Page 1 OM4106D and OM4006D Coherent Lightwave Signal Analyzer User Manual *P071316002* 071-3160-02...
Page 3 OM4106D and OM4006D Coherent Lightwave Signal Analyzer User Manual www.tektronix.com 071-3160-02...
Page 4 Copyright © Tektronix. All rights reserved. Licensed software products are owned by Tektronix or its subsidiaries or suppliers, and are protected by national copyright laws and international treaty provisions. Tektronix products are covered by U.S. and foreign patents, issued and pending. Information in this publication supersedes that in all previously published material.
Page 5 Tektronix, with shipping charges prepaid. Tektronix shall pay for the return of the product to Customer if the shipment is to a location within the country in which the Tektronix service center is located. Customer shall be responsible for paying all shipping charges, duties, taxes, and any other charges for products returned to any other locations.
Page 7: Table Of Contents
Table of Contents Important safety information ..................General safety summary ..................Service safety summary ..................viii Terms in this manual ..................Symbols and terms on the product ................Compliance information ..................EMC compliance .................... Safety compliance ................... xiii Environmental considerations ................Preface ......................
Page 8 Table of Contents Detailed conﬁguration of experiments ................References ..................... Core processing software guide .................. Interaction with OUI ..................MATLAB variables................... MATLAB functions ..................Signal processing steps in CoreProcessing..............Block processing....................Alerts management ................... Core Processing function reference................AlignTribs ..................... ApplyPhase ....................
Page 9 Table of Contents OUI overview (ET) ..................OUI Controls panel (ET)................... Analysis Parameters window (ET)................ Appendix F: Conﬁguring two Tektronix 70000 series oscilloscopes ........Oscilloscope settings ..................OUI settings for 2-oscilloscope operation ............... Appendix G: The automated test equipment (ATE) interface ..........
Page 10 Table of Contents List of Figures Figure 1: Real-time (RT) oscilloscope setup diagram ............Figure 2: Equivalent-time (ET) oscilloscope setup diagram..........Figure 3: Color grade constellation- ﬁne traces ..............Figure 4: Color Key constellation ................Figure 5: Multicarrier Setup button (Home ribbon) ............Figure 6: Multicarrier setup window ................
Page 11 Table of Contents List of Tables Table 1: Standard and optional accessories..............Table 2: OM4000 options ..................Table 3: Software options ..................Table 4: OM4000 environmental requirements ..............Table 5: AC line power requirements ................Table 6: List of controller PC (oscilloscope or PC) software..........Table 7: Software install: oscilloscope................
Page 12: Important Safety Information
Important safety information Important safety information This manual contains information and warnings that must be followed by the user for safe operation and to keep the product in a safe condition. To safely perform service on this product, additional information is provided at the end of this section.
Page 13 Important safety information is difﬁcult to disconnect the power cord; it must remain accessible to the user at all times to allow for quick disconnection if needed. Observe all terminal ratings. To avoid ﬁre or shock hazard, observe all ratings and markings on the product.
Page 14: Service Safety Summary
Important safety information Slots and openings are provided for ventilation and should never be covered or otherwise obstructed. Do not push objects into any of the openings. Provide a safe working environment. Always place the product in a location convenient for viewing the display and indicators. Avoid improper or prolonged use of keyboards, pointers, and button pads.
Page 15: Terms In This Manual
Important safety information Terms in this manual These terms may appear in this manual: WARNING. Warning statements identify conditions or practices that could result in injury or loss of life. CAUTION. Caution statements identify conditions or practices that could result in damage to this product or other property.
Page 16 Important safety information Front panel labels Item Description Indicates the location of laser apertures On inside cover of the instrument OM4000D Series Coherent Lightwave Signal Analyzer...
Page 17 Important safety information Rear panel labels Item Description Instrument model and serial number label Fuse safety information COMPLIES WITH 21CFR1040.10 EXCEPT FOR DEVIATIONS PURSUANT TO LASER NOTICE NO. 50, DATED JUNE 24, 2007 OM4000D Series Coherent Lightwave Signal Analyzer...
Page 18: Compliance Information
IEC 61000-4-6:2003. Conducted RF immunity IEC 61000-4-11:2004. Voltage dips and interruptions immunity EN 61000-3-2:2006. AC power line harmonic emissions EN 61000-3-3:1995. Voltage changes, ﬂuctuations, and ﬂicker European contact. Tektronix UK, Ltd. Western Peninsula Western Road Bracknell, RG12 1RF United Kingdom This product is intended for use in nonresidential areas only.
Page 19: Safety Compliance
Compliance information Australia / New Zealand Complies with the EMC provision of the Radiocommunications Act per the following standard, in accordance with ACMA: Declaration of Conformity – EMC CISPR 11:2003. Radiated and Conducted Emissions, Group 1, Class A, in accordance with EN 61326-1:2006. Australia / New Zealand contact.
Page 20 Compliance information Safety class Class 1 – grounded product. Pollution degree A measure of the contaminants that could occur in the environment around and within a product. Typically the internal environment inside a product is descriptions considered to be the same as the external. Products should be used only in the environment for which they are rated.
Page 21: Environmental Considerations
(WEEE) and batteries. For information about recycling options, check the Support/Service section of the Tektronix Web site (www.tektronix.com). Perchlorate materials. This product contains one or more type CR lithium batteries. According to the state of California, CR lithium batteries are classiﬁed as perchlorate materials and require special handling.
Page 22 Compliance information OM4000D Series Coherent Lightwave Signal Analyzer...
Page 23: Preface
This manual describes how to install and operate the OM4000 instrument Coherent Lightwave Signal Analyzers. Supported products The information in this manual applies to the following Tektronix products: OM4006D Coherent Lightwave Signal Analyzer OM4106D Coherent Lightwave Signal Analyzer OM1106 Coherent Lightwave Signal Analyzer stand-alone software (OUI)
Page 24 Preface xviii OM4000D Series Coherent Lightwave Signal Analyzer...
Page 25: Getting Started
A remote interlock for the laser, located on the rear of the unit, allows for remote locking of laser output. You can use the OM4000 instrument along with a Tektronix OM2012 and OM2210, as well as supported real-time and equivalent-time oscilloscopes, for a complete optical calibration and testing system.
Page 26: Accessories
The following table lists some of the options that can be ordered with the OM4000. See the Coherent Lightwave Signal Analyzer OM4000 Series Datasheet (Tektronix part number 52W-27474-x) for a complete listing of options and recommended conﬁgurations. Table 2: OM4000 options...
Page 27: Initial Product Inspection
Getting started Table 2: OM4000 options (cont.) Model Option Description OM4106D 33 GHz Two C-band lasers One C-band and one L-band laser Two L-band lasers Table 3: Software options Option Description Adds QAM and other software demodulators Adds multicarrier superchannel support NOTE.
Page 28: Environmental Operating Requirements
3. Verify that the shipping carton contains the basic instrument, the standard accessories and any optional accessories that you ordered. (See Table 1.) Contact your local Tektronix Field Ofﬁce or representative if there is a problem with your instrument or if your shipment is incomplete.
Page 29: Power Requirements
After powering on, make sure that the fan on the rear panel is working. If the fan is not working, turn off the power by disconnecting the power cable from the AC power source, and then contact your local Tektronix Field Ofﬁce or representative.
Page 30: Pc Requirements
Getting started PC requirements The equipment and DUT used with the OM4000 determine the controller PC requirements. Following are the requirements to use the OM4000 Series Coherent Lightwave Signal Analyzers or OM2210 Coherent Receiver Calibration Source: Item Description Operating U.S.A. Microsoft Windows 7 64-bit system U.S.A.
Page 31: Table 6: List Of Controller Pc (Oscilloscope Or Pc) Software
Getting started Install software on the controller PC Table 6: List of controller PC (oscilloscope or PC) software Program Description Path (from root directory of USB drive) TekVISA Instrument USB and Ethernet OUI\ISSetupPrerequisites\TekVISA_v3.3.8\TekVISA\setup.exe connectivity software. NOTE. TekVISA is only required when using MSO/DSO70000 or 70000B series oscilloscopes, or when using the HRC software.
Page 32: Set The Instrument Ip Address
Set the instrument IP address Use the Laser Receiver Control Panel (LRCP) application to verify and/or set the IP address of OM instruments (OM4106D, OM4006D, OM2210, OM2012) if required for your network test setup. All OM instruments must be set to the same network subnet (DHCP-enabled networks do this automatically) to communicate with each other using the LRCP and OM4000 User Interface (OUI) software.
Page 33 Getting started Set the IP address for The OM instruments are set with automatic IP assignment (DHCP) enabled by default. Therefore you do not need to speciﬁcally set the instrument IP address, as DHCP-enabled networks the DHCP server automatically assigns an IP address during instrument power-on (when powering on with the rear-panel power switch).
Page 34 IP address to the instrument. If you are setting up a new isolated network just for controlling OM and associated instruments, Tektronix recommends using the OM instrument default IP subnet address of 172.17.200.XXX, where XXX is any number between 0 and 255. Use the operating systems of the oscilloscope and computer to set their IP addresses.
Page 35 Getting started Use direct PC connection to change instrument IP address. To use a direct PC connection to change the default IP address of an OM series instrument, you need to: Install LRPC on the PC Use the Windows Network tools to set the IP address of the PC to match that of the current subnet setting of the OM series instrument whose IP address you need to change Connect the OM instrument directly to the PC, or through a hub or switch...
Page 36 Getting started 12. On the PC, start the LRCP program. (See page 19, The Laser Receiver Control Panel (LRCP) user interface.) 13. Enter password 1234 when requested. 14. Select Conﬁguration > Device Setup from the menu to open the Device Setup window.
Page 37: Equipment Setup
Getting started Equipment setup Real-time (RT) See the following ﬁgure for how to connect the OM4000 instrument to take measurements with real-time oscilloscopes (Tektronix MSO/DSO70000 series). oscilloscopes Figure 1: Real-time (RT) oscilloscope setup diagram OM4000D Series Coherent Lightwave Signal Analyzer...
Page 38: Figure 2: Equivalent-Time (Et) Oscilloscope Setup Diagram
Getting started Equivalent-time (ET) See the following ﬁgure for how to connect the OM4000 instrument to take measurements with real-time oscilloscopes (Tektronix DSA8300 or oscilloscopes setup DSA8200 sampling oscilloscopes). Appendix E has more information on using an ET oscilloscope to take measurements. (See page 123, Equivalent-Time (ET) oscilloscope operation.)
Page 39 Getting started so that while the modulating frequency, f is still the same, the frequency deviation, , has been reduced by 2πf ∆t where ∆t is the time difference for the two paths. Some lasers can have frequency deviations in the 200 MHz range over 1 ms. To minimize the FM bandwidth after detection, reduce the frequency deviation to ~ 1 kHz.
Page 40 Getting started The power light turns off and the unit is disabled any time AC power is removed or the IP address is changed. Press the power button to re-enable. This feature prevents a remote user from activating the lasers when the local user may not be ready.
Page 41: Operating Basics
Operating basics OM4000 controls and connectors Front panel 1. On/Off standby switch 2. Laser 1 output 3. Optical Input (Signal input) 4. X, Y I/Q outputs (RF connectors, to connect to the oscilloscope) 5. Reference Input 6. Laser 2 output (may be internally connected at the factory) OM4000D Series Coherent Lightwave Signal Analyzer...
Page 42: Software Overview
Operating basics Rear panel 1. BNC connector for optional laser remote interlock 2. Power switch 3. Fuse holder 4. Power cable connector 5. 10/100/1000 Ethernet port Software overview The OM4000 instrument uses two primary software programs, the OM4000 User Interface (OUI) and the Laser Receiver Control Panel (LRCP). The OUI: Sets up measurement parameters for the OM4000 Takes input from the OM4000, oscilloscope, and LRCP...
Page 43: The Laser Receiver Control Panel (Lrcp) User Interface
Operating basics The OM4000 also makes use of a third party program, MATLAB by MathWorks, which must be installed on the same PC as the other two applications. The OUI automatically launches the MATLAB application and then interfaces with MATLAB using engine mode. The user does not have to interact with MATLAB for basic operation of the OM4000.
Page 44 Operating basics Device setup and auto Click the Device Setup button to open the Device Setup dialog box. Use this dialog box on initial setup of the controllers and anytime network conﬁguration conﬁgure changes and devices are moved to a new IP address. Click the Auto Conﬁgure button to have LRCP search for and list detected OM devices.
Page 45 Operating basics If the lasers are used in conjunction with the OM4000 instrument and OUI, the laser usage type needs to be set using the dialog on the lower right corner of each laser panel. The OUI uses the setting to determine from which laser frequency information is retrieved.
Page 46 Operating basics Power: Sets the laser power level. Type or use the up/down arrows to choose the desired laser power level. The allowed power range is shown next to the control. Fine Tune: The Intel/Emcore lasers can be tuned off grid up to 12 GHz. This can be done by typing a number in the text box or by dragging the slider.
Page 47: The Om4000 User Interface (Oui)
Operating basics Once the channel and power for each laser is set, turn on laser emission for each laser by clicking on its Laser Emission button; the emission status is indicated both by the orange background of the button and by the corresponding green LED on the OM4000 instrument front panel.
Page 48 Operating basics The OUI is designed to allow you maximum control of the graphical presentation. There are three types of displays in the OUI: ribbons, ﬂy-out panels, and windows. The Home ribbon, shown below, normally displayed, provides fast access to key tasks.
Page 49: Table 8: Oui Plots (Real-Time Oscilloscopes)
Operating basics OUI plots and The following table is an overview of available OUI plots and measurements measurements Table 8: OUI plots (real-time oscilloscopes) Plot Description Constellation Diagram for X or Y signal polarization with numerical readout bottom tabs. Right-click to see graphics options Symbol-center values are shown in blue Symbol errors are shown in red Right-click for other color options.
Page 50 Operating basics Table 8: OUI plots (real-time oscilloscopes) (cont.) Plot Description The coherent eye diagram for X or Y signal polarization shows the In-Phase or Quadrature components vs. time modulo two bit periods. The Q-factor results are provided in a tab below accessed by clicking on the arrows in the lower left corner. Right-click on the coherent eye diagram to get options including transition and eye averaging.
Page 51 Operating basics Table 8: OUI plots (real-time oscilloscopes) (cont.) Plot Description BER is shown by physical tributary and in total. Color changes on synch loss. 2d Poincaré shows the position of the data signal polarizations relative to the receiver’s H (1, 2) and V (3, 4).
Page 52 Operating basics Table 8: OUI plots (real-time oscilloscopes) (cont.) Plot Description The frequency spectrum of the signal ﬁeld is calculated using an FFT after polarization separation to obtain the spectrum of each signal polarization. The laser phase noise spectrum is obtained by taking an FFT of the e , where θ...
Page 53 Operating basics Table 8: OUI plots (real-time oscilloscopes) (cont.) Plot Description The Measurements Tab provides a convenient place to ﬁnd almost all of the numerical outputs provided by the OUI with statistics on each value. Multicarrier measurements. (See page 66, Multicarrier support (MCS) option.) OM4000D Series Coherent Lightwave Signal Analyzer...
Page 54: Table 9: Controls Panel Elements
Operating basics OUI Controls panel The Controls panel is typically pinned to the left side for easy access to signal acquisition and plot scale controls. Table 9: Controls panel elements Control Description Rec Len Record Length. Determines the oscilloscope record length for the next acquisition.
Page 55 Operating basics Table 9: Controls panel elements (cont.) Control Description For record sizes between 1,000,000 and the oscilloscope memory limit (usually many tens or hundreds of megapoints), it is essential to break processing into blocks to avoid running out of processor memory. In addition, since neither the entire waveform, nor the entire processed variables will ﬁt in computer memory at one time, it is necessary to make some decisions as to what information will be retained as each block is...
Page 56: Table 10: Record Length And Block Interaction Behavior
Operating basics Table 10: Record length and block interaction behavior Record length Block size Behavior <1,000,000 ≥Rec Len All data processed in one block. Aggregated variables such as constellation and eye diagrams available for plotting. <1,000,000 <Rec Len Data broken up into blocks for processing. Aggregated variables such as constellation and eye diagrams available for plotting after each block has completed.
Page 57: Table 11: Oui: Analysis Parameters Window
Operating basics The following controls are relevant to both equivalent-time and real-time oscilloscopes except where noted. Table 11: OUI: Analysis Parameters window Parameter Description Signal type Sets the type of signal to be analyzed and the algorithms to be applied corresponding to that type. Pure phase modulation Sets the clock recovery for when there is no amplitude modulation.
Page 58 Operating basics Table 11: OUI: Analysis Parameters window (cont.) Parameter Description 2nd Phase Estimate Checking this box forces Core Processing to do a second estimate of the laser phase after the data is recovered. This second estimate can catch cycle slips, that is, an error in phase recovery that results in the entire constellation rotating by a multiple of 90 degrees.
Page 59 Operating basics Table 11: OUI: Analysis Parameters window (cont.) Parameter Description The selection of the optimum value of Alpha is discussed later in the CoreProcessing guide. (See page 99, EstimatePhase.) This optimum value depends on the laser linewidth and level of additive noise moving from a value near 1 when the additive noise is vastly greater than the phase noise to a value near zero when phase noise is the only consideration (e.g.
Page 60 Operating basics Table 11: OUI: Analysis Parameters window (cont.) Parameter Description Apply Gray coding for If checked then the bit error rate reported with a QAM signal is the BER after applying Gray decoding. The Gray coded BER is typically less than the base BER. Continuous trace points Sets the number of samples per symbol for the clock retiming per symbol...
Page 61 Operating basics Table 11: OUI: Analysis Parameters window (cont.) Parameter Description Chromatic Dispersion The value of Dpsnm used by the Compensate CD function in ps/nm. The sign of Dpsnm should be the same as that of the dispersion compensating ﬁber that it replaces. In other words, Compensate CD is a dispersion compensator with dispersion of Dpsnm.
Page 62 Operating basics Front end ﬁltering. The signal may be ﬁltered according to the settings of the Front end ﬁlter group. The ﬁlter is a bandpass ﬁlter in the optical domain, which is equivalent to a lowpass ﬁlter acting on the electrical input signals to the oscilloscope (assuming that the center frequency is zero).
Page 63 Operating basics When the Nyquist ﬁlter type option is selected a ﬁlter is inserted such that the combination of the signal’s impulse response with the ﬁlter’s impulse response is a Nyquist function, having zero ISI. In principle, there are many possible Nyquist functions.
Page 64 Operating basics PattXlm.SyncFrameEnd = 100; PattYRe.Values = Seq3; PattYRe.SyncFrameEnd = 100; PattYlm.Values = Seq4; PattYlm.SyncFrameEnd = 100; The code assigns the user’s pattern variables Seq1, Seq2, Seq3, and Seq4 to the four tributaries. These variables must be loaded into the separate MATLAB Command Window as shown in the following ﬁgure.
Page 65 Operating basics 4. Set the record length long enough to capture the entire data pattern. For example, you need 32,767 bits to capture a 2 pattern. So if this is at 15-1 28 Gbaud and the scope has a sampling rate of 50 Gs/s, then you need at least 32,767*50/28 = 58,513 points in the record.
Page 66 Operating basics Constellation diagrams Many types of constellation diagrams can be chosen by clicking on the constellation icon. Once the laser phase and frequency ﬂuctuations are removed, the resulting electric ﬁeld can be plotted in the complex plane. When only the values at the symbol centers are plotted, this is called a Constellation Diagram.
Page 67 Operating basics Imag Bias: The imaginary part of the mean value of all symbols divided by the magnitude; expressed as a percent. A positive value means the constellation is shifted up. Magnitude: The mean value of the magnitude of all symbols with units given on the plot.
Page 68 Operating basics The Q calculation can cause alerts if it can’t calculate a Q factor for the outer transitions. For example, in 32-QAM. 32-QAM is a subset of 64-QAM, where the outer constellation points are never used. It is not possible to calculate a Q factor for those outer slices, hence the alert.
Page 69: Figure 3: Color Grade Constellation- Fine Traces
Operating basics Figure 3: Color grade constellation- ﬁne traces The Color Grade option provides an inﬁnite persistence plot where the frequency of occurrence of a point on the plot is indicated by its color. This mode helps reveal patterns not readily apparent in monochrome. Persistence can be cleared or set from the Right-Click menu as well.
Page 70 Operating basics The Color Key colors: If the prior symbol was in Quadrant 1 (upper right) then the current symbol is colored Yellow If the prior symbol was in Quadrant 2 (upper left) then the current symbol is colored Magenta If the prior symbol was in Quadrant 3 (lower left) then the current symbol is colored light blue (Cyan) If the prior symbol was in Quadrant 4 (lower right) then the current symbol...
Page 71 Operating basics Signal vs. Time Several plots of ﬁeld components as a function of time are available by selecting Signal vs. Time after clicking the waveform icon under the Home tab of the main ribbon. Sig vs T is different from other plots in that it allows many different variables to be displayed, and the user chooses which variables.
Page 72 Operating basics Waveform averaging Two types of averaged display of the eye diagram and signal vs. time are available. These show a cleaner version of the signal, having a reduced level of additive noise. The transition average is available by checking Averaging: Show Transition Average under Analysis Parameters and selecting Show Transition Average from the right click menu of the eye diagram where the average is to be displayed.
Page 73 Operating basics The linear average is obtained using a two-step process: The impulse response associated with the signal is calculated by a deconvolution process That impulse response is applied to the known data content of the signal to produce a linear average. The linear average assumes that the signal has a linear dependence on the data bits.
Page 74 Operating basics Current Signal Spectrum The Current Signal Spectrum plot is accessed by clicking on the spectrum icon button on the Home tab. Right-click on the plot to select what to display. The plot OUI displays the input signal spectrum by default. Measurements Statistics The Measurement Statistics table is displayed by the Tabular-Data menu (click on the Tabular Data icon).
Page 75 Operating basics Frequency. PER is the polarization extinction ratio of the transmitter calculated when Assume Orthogonal SOPs is no checked. PDL is the relative size of the X and Y constellations (PDL of a PM modulator). PMD: (See page 52, PMD measurement.) 2D Poincaré...
Page 76 Operating basics Bit-Error-Rate reporting Bit error rates are determined by examination of the data payload. You may choose BER or Differential BER. Differential BER compares the output of a simulated delay-line interferometer to a differential form of the data pattern speciﬁed in the Analysis Parameters.
Page 77 Operating basics Recording and playback You can record the workspace as a sequence of .mat ﬁles using the Record button in the Ofﬂine ribbon. These are recorded to C:\Users\<user>\Documents\TekApplications\OUI\MAT Files. You can play back the workspace from a sequence of .mat ﬁles by ﬁrst using the Load button in the Ofﬂine Commands section of the Home ribbon.
Page 78 Operating basics There are two parts to setting this up. First you need a unique ﬁle name that can be created automatically, second you need to design an if-statement to trigger on the proper event. Examples of save statements for unique ﬁle names. The following command saves data to ﬁles with the name testn.mat, where the n is replaced with whichever block is being processed at the time.
Page 79 Operating basics num2str(Clk(4)),'_',num2str(Clk(5)),'_',num2str(round(Clk(6))), '.mat'], Vblock) The following example triggers on an alert, using the Alert variable existence or the type of alert as a trigger if(isfield(Alerts,'Active')) Clk = clock; save(['HybridCal',num2str(Clk(2)),'_',num2str(Clk(3)), '_',num2str(Clk(1)),'_', ... num2str(Clk(4)),'_',num2str(Clk(5)),'_',num2str(round(Clk(6))), '.mat'], Vblock) Using the OUI with other The OUI software may be used to process data taken from any receiver that has the following properties: receivers...
Page 80 Operating basics page 115, Hybrid calibration (RT).), put the following statement in the Engine Command Window in the OUI before the DispCalEllipses statement: CorrectPhase = true; The resulting pHyb statement replaces the one in step 1. Hybrid Calibration is optional if the receiver gain and phase accuracy is good enough to be approximated by the ideal hybrid model in step 1.
Page 81: Conﬁguring The Om4000 User Interface (Oui)
Software required on oscilloscope LAN server Scope Service Utility or ET Scope Service Utility Real-time oscilloscope compatibility Any real-time C and D-model Tektronix 70000 series oscilloscope oscilloscopes with supported by the ﬁrmware v6.4 or IVI driver later Equivalent-time oscilloscope compatibility...
Page 82 Conﬁguring the OM4000 user interface (OUI) After clicking Connect, the drop down boxes will be populated for channel conﬁguration. Choose the oscilloscope channel name which corresponds to each receiver output and MATLAB variable name. These are: Vblock(1) – X-polarization, In-Phase Vblock(2) –...
Page 83: Non-Visa Oscilloscope Connections (Scope Service Utility)
Conﬁguring the OM4000 user interface (OUI) Non-VISA oscilloscope connections (Scope Service Utility) As mentioned above, the other choice for connecting to the oscilloscope and collecting data is the Scope Service Utility (SSU). The SSU is a program that runs on each oscilloscope to be connected to the OUI. NOTE.
Page 84 Conﬁguring the OM4000 user interface (OUI) When connecting from the OUI, you will see a check box for VISA. Do not check the box unless you require a VISA connection. NOTE. Clicking Connect on the OUI Setup Tab opens the Scope Connection dialog box for connecting to the Scope Service Utility.
Page 85: Two-Oscilloscope Conﬁguration
Once connected and conﬁgured, close the connect dialog box. The OUI is ready to use. Two-oscilloscope conﬁguration OUI Versions 1.5 and later support a conﬁguration where two Tektronix MSO/DSO70000C- or D-Series oscilloscopes are both connected to an OM4000. (See page 145, Conﬁguring two Tektronix 70000 series oscilloscopes.)
Page 86: Matlab
MATLAB MATLAB Launching the OUI also launches the installed MATLAB application. The MATLAB default working directory is the installation directory. Use the cd command to change to another directory if desired. Any ﬁles saved will go to the working directory. Once the OUI is running, the MATLAB Command Window is populated with the variables and functions used in coherent signal processing: OM4000D Series Coherent Lightwave Signal Analyzer...
Page 87: Taking Measurements
Taking measurements Setting up your measurement Since the OM4000 is a reconﬁgurable (complex, dual-polarized) reference receiver, it requires a modulated signal on the input ﬁber. Depending on the options conﬁgured in the receiver, this modulation can be single- or dual-polarized, with several formats available, including OOK (on-off keying), BPSK (binary phase-shift keying), and QPSK (quadrature phase-shift keying), and either coherent or differential QAM and other formats are also available.
Page 88: Matlab Engine File
Taking measurements MATLAB Engine ﬁle You can conﬁgure MATLAB to perform a wide range of mathematical operations on the raw or processed data using the Engine window. Normally the only call is to CoreProcessingCommands, the set of routines performing phase and clock recovery.
Page 89: Taking Measurements
Taking measurements EqFiltInUse – a string which contains the properties of the equalization ﬁlter in use pHybInUse – a string which contains the properties of the optical calibration in use DebugSave – logical variable that controls saving of detailed .mat ﬁles for analysis: DebugSave = 1 in the MATLAB Engine Command window results in two ﬁles saved per block plus one ﬁnal save.
Page 90: Multicarrier Support (Mcs) Option
Taking measurements Multicarrier support (MCS) option As network operators seek to increase the capacity of their ﬁber-optic transmission systems, moving wavelength division multiplexing (WDM) signals closer together is an attractive option. The densely packed signals are more readily separated using digital ﬁlters after coherent detection rather than more coarse WDM ﬁlters. This also simpliﬁes routing since more is under digital control.
Page 91: Figure 6: Multicarrier Setup Window
Taking measurements Figure 6: Multicarrier setup window Multicarrier channel List. The main part of this section is the channel deﬁnition table. There are two types of channel deﬁnition table: absolute and relative. The default table type is absolute. A relative table may be entered by selecting Channel List Options: Add channel list: Add a new relative channel list.
Page 92 Taking measurements The OUI identiﬁes the channel by the difference between its absolute frequency (in the Frequency column) and the LO frequency. The ﬁnal column decides whether a channel will be included in the automatic scan. The relative channel deﬁnition table has only three columns. The second column, called Offset Frequency, contains the difference frequency between the channel and current local oscillator frequency.
Page 93: Figure 7: Multicarrier Spectrum Context Menu
Taking measurements Multicarrier spectrum. The Multicarrier Spectrum plot is accessed by clicking on the spectrum icon button on the Home tab. Right-click on the plot to select what to display. By default the Input Signal spectrum is displayed. Each spectrum is labeled with its channel number appearing at its center frequency.
Page 94: Figure 8: Multicarrier Spectrum Plot
Taking measurements Table 14: Multicarrier spectrum controls Item Description Freq/Div Click the narrow spectrum icon (narrower spectrum, more GHz/Div) or wide spectrum icon (wider spectrum, less GHz/Div) to change the horizontal frequency axis scale. Units are selectable via the drop-down menu but also change automatically when a change is made to the Absolute/Relative/Autocenter choices.
Page 95 Taking measurements Like the other multicarrier plots, the Multicarrier Spectrum plot saves data from each channel analyzed to form a composite view of the channel group. In the example shown above, this means that the Input Signal spectrum calculated while analyzing channel 1 is plotted in green together with that calculated while analyzing channel 2 in red.
Page 96: Figure 9: Multicarrier Spectrum Plot Details
Taking measurements Figure 9: Multicarrier spectrum plot details The ﬁgure above shows some of the other features of the Multicarrier Spectrum plot. Here the X-pol signal after front-end processing is shown together with the digital ﬁlter used. Notice that the X-pol signal (purple or orange) show much deeper nulls than the total power spectrum (red or green).
Page 97: Figure 10: Multicarrier Constellation Plots
Taking measurements As each channel is analyzed, only that portion of the plot will be updated while the most recent data displayed will continue to be shown in the other regions so that an aggregate view of the multicarrier group can be displayed. Use the Clear Data button to discard prior data.
Page 98: Figure 11: Multicarrier Eye Diagrams Plot
Taking measurements Figure 11: Multicarrier Eye diagrams plot EVM vs. Channel and Q vs. Channel. The EVM vs. Channel and Q vs. Channel plots are accessed by clicking on the Q icon button on the Home tab. These plots display the most recently measured EVM or Q factor for each channel. Only the current channel will be updated while the most recent data displayed will continue to be shown for the other channels so that an aggregate plot of the multicarrier group can be displayed.
Page 99: Figure 13: Q Vs. Channel Plot
Taking measurements Figure 13: Q vs. Channel plot Measurement vs. Channel. The Measurement vs. Channel table is accessed by clicking on the tabular data icon on the Home tab. This table is similar to the Measurement Statistics table except that only the most recent value is shown so that data from every channel can be displayed in one plot.
Page 100 Taking measurements OM4000D Series Coherent Lightwave Signal Analyzer...
Page 101: Detailed Conﬁguration Of Experiments
Detailed conﬁguration of experiments Coherent detection has been recognized for some time as offering superior performance to direct detection. Until recently coherent receivers were prohibitively expensive, and that is why all commercial optical communications receivers use direct detection. However, a coherent receiver which uses real-time digital signal processing technology can meet both the performance and cost needs of future optical communications networks.
Page 102 Detailed conﬁguration of experiments S. Tsukamoto, D.-S. Ly-Gagnon, K. Katoh, K. Kikuchi, "Coherent Demodulation of 40-Gbit/s Polarization-Multiplexed QPSK Signals with 16-GHz Spacing after 200-km Transmission," OFC 2005 conference, Anaheim, US, PDP29, 2005. M.G. Taylor, "Accurate Digital Phase Estimation Process for Coherent Detection Using a Parallel Digital Processor,"...
Page 103: Core Processing Software Guide
Core processing software guide Interaction with OUI The core processing software performs all the computations to obtain the quantities displayed in the OM4000 User Interface (OUI), starting from the raw data records acquired by the oscilloscope. Core processing is written in MATLAB. The code is executed on an instance of MATLAB launched and controlled in engine mode by the OUI.
Page 104: Matlab Variables
Core processing software guide 5. OUI retrieves output variables from MATLAB workspace 6. OUI displays output variables as eye diagrams, constellation diagrams, numerical values, etc. In fact when the record size is larger than the block size multiples calls to CoreProcessing are executed for each oscilloscope record.
Page 105: Matlab Functions
Core processing software guide Some of the important input variables to CoreProcessing are listed in the Core Processing function reference section. (See page 91.) MATLAB functions The core processing code calls several MATLAB functions, that are key to processing the signal. A function typically acts on many variables as input, and produces many variables as an output.
Page 106: Signal Processing Steps In Coreprocessing
Core processing software guide Signal processing steps in CoreProcessing CoreProcessing.m is a long ﬁle because it includes all the signal processing options for the many possible modulation formats. There are several “switch SigType” statements, where one case includes some repetition of code from an earlier case. If a user is interested in only one modulation format it is expedient to delete all the case statements that are not of interest (after making a copy of the original CoreProcessing.m).
Page 107 Core processing software guide Clock recovery The variable Vblock is a 1x4 array of data structures, and contains the four oscilloscope channel voltages vs. time. Vblock(1) is a time series (having .t0, .dt and .Values ﬁelds) of scope channel 1 voltage, and similarly for Vblock(2) ...
Page 108 Core processing software guide This worked example is for a single polarization QPSK signal. If a dual polarization signal were used, then before the polarization rotation each polarization of pSym would contain a mixture of the two polarization tributaries. After polarization rotation the top row of pSym.Values would contain one polarization tributary, and the bottom row the other.
Page 109 Core processing software guide AlignTribs returns the pattern variables, PattXRe etc., as outputs in addition to DRotM. The pattern variable outputs have additional ﬁelds compared to the pattern variable inputs, to indicate the synchronization location within the pattern. For example, if PattXRe speciﬁes a pseudorandom bit sequence (PRBS), the output PattXRe has a ﬁeld .Seed which contains the contents of the PRBS shift register at time PattXRe.t0.
Page 110 Core processing software guide Count bit errors A decision is made on each component of the QPSK signal by testing whether zXSym > 0. The decided values are compared with the known true data values, via the xor function, to locate bit errors. The number of bit errors is stored in variable Errs.
Page 111: Block Processing
Core processing software guide Block processing The OM4000 core processing software is able to cope with very large record sizes, for example 250M samples, by breaking down the record into smaller pieces, or blocks, and processing them in sequence. All functions are designed so that the output is near-identical if block processing is used compared to performing the processing in a single block.
Page 112: Alerts Management
Core processing software guide The way the information is passed from one block to the next is via a boundary values variable (which includes “BoundVals” in its name). The boundary values variables are declared as persistent variables in CoreProcessing.m. They are listed after the keyword “persistent”...
Page 113 Core processing software guide These ﬁelds correspond to the columns of the Alerts table in the OUI. The purpose of the .Zone ﬁeld is to identify not just which function triggered the alert, but where in the code it was triggered. The value of the .Zone ﬁeld is assigned to the value of Alerts.CurrZone when the function triggering the alert is called.
Page 114 Core processing software guide The integer Code values <code number 1> and <code number 2> must be different from one another and from any other alert code values using in core processing. To save the user from searching through all the alert codes in use, the ﬁrst time core processing is executed (or after entering “clear all”...
Page 115: Core Processing Function Reference
Core Processing function reference AlignTribs [Rot,PattXReOut,PattXImOut,PattYReOut,PattYImOut,BoundValsOut,AlertsOut] = AlignTribs(pSym,SigType,PattXReIn,PattXImIn,PattYReIn,PattYImIn, BoundValsIn,AlertsIn) pSym – single or dual polarization parameter vs. time: .t0 – time of ﬁrst symbol .dt – symbol duration .Values – 1xN or 2xN array of complex values SigType – integer value indicating signal modulation format PattXReIn –...
Page 116 Core Processing function reference pSym may be a dual polarization of single polarization parameter. The result of aligning the tributaries is reported in RotM. When input parameter pSym is single polarization RotM is a complex number, and when pSym is dual polarization RotM is a 2x2 Jones matrix.
Page 117 Core Processing function reference The four tributaries are compared with PattXReIn: If one tributary is found to match, then assignment of PattXReIn is complete. If more than one tributary matches, the matched tributaries are compared in time, and the earliest (shortest delay) is assigned to PattXReIn. If no tributaries are found to synchronize with PattXReIn, then that pattern is left unassigned.
Page 118: Applyphase
Core Processing function reference ApplyPhase [Y,BoundValsOut,AlertsOut] = ApplyPhase(X,Theta,BoundValsIn,AlertsIn) X – single or dual polarization parameter vs. time: .t0 – time of ﬁrst symbol .dt – symbol duration .Values – 1xN or 2xN array of complex values Theta – phase to be applied: .t0 –...
Page 119: Diffdetection
Core Processing function reference pHyb – 2x4 array (4 column vectors) containing characteristic Jones vectors of optical hybrid ports, usually obtained by separate calibration Clock – structure having ﬁelds (and may have more ﬁelds) deﬁning the output time grid: .t0 – time of ﬁrst symbol .dt –...
Page 120 Core Processing function reference CentFreq – real value, optical frequency of signal compared to multiple of 1/Delay BalancedDiffDetection – 0 = single-ended detection; 1 = balanced detection BoundValsIn – structure of boundary values from previous block AlertsIn – structure of alerts accumulated before executing function v – structure giving optical power at output of delay discriminator: .t0 –...
Page 121: Estimateclock
Core Processing function reference R.A. Grifﬁn, A.C. Carter, "Optical differential quadrature phase-shift key (oDQPSK) for high capacity optical transmission," OFC 2002 conference, Anaheim, US, paper WX6, 2002. EstimateClock function [Clock,BoundValsOut,AlertsOut] = EstimateClock(V,ChDelay,pHyb,FreqWindow,NonlinFunc,BoundValsIn,AlertsIn) V – 1x4 array of structures, each containing waveform (voltage values) from scope ChDelay –...
Page 122 Core Processing function reference 1. The oscilloscope waveforms are adjusted for the known relative delays ChDelay between the four scope channels. The delay-adjusted values are integrated into a dual polarization representation (a Jones vector) vs. time, given the known relative phase and polarizations of the optical hybrid pHyb.
Page 123: Estimatephase
Core Processing function reference EstimatePhase [Theta,BoundValsOut,AlertsOut] = EstimatePhase(zSym,SigType,Alpha,BoundValsIn,AlertsIn) zSym – complex electric ﬁeld values (single polarization) vs. time: .t0 – time of ﬁrst symbol .dt – symbol duration .Values – 1xN array (row vector of complex values), symbol center signal values SigType –...
Page 124: Estimatesop
Core Processing function reference Theta.CentFreq + (Theta.Values(end)-Theta.Values(1))/2/pi/number of symbols/Theta.dt Although it reports the same value for .CentFreq every block, the function internally estimates a new heterodyne offset frequency for each block. This means that it is able to track a slowly varying frequency change. The block size must be smaller than the time taken for the frequency to shift in order to track it accurately.
Page 125: Maskcount
Core Processing function reference The function employs a different algorithm for each modulation format. The standard SigType values are supported (1 to 5), as well as 0. With SigType = 0 the function ﬁnds an unmodulated tributary from a mix of other bipolar-modulated channels and noise.
Page 126: Genpattern
Core Processing function reference The function returns the number of mask violations corresponding to each symbol. A mask violation occurs when the instantaneous EVM exceeds a set threshold. The function returns MaskViolations as a vector with one entry for each constellation point. The value of the threshold used to count the number of mask violations can be set from the Engine Command Window in OUI as (using 60% as an example): MaskThreshold = 0.6;...
Page 127: Jones2Stokes
Core Processing function reference NumBitsVar takes on one of two forms. If it is a positive integer value then that is used as the number of bits to generate in output parameter Seq. The time ﬁeld Patt.t0 is ignored (if it exists). The output sequence starts with Patt.Seed in the case of a PRBS, or Seq starts at position Patt.Start in the case of a speciﬁed data pattern.
Page 128: Laserspectrum
Core Processing function reference LaserSpectrum [Lspectrum] = LaserSpectrum(ThetaSym, RBW) ThetaSym – symbol rate phase estimates: .t0 – time of ﬁrst symbol .dt – symbol period .Values – (1xN) array (row vector of complex values) of signal values RBW – desired resolution bandwidth The function LaserSpectrum estimates the power spectral density of the combined laser waveform in units of dBc.
Page 129 Core Processing function reference Rail0 – structure describing straight line ﬁt to 0 rail: .S – row vector of signal values used for ﬁt, at which decision threshold was set .Q – inverse error function of bit error rate at decision threshold values S .Mean –...
Page 130: Zspectrum
Core Processing function reference zSpectrum [zSpectrum] = zSpectrum(z, RBW, vdt) z – complex oversampled signal (usually zX or zY) with ﬁelds: .t0 – time of ﬁrst element .dt – sampling period .Values – (1xN) array (row vector of complex values) of signal values RBW –...
Page 131: Appendix A: Matlab Variables Used By Core Processing
Appendix A: MATLAB variables used by core processing Vblock – voltage vs. time on four scope channels SigType – integer value indicating the modulation format of the signal 1 – single polarization binary phase shift keying (BPSK) 2 – single polarization quadrature phase shift keying (QPSK) 3 –...
Page 132 Appendix A: MATLAB variables used by core processing OM4000D Series Coherent Lightwave Signal Analyzer...
Page 133: Appendix B: Alerts
Appendix B: Alerts Alerts may appear in the Alerts section of the main ribbon, accompanied by a change in the “Alerts” text as notiﬁcation. Table 15: Alert code descriptions Code Calling function Description EngineCommandPre Local oscillator (LO) frequency not set. Set the LO frequency automatically by opening the Laser Receiver Control Panel, or manually under the Setup tab in OUI.
Page 134 Appendix B: Alerts Table 15: Alert code descriptions (cont.) Code Calling function Description EstimatePhase Size of block or record too small to produce sufﬁcient number of symbols given FreqWindow.High. Returning clock frequency outside given window. EstimatePhase Clock frequency may be incorrect because of aliasing. Specify narrower frequency window.
Page 135: Appendix C: Calibration And Adjustment (Rt Oscilloscope)
Appendix C: Calibration and adjustment (RT oscilloscope) Calibration and adjustment (RT) The OM4000 receiver requires the following calibration before taking measurements: DC calibration (to compensate for any offsets in the photodiode outputs) Delay adjustment (channel to channel skew in the scope connections) Hybrid calibration (correction for cross-talk and phase error in the hybrid) Laser linewidth factor (choosing the correct ﬁlter for phase recovery) (See page 34.)
Page 136 Appendix C: Calibration and adjustment (RT oscilloscope) Each slider indicates the relative delay for the given channel pair. The corresponding waveforms will be shifted to account for this skew. Delay (1:2) means the delay of RX channel 2 (the X-Q channel) relative to RX channel 1 (the X-I channel).
Page 137 Appendix C: Calibration and adjustment (RT oscilloscope) ChDelay(3): delay of OM4000 RX channel Y-I relative to X-I ChDelay(4): delay of OM4000 RX channel Y-Q relative to X-I This will also include connecting cable and digitizer delays if the digitizer/cable combination has not been de-skewed separately. Manual ChDelay determination with a 1-pol BPSK input signal.
Page 138: Figure 15: When Adjusting The Middle Slider, Watch The Y-Eye And Y-Const To Minimize The Signal In The
Appendix C: Calibration and adjustment (RT oscilloscope) 9. Once this is done get approximately equal signal on both polarizations by deleting everything from the Engine Command Window except for CoreProcessingCommands and adjusting the input polarization as needed. 10. Set the middle slider to achieve minimum signal in the Y-polarization. Since the input is a single-pol signal at this point, nothing should be in the Y constellation or eyes except for noise.
Page 139: Hybrid Calibration (Rt)
Appendix C: Calibration and adjustment (RT oscilloscope) Hybrid calibration (RT) This is a factory calibration. Imperfections in the OM4000 instrument receiver are corrected using a factory-supplied calibration table. Check the Setup tab for a green indicator to be sure the OUI is successfully retrieving the Reference laser (Local Oscillator) frequency and power which are needed to choose the correction factors from the calibration table.
Page 140 Appendix C: Calibration and adjustment (RT oscilloscope) Click Run on the oscilloscope to get a rapidly updating display. You should see 100 to 500 MHz sine waves. Move the SM ﬁber around until you get most signal on RX channels X-I and X-Q (at least 3:1 ratio between X-I and Y-I.
Page 141 Appendix C: Calibration and adjustment (RT oscilloscope) 7. Click Run. The green trace should now be circular. View and correct the 1. Move the input ﬁber to get most of the signal on RX channels Y-I and Y-Q. Tape it down. Y-polarization calibration (RT) 2.
Page 142 Appendix C: Calibration and adjustment (RT oscilloscope) Correct the relative X-Y 1. You must complete all of the above steps ﬁrst including CorrectX and CorrectY. gain (RT) 2. Type CorrectXY in the separate MATLAB Application Window. 3. Copy and paste the resulting pHyb statement before DispCalEllipses, replacing any other pHyb statement.
Page 143: Absolute Power Calibration
Appendix C: Calibration and adjustment (RT oscilloscope) Absolute power calibration As of OM4000 version 1.2.0, OUI can plot signal data on an absolute scale independent of the LO signal strength. This requires absolute scaling of the pHybCalib.mat ﬁle, which was not available on all earlier versions of OUI. The following power calibration should be accurate to 15%: 1.
Page 144 Appendix C: Calibration and adjustment (RT oscilloscope) Equalization is speciﬁc to the sampling rate of the oscilloscope. As an example, if the bandwidth of the OM4000 is 30 GHz and the sampling rate of the oscilloscope is 80 Gs/s, the combined effect of the OM4000 receiver front end response and the digital equalization ﬁlter will be that of a 4th order digital Bessel ﬁlter with 3 dB cutoff at 32 GHz, as shown in the following graph.
Page 145: Appendix D: Automatic Receiver Deskew
Appendix D: Automatic receiver deskew When setting up for the ﬁrst time or whenever the channel delays are completely unknown, it is best to use the utility CalChDelay as shown in the ﬁgure at step 6. To use this utility, do the following steps: 1.
Page 146 Appendix D: Automatic receiver deskew OM4000D Series Coherent Lightwave Signal Analyzer...
Page 147: Appendix E: Equivalent-Time (Et) Oscilloscope Operation
Appendix E: Equivalent-Time (ET) oscilloscope operation Conﬁguring hardware (ET) Ensure that the required power sources for the OM4000 Series (100, 115 or 230 VAC, 50–60 Hz, 0.4 A), the associated oscilloscope, and the external computer (if used) are available. The OM4000 Series Coherent Modulation Receiver, along with proprietary software comprises the OM4000 Series Coherent Lightwave Signal Analyzer (CLSA).
Page 148: Figure 17: Typical Et Oscilloscope Setup Diagram
Appendix E: Equivalent-Time (ET) oscilloscope operation Figure 17: Typical ET oscilloscope setup diagram The Tx Laser Reference should be connected with Polarization-Maintaining (PM) ﬁber. Ethernet connections are not shown. All instruments need to be connected to the same network. Connections list (ET) OM4000 Series Complex Modulation Receiver: Power cable Ethernet cable...
Page 149 Appendix E: Equivalent-Time (ET) oscilloscope operation Supported oscilloscope (1 of the following): Real-time Tektronix Oscilloscope with at least 20 GS/s sampling rate on two or four channels in the 70000 Series (see primary User Guide for information on Real-time) Equivalent-Time Tektronix oscilloscope DSA8300 or DSA8200 with supported sampling heads.
Page 150: Conﬁguring The Software (Et)
My Documents\TekScope\UI\default.stp. You can change the default setup at any time by over-writing the default.stp ﬁle in the Tektronix Scope Utility for ET folder. Make sure to set the following in the DSA8300 instrument:...
Page 151 Appendix E: Equivalent-Time (ET) oscilloscope operation Setup > Mode/Trigger tab: Select the Trigger Source as either Clock or Direct, based on which trigger input is connected. Click the Pattern Sync/FrameScan Setup button and enter the appropriate parameters into the Pattern Sync/FrameScan Setup dialog box, based on settings from the data generator.
Page 152: Om4000 User Interface (Oui) (Et)
Appendix E: Equivalent-Time (ET) oscilloscope operation When the oscilloscope is correctly conﬁgured for your signals, click OK to allow the SSU to ﬁnish its initial launch. This conﬁguration will be recalled any time you launch the SSU. This is done so that the oscilloscope may be used for other tasks and easily made ready for use with the OUI again.
Page 153 Appendix E: Equivalent-Time (ET) oscilloscope operation The green bar at the top indicates that the software is searching for oscilloscopes on the same subnet that are running the Scope Service Utility. As they are found they are added to the drop-down menu. If the OUI Scope Connection Dialog box reports 0 Scopes Found, you will have to type in the IP address manually.
Page 154: Calibration And Adjustment (Et)
Appendix E: Equivalent-Time (ET) oscilloscope operation Once connected and conﬁgured, close the connect dialog box. The OUI is ready to use. Calibration and adjustment (ET) The OM4000 receiver requires the following calibration before taking measurements: DC calibration (to compensate for any offsets in the photodiode outputs) Delay adjustment (channel to channel skew in the scope connections) Hybrid calibration (correction for cross-talk and phase error in the hybrid) Laser linewidth factor (choosing the correct ﬁlter for phase recovery) (See...
Page 155 Appendix E: Equivalent-Time (ET) oscilloscope operation 1. Set up all of the connections for your anticipated measurement. Connect to the receiver using the LRCP and turn on the sources you require. Verify that the oscilloscope is set up correctly. 2. Disconnect the Signal Input to the receiver, so that only the Reference (LO) is present.
Page 156: Figure 18: Chdelay(2) Off By 2 Ps Causes Curvature On Constellation And Signal On Q-Eye For 28 Gbps
Appendix E: Equivalent-Time (ET) oscilloscope operation Use the sliders to get the best possible eye diagram and constellation diagram. Improper skew will cause horizontal eye closure and ﬁlling in of the constellation diagram. If the I and Q channels have unequal delay, there will be a phase offset proportional to the difference frequency between the reference and signal laser oscillation frequencies.
Page 157 Appendix E: Equivalent-Time (ET) oscilloscope operation 4. Now only the top slider will make any difference. Click Run to get a repeating constellation and eye-diagram update. Click the + and – to make 0.1-ps adjustments to the top slider until the BPSK constellation shows as perfectly straight lines connecting the two groups of constellation points as shown above.
Page 158: Figure 19: When Adjusting The Middle Slider, Watch The Y-Eye And Y-Const To Minimize The Signal In The
Appendix E: Equivalent-Time (ET) oscilloscope operation 8. Once this is done get equal signal on both polarizations by re-enabling all four channels: 9. The last step is to set the middle slider to achieve minimum signal in the Y-polarization. Since the input is a single-pol signal at this point, nothing should be in the Y constellation or eyes except for noise.
Page 159: Figure 20: Final Channel Delay Values Provide Only Noise In Y Polarization
Appendix E: Equivalent-Time (ET) oscilloscope operation Figure 20: Final channel delay values provide only noise in Y polarization Hybrid calibration (ET) This is a factory calibration. Imperfections in the OM4000 instrument receiver are corrected using a factory-supplied calibration table. Check the Setup tab for a green indicator to be sure the OUI is successfully retrieving the Reference laser (Local Oscillator) frequency and power which are needed to choose the correction factors from the calibration table.
Page 160 Appendix E: Equivalent-Time (ET) oscilloscope operation Prerequisites. 1. System should be set up and de-skewed following the procedure above. 2. Connect the Reference from Laser 2 to the Reference input with short PM/APC jumper. 3. Use a standard SM/APC (not PM) ﬁber to connect the Laser 1 to the Signal input.
Page 161 Appendix E: Equivalent-Time (ET) oscilloscope operation 7. If the green trace in X-Constellation is elliptical: Click Stop. Type CorrectX in the separate Matlab Application Window. Copy and paste the resulting pHyb statement before DispCalEllipses in the Matlab Engine Window in the OUI as shown below. 8.
Page 162 Appendix E: Equivalent-Time (ET) oscilloscope operation Procedure to Correct the relative X-Y gain (ET). 1. You must complete all of the above steps ﬁrst including CorrectX and CorrectY. 2. Type CorrectXY in the separate Matlab Application Window. 3. Copy and paste the resulting pHyb statement before DispCalEllipses, replacing any other pHyb statement.
Page 163 Appendix E: Equivalent-Time (ET) oscilloscope operation Reference magnitude Oscilloscope sampling rate response reference phase Flat Linear ≤ 2x the bandwidth of the OM4000 (BW) > 2x the bandwidth of the 4th order digital (bilinear) Linear OM4000 (BW) Bessel ﬁlter with 3 dB cutoff at BW + 2 GHz Equalization is speciﬁc to the sampling rate of the oscilloscope.
Page 164: Setting Up An Et Oscilloscope
Appendix E: Equivalent-Time (ET) oscilloscope operation Setting up an ET Oscilloscope Equivalent-time See the following ﬁgure for how to connect the OM4000 instrument to take measurements with equivalent-time (ET) oscilloscopes (Tektronix DSA8300 oscilloscope setup or DSA8200 sampling oscilloscopes). Figure 21: Equivalent-time (ET) oscilloscope setup diagram...
Page 165: Matlab Engine File (Et)
Appendix E: Equivalent-Time (ET) oscilloscope operation While the modulating frequency, f is still the same, the frequency deviation, f has been reduced by 2πf ∆t where ∆t is the time difference for the two paths. Some lasers can have frequency deviations in the 200 MHz range over 1 ms. To minimize the FM bandwidth after detection, reduce the frequency deviation to ~ 1 kHz.
Page 166: Taking Measurements (Et)
Appendix E: Equivalent-Time (ET) oscilloscope operation As with all other settings, the last engine ﬁle used is recalled; you can locate or create another appropriate engine ﬁle and paste it into the OUI Matlab Command window. Subsequent chapters explain in detail the operations of Core Processing. In addition to any valid MATLAB operations you use, there are some special variables that can be set or read from this window to control processing for a few special cases:...
Page 167: Analysis Parameters Window (Et)
Appendix E: Equivalent-Time (ET) oscilloscope operation This control reduces the need to use the oscilloscope front-panel controls while using the OUI. The resolution readout is provided for convenience. Analysis Parameters window (ET) (See page 32, Analysis Parameters window.) The following controls are relevant to Equivalent Time processing: Signal Type: Chooses the type of signal to be analyzed and so also the algorithms to be applied corresponding to that type.
Page 168 Appendix E: Equivalent-Time (ET) oscilloscope operation which symbols to color blue. At present, the sample closest to symbol center is used to represent that symbol for calculations such as BER and Q-factor. Continuous trace points per symbol: The number of samples per symbol for the clock retiming that is done to create the ﬁtted curves such as Eye and Signal Average and Transition Average.
Page 169: Appendix F: Conﬁguring Two Tektronix 70000 Series Oscilloscopes
Appendix F: Conﬁguring two Tektronix 70000 series oscilloscopes OUI Version 1.5 supports a new conﬁguration where two Tektronix 70000-series C- or D-model oscilloscopes are both connected to an OM4000. In this case, the Scope Service Utility (SSU) is installed and run on both oscilloscopes. The OUI connects independently to the two oscilloscopes using the Scope Service Utility running on each oscilloscope.
Page 170 Appendix F: Conﬁguring two Tektronix 70000 series oscilloscopes Ethernet. Connect each instrument to the GigE switch. If you are using an external PC connect this too. See instructions provided above for conﬁguring the IP addresses. USB cable. Connect the standard USB cable between one of the ports on the scopes and the Sync Board.
Page 171: Oscilloscope Settings
Appendix F: Conﬁguring two Tektronix 70000 series oscilloscopes If using an external trigger source instead of self-triggering, drive Ch 2 of the Master with the external source instead of using the Fast Edge of the Master. Conﬁgure the master Ch 2 input as needed to trigger off of your trigger source.
Page 172 Appendix F: Conﬁguring two Tektronix 70000 series oscilloscopes Set the A Event to Ch 2 with appropriate settings for the Ch 2 input. The settings shown are for the Fast Edge oscilloscope output. This is the primary system trigger. The master scope gets two triggers: the primary “A” trigger which arms the system, and the “B”...
Page 173 Appendix F: Conﬁguring two Tektronix 70000 series oscilloscopes The trigger holdoff is set to a ﬁxed time which is managed by the OUI. Longer holdoffs are required for longer records. In the Options tab, set the Master Scope Trigger Holdoff as required. Make sure that the Slave Scope Trigger Holdoff is set to minimum time.
Page 174: Oui Settings For 2-Oscilloscope Operation
Appendix F: Conﬁguring two Tektronix 70000 series oscilloscopes Turn off Channels 2 and 4 when trigger is setup. Set the oscilloscope for 100 Gs/s operation on channels 1 and 3. Select the maximum corrected bandwidth (not the HW setting). OUI settings for 2-oscilloscope operation 1.
Page 175 Appendix F: Conﬁguring two Tektronix 70000 series oscilloscopes 3. To remove inter-scope jitter, add the SkewControl command to the Engine Window as shown in the following ﬁgure. SkewControl removes scope to scope jitter by aligning transitions found in the data. Its utility depends on the quality of the data;...
Page 176 Appendix F: Conﬁguring two Tektronix 70000 series oscilloscopes OM4000D Series Coherent Lightwave Signal Analyzer...
Page 177: Appendix G: The Automated Test Equipment (Ate) Interface
Appendix G: The automated test equipment (ATE) interface Both the OUI and the LRCP have two types of WCF interfaces to allow control from a user application. Both types are provided to achieve full functionality and compatibility with simple interfaces such as MATLAB and via a client application program.
Page 178 Appendix G: The automated test equipment (ATE) interface LRCP service interface The following are the available commands in both the basic and advanced service interfaces and demonstrate their functionality using the MATLAB syntax. Setting function list laser parameters has more information on the LRCP functionality of these exposed functions.
Page 179 Appendix G: The automated test equipment (ATE) interface short GetActualFineTuneFrequency(classname); Description: Returns the actual ﬁne tune frequency (in MHz) of the active laser. Controller Types: 4006, 4106, 2210, 2012 Example: GetActualFineTuneFrequency(Obj); Returns: ans = 0 double GetActualGridSpacing(classname); Description: Returns the actual grid spacing (in THz) of the active laser. Controller Types: 4006, 4106, 2210, 2012 Example: GetActualFineTuneFrequency(Obj);...
Page 180 Appendix G: The automated test equipment (ATE) interface bool GetInterlock(classname); Description: Returns the current interlock state of the active controller. The normal, working state is TRUE. If the interlock is disconnected from the back of the instrument or if the instrument is powered off, this function returns FALSE.
Page 181 Appendix G: The automated test equipment (ATE) interface bool SetActiveControllerByName(classname, string_activeController); Description: Sets the active controller by name. True = Successful. Controller Types: All Example: SetActiveControllerByName(Obj, 'OM4106:6300121'); Returns: ans = true bool SetActiveLaser(classname, byte_activeLaser); Description: Sets the active laser. Returning True = Successful. Controller Types: 4106, 4006, 2210, 2012 Example: SetActiveLaser(Obj, 2);...
Page 182 Appendix G: The automated test equipment (ATE) interface bool SetDesiredEmittingOff(classname); Description: Sets the Active Laser to Off (not emitting). Returning True = Successful. Controller Types: 4006, 4106, 2210, 2012 Example: SetDesiredEmittingOff(Obj); Returns: ans = true bool SetDesiredEmittingOn(classname); Description: Sets the Active Laser to emitting. Returning True = Successful. Controller Types: 4006, 4106, 2210, 2012 Example: SetDesiredEmittingOn(Obj);...
Page 183: The Oui4000 Ate Interface
Appendix G: The automated test equipment (ATE) interface bool SetReceiverOff(classname); Description: Turns the receiver off in the active controller. Returning True = Successful. CAUTION. Ensure laser power is reduced to zero before running this command, otherwise the photoreceiver could be damaged. NOTE.
Page 184 Appendix G: The automated test equipment (ATE) interface OUI setup for ATE There is some setup that is done in the OUI4006 application in preparation for an ATE application. It is necessary to add function calls that perform additional calculations. Variables used in these function calls and shared with the ATE application should be declared as “global”...
Page 185 Appendix G: The automated test equipment (ATE) interface The advanced service, implemented using a wsHTTPBinding and not available in MATLAB, uses events to provide a time-efﬁcient interface. This service, which is only visible when the OIU4006 application is run as administrator, has two components which reside at the following URLs: http://localhost:9200/Optametra/OM4006/WCFServiceOM4006/ http://localhost:9200/Optametra/OM4006/WCFServiceOM4006Bulk/...
Page 186 Appendix G: The automated test equipment (ATE) interface Example: GetBlockSize(Obj); Returns: ans = 50000 double GetMeasurementForChannel(string channel, string name); Description: Returns a double containing information for the speciﬁed channel measurement. Example: GetMeasurementForChannel(obj, "Channel 1", "Pow Crossing Point"); Returns: ans = double The value for channel is either “”...
Page 187 Appendix G: The automated test equipment (ATE) interface uint GetNumberOfProcessedAcquisitions(classname); Description: Returns the number of processed acquistion records taken by the OUI as an unsigned integer. Example: GetNumberOfProcessedAcquisitions(Obj); Returns: ans = 1357 uint GetRecordLength(classname); Description: Returns the current record length from the OUI as an unsigned integer.
Page 188 Appendix G: The automated test equipment (ATE) interface bool IsScopeConnected(classname); Description: Returns a boolean ﬂag of the scope interface state; True = Application is connected to a scope Example: IsScopeConnected(Obj); Returns: ans = true void SetBlockSize(classname, uint newBlockSize); Description: Sets the desired block size in the OUI as an unsigned integer for the next acquisition.
Page 189 Appendix G: The automated test equipment (ATE) interface The following commands are available only in the advanced service interface: public AnalysisParameters GetAnalysisParameters() Description: Returns a analysis parameters object containing the OUI variables. void SetAnalysisParameters(AnalysisParameters analysisParameters) Description: Sets the analysis parameters to new values. double GetDouble(string vname) Description: Returns the value of the passed variable as a double.
Page 190 Appendix G: The automated test equipment (ATE) interface string SendMATLABCommand(string MATLABCommand) Description: This command is used to execuate a MATLAB statement. NOTE. this can only be used when the normal CoreProcessing is disabled or there will be contention with the OUI MATLAB engine. See MATLAB section for usage. void ExecuteMATLABCommands(string commandsToexecute) Description: This command is used to execute a block of MATLAB statements.
Page 191: Ate Functionality In Matlab
Appendix G: The automated test equipment (ATE) interface ATE functionality in MATLAB MATLAB supports a limited subset of the OM4000 Series services, namely the Basic service. This section describes how to create and address the functions from MATLAB. LRCP control The Laser/Receiver Control Panel communicates with other programs using port 9000 on the computer running the Control Panel software.
Page 192 Appendix G: The automated test equipment (ATE) interface OUI control in MATLAB The OM4000 OUI software communicates with other programs via port 9200 on the computer running the OUI software. NOTE. Ensure that the OUI is running before using this interface. To get an up-to-date listing of methods for the OUI basic service type the following: methods(obj) MATLAB should return the same functions (See page 168, OUI control in MATLAB.) and any new functions that have been added.
Page 193: Building An Om4006 Ate Client In Vb.net
Appendix G: The automated test equipment (ATE) interface Building an OM4006 ATE client in VB.NET The following document explains how to build an OM4006 ATE Client application in VB.NET using the OM4006ATEClient .NET Assembly provided with the OUI4006 ATE Toolkit. The ATE interface to OUI4006.EXE is implemented using several WCF Services.
Page 194 Appendix G: The automated test equipment (ATE) interface Add service references in The OM4006Client assembly will need to know where to look for the WCF Services. Those services can reside on the local machine or on a remote computer. APP.CONFIG ﬁle of the ATE The information is used by the OM4006ATEClient assembly to establish a client application connection to the host OUI4006 application.
Page 195 Appendix G: The automated test equipment (ATE) interface maxStringContentLength="1000000000" maxArrayLength="1000000000" maxBytesPerRead="1000000000" maxNameTableCharCount="1000000000" /> </binding> </basicHttpBinding> <wsDualHttpBinding> <binding name="WSDualHttpBinding_IWCFServiceOM4006" closeTimeout="00:10:00" openTimeout="00:01:00" receiveTimeout="00:10:00" sendTimeout="00:10:00" bypassProxyOnLocal="false" transactionFlow="false" hostNameComparisonMode="StrongWildcard" maxBufferPoolSize="524288" maxReceivedMessageSize="65536" messageEncoding="Text" textEncoding="utf-8" useDefaultWebProxy="true"> <readerQuotas maxDepth="32" maxStringContentLength="8192" maxArrayLength="16384" maxBytesPerRead="4096" maxNameTableCharCount="16384" /> <reliableSession ordered="true" inactivityTimeout="00:10:00" /> <security mode="Message">...
Page 196 Appendix G: The automated test equipment (ATE) interface OM4006Bulk" contract="WCFServiceOM4006Bulk.IWCFServiceOM4006Bulk" name="BasicHttpBinding_IWCFServiceOM4006Bulk"> <identity> <dns value="localhost" /> </identity> </endpoint> </client> </system.serviceModel> OM4006ATEClientNET This assembly includes a basic interface for retrieving MATLAB variable values and an object oriented interface that includes specialized .NET classes for all assembly of the OM4000 instrument speciﬁc variables.
Page 197 Appendix G: The automated test equipment (ATE) interface Dim processingDone As ManualResetEvent = New ManualResetEvent(false) ' this event handler will register the “BER” variable ' for update at the end of a block, connect to a scope ' and do a single acquisition Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load...
Page 198 Appendix G: The automated test equipment (ATE) interface Use of this method requires a bit more knowledge of object oriented development and the use of classes. It requires less code to implement and it deals with the string case sensitivity within the specialized variable classes so it is less prone to error.
Page 199 Appendix G: The automated test equipment (ATE) interface ' be referenced like any other .NET class totalBits = myBER.TotalBits processingDone.Set() ' signals the main thread that the event has been handled End Sub End Class If there is a desire by the customer to access their custom variables using the second method they can develop their own classes by inheriting from the appropriate MATLABVariable*.
Page 200 Appendix G: The automated test equipment (ATE) interface The following user control (ucATESecurity) is provided in the OM4006Client. A password is required and is saved in an encrypted form in the App.Conﬁg.AppSettings along with the unscrambled user name and machine name.
Page 201: Appendix H: Cleaning And Maintenance
Appendix H: Cleaning and maintenance Cleaning To clean the outside of the OM4000 enclosure, use a dry, soft cotton cloth. Do not use any liquid cleaning agents or chemicals that could possibly inﬁltrate the enclosure, or that could damage markings or labels. If the dust ﬁlter on the underside of the unit becomes clogged, use a small vacuum or brush to clean the ﬁlter.
Page 202 Appendix H: Cleaning and maintenance OM4000D Series Coherent Lightwave Signal Analyzer...
Page 203: Index
Index Symbols and Numbers Core processing software Front panel labels, x guide, 79 2D Poincare sphere, 51 Count bit errors, 86 General safety summary, vi Absolute power calibration, 119 Delay adjustment (system AC line voltage requirements, 5 deskew), 131 Accessories Hybrid calibration, 135 Delay adjustment (system deskew) optional, 2...
Page 204 Index Matlab Engine ﬁle (ET), 141 OM4000 user interface (OUI) Requirements MATLAB functions, 81 2D Poincare sphere, 51 AC line voltage, 5 MATLAB variables, 80 Analysis parameters, 32 environmental, 4 assignment of pattern operating, 4 about the multicarrier variables, 39 PC, 6 spectrum plot, 70 assignment of pattern...
Page 205 Index Waveform averaging, 48 OM4000D Series Coherent Lightwave Signal Analyzer...

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