User Guide PSO-100 Optical Sampling Oscilloscope Series
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.
Contents 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 ...................
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 .....................
Contents 7 Warranty ..................................................................................................... 97 General Information .............................................................................................................97 Liability .................................................................................................................................98 Exclusions .....................................................................................................
Certification Information 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.
Certification Information DECLARATION OF CONFORMITY Application of Council Directives: Manufacturer’s Name: Manufacturer’s Address: Equipment Type/Environment: Trade Name/Model No.: 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 EXFO Inc.
1 Introducing the PSO-100 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.
Introducing the PSO-100 Optical Sampling Oscilloscope Series Delay adjustment for Input B (optional) LED ON/OFF indicator Optical fiber input B, FC/PC connection External clock input (optional) Optical fiber input A, FC/PC connection Front View (PSO-102) Power switch 110-240 V AC voltage supply input Fan Rear View USB 2.0 connection to the host computer IMPORTANT All instruction or information in this user documentation pertain to both models, unless specified otherwise.
Introducing the PSO-100 Optical Sampling Oscilloscope Series PSO-100 Optical Sampling Oscilloscope Series Basic Theory 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.
Introducing the PSO-100 Optical Sampling Oscilloscope Series Typical Applications 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.
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.
Introducing the PSO-100 Optical Sampling Oscilloscope Series Conventions 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.
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.
Safety Information Electrical 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 8 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.
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.
Safety Information Electrical Safety Information Equipment Ratings Temperature ³ Operation 18 °C to 30 °C (64 °F to 86 °F) ³ Storage 0 °C to 50 °C (32 °F to 122 °F) Relative humidity a 80 % non-condensing Maximum operation altitude Pollution degree 3000 m (9843 ft) 2 Installation category b Power supply rating II 100 V to 240 V (50 Hz/60 Hz) maximum input power 20 VA a. b. Measured in 0 °C to 31 °C (32 °F to 87.8 °F) range, decreasing linearly to 50 % at 40 °C (104 °F).
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 2 Gb 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.
Getting Started with Your Optical Sampling Oscilloscope Installing the Matlab Runtime, USB Drivers and Optical Sampling Oscilloscope Software 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.
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.
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.
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.
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.
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.
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.
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.
Getting Started with Your Optical Sampling Oscilloscope Installing and Starting the 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.
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.
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.
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.
Getting Started with Your Optical Sampling Oscilloscope Turning off the 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.
Getting Started with Your Optical Sampling Oscilloscope Cleaning and Connecting Optical Fibers 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.
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.
Getting Started with Your Optical Sampling Oscilloscope Installing the EXFO Universal Interface (EUI) 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. Green border indicates APC option Bare metal (or blue border) indicates UPC option To install an EUI connector adapter onto the EUI baseplate: 1.
4 Setting up and Using the Optical Sampling Oscilloscope Once the unit and application are started, you can begin using the Optical Sampling Oscilloscope. Menu bar Zoom controls Input controls Starts/Stops sampling Clears sample screen Sample screen Switches between eye diagram view and pattern view (you can also select the display mode in the Setup > Display Mode menu.
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.
Setting up and Using the Optical Sampling Oscilloscope 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.
Setting up and Using the Optical Sampling Oscilloscope Adjusting the Zero Level (Nulling Offsets) 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.
Setting up and Using the Optical Sampling Oscilloscope Managing SoftSync Input 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. Signal frequency Data symbol rate (for example, 1/4 for a signal frequency of 40 GHz and a clock frequency of 10 GHz).
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.
Setting up and Using the Optical Sampling Oscilloscope Scaling Channel 1 to Channel 2 (PSO-102 Models) 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.
Setting up and Using the Optical Sampling Oscilloscope Finding a Pattern in a Sampling 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.
Setting up and Using the Optical Sampling Oscilloscope Using the Zoom Functions 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.
Setting up and Using the Optical Sampling Oscilloscope Synchronizing the Input to a Specific Channel 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.
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.
Setting up and Using the Optical Sampling Oscilloscope Selecting the Channels (PSO-102 Only) 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.
Setting up and Using the Optical Sampling Oscilloscope Selecting Trace and Background Colors 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.
Setting up and Using the Optical Sampling Oscilloscope Using the Dual Window View 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.
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.
Setting up and Using the Optical Sampling Oscilloscope Using the Clock Input 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.
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.
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.
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.
Setting up and Using the Optical Sampling Oscilloscope Selecting the Number of Samples per Layer of Display 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.
Setting up and Using the Optical Sampling Oscilloscope Changing the Persistence Time 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.
Setting up and Using the Optical Sampling Oscilloscope Changing the Averaging Value 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.
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.
Setting up and Using the Optical Sampling Oscilloscope Displaying Histograms 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.
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.
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.
Setting up and Using the Optical Sampling Oscilloscope Managing Filters 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.
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.
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, 5th order Butterworth filter.
Setting up and Using the Optical Sampling Oscilloscope Using Colorgrade 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.
Setting up and Using the Optical Sampling Oscilloscope Using Markers 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.
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. OR 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. OR Select the Display menu, then Markers to select the marker and remove the check mark.
Setting up and Using the Optical Sampling Oscilloscope Using the Eyeline Mode 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.
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.
Setting up and Using the Optical Sampling Oscilloscope Using Masks 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.
Setting up and Using the Optical Sampling Oscilloscope 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 (Pone-Pzero), and a width of 20 % of the eye period. Margin Mask To set up the mask parameters: 1. From the main window, select the Display menu. 2. Select Mask test, then Settings.
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.
Setting up and Using the Optical Sampling Oscilloscope Displaying the FFT Spectrum of a Sampled Signal 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.
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.
Setting up and Using the Optical Sampling Oscilloscope Displaying a Reference Trace for your Measurements 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.
Setting up and Using the Optical Sampling Oscilloscope Managing Measurement Parameters 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.
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.
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 %).
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.
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.
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..
Setting up and Using the Optical Sampling Oscilloscope Managing Synchronization 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.
Setting up and Using the Optical Sampling Oscilloscope Setting the Data Phase Tracking Algorithm 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.
Setting up and Using the Optical Sampling Oscilloscope Filter-Based Phase Tracking 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.
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.
Setting up and Using the Optical Sampling Oscilloscope Saving Sample Files 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.
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.
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.
Maintenance Cleaning EUI Connectors Cleaning EUI Connectors Regular cleaning of EUI connectors will help maintain optimum performance. There is no need to disassemble the unit. IMPORTANT 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. Turn Pull Push 2. Moisten a 2.
Maintenance 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.
Maintenance Replacing Fuses 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. Fuse holder 3. Check and replace the fuses, if necessary. 4. Insert the new fuse into the fuse holder.
Maintenance Recycling and Disposal (Applies to European Union Only) 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).
6 Troubleshooting Solving Common Problems Problem Cause Possible Solution Nothing happens when you ³ The samples are ³ Zoom out or pan start sampling, but you can use outside the to find the the Start/Stop button. sampling screen. samples. ³ The input power is too high. ³ Reduce input power. The application freezes and you ³ The unit was cannot use the Start/Stop turned off while button. the application was sampling.
Troubleshooting Solving Common Problems Problem The application was just started, but you can see a message that indicates "USB connection failed" . Cause Possible Solution ³ The USB cable is ³ Connect the USB ³ The USB ³ Disconnect the not connected. communication is broken and does not resume in a hot-swap situation. cable to the computer in the correct USB port, and restart the application. USB cable and connect it again. Restart the application.
Troubleshooting Solving Common Problems Problem Cause Possible Solution USB connection is up, ³ Make sure the The application was just but the instrument is started. In the DOS window unit is turned on. "USB connection OK" is shown. not triggering. ³ If it does not help, When you click Start in the the internal pulse application nothing happens source has not and in the DOS window started correctly. TriggerTest is not passed. Make sure that the surrounding temperature is within specifications.
Troubleshooting Solving Common Problems Problem Cause Possible Solution No signal is shown in the ³ Power is too low. ³ Increase signal application, only samples at the power. zero level. ³ Wavelength is not ³ Use the appropriate. 1520-1565 nm wavelength region. ³ Dirty contacts. 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.
Troubleshooting Solving Common Problems Problem Cause The update rate is very slow, ³ You are using a even in Freerun mode and with USB 1.1 port. 16 k samples. ³ Your computer is slow . ³ You have several Possible Solution 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. other applications ³ Close some running. applications, restart the computer if necessary.
Troubleshooting Solving Common Problems Problem The sampled data looks very noisy, jittery or distorted. The software does not seem to be able to synchronize the data. Cause Possible Solution ³ The input signal is ³ Increase the too low. signal power ³ The signal has ³ Try to use the ³ The waveform ³ Set the ³ There are ³ Click clear. very poor OSNR or suffers from dispersion. format is incorrect. frequency holes. ³ The data signal suffers from large phase noise.
Troubleshooting Solving Common Problems Problem Cause My short RZ pulses look like an It is difficult to eye diagram. correctly synchronize very low duty cycle pulses <1 %. The eye diagram looks jittery even if you use an external clock Possible Solution Start and stop the sampling to resynchronize the pulses, until it looks like short pulses. If it does not work, use the external clock. The clock signal may Change the phase suffer from large tracking algorithm phase noise.
Troubleshooting Solving Common Problems Problem 94 Cause Possible Solution The LED indicator on the front panel is off even if the unit is turned on. AC adapter is not plugged in correctly. Plug in the AC adapter. The instrument chassis is warm. The fan is off. Contact EXFO.
Troubleshooting Contacting the Technical Support Group Contacting the Technical Support Group To obtain after-sales service or technical support for this product, contact EXFO at one of the following numbers. The Technical Support Group is available to take your calls from Monday to Friday, 8:00 a.m. to 7:00 p.m. (Eastern Time in North America). For detailed information about technical support, visit the EXFO Web site at www.exfo.comwww.exfo.com.
Troubleshooting Transportation Transportation Maintain a temperature range within specifications when transporting the unit. Transportation damage can occur from improper handling. The following steps are recommended to minimize the possibility of damage: 96 ³ Pack the unit in its original packing material when shipping. ³ Avoid high humidity or large temperature fluctuations. ³ Keep the unit out of direct sunlight. ³ Avoid unnecessary shocks and vibrations.
7 Warranty General Information EXFO Inc. (EXFO) warrants this equipment against defects in material and workmanship for a period of one year from the date of original shipment. EXFO also warrants that this equipment will meet applicable specifications under normal use.
Warranty Liability Liability EXFO shall not be liable for damages resulting from the use of the product, nor shall be responsible for any failure in the performance of other items to which the product is connected or the operation of any system of which the product may be a part. EXFO shall not be liable for damages resulting from improper usage or unauthorized modification of the product, its accompanying accessories and software.
Warranty Exclusions Exclusions EXFO reserves the right to make changes in the design or construction of any of its products at any time without incurring obligation to make any changes whatsoever on units purchased. Accessories, including but not limited to fuses, pilot lamps, batteries and universal interfaces (EUI) used with EXFO products are not covered by this warranty.
Warranty Service and Repairs Service and Repairs EXFO commits to providing product service and repair for five years following the date of purchase. To send any equipment for service or repair: 1. Call one of EXFO’s authorized service centers (see EXFO Service Centers Worldwide on page 101). Support personnel will determine if the equipment requires service, repair, or calibration. 2.
Warranty EXFO Service Centers Worldwide EXFO Service Centers Worldwide If your product requires servicing, contact your nearest authorized service center. EXFO Headquarters Service Center 400 Godin Avenue Quebec (Quebec) G1M 2K2 CANADA EXFO Europe Service Center Omega Enterprise Park, Electron Way Chandlers Ford, Hampshire S053 4SE ENGLAND EXFO Telecom Equipment (Shenzhen) Ltd. 3rd Floor, Building 10, Yu Sheng Industrial Park (Gu Shu Crossing), No.
A Technical Specifications IMPORTANT The following technical specifications can change without notice. The information presented in this section is provided as a reference only. To obtain this product’s most recent technical specifications, visit the EXFO Web site at www.exfo.com. PSO-101 1 Number of channels Wavelength range (nm) b PSO-102 2 C: 1525/1563 L: 1575/1608 500 1 100, 50 b 2 1 200 100 1 1 0.001 to 12.5 0.
B Burst Mode Measurements The burst mode is very useful for example in circulating loop experiments. For this function to work, you must have the external clock option. In the figure below, we see an example with 42.3 Gb/s NRZ data modulation that come in bursts from a circulating loop. Laser 1550 nm Mach-Zender modulator EDFA AOM Chop data into bursts Driver Amplifier 27 km SMF 4.
Burst Mode Measurements Then, select Gated from the Clock menu. A window pops up, according to the figure below. burst period Rise time Fall time Trigger level Presented samples Insert the burst period, duty factor, rise- and fall times, and the burst trigger level. In this case, the burst period is 0.775 ms, the burst duration is 155 μs, that is, a 20 % duty factor. The AOM have rise and fall times of 100 ns.
Burst Mode Measurements The yellow samples are then visualized in an eye diagram in the lower window, while the white samples are removed, according to the figure below. In this way, you can determine whether the burst parameters are set correctly or not. For example, if the rise time parameter is too low, you will observe samples in the middle of the eye, and if the trigger level is too high, the refresh rate will become very low since it does not trig until the trigger timeout value is reached.
C Measurement Definitions The measurement definitions essentially follow the conventional standard from electrical sampling oscilloscopes. All measurements are based on histograms taken over samples that build up the signal. The measurement procedure is somewhat different if you are analyzing an eye diagram or waveform. In eye-mode, the histograms are placed at the same eye in time, where both a one level and a zero level are present. This is not possible if a pattern is analyzed.
Measurement Definitions One Level One Level The one level, Pone, is the logic one level in the eye diagram. The mean level within the histogram window determines the one level. Measurement window One level Histogram Zero Level The zero level, Pzero, is the logic zero level in the eye diagram. The mean level within the histogram window determines the zero level.
Measurement Definitions Signal-to-Noise Ratio Signal-to-Noise Ratio The eye signal-to-noise ratio (SNR) is a figure of merit of an eye diagram indicating the eye opening relative to the noise in both the one and zero levels. The eye SNR is defined as: ( P one – P zero ) EyeSNR = 20log 10 ----------------------------------( σ one + σ zero ) The noise in the one and zero levels, σ one and σ zero , are the standard deviations of the histogram at each level.
Measurement Definitions Timing Jitter Timing Jitter The timing jitter of an NRZ eye diagram is a measurement of the variance in time locations of the crossing point. Horizontal time histograms are constructed, and the histogram having the smallest variance determines the crossing point. The standard deviation of this histogram determines the RMS timing jitter and the extreme points (the largest and the smallest time value) in the histogram determine the peak-to-peak timing jitter.
Measurement Definitions Rise Time and Fall Time Rise Time and Fall Time The rise time is calculated from horizontal histograms according to the figure below. 90 % 10 % Histograms Rise time The time delay between the times where the slope transits through the 10 % and up to the 90 % thresholds determines the rise time. In the same way, the fall time is calculated as the time delay between the transit times through the 90 % level down to the 10 % level.
Measurement Definitions Eye Height Eye Height The eye height (EH) is a measurement of the vertical opening of an eye diagram and it is defined as: EH = ( P one – 3σ one ) – ( P zero + 3σ zero ) Eye Amplitude The eye amplitude (EA) is simply defined as the difference between the one and zero levels according to: EA = P one – P zero Eye Opening Factor The eye-opening factor is a measurement of the vertical eye opening according to: ( P one – σ one ) – ( P zero + σ zero ) EOF = -----------------------------
Measurement Definitions Eye Width Eye Width The eye width is a measurement of the horizontal opening of the eye. The eye width is defined as: EW = ( T cross2 – 3σ cross2 ) – ( T cross1 + 3σ cross1 ) where the mean crossing points, Tcross, and horizontal standard deviations σ cross are measured from the histograms in the eye diagram.
Measurement Definitions Duty Cycle Distortion Duty Cycle Distortion The duty cycle distortion (DCD) is a measurement of the time separation of the rising and falling edge of the eye at the center (50 %) level. The DCD is defined in percentage of the bit period as: T rise,center – T fall,center DCD = 100% -----------------------------------------------------bit period In a "perfect" eye with no timing- and amplitude jitter, and a 50 % crossing, the DCD is zero.
Measurement Definitions Pulse Width Pulse Width The pulse width measurement is only possible for RZ pulses. It can be used both for eye diagrams and pulses without data modulation. From a thin horizontal histogram at the 50 % threshold between the one and zero levels the mean crossing points determine the pulse width. Pulse width Contrast Ratio The contrast ratio (CR) is only defined for RZ data as the ratio between the one level and the level between the pulses, that is CR = P one ⁄ P contrast .
Measurement Definitions Duty Cycle Duty Cycle The duty cycle is only defined for RZ pulses or data as the ratio between the pulse width and the pulse repetition time.
D Asynchronous Sampling Principle Since the instrument has no hardware trigger, there is no way for the system to control the sampling frequency relative to the signal frequency, that is, the frequencies are asynchronous, and the sampling points will appear at seemingly random positions in time. In order to synchronize the data, the instrument relies on software synchronization.
Asynchronous Sampling Principle Frequency Holes The offset frequency Δf is more conveniently expressed in terms of a corresponding time step, Δt (ps/sample), given by 1 M Δt = ---- – ----fs B and referred to as the bit-slot scanning step. For correct synchronization you provide an estimate of the bit rate (in correct fs/2 interval) and then the software computes Δt.
Asynchronous Sampling Principle Frequency Holes The samples are evenly distributed, but sometimes the samples could be unevenly distributed. In rare cases, the samples could originate from just a few points in the eye diagram. We call this phenomenon frequency holes, since there are certain distinct offsets between the signal frequency and the sample frequency that give rise to this effect.
Asynchronous Sampling Principle Frequency Holes Directly after startup of the instrument the sampling frequency drifts relatively fast until it settles. During this time, you may pass a number of frequency holes. If you still have ended up in a situation with recurrent frequency holes, a possibility is to tune the signal frequency by only a few 100 Hz to jump out of the frequency hole.
Asynchronous Sampling Principle Pattern Effects Pattern Effects The software synchronization principle also results in another phenomenon. If there is no external clock present and you must rely on the internal signal synchronization, there may be pattern depending effects in some situations. For example if you sample a 26-1 = 63 bit PRBS eye diagram and chose to visualize 3 eyes. Since 63 is evenly divisible by 3 you would see that not all combinations of transitions occur for every eye.
Index Index A AC requirements ......................................... 10 adjusting zero level ..................................... 32 after-sales service ........................................ 95 application, starting .................................... 21 applying a mask .......................................... 63 asynchronous sampling principle .............. 119 averaged spectrum...................................... 66 averaging value ...........................................
Index E G eliminating offsets/dark current .................. 32 equipment returns .................................... 100 EUI connector adapter ................................. 27 dust cap................................................. 27 EUI connectors, cleaning ............................. 82 external clock output ................................................. 1, 2 using ..................................................... 44 extinction ratio measurement ...................
Index mask applying................................................. 63 margin................................................... 65 Matlab drivers ............................................. 12 maximum input current .............................. 10 measure menu ............................................ 30 measurements........................................... 113 burst mode .......................................... 105 contrast ratio ....................................... 117 crossing ...........
Index R ratio, channels............................................. 35 reference trace ...................................................... 68 zero power ............................................ 32 repairing unit ................................................ 9 replacing fuses ............................................ 84 return merchandise authorization (RMA) .. 100 rise and fall times, thresholds...................... 71 rise time measurement..............................
Index V value averaging............................................... 50 of sample batch..................................... 76 ventilation ..................................................... 9 vertical histogram ....................................... 52 view menu .................................................. 40 W warranty certification ........................................... 99 exclusions .............................................. 99 general .............................................
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MARKING REQUIREMENTS 㪖㽷尐㻑 Product Environmental protection use period (years) Logo ℶ❐ 䘾⬒≬㔳∎䞷㦮棟 ( ) 㪖㉦ This Exfo product 㦻 EXFO ℶ❐ Batterya 䟄㻯 a a. If applicable.
P/N: 1056317 www.EXFO.com · info@exfo.com CORPORATE HEADQUARTERS 400 Godin Avenue Quebec (Quebec) G1M 2K2 CANADA Tel.: 1 418 683-0211 · Fax: 1 418 683-2170 EXFO AMERICA 3701 Plano Parkway, Suite 160 Plano TX, 75075 USA Tel.: 1 972 907-1505 · Fax: 1 972 836-0164 EXFO EUROPE Omega Enterprise Park, Electron Way Chandlers Ford, Hampshire S053 4SE ENGLAND Tel.: +44 2380 246810 · Fax: +44 2380 246801 EXFO ASIA-PACIFIC 151 Chin Swee Road #03-29, Manhattan House SINGAPORE 169876 Tel.
