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Optical Modulation Analyzer

Your system should look similar to this:

Connect Optical Signals

CAUTION

Teledyne LeCroy coherent receivers utilize good quality connectors in compliance with EIA-

455-21A standards. To keep connectors clean and in good condition, inspect them with a

fiber-inspection probe before connecting them. Failure to do so will result in permanent

damage to the connectors and degradation in measurements.

LEAN

PTICAL

IBERS

Clean the fiber ends as follows:

Gently wipe the fiber end with a lint-free swab moistened with isopropyl alcohol.

Use compressed air to dry it completely.

Visually inspect the fiber end to ensure its cleanliness.

Содержание IQS25

Страница 1: ...Operator s Manual Optical Modulation Analyzer ...

Страница 2: ......

Страница 3: ...Optical Modulation Analyzer Operator s Manual August 2016 ...

Страница 4: ...n purposes is strictly prohibited However clients are encouraged to duplicate and distribute Teledyne LeCroy documentation internally for their own educational purposes LabMaster X Stream and Teledyne LeCroy are trademarks of Teledyne LeCroy Inc Other product or brand names are trademarks or requested trademarks of their respective holders Information in this publication supersedes all earlier ver...

Страница 5: ...cture 5 Safety 7 Symbols 7 Oscilloscope Precautions 7 Coherent Receiver Precautions 8 Operating Environment 8 Cooling 9 Cleaning 9 Calibration 9 Lifting and Moving 9 Power 10 Fuse Replacement 10 Grounding 10 System Installation 11 Hardware Configuration 11 Optical Configuration 14 Coherent Receiver LCD Control Interface 20 Navigating the LCD Control Interface 20 Changing Numerical Values 20 Changi...

Страница 6: ...ATLAB Scripts 50 Using X Stream Browser 51 Applying Math and Measurements to OMA Data 52 Applying Math Functions 52 Applying Measurements 53 Maintenance 54 Troubleshooting 54 Technical Support 55 Returning a Product 56 Warranty 57 Certifications 58 Appendix 1 OMA Calibration 61 Coherent Receiver Factory Calibrations 61 Full System Factory Calibrations 61 Manual Calibrations 61 Dynamic Calibrations...

Страница 7: ...t Definitions 66 I and Q Bias Offset 66 IQ Offset 67 IQ Quadrature Error 67 IQ Skew 68 IQ RF Imbalance 69 Error Vector Magnitude 70 Magnitude Error 71 PMD 71 PDL 72 XY Skew 72 Q Factor 72 BER Estimate 72 Appendix 4 Reference Symbols and Encodings 73 ...

Страница 8: ...i A or one of the compatible acquisition modules listed on page 4 Coherent receiver Teledyne LeCroy IQS25 IQS42 or IQS70 or Coherent Solutions IQScope RT OMA Software The Optical LinQ optical modulation analysis software v 8 0 x x or higher Firmware The X Stream oscilloscope software About Teledyne LeCroy Teledyne LeCroy is a leading manufacturer of advanced test instruments that measure analyze a...

Страница 9: ...r s high bandwidth and long acquisition memory the coherent receiver enables high speed and accurate characterization of complex optical modulations Optical Modulation Analyzer hardware The fully integrated Optical LinQ software provides intuitive touch screen control of the OMA system measurements designed for optical analysis and powerful signal visualization capabilities Optical Modulation Anal...

Страница 10: ...le 1 IQS25 Coherent Receiver 1 36 GBaud LM 10 36Zi A Acquisition Module 1 IQS42 Coherent Receiver 1 56 GBaud LM 10 65Zi A Acquisition Module 1 2 IQS70 Coherent Receiver 1 Depending on desired number of high bandwidth polarizations OMA Accessories The following may be purchased separately for an OMA system Contact your regional sales representative Item PN Quantity Receiver Rackmount Kit for use wi...

Страница 11: ... Control dial for LCD control interface 5 Y Pol I RF output 6 Y Pol Q RF output 7 Laser On Off 8 Power On Off 9 Built in laser output PM FC PM 10 Reference LO input PM FC PC 11 Modulated optical signal input FC PC 12 USB connection to MCM Zi A 13 Mains power isolation switch 14 AC power inlet 100 240 V 50 60 Hz 20W max ...

Страница 12: ...of a complete Teledyne LeCroy OMA system The following hardware has been tested to be compatible with each other and the Optical LinQ OMA software Coherent Receivers Coherent Solutions IQScope RT Master Control Modules LabMaster MCM Zi Zi A LabMaster 9CZi A Acquisition Modules LabMaster 10 20Zi Zi A LabMaster 10 25Zi Zi A LabMaster 10 30Zi Zi A LabMaster 10 36Zi Zi A LabMaster 10 50Zi Zi A LabMast...

Страница 13: ...he front end sampling and present this data to the OpticalLinQ OMA software for analysis The first step in this process is receiver calibration and correction which must be performed every time an acquisition session is to be started The next stage in the process is a set of Digital Signal Processing DSP algorithms which form the core of the OMA functionality The DSP operates in three stages Dispe...

Страница 14: ...Optical Modulation Analyzer 6 OMA system architecture with an emphasis on signal flow through the various components ...

Страница 15: ...ower On rear Power switch connected to AC mains Power Off rear Power switch disconnected from AC mains Oscilloscope Precautions Comply with the following instructions to avoid personal injury or damage to your equipment Maintain ground This product is grounded through the power cord grounding conductor To avoid electric shock connect only to a grounded mating outlet Connect and disconnect properly...

Страница 16: ...Use a torque wrench to control the tightening pressure on all RF connections Optical Connections WARNING Do not install or terminate fibers while a light source is active Care must be taken to ensure that any connected light sources and the instrument have been turned off before inspecting the end face s of the instrument or any optical patch cords connected to the instrument Never look directly i...

Страница 17: ...rts Refer to qualified service personnel See Clean Optical Fiber and Clean Optical Bulkhead Connector for optical cleaning instructions Calibration The oscilloscope and the coherent receiver are calibrated at the factory prior to being shipped The recommended calibration interval for both is one year CAUTION Calibration should be performed by qualified personnel only Schedule an annual factory cal...

Страница 18: ...t with a new 5 X 20 mm T rated 1 0 A 250 V fuse 3 Replace the fuse holder Grounding The MCM Zi A Master Control Module is provided with a 10A 250V rated grounded cord set containing a molded three terminal polarized plug with a standard IEC 60320 Type C13 connector The LM 10 36Zi A LM 10 25Zi A and LM 10 65Zi A acquisition modules are provided with a 16A 250V or 15A 125V rated grounded cord set co...

Страница 19: ...A components are heavy Do not attempt these installation procedures without assistance Standard Bench Top Configuration The depth of the coherent receiver case has been designed to provide solid support for the MCM Zi A Place the coherent receiver on top of the acquisition module then place the control module on top of the coherent receiver Go on to make the power USB and other cable connections o...

Страница 20: ...o the threaded holes located at the front of both sides of the coherent receiver Ensure all four screws of both brackets are securely fastened 2 With assistance position the coherent receiver within the instrument rack IMPORTANT Ensure sufficient room to mount the other units around the receiver This varies depending on the number of acquisition modules 3 With the coherent receiver held in positio...

Страница 21: ...illuminate indicating that the AC power supply is live and the coherent receiver is ready to be powered on Press the Power On Off button on the front of the coherent receiver to power on Connect Coherent Receiver to Control Module The coherent receiver must have a USB connection to the control module in order for the OMA software to read the factory calibration data from the instrument and perform...

Страница 22: ...Optical Modulation Analyzer 14 Optical Configuration Typical dual polarization optical configuration ...

Страница 23: ...Operator s Manual 15 Example Optical Configurations DUAL POLARIZATION BUILT IN LO DUAL POLARIZATION USER SUPPLIED LO SINGLE POLARIZATION BUILT IN LO ...

Страница 24: ...he XI RF cable attach the 1 85mm 2 4mm connector to the X Pol I port on the coherent receiver Then attach the 2 92mm connector to the CH1 port of the acquisition module 2 Repeat this using the following cables and inputs Attach the XQ RF cable from the X Pol Q port on the coherent receiver to the CH2 port of the LabMaster acquisition module Attach the YI RF cable from the Y Pol I port on the coher...

Страница 25: ...ol I output of the coherent receiver to a DBI channel of the LabMaster acquisition module e g CH2B 2 Using the XQ RF cable connect X Pol Q output of the Coherent receiverto a DBI channel of the LabMaster acquisition module e g CH3B Your system should look similar to this For dual polarization set up with two DBI acquisition modules continue with the Y polarization connections 3 Using the YI RF cab...

Страница 26: ... clean and in good condition inspect them with a fiber inspection probe before connecting them Failure to do so will result in permanent damage to the connectors and degradation in measurements CLEAN OPTICAL FIBERS Clean the fiber ends as follows 1 Gently wipe the fiber end with a lint free swab moistened with isopropyl alcohol 2 Use compressed air to dry it completely 3 Visually inspect the fiber...

Страница 27: ...ut of the coherent receiver CONNECT OPTICAL FIBER Connect the modulated signal you wish to measure into the Modulated Signal optical port of the coherent receiver The fiber type can be either PM or non PM The optical connector type is FC PC IMPORTANT The power level going into the Modulated Signal input must be between 0 dBm and 12 dBm 1 Carefully align the connector and port to prevent the fiber ...

Страница 28: ...e cursor up or right to move the cursor down Once the cursor is at the desired menu item select it by pressing in the control dial once Changing Numerical Values 1 Move the cursor to select the line containing the value 2 Turn the dial until the digit you wish to change is flashing 3 Press the dial in once then turn it until the desired value is shown 4 Press the dial again to exit the current sel...

Страница 29: ...rn the dial to select the STEP SIZE menu then press 3 Continue pressing the dial until you see the desired step increment The value can be toggled from 0 1GHz to 25GHz 4 Turn the dial until DONE is selected then press Changing the Output Power The second line on the menu for the output laser is the power output This has units of either dBm or mW The values can be adjusted in steps of 0 01 dBm or 0...

Страница 30: ...the LabMaster is set up for the first time and thereafter whenever a new acquisition module is installed NOTE You will need a high bandwidth RF cable to connect from the Fast Edge output of the MCM Zi A to each of the input channels on the acquisition module 1 From the menu bar choose Vertical Channel 1 Setup and click the ChannelSync Cal button 2 On the ChannelSync Calibration Wizard choose the i...

Страница 31: ...TIP You can also turn off linear interpolation and display only discrete samples Go to Display Setup Response Optimization Mode The frequency response and group delay of the oscilloscope contribute to the pulse response characteristics of the instrument The characteristic response of the oscilloscope can be optimized for your specific application by adjusting the Optimize setting on the Channel Ve...

Страница 32: ...l LinQ Teledyne LeCroy s optical modulation analysis software is fully integrated into the LabMaster X Stream firmware application It can be started by choosing Analysis OMA from the LabMaster touch screen menu bar The OMA dialog appears at the bottom of the touch screen for you to begin to configure the inputs ...

Страница 33: ...rresponding configuration subdialogs E Configurations dialogs present the optical input electrical input signal processing graphing and measurement settings Acquisition Controls These parameters control the time domain of the acquisition The default values are filled in at startup Longer acquisition implies that OMA will update its output slowly Typically 2000 3000 symbols and 10 20 samples per sy...

Страница 34: ...ter side such as output power change then a manual calibration Force Calibration may be required for better signal characterization Control Action 2 Pol Specifies signal is polarization multiplexed 1 Pol Specifies signal is not polarization multiplexed Force Calibration Repeats calibration Modulation Type Sets signal s digital modulation scheme Select from a wide variety of complex modulation form...

Страница 35: ...pear Use the Symbol Definition dialog to enter symbol definitions QPSK example shown below Control Action Edit Symbols Opens the Symbol Editor Load From File Allows you to browse to and load a previously saved symbol file Safe to File Saves contents of the Editor window to a new symbol file Close Submits symbol list ...

Страница 36: ... measures its own output power This figure is displayed below the Power control This measurement can differ slightly from the Power control setting Control Action Enabled Turns the laser on off Power Sets the output power specified in dBm Set v or ʎ Changes the units frequency wavelength Frequency Sets the output frequency specified in the selected units Locked Indicates whether laser is at the re...

Страница 37: ...d to select the calibration script used by the receiver If using a Teledyne LeCroy IQSxx or a legacy Coherent Solutions IQScope RT select IQScope The IQScope Connected status checkbox will turn green when the software detects an IQScope via USB interface If using a third party coherent receiver select Custom then touch Browse and select your custom calibration script CRS file NOTE The default scri...

Страница 38: ...lIQPhaseError_rads 0 YpolIQPhaseError_rads 0 skew Units picoseconds Type float Range 1 us to 1 us Default 0 XqtoXiSkew_ps 0 YitoXiSkew_ps 0 YqtoXiSkew_ps 0 frequency Units Hz Type Float array Range 0 to 1 THz Default 0 FrequencyAxis_Hz 0 2068965517 24138 4137931034 48276 6206896551 72414 8275862068 96552 10344827586 2069 12413793103 4483 14482758620 6897 16551724137 9310 18620689655 1724 206896551...

Страница 39: ...Magnitude 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Units radians Type Float array Range pi to pi Default 0 Max size of the array 1024 1K Length must be the same as FrequencyAxis_Hz XiPhase_rads 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 XqPhase_rads 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 YiPhase_rads 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0...

Страница 40: ...t the algorithms to be applied to the signal Control Action Pre processor First stage in the DSP chain Can be set to built in Filters a Custom algorithm or None Dispersion Compensation Sets dispersion compensation algorithm used Frequency based FIR Finite Impulse Response a Custom algorithm or None Pol DeMux Sets polarization de multiplexing algorithm used CMA MMA a Custom algorithm or None Carrie...

Страница 41: ... function RC Raised Cosine frequency spectrum resembles a cosine function and RRC Raised Root Cosine the square root of the RC filter The controlling parameters for these filters are described below Control Action Bandwidth Sets filter s bandwidth the difference between upper and lower cutoff frequencies Center Frequency Sets central frequency between upper and lower cutoff Rolloff Controls the st...

Страница 42: ...lyzer 34 When the Custom filter option is selected the Pre Custom subdialog is displayed Click Edit Code to open the MATLAB editor and input your algorithm More information can be found in Using Custom MATLAB Scripts on p 50 ...

Страница 43: ...iber in s m2 Total Dispersion Displays the product of the above two parameters or can be used to directly specify the value Num Taps FIR only Sets the number of filter taps Polarization De Multiplexing Parameters Demux Use the Demux subdialog to specify the parameters for the selected polarization de multiplexing algorithm Control Action Gradient Sets speed and accuracy of the adaptation Symbols S...

Страница 44: ...divided by M The resulting angle is adjusted in case it lies outside π 2 or π 2 Finally the estimated phase error is applied to the signal The modified VV algorithm suits PSK modulation formats where all symbol phases are equidistant For high density QAM the DD algorithm is provided which uses a feed forward mechanism Here we consider each symbol and match it with the closest reference symbol The ...

Страница 45: ...7 Post processor Filter Parameters Post Filter This is similar to the Pre processor stage p 33 where a range of built in filters can be selected You can input a custom algorithm via MATLAB or set to None to simply bypass ...

Страница 46: ...speed and accuracy of the adaptation The value ranges from 1e 6 to 1 Smaller numbers will result longer convergence time over the training symbols but better results in presence of noise and vice versa for higher numbers The default is a good compromise between the two as seen over a range of signals Symbols Enter the length of the training set Num Taps Enter the number of taps in the equalizer ke...

Страница 47: ...ster display features can also be applied to OMA graphs Traces and eye diagrams can be moved to different grids simply by dragging and dropping the descriptor box onto the destination grid NOTE The I Q grid which shows the constellation and trajectories is an exception other plots cannot be moved to this grid Traces can be labeled with custom annotations using the Label feature or LabNotebook Disp...

Страница 48: ...Optical Modulation Analyzer 40 OMA display with 3D color persistence applied to highlight more frequently occurring samples ...

Страница 49: ...e LabMaster Math functions allow further processing of the OMA trace data See Applying Math Functions on p 52 TRACE DISPLAY MODE When in Single mode selected at top right corner of the menu bar X and Y pols are each displayed in different tabs as shown here In Mosaic mode these tabs are shown side by side ...

Страница 50: ...olution Intensity Magnitude of the electric field Phase Phase of the electric field Units are in degrees EVM Error vector as a percentage See p 70 for details on how this value is computed Phase Error Estimated phase error Units are in degrees Carrier Phase Estimated phase of the carrier wave Units are in degrees Spectrum Spectrum Efield Power spectrum of the Efield Units are in dB SpectrumI Spect...

Страница 51: ...d Constellation diagrams As with traces these diagrams can be shown in Mosaic mode or Single mode Constellation diagrams for a QPSK dual Pol signal arranged in mosaic mode The Scale Factor on the I Q dialog controls how much area will be occupied by the plot inside the window ...

Страница 52: ...ye diagrams to compute from the Eyes subdialog I and Q eye diagrams for a QPSK dual Pol signal arranged in mosaic mode The Scale Factor controls how much area will be occupied by the plot inside the window This is the same variable as for the I Q plots and changing it will change their scale too and vice versa ...

Страница 53: ... between the signal vector and the ideal reference vector Q Factor An alternate representation of the signal to noise ratio presented in dB BER Estimate An instantaneous estimation of the bit error rate calculated from the Q Factor A less time consuming alternative to actual bit counting I Bias Error Center of the I component with reference to the ideal center point presented as a percentage Q Bia...

Страница 54: ...ween the reference symbol and the signal vector Phase Error Phase difference between the signal vector and the ideal reference vector PMD Polarization Mode Dispersion parameter calculated within the Polarization Demultiplexing Algorithm Requires the selection of a Polarization De multiplexing algorithm XY Skew The difference between the X polarization and Y polarization symbol centers Requires the...

Страница 55: ...nge of Pseudo Random Bit Sequences PRBS are provided to support common cases You can also define custom bit patterns Touch the BER button to access the BER subdialog group BER SETTINGS Control Selection Action Description Streams Enable BER Turns on off BER functionality Pattern Mapping Independent Xi Xq Yi and Yq are considered independent data streams Yi and Yq will only be available in Dual Pol...

Страница 56: ...d in Appendix 4 Reference Symbols and Encodings on p 73 Custom BER encoding defined through Optical LinQ software You may input a Custom symbol to code map Touch View Edit and input your symbol codes one per line on the BER Encoding window The order of these codes must match the custom reference symbols you input on the Optical Inputs Modulation Type dialog ...

Страница 57: ...pattern to be specified BIT ERROR RATE Once patterns mapping and selection has been performed the results can be seen on the Bit Error Rate subdialog The number of rows in this table depends on how many output streams are present A cumulative bit and error count is displayed which can be cleared using the Reset button A green checkmark in Lock indicates that the pattern was found in the incoming d...

Страница 58: ...s An example template MATLAB m file is installed on the LabMaster at D Scripts This file will guide you in setting up the input and output parameters Choosing Custom Algorithms When you make a Custom selection for any of the Signal Processing algorithms the parameter input subdialogs provide access to the MATLAB Editor window From there you can navigate to and load a MATLAB script file or begin sc...

Страница 59: ...r Windows desktop 2 Double click the X Stream Browser icon 3 In the X Stream Browser window click the top left icon to connect to the local oscilloscope application Navigating to OMA will show the data corresponding to the current state of the OMA software Some values can be changed from within this application by right clicking and entering new data The LabMaster automatically shows the updated r...

Страница 60: ...aster Math functions can be operated on any of the OMA s data outputs There are 12 math function slots available for use F1 F12 When a function is configured and turned on a new Math trace appears on the display showing the result of the operation applied to the OMA data Choose Math Math Setup from the menu bar then open a function tab Fx Check Trace On to show the Math trace When selecting the fu...

Страница 61: ...hoose Measure Measure Setup from the menu bar Be sure to check Show Table to display the measurement table then open one of the parameter Px dialogs When selecting the parameter Source navigate to the Main OMA submenu and choose from the OMA output traces and data Back on the Px dialog select the Measure ment as usual You may optionally show measurement statistics in addition to the acquired value...

Страница 62: ... the wavelength of the laser internal or external matches that of the transmitter 3 Check RAW traces in OMA to make sure that signal values are not clipped or too low Some transmitters do not send stable signals right after they are powered on Any RX calibration during this phase will fail as the signal may clip when out of range Another common failure mode is that calibration succeeds but output ...

Страница 63: ...ifications Oscilloscope System Recovery Tools and Procedures contains instructions for using the Acronis True Image Home recovery application included with the instrument You can also submit Technical Support requests via the website at teledynelecroy com support techhelp Service Centers For a complete list of offices by country including our sales distribution partners visit teledynelecroy com su...

Страница 64: ... case with a tag containing The RMA Name and address of the owner Product model and serial number Description of failure or requisite service 4 Pack the product case in a cardboard shipping box with adequate padding to avoid damage in transit 5 Mark the outside of the box with the shipping address given to you by Teledyne LeCroy Be sure to add the following ATTN RMA code assigned by Teledyne LeCro...

Страница 65: ...ine the product and find that it is defective due to workmanship or materials and not due to misuse neglect accident or abnormal conditions or operation The instrument s firmware has been thoroughly tested and is presumed to be functional Nevertheless it is supplied without warranty of any kind covering detailed performance Teledyne LeCroy shall not be responsible for any defect damage or failure ...

Страница 66: ...ectromagnetic Field 3 V m 80 1000 MHz 3 V m 1400 MHz 2 GHz 1 V m 2 GHz 2 7 GHz EN 61000 4 4 A1 2010 Electrical Fast Transient Burst 1 kV on power supply lines 0 5 kV on I O signal data and control lines 4 EN 61000 4 5 2006 Power Line Surge 1 kV AC Mains L N L PE N PE 4 EN 61000 4 6 2009 RF Conducted Electromagnetic Field 3 Vrms 0 15 MHz 80 MHz EN 61000 4 11 2004 Mains Dips and Interruptions 0 1 cy...

Страница 67: ... control and laboratory use Part 1 General requirements EN 61010 2 030 2010 Safety requirements for electrical equipment for measurement control and laboratory use Part 2 030 Particular requirements for testing and measuring circuits The design has been verified to conform to the following limits put forth by these standards Mains Power Supply Circuits Overvoltage Category II instrument intended t...

Страница 68: ...equirements to Directives 2012 19 EU and 2013 56 EU on Waste Electrical and Electronic Equipment WEEE and Batteries The instruments are subject to disposal and recycling regulations that vary by country and region Many countries prohibit the disposal of waste electronic equipment in standard waste receptacles For more information about proper disposal and recycling of your Teledyne LeCroy product ...

Страница 69: ...iver Full System Factory Calibrations X pol and Y pol channel balance of the complete system including the oscilloscope Manual Calibrations LabMaster ChannelSync deskew calibration Dynamic Calibrations LabMaster temperature dependent calibration 5 C factory calibration temperature OMA software calibrations prior to each signal measurement These dynamic calibrations include o Voltage scale optimiza...

Страница 70: ...SMF and polarization mode dispersion is treated as the main non linear dispersion Uncorrected fiber dispersion distorts the optical signal and it needs to be corrected for to obtain the transmitted signal information OMA parameters for correcting chromatic dispersion Chromatic Dispersion CD is a linear process and it can be compensated by applying the opposite dispersion in either the frequency do...

Страница 71: ...to fiber birefringence These effects cannot easily be predicted since they are dependent on stresses and strains on different parts of the fiber NOTE A specially designed type of fiber known as polarization maintaining PM fiber does not allow the polarization to rotate so that the light exits fiber at a known polarization state One of the most common Polarization De multiplexing Algorithm is Const...

Страница 72: ... The DSP scans the entire range of frequency offset and finds the value which gives the minimum error The DSP automatically corrects this frequency offset The maximum frequency offset that the DSP can handle is 10 of the baud rate For more information on the frequency offset compensation technique please refer to Y Wang E Serpedin and P Ciblat Non Data Aided Feedforward Estimation of PSK Modulated...

Страница 73: ... be the average and the symbol will be shifted to the ideal position when the average phase error is corrected The frequency estimate and phase estimate algorithms can be performed on each polarization independently or you can speed up the processing time by assuming that they are identical for each state of polarization for dual polarization signals originating from a single laser source Pols Sep...

Страница 74: ...bias errors in percentages since this makes it independent of the average optical power Additionally the bias error can be separated into orthogonal components I and Q as shown in Equation 1 to help identify the origin of the bias error Since the electrical to optical transfer function of optical modulators is typically non linear a 5 bias offset as measured in the optical domain may not necessari...

Страница 75: ...e Error The quadrature error is a measure of the phase error of the constellation points with respect to the ideal phase relationship between the constellation points For QPSK and QAM modulation formats the ideal phase between the constellation points is 90 The quadrature error is an average measurement taken over all the constellation points Equation 2 Equation 2 Quadrature error calculation Quad...

Страница 76: ...nalyzer 68 IQ Skew The IQ skew is a measure of the time difference between the in phase and quadrature crossing points in the eye diagrams as shown below Equation 3 Skew timing calculation Eye diagrams of QPSK signal skew ...

Страница 77: ...hase component versus the Quadrature component of the constellation points The ratio is represented as a percentage so 10 IQ RF imbalance would mean that the In phase component is 10 larger than the Quadrature component Equation 4 IQ RF imbalance calculation IQ RF imbalance for QPSK ...

Страница 78: ...ctor and the ideal reference vector It is more convenient to represent the EVM as a percentage such that it is unaffected by the average signal power Equation 5 The numerical value displayed as EVM in the software is the RMS of all the symbols captured during that acquisition Equation 5 Error vector magnitude calculation Error vector magnitude single sample point ...

Страница 80: ... this measurement is determined by the number of samples per baud Q Factor Q Factor is an alternate representation of the signal to noise ratio that is commonly used since its relationship with the BER is more intuitive Q factor is often represented in dB Q factor 3 log2 𝐿𝐿 𝐿𝐿2 1 2 𝐸𝐸𝐸𝐸𝐸𝐸 100 2 log2 2𝑆𝑆𝑝𝑝𝐵𝐵 Equation 9 Q Factor calculation Q factor𝑑𝑑𝑑𝑑 20 log10 𝑄𝑄 𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓 Equation 10 Q Factor ...

Страница 81: ...ncoding Binary Gray1 Gray2 0 0 0000 0 1 1 4142 1 Modulation BPSK bitsPerSymbol 2 Index Symbol Encoding Binary Gray1 Gray2 0 1 1 1 1 0 Modulation QPSK bitsPerSymbol 2 Index Symbol Encoding Binary N A Gray1 Gray2 0 0 7071 0 7071i 11 1 0 7071 0 7071i 01 2 0 7071 0 7071i 00 3 0 7071 0 7071i 10 Modulation 8PSK bitsPerSymbol 3 Index Symbol Encoding Binary N A Gray1 Gray2 0 1 0i 000 1 0 7071 0 7071i 001 ...

Страница 82: ... Gray2 0 0 316 0 316i 0101 0101 0111 1 0 316 0 316i 1001 1101 1111 2 0 316 0 316i 1010 1111 1101 3 0 316 0 316i 0110 0111 0101 4 0 9487 0 316i 0001 0001 0011 5 0 316 0 9487i 0100 0100 0110 6 0 316 0 9487i 1000 1100 1110 7 0 9487 0 316i 1101 1001 1011 8 0 9487 0 316i 1110 1011 1001 9 0 316 0 9487i 1011 1110 1100 10 0 316 0 9487i 0111 0110 0100 11 0 9487 0 316i 0010 0011 0001 12 0 9487 0 9487i 0000 ...

Страница 83: ...i 10000 10 0 2234 0 6708i 01100 11 0 6708 0 2234i 01001 12 0 6708 0 6708i 01011 13 0 6708 0 6708i 10111 14 0 6708 0 6708i 10100 15 0 6708 0 6708i 01000 16 1 118 0 2234i 00110 17 0 2234 1 118i 00010 18 0 2234 1 118i 11110 19 1 118 0 2234i 11010 20 1 118 0 2234i 11001 21 0 2234 1 118i 11101 22 0 2234 1 118i 00001 23 1 118 0 2234i 00101 24 1 118 0 6708i 00111 25 0 6708 1 118i 00011 26 0 6708 1 118i 1...

Страница 84: ...11110 12 0 4630 0 4630i 010010 011011 13 0 4630 0 4630i 101010 111011 14 0 4630 0 4630i 101101 111111 15 0 4630 0 4630i 010101 011111 16 0 7715 0 1543i 001011 001010 17 0 1543 0 7715i 011001 010001 18 0 1543 0 7715i 100001 110001 19 0 7715 0 1543i 110011 101010 20 0 7715 0 1543i 110100 101110 21 0 1543 0 7715i 100110 110101 22 0 1543 0 7715i 011110 010101 23 0 7715 0 1543i 001100 001110 24 0 7715 ...

Страница 85: ...i 000010 000011 45 0 4630 1 0801i 010000 011000 46 0 4630 1 0801i 101000 111000 47 1 0801 0 4630i 111010 100011 48 1 0801 0 4630i 111101 100111 49 0 4630 1 0801i 101111 111100 50 0 4630 1 0801i 010111 011100 51 1 0801 0 4630i 000101 000111 52 1 0801 0 7715i 000001 000001 53 0 7715 1 0801i 001000 001000 54 0 7715 1 0801i 110000 101000 55 1 0801 0 7715i 111001 100001 56 1 0801 0 7715i 111110 100101 ...

Страница 86: ...Optical Modulation Analyzer 78 ...

Страница 87: ......

Страница 88: ...927295 00 Rev A August 2016 ...

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