, or .mat for Matlab format).

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5 Maintenance

To help ensure long, trouble-free operation:

³ Always inspect fiber-optic connectors before using them and clean

them if necessary.

³ Keep the unit free of dust.

³ Clean the unit casing and front panel with a cloth slightly dampened

with water.

³ Store unit at room temperature in a clean and dry area. Keep the unit

out of direct sunlight.

³ Avoid high humidity or significant temperature fluctuations.

³ Avoid unnecessary shocks and vibrations.

³ If any liquids are spilled on or into the unit, turn off the power

immediately, disconnect from any external power source and let the unit dry completely.

Use of controls, adjustments, and procedures for operation and maintenance other than those specified herein may result in hazardous radiation exposure.

WARNING

There are no operator serviceable parts inside the unit. Please refer all servicing to EXFO personnel.

³ The unit has a fan for active cooling. Make sure there is sufficient

airflow to cool the device, any objects that cover the ventilation holes must be removed.

³ Do not apply too large torque when connecting the clock input. Use a

torque wrench.

³ The instrument is somewhat temperature sensitive during the start

procedure. Avoid placing the unit in a hot cabinet.

Optical Sampling Oscilloscope 81

Maintenance

Push

Tur n

Pull

Cleaning EUI Connectors

Regular cleaning of EUI connectors will help maintain optimum performance. There is no need to disassemble the unit.

If any damage occurs to internal connectors, the module casing will have to be opened and a new calibration will be required.

To clean EUI connectors:

1. Remove the EUI from the instrument to expose the connector

baseplate and ferrule.

IMPORTANT

2. Moisten a 2.5 mm cleaning tip with one drop of isopropyl alcohol (alcohol may leave traces if used abundantly).

3. Slowly insert the cleaning tip into the EUI adapter until it comes out on the other side (a slow clockwise rotating movement may help).

4. Gently turn the cleaning tip one full turn, then continue to turn as you withdraw it.

82 PSO-100

Cleaning EUI Connectors

5. Repeat steps 3 to 4 with a dry cleaning tip.

Note: Make sure you don’t touch the soft end of the cleaning tip.

6. Clean the ferrule in the connector port as follows:

6a. Deposit one drop of isopropyl alcohol on a lint-free wiping cloth.

IMPORTANT

Isopropyl alcohol may leave residues if used abundantly or left to evaporate (about 10 seconds).

Avoid contact between the tip of the bottle and the wiping cloth, and dry the surface quickly.

6b. Gently wipe the connector and ferrule.

6c. With a dry lint-free wiping cloth, gently wipe the same surfaces to

ensure that the connector and ferrule are perfectly dry.

6d. Verify connector surface with a portable fiber-optic microscope

(for example, EXFO’s FOMS) or fiber inspection probe (for example, EXFO’s FIP).

Maintenance

WARNING

Verifying the surface of the connector WHILE THE UNIT IS ACTIVE WILL result in permanent eye damage.

7. Put the EUI back onto the instrument (push and turn clockwise).

8. Throw out cleaning tips and wiping cloths after one use.

Optical Sampling Oscilloscope 83

Maintenance

Fuse holder

Fuse

Fuse holder

Replacing Fuses

The unit contains two fuses (T2.5A L, 5 mm x 20 mm (0.197 in x 0.787 in), slow-blow, low-breaking capacity, 250 V). The fuse holder is located at the back of the unit, just below the power inlet.

To replace a fuse:

1. Turn off the unit and unplug the power cord.

2. Using a flat-head screwdriver as a lever, pull the fuse holder out of the

unit.

3. Check and replace the fuses, if necessary.

4. Insert the new fuse into the fuse holder.

5. Make sure the fuses are placed firmly in the holder prior to reinsertion.

6. Firmly push the fuse holder into place.

84 PSO-100

Maintenance

Recycling and Disposal (Applies to European Union Only)

Recycle or dispose of your product (including electric and electronic accessories) properly, in accordance with local regulations. Do not dispose of it in ordinary garbage receptacles.

This equipment was sold after August 13, 2005 (as identified by the black rectangle).

³ Unless otherwise noted in a separate agreement between EXFO and a

customer, distributor, or commercial partner, EXFO will cover costs related to the collection, treatment, recovery, and disposal of end-of-lifecycle waste generated by electronic equipment introduced after August 13, 2005 to an European Union member state with legislation regarding Directive 2002/96/EC.

³ Except for reasons of safety or environmental benefit, equipment

manufactured by EXFO, under its brand name, is generally designed to facilitate dismantling and reclamation.

For complete recycling/disposal procedures and contact information, visit the EXFO Web site at www.exfo.com/recycle.

Optical Sampling Oscilloscope 85

6 Troubleshooting

Solving Common Problems

Problem Cause Possible Solution

Nothing happens when you start sampling, but you can use the Start/Stop button.

The application freezes and you cannot use the Start/Stop button.

The application does not start at all

³ The samples are

outside the sampling screen.

³ The input power

is too high.

³ The unit was

turned off while the application was sampling.

³ The MCR is not

installed

³ The system path

is incorrect

³ The MCR version

is incorrect

³ Zoom out or pan

to find the samples.

³ Reduce input

power.

³ Tur n on t he un it

again, then restart the application on the host computer.

³ Install the MCR

using the MCRinstaller

³ See Installing the

Matlab Runtime, USB Drivers and Optical Sampling Oscilloscope Software on

page 12.

³ When receiving a

new software update from EXFO, make sure that you use the correct MCR version.

Optical Sampling Oscilloscope 87

Troubleshooting

Solving Common Problems

Problem Cause Possible Solution

The application was just started, but you can see a message that indicates "USB connection failed" .

³ The USB cable is

not connected.

³ The USB

communication is broken and does not resume in a hot-swap situation.

³ The USB driver is

not correctly installed.

³ Connect the USB

cable to the computer in the correct USB port, and restart the application.

³ Disconnect the

USB cable and connect it again. Restart the application.

³ Install the USB

driver.

88 PSO-100

Troubleshooting

Solving Common Problems

Problem Cause Possible Solution

The application was just started. In the DOS window "USB connection OK" is shown. When you click Start in the application nothing happens and in the DOS window TriggerTest is not passed.

USB connection is up, but the instrument is not triggering.

³ Make sure the

unit is turned on.

³ If it does not help,

the internal pulse source has not started correctly. Make sure that the surrounding temperature is within specifications.

³ If the unit was

recently turned off, let it cool down for a few minutes before you turn it on again.

³ If the problem

persists, contact EXFO.

Optical Sampling Oscilloscope 89

Troubleshooting

Solving Common Problems

Problem Cause Possible Solution

No signal is shown in the application, only samples at the zero level.

Windows indocates that it found new hardware when you insert the USB cable

³ Pow er is t oo low.

³ Wavelength is not

appropriate.

³ Dirty contacts.

³ You are using a

new USB port (Windows XP).

³ Increase signal

power.

³ Use the

1520-1565 nm wavelength region.

³ Clean the input

contacts. If you send in a lot of power and the contacts are dirty, the input contact may be damaged and must be repaired.

³ Use the correct

USB port (the one you used when the USB driver was installed) or install the driver on the new port.

³ The USB driver is

not installed.

90 PSO-100

³ Install the USB

driver.

Troubleshooting

Solving Common Problems

Problem Cause Possible Solution

The update rate is very slow, even in Freerun mode and with 16 k samples.

The power level shown in the application is much lower than expected.

³ You are using a

USB 1.1 port.

³ Your computer is

slow .

³ You have several

other applications running.

³ Signal

wavelength is outside the 1525-1565 nm span.

Dirty contacts.

³ If you have a

USB 2.0 port on your computer connect the USB cable to that port and reinstall the USB driver.

³ Install the

application on a faster computer.

³ Close some

applications, restart the computer if necessary.

³ Use the

1525-1565 nm span.

³ Clean the

contacts.

Optical Sampling Oscilloscope 91

Troubleshooting

Solving Common Problems

Problem Cause Possible Solution

The sampled data looks very noisy, jittery or distorted. The software does not seem to be able to synchronize the data.

³ The input signal is

too low.

³ The signal has

very poor OSNR or suffers from dispersion.

³ The waveform

format is incorrect.

³ There are

frequency holes.

³ The data signal

suffers from large phase noise.

³ The signal

wavelength is in the 1567-1570 nm span.

³ The internal

sampling pulse source has not locked yet.

³ Increase the

signal power

³ Try to use the

external clock

³ Set the

appropriate waveform format or use the external clock.

³ Click clear.

³ Change the phase

tracking algorithm (Utilities > Advanced menu), or use the external clock in adaptive mode.

³ Use

1525-1565 nm.

³ Turn off the

optical input signal. Wait and let the unit warm up until it locks.

My OTDM data jumps around on the screen.

It is difficult to synchronize a sub-optimally

Use the external clock with a subrate

clock. multiplexed data signal.

92 PSO-100

EXFO PSO-100 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Certification Information

PSO-100 Optical Sampling Oscilloscope Series Basic Theory

Typi c a l A pp licat i o ns

Conventions

2 Safety Information

Laser Safety Information

Electrical Safety Information

Host Computer Minimum Requirements

Installing the Matlab Runtime, USB Drivers and Optical Sampling Oscilloscope Software

Installing and Starting the Optical Sampling Oscilloscope

Turning off the Optical Sampling Oscilloscope

Cleaning and Connecting Optical Fibers

Installing the EXFO Universal Interface (EUI)

Adjusting the Zero Level (Nulling Offsets)

Managing SoftSync Input

Scaling Channel 1 to Channel 2 (PSO-102 Models)

Finding a Pattern in a Sampling

Using the Zoom Functions

Synchronizing the Input to a Specific Channel

Selecting Sync Format

Selecting the Channels (PSO-102 Only)

Selecting Trace and Background Colors

Using the Dual Window View

Using the Clock Input

Selecting the Number of Samples per Layer of Display

Changing the Persistence Time

Changing the Averaging Value

Displaying Histograms

Managing Filters

Using Colorgrade

Using Markers

Using the Eyeline Mode

Using Masks

Displaying the FFT Spectrum of a Sampled Signal

Displaying a Reference Trace for your Measurements

Managing Measurement Parameters

Managing Synchronization

Setting the Data Phase Tracking Algorithm

Filter-Based Phase Tracking

Saving Sample Files

5 Maintenance

Cleaning EUI Connectors

Replacing Fuses

Recycling and Disposal (Applies to European Union Only)

6 Troubleshooting

Solving Common Problems