OM1106 Coherent Lightwave Analyzer Software Datasheet
Contents
1. Od Eve Hescht Rall Std Dew Radil Std Dew 15 66 dB 2465 01974 02114 l 15 83 dB 2512 01989 02072 15 87 dB 2495 01904 02022 bl Field eye diagram Field eye measurements Measurement Description Q dB Computed from 20 x Log10 of the linear decision threshold Q factor of the eye Eye Height The distance from the mean 1 level to the mean 0 level units of plot Raild Std Dev The standard deviation of the 0 level as determined from the decision threshold Q factor measurement Rail1 Std Dev The standard deviation of the 1 level as determined from the decision threshold Q factor measurement In the case of multilevel signals the above measurements are listed in the order of the corresponding eye openings in the plot The top row values correspond to the top most eye opening The above functions involving Q factor use the decision threshold method described in the paper by Bergano 2 When the number of bit errors in the measurement interval is small as is often the case the Q factor derived from the bit error rate may not be an accurate measure of the signal quality However the decision threshold Q factor is accurate because it is based on all the signal values not just those that cross a defined boundary Additional measurements available for nonoffset formats Measurement Description Overshoot The fractional overshoot of the signal One value is reported for the tributary and for a multilevel2. Q plots are a great way to get a handle on your data signal quality Numerous BER measurements vs decision threshold are made on the signal after each data acquisition Plotting BER vs decision threshold shows the noise properties of the signal Gaussian noise will produce a Straight line on the Q plot The optimum decision threshold and extrapolated BER are also calculated This gives you two BER values the actual counted errors divided by the number of bits counted as well as the extrapolated BER for use when the BER is too low to measure quickly OM1106 Q plot Constellation diagrams 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 When continuous traces are also shown in the complex plane this is often called a Phase Diagram Since the continuous traces can be turned on or off we refer to both as the Constellation Diagram The scatter of the symbol points indicates how close the modulation is to ideal The symbol points spread out due to additive noise transmitter eye closure or fiber impairments The scatter can be measured by symbol standard deviation error vector magnitude or mask violations PSphere LEE Constellation diagram www tektronix com 3 Datasheet Constellation measurements Measurements made on constellation diagrams are
3. time in the complex plane FFT of power X signal or laser phase noise MATLAB Window Commands may be entered that execute each time signals are acquired X X and processed Measurements vs Time Optical field symbol center values errors and averaged waveforms are X X displayed vs time in the OUI any parameter can be plotted vs time using the appropriate MATLAB expression 3D Measurements 3D Eye complex field values vs time and 3D Poincar Sphere for X symbol and tributary polarization display Differential Eye Diagram Display Balanced or single ended balanced detection is emulated and displayed X in the Differential Eye Diagram Frequency Offset Frequency offset between signal and reference lasers is displayed in X Measurement panel Poincar Sphere Polarizations of the Pol muxed signal tributaries are tracked and X X displayed on the Poincar Sphere PER is measured Signal Quality EVM Q factor and mask violations X X Tributary Skew A time offset for each tributary is reported in the Measurement panel X X CD Compensation No intrinsic limit for offline processing FFT based filter to remove CD in X frequency domain based on a given dispersion value PMD Measurement PMD values are displayed in the Measurement panel for Polarization X multiplexed formats with a user specified number of PMD orders Oscilloscope and or Cable Delay Compensation Cable oscilloscope and receiver skew is corrected through interpolation 0 5 ns
4. 90 19 90 19 90 18 90 17 90 17 deg f Yconst Magnitude 22 079 22 072 22 097 22 099 22 091 ymw j Yconst EVM Average 15 01 14 09 14 33 14 95 16 16 Yconst Mask Violat 0 5 5 12 3 pe Yconst Symbols Dis 2992 2992 2992 2992 2992 i Yconst Symbol Std 0 074 0 072 0 069 0 070 0 069 ymw X Trans Y Trans Pow Trans XY Measurements PMD Clear Statistics Multi carrier measurements OM1106 User definable superchannels For manufacturers getting a jump on superchannels or researchers investigating alternatives user definable superchannel configurations are a must Option MCS allows the user to set up as many carriers within the superchannel definition as necessary Each carrier can have an arbitrary center frequency no carrier grid spacing is imposed The carrier center frequencies can be set as absolute values in THz or as relative values in GHz Typically the OUI will retune the OM4106D local oscillator for each carrier However in cases where multiple carriers may fit within the oscilloscope bandwidth multiple carriers can be demodulated in software from a common local oscillator frequency The user is given the flexibility to specify the preferred local oscillator frequency for each carrier 20 GHz gt A LAMFreq Div 194 0200 THz lt gt Cent Freq 34 RefaBw5 Al aldBDiv Superchannel spectrum Automated measurements Once the superchannel is configured the system can take
5. AI 132 19 Annotated measurement r sulis table im OUI Make adjustments faster The OUI is designed to collect data from the oscilloscope and move it into the MATLAB workspace with extreme speed to provide the maximum data refresh rate The data is then processed in MATLAB and the resulting variables are extracted for display Take control with tight MATLAB integration Since 100 of the data processing occurs in MATLAB test engineers can easily probe into the processing to understand each step along the way R amp D labs can also take advantage of the tight MATLAB integration by writing their own MATLAB algorithms for new techniques under development Use the optimum algorithm Don t worry about which algorithm to use When you select a signal type in the OUI for example PM QPSK the software applies optimal algorithm to the data for that signal type Each signal type has a specially designed signal processing approach that is best for the application This means that you can get results right away Don t get stymied by laser phase noise Signal processing algorithms designed for electrical wireless signals don t always work well with the much noisier sources used for complex optical modulation signals Our robust signal processing methods tolerate enough phase noise to even make it possible to test signals which would traditionally be measured by differential or direct detection such as DQPSK Find the right BER
6. OM2210 LL L Band Coherent Receiver Calibration Source with two L band lasers OM2210 CL C L Band Coherent Receiver Calibration Source with coupled C and L lasers OM2210 NL Receiver calibrated over C L C Band amp L Band laser sources OM2012 nLaser requires choice of laser configuration OM2012 CC C Band nLaser with two C band lasers OM2012 CL C L Band nLaser with one C band laser and one L band laser OM2012 LL L Band nLaser with two L band lasers Tektronix is registered to ISO 9001 and ISO 14001 by SRI Quality System Registrar Product Area Assessed The planning design development and manufacture of electronic Test and Measurement instruments ASEAN Australasia 65 6356 3900 Austria 00800 2255 4835 Balkans Israel South Africa and other ISE Countries 41 52 675 3777 Belgium 00800 2255 4835 Brazil 55 11 3759 7627 Canada 1 800 833 9200 Central East Europe and the Baltics 41 52 675 3777 Central Europe amp Greece 41 52 675 3777 Denmark 45 80 88 1401 Finland 41 52 675 3777 France 00800 2255 4835 Germany 00800 2255 4835 Hong Kong 400 820 5835 India 000 800 650 1835 Italy 00800 2255 4835 Japan 81 3 6714 3010 Luxembourg 41 52 675 3777 Mexico Central South America amp Caribbean 52 55 56 04 50 90 Middle East Asia and North Africa 41 52 675 3777 The Netherlands 00800 2255 4835 Norway 800 16098 People s Republic of China 400 820 5835 Poland 41 52 675 3777 Portugal 80 08 12370 Republic of Korea 001
7. available on the fly out panel associated with each graphic window The measurements available for constellations are described below Constellation measurements Measurement Description Elongation The ratio of the Q modulation amplitude to the modulation amplitude is a measure of how well balanced the modulation is for the and Q branches of a particular polarization s signal Real Bias Expressed as a percent this says how much the constellation is shifted left or right Real In phase bias other than zero is usually a sign that the In phase Tributary of the transmitter modulator is not being driven symmetrically at eye center Imag Bias Expressed as a percent this says how much the constellation is shifted up or down Imaginary Quadrature bias other than zero is usually a sign that the Quadrature Tributary of the transmitter modulator is not being driven symmetrically at eye center Magnitude The mean value of the magnitude of all symbols with units given on the plot This can be used to find the relative sizes of the two Polarization Signals Phase Angle StdDev by Quadrant The transmitter I Q phase bias It should normally be 90 The standard deviation of symbol point distance from the mean symbol in units given on the plot This is displayed for BPSK and QPSK EVM The RMS distance of each symbol point from the ideal symbol point divided by the magnitude of the ideal sym
8. clock frequencies is required Signal Type The signal type such as PM QPSK determines the algorithm used to process the data Data Patterns Specifying the known PRBS or user pattern by physical tributary permits error counting constellation orientation and two stage phase estimation User patterns may be assigned in the MATLAB window shown here The data pattern can be input into MATLAB or found directly through measurement of a high SNR signal Signal spectra An FFT of the corrected electric field vs time can reveal much about the data signal Asymmetric or shifted spectra can indicate excessive laser frequency error Periodicity in the spectrum shows correlation between data tributaries The FFT of the laser phase vs time data can be used to measure laser phase noise signal Spectrum LaserPhaseSpectrumx d F Horiz 1 000E 000 GHz div Vert 1 000E 001 dB Div LaserPhaseSpectrums 10 dB Div 0 00 A Ref Level dB o 1 2 GHz dv Res Bandwidth 25 1584 MHz Laser Phase Spectrum window www tektronix com 7 Datasheet Poincar Sphere Polarization data signals typically start out well aligned to the PM fiber axes However once in standard single mode fiber the polarization states will start to drift However it is still possible to measure the polarization States and determine the polarization extinction ratio The software locks on each polarization signal The polarization states of
9. i 441 Alerts CurrZone Initial phase estimate Customizing the CoreProcessing algorithms provide an excellent way 442 EstPhParams struct Alpha Alpha Homodyne false CentFrea switc igType conduct signal processing research In order to speed up development of ae See E E se ceed ed E ae ese a signal processing the OM Series User Interface OUI provides a dynamic mor be inp aaa zM F i a 3 446 zXSym ApplyPhaseBoundValsi Alerts ApplyPhase zXSym Theta a Matlab integration window Any Matlab code typed In this window IS 447 ThetaSymY EstimatePhaseBoundVals2 Alerts EstimatePhase z A ag zYSym Z laseBoundVals ALCIFTSs ase Zz Theta executed on every pass through the signal processing loop This allows you ae a ne meetin mene to quickly add or comment out function calls write specific values into 450 ThetasymX EstimatePhaseBoundVals1 Alerts EstimatePhase z data structures or modify signal processing parameters on the fly without ede a ee i i E having to stop the processing loop or modify the Matlab source code SE aoe 12 454 ThetaSymx EstimatePhaseBoundValsi Alerts EstimatePhase z _ 55 ee ThetaSymyY EstimatePhaseBoundVals2 Alerts EstimatePhase z 456 zXHalfSym ApplyPhaseBoundValsi Alerts ApplyPhase zXHalfs AS zYHalfSym ApplyPhaseBoundVals2 Alerts ApplyPhase zYHalfs 458 case 13 459 ThetaSymx EstimatePhaseBoundValsi Alerts Es
10. in the OUI Additional cable adjustment is available using the oscilloscope UI Oscilloscope Skew Adjustment Equivalent time oscilloscope skew is adjusted using the Delay feature in 100 the supported sampling head plug ins Calibration Routines Receiver Skew DC Offset and Path Gain Mismatch Hybrid angle and X X state of polarization are factory calibrated Data Export Formats MATLAB other formats available through MATLAB or ATE interface X X PNG Raw Data Replay with Different Parameter Movie mode and reprocessing X X Setting Bit Error Ratio Measurements Number of counted bits symbols X X Number or errors detected X X Bit error ratio X X Differential detection errors X X Save acquisition on detected error X X Offline Processing Run software on a separate PC or on the oscilloscope X X Coherent Eye Diagram Shows the In Phase or Quadrature components vs time modulo two bit X X periods Power Eye Diagram Shows the computed power per polarization vs time modulo 2 bit periods X X www tektronix com 13 Datasheet System requirements Supported platforms for the OM1106 software OUI Computer with nVidia graphics card running US Windows 7 64 bit and MATLAB 201 1b 64 bit Computer with nVidia graphics card running US Windows XP 32 bit and MATLAB 2009a 32 bit The following platforms are supported but may not be able to use certain advanced graphics features such as color grade and 3D Tektronix 70000 Seri
11. measurements on each channel without further intervention by the user The OUI automatically tunes the OM4106D local oscillator takes measurements at that channel re tunes to the next channel and so forth until measurements of the entire superchannel have been taken Results of each channel are displayed in real time and persist after all measurements are made for easy comparison www tektronix com 9 Datasheet Integrated measurement results All of the same measurement results that are made for single channels are also available for individual channels in a superchannel configuration Additionally multi carrier measurement results are available side by side for comparison between channels Visualizations such as eye diagrams constellation diagrams and optical spectrum plots can be viewed a single channel at a time or with all channels superimposed for fast comparison For separating channels in a multi carrier group several different filters can be applied including raised cosine Bessel Butterworth Nyquist and user defined filters These filters can be any order or roll off factor and track the signal frequency Coherent optical signal generation Tektronix offers several signal generation instruments capable of generating coherent optical waveforms The AWG70000 Series Arbitrary Waveform Generators AWG and the PPG3000 Series Programmable Pattern Generators offer the flexibility to choose the type of signal generation instru
12. 1 upper right then the ee current symbol is colored Yellow If the prior symbol was in Quadrant 2 upper left then Color Key Constellation Points is a special feature that works when not in the current symbol is colored Magenta If the prior symbol was in Quadrant 3 lower left Color Grade In this case the symbol color is determined by the value of the then the current symbol is colored Light Blue Cyan If the prior symbol was in Quadrant previous symbol This helps reveal pattern dependence Here it shows that 4 lower right then the current symbol is colored Solid Blue pattern dependence is to blame for the poor EVM on the other groups The modulator nonlinearity would normally mask this type of pattern dependence due to RF cable loss but here the improper modulator bias is allowing that to be transferred to the optical signal www tektronix com 5 Datasheet Eye diagrams Eye diagram plots can be selected for appropriate modulation formats Supported eye formats include Field Eye which is simply the real part of the phase trace in the complex plane Power Eye which simulates the eye displayed with a Tektronix oscilloscope optical input and Diff Eye which simulates the eye generated by using a 1 bit delay line interferometer As with the Constellation Plot you can right click to choose color options as well The Field Eye diagram provides the following measurements LEI Eye db lert 1 200 001 Widiv Summary
13. 800 8255 2835 Russia amp CIS 7 495 6647564 South Africa 41 52 675 3777 Spain 00800 2255 4835 Sweden 00800 2255 4835 Switzerland 00800 2255 4835 Taiwan 886 2 2656 6688 United Kingdom amp Ireland 00800 2255 4835 USA 1 800 833 9200 European toll free number If not accessible call 41 52 675 3777 For Further Information Tektronix maintains a comprehensive constantly expanding collection of application notes technical briefs and other resources to help engineers working on the cutting edge of technology Please visit www tektronix com Copyright Tektronix Inc All rights reserved Tektronix products are covered by U S and foreign patents issued and pending Information in this publication supersedes that in all previously published material Specification and SK price change privileges reserved TEKTRONIX and TEK are registered trademarks of Tektronix Inc All other trade names referenced are the service marks trademarks or registered trademarks of their respective companies Lor y 13 Jan 2015 85W 31037 0 www tektronix com Tektronix S
14. QAM signal it is the average of all the overshoots Undershoot The fractional undershoot of the signal overshoot of the negative going transition Risetime The 10 90 rise time of the signal One value is reported for the tributary and for a multilevel QAM signal it is the average of all the rise times Falltime The 90 10 fall time of the signal Skew The time relative to the center of the power eye of the midpoint between the crossing points for a particular tributary Crossing Point The fractional vertical position at the crossing of the rising and falling edges Measurements vs Time In addition to the eye diagram it is often important to view signals versus time For example it is instructive to see what the field values were doing in the vicinity of a bit error All of the plots which display symbol center values will indicate if that symbol is errored by coloring the point red assuming that the data is synchronized to the indicated pattern The Measurement vs Time plot is particularly useful in this way as it helps to distinguish errors due to noise pattern dependence or pattern errors AnalysisParameters Matlab XvtT 1 Errored symbol in Measurement vs Time plot 2 N S Bergano F W Kerfoot C R Davidson Margin measurements in optical amplifier systems IEEE Phot Tech Lett 5 no 3 pp 304 306 1993 6 www tektronix com 3D visualization tools Complex modulation signals
15. Tektronix Coherent Lightwave Signal Analyzer Software OM1106 Software Datasheet le x 3 al a a 5 y 4 gt tr ra ad gt g v gt gt 7 x naur e BS Ger 2S 4ATULT be age x The OM1106 Coherent Lightwave Signal Analyzer software provides an ideal platform for research and testing of coherent optical systems It offers a complete software package for acquiring demodulating analyzing and visualizing complex modulated systems from an easy to use user interface The software performs all calibration and processing functions to enable real time burst mode constellation diagram display eye diagram display Poincar sphere and bit error detection Advanced users can take advantage of the provided MATLAB signal analysis source code and modify the signal processing algorithms while still taking advantage of the rich user interface for acquisition signal visualization and numerical measurements Key features Complete coherent signal analysis system for polarization multiplexed QPSK QAM differential BPSK QPSK and other advanced modulation formats Displays constellation diagrams phase eye diagrams Q factor Q plot spectral plots Poincar Sphere signal vs time laser phase characteristics BER with additional plots and analyses available through the MATLAB interface Measures polarization mode dispersion PMD of arbitrary order with most polarization multiplexed signals Smart polariz
16. are inherently 3D since in phase and quadrature components are being changed vs time The 3D Eye Diagram provides a helpful combination of the Constellation and Eye diagrams into a single 3D diagram This helps to visualize how the complex quantity is changing through the bit period The diagram can be rotated and scaled Also available in 3D is the Poincar Sphere The 3D view is helpful when viewing the polarization state of every symbol The symbols tend to form clusters on the Poincar Sphere which can be revealing to expert users The non normalized Stokes Vectors can also be plotted in this view Analysis Controls The Analysis Controls window allows you to set parameters relevant to the system and its measurements AnalysisParameters Matlab 4b Matlab Engine Command ___________ Patt Re Values Seq Patt Re SyncFrameEnd 100 Patt lm Values Seq Patt lm SyncFrameEnd 100 Patt Re Values Seq3 Patt Re SyncFrameEnd 100 Patt lm Values Seg4 Patim SyncFrameEnd 100 Wi Core Processing MATLAB window SignalSpectrumX LaserPhaseSpectrum amp 4 gt Horiz 5 000E 000 GHz Div Vert 1 000E 001 dB Div 10 dB Div 0 00 Ref Level dBm 5 G GHz Div Time Windows lt Signal Spectrum window i OM1106 Analysis parameters Parameter Description Frequency Clock recovery is performed in software so only a frequency range of expected
17. ary bias magnitude phase angle EVM and others Eye diagram measurements include many key time domain metrics such as eye height overshoot undershoot risetime falltime skew crossing point etc Statistics are provided for all numerical measurements to facilitate data gathering over longer periods of time x Eye 1 n r io Matlab i K Comat Pipher DPA e se HH oo ca lt Y ane OM series user interface OUI showing color grade graphics options Symbols can also be colored to a key indicating prior state Data shown is 112 Gb s PM QPSK W Eve t tye 1 vl Eye 2 hye it a ste a 4 OUI showing display of select equivalent time measurements 2 www tektronix com Get up and running fast with the easy to use OUI The OUI allows you to easily configure and display your measurements and also provides software control for third party applications using WCF or NET communication The OUI can also be controlled from MATLAB or LabVIEW The following image shows a QAM measurement setup The plots can be moved docked or resized You can close or create plots to display just the information you need QAM measurements on the OM series user interface OUI In addition to the numerical measurements provided on the plots the measurements are also summarized on the Measurements window where Statistics are also displayed An example of some of these measurements is shown in the following fig
18. ation separation follows signal polarization User access to internal functions with a direct MATLAB interface Remote access available through Ethernet Superior user interface offers comprehensive visualization for ease of use combined with the power of MATLAB Multi carrier software option allows user definable superchannel setup Superchannel configuration allows user to define number of channels channel frequency and channel modulation format 1 MATLAB is a registered trademark of MathWorks Test automation acquires complete measurements at each channel Integrated measurement results allow easy channel to channel comparisons Introduction A common thread throughout the Tektronix OM series coherent optical products is the OM1106 Coherent Optical Analysis Software This software is included with all Tektronix OM4000 series optical modulation analyzers OMA and is also available as a stand alone software package for customers to use with own OMAS or as a coherent optical research tool The OM1106 analysis software consists of a number of major building blocks At the heart of the software is a complete library of analysis algorithms These algorithms have not been re purposed from the wireless communications world they are specifically designed for coherent optical analysis executed in a customer supplied MATLAB installation The OM1106 software also provides a complete applications programmatic interface API to
19. band L band lasers receiver tested over L band Coupled C and L band lasers receiver calibrated over Cand L band No lasers receiver calibrated over C and L band Adds external connections for reference laser Adds QAM and other software demodulators Adds multi carrier superchannel support 33 GHz optical modulation analyzer OM4106D OM4106D CC OM4106D LL OM4106D CL OM4106D NL OM4106D EXT OM4106D QAM OM4106D MCS 33 GHz Coherent Lightwave Signal Analyzer requires choice of lasers C band lasers receiver tested over C band L band lasers receiver tested over L band Coupled C and L band lasers receiver calibrated over Cand L band No lasers receiver calibrated over C and L band Adds external connections for reference laser Adds QAM and other software demodulators Adds multi carrier superchannel support www tektronix com 15 Datasheet Coherent optical transmitter OM5110 46 GBaud Dual Polarization Coherent Optical IQ Transmitter OM5110 C C band laser factory installed OM5110 L L band laser factory installed OM5110 NL No laser installed requires external laser Coherent receiver calibration source OM2210 33 GHz Coherent Lightwave Signal Analyzer requires choice of lasers OM2210 C C Band Coherent Receiver Calibration Source with single C band laser OM2210 CC C Band Coherent Receiver Calibration Source with two C band lasers OM2210L L Band Coherent Receiver Calibration Source with single L band laser
20. bol expressed as a percent EVM Tab The separate EVM tab shown in the right figure provides the EVM by constellation group The numbers are arranged to correspond to the symbol arrangement This is ideal for setting Transmitter modulator bias For example if the left side groups have higher EVM than the right side adjust the In phase Transmitter modulator bias to drive the negative rail harder Mask Tab The separate Mask tab shown in the right figure provides the number of mask violations by constellation group The numbers are arranged to correspond to the symbol arrangement The mask threshold is set in the Engine window and can be used for pass fail transmitter testing 4 www tektronix com Color features The Color Grade feature 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 Note that the lower constellation groups of the example below have higher EVM than the top groups In most cases this indicates that the quadrature modulator bias was too far toward the positive rail This is not evident from the crossing points which are approximately correct In this case an improperly biased modulator is concealing an improperly biased driver amp Color Grade Constellation OM1106 Color Grade with fine traces Color Key Constellation If the prior symbol was in Quadrant
21. ers of DP 16QAM Other proposals are for 500 Gb s consisting of 10 or more carriers of DP QPSK Some of these carriers are arranged on a standard ITU carrier grid while others support 12 5 GHz grid less layouts Clearly flexible test tools are needed for such next generation systems Option MCS to the OM4106D and OM1106 offers the complete flexibility to carrier out such tests Multicarnier Setup Preset Default Frequency mode Relative Absolute Frequency Prefered Channel Tu Ly Include THz LO THz 1 193 40 193 40 Pi 2 193 45 193 45 vf 3 133 50 133 50 Pj 4 193 55 193 55 Ei 5 133 60 193 60 Pi 6 193 72 193 72 Pi 7 193 85 193 85 af o 40939 47 4093 97 F Multi carrier setup Multicarrier Measurements Measurement Channel i Channel 2 Channel 3 Channel 4 Channel 5 Unit x Eye X Q Q Factor 15 473 16 526 14 576 16 350 14 654 dB po X Q Eye Height 31 528 31 555 31 530 31 551 31 574 ymw X Q Rail 0 Std Dev 2 644 2 769 2 691 2 591 2 438 ymw pe X Q Rail 1 Std Dev 2 665 2 765 2 661 2 667 2 753 ymw a X I Q Factor 21 796 20 111 22 668 21 419 22 648 dB j X I Eye Height 28 743 28 504 28 658 28 515 28 661 ymw X I Rail 0 Std Dev 1 239 1 216 1 043 1 281 1 161 ymw i X I Rail 1 Std Dev 1 099 0 901 ileal 1 283 1 040 ymw p Y Eye X Const a Y Const Yconst IQ Imbalance 1 006 1 006 1 006 1 007 1 006 j Yconst Bias Real 0 07 0 05 0 09 0 06 0 01 Yconst Bias Imag 0 03 0 02 0 01 0 04 0 01 pe YconstPhaseAngle
22. es Oscilloscopes running Windows 7 64 bit and MATLAB 2011b 64 bit Computer with non nVidia graphics running US Windows 7 64 bit and MATLAB 2011b 64 bit Computer with non nVidia graphics running US Windows XP 32 bit and MATLAB 2009a 32 bit Please check with Tektronix when ordering for the most up to date requirements including support for the latest releases of MATLAB software Please contact Tektronix for a price quote or to arrange a demonstration All product descriptions and specifications are subject to change without notice 14 www tektronix com OM1106 Ordering information Signal analyzer software OM1106 OM1106 options OM1106 OM1106 QAM OM1106 MCS OM1106 LO OM11UP OM11UP MCS OM11UP QAM OM11UP SHIP OMADDLSW Related products Coherent Lightwave Signal Analyzer software OUI signal analysis software only Adds QAM and other software demodulators Adds multi carrier superchannel support English manual Upgrade kits to the Coherent Lightwave Signal Analyzer Software Adds Multi carrier superchannel support Adds QAM and other software demodulators Customer Requests Shipment or Export Requirement Adds additional seat of Coherent Lightwave Signal Analyzer Software 23 GHz optical modulation analyzer OM4006D OM4006D CC OM4006D LL OM4006D CL OM4006D NL OM4006D EXT OM406D QAM OM4006D MCS 23 GHz Coherent Lightwave Signal Analyzer requires choice of lasers C band lasers receiver tested over C
23. hms shown as upper path in the figure The data is also re sampled at 10X the baud rate user settable to define the traces that interconnect the symbols in the eye diagram or constellation shown as the lower path The clock recovery approach depends on the chosen signal type Laser phase is then recovered based on the symbol center samples Once the laser phase is recovered the modulation part of the field is available for alignment to the expected data for each tributary At this point bit errors can be counted by looking for the difference between the actual and expected data after accounting for all possible ambiguities in data polarity The software selects the polarity with the lowest BER Once the actual data is known a second phase estimate can be done to remove errors that may result from a laser phase jump Once the field variables are calculated they are available for retrieval and display by the OUI At each step the best algorithms are chosen for the specified data type requiring no user intervention unless desired OM1106 Matlab scope sample rate symbol rate ese ee e ew ee ee ee ee ee ee ee ee ee ee gt mel Matlab Engine Command ClockRetime ApplyPhase ApplyPhase center om mi iaa DispCalElipses E ChDelay Uncertainty CalChDelay Vblock 1E 9 1 disp Estimated delay s num 2stri ChDelay EstimateClock EstimateSOP EstimatePhase AlignTribs EstimatePhase count bit e
24. is 1 ps at 10 Gbaud There is no intrinsic limit to the CD compensation algorithm It has been used successfully to compensate for many thousands of ps nm Recording and playback You can record the workspace as a sequence of MAT files using the Record button in the Offline ribbon These files are recorded in a default directory usually the MATLAB working directory unless previously changed 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 Load a sequence by marking the files you want to load using the Ctrl key and marking the filenames with the mouse You can also load a contiguous series using the Shift key and marking the first and last filenames in the series with the mouse Use the Run button in the Offline Commands section of the Home ribbon to cycle through the MAT files you recorded All filtering and processing you have implemented occurs on the recorded files as they are replayed Offline Home Setup Calibrate Loop Offline Data Record Load Run Stop es ee ee ee ee ee Workspace record and playback Multi carrier superchannel support Even as 100G coherent optical systems are being deployed architectures for 400G and beyond are being proposed and developed One architecture gaining prominence is the superchannel The configurations of superchannels vary considerably Some proposals call for 400G to be achieved by 2 carri
25. ishing tributaries will not usually work when using separate data pattern generators programmed with the same PRBS Spect estimates the power spectral density of the optical signal using a discrete Fourier transform It can take any many of our time waveforms as input such as corrected oscilloscope input data front end processed data polarization separated data averaged data and FIR data It can also apply Hanning or Flat Top window filters and produce the desired resolution bandwidth over a set frequency range GenPattern generates a sequence of logical values 0s and 1s given an exact data pattern The exact pattern specifies not only the form of the sequence but also the place it starts and the data polarity The data pattern specified may be a pseudo random bit sequence PRBS or a specified sequence LaserSpectrum estimates the power spectral density of the laser waveform in units of dBc The function LaserSpectrum takes ThetaSym the estimated relative laser phase sampled at the symbol rate as input and defines the frequency centered laser waveform This waveform is then scaled by a hamming window and the power spectral density of the waveform is estimated as the discrete Fourier transform of this signal QDecTh uses the decision threshold method to estimate the Q factor of a component of the optical signal The method is useful because it quickly gives an accurate estimate of Q factor the output signal to noise ratio even if the
26. ment suited to the test requirements The AWG70000 Series can reach sampling rates as high as 50GSa s with 10 bits vertical resolution This level of performance allows for the direct generation of IQ basebands signals required by modern coherent optical communication systems The arbitrary waveform generation capabilities of the AWG70000 Series makes it possible to create multi level signals such as 16QAM or 64QAM add impairments to a signal or to create waveforms that are pre compensated for the real world effects of the test system The PPG3000 Series can generate patterns up to 32 Gb s and offers 1 2 or 4 channels in a single instrument The patterns can be standard PRBS patterns or user defined Using a 4 channel pattern generator makes creating dual polarization Q waveforms very simple Coherent optical signal generation is one of the more demanding applications for an AWG The requirements in terms of number of channels sampling rate bandwidth record length and timing and synchronization quality can be only met by the highest performance instruments such as the Tektronix AWG70000 series The unique capability of generating ideal or distorted signals and the ease to add new modulation schemes and signal processing algorithms without the need to add any extra hardware make AWGs an ideal tool for coherent optical communication research and development 10 www tektronix com Interaction between OUI and MATLAB The OUI takes info
27. re are no bit errors or if it would take a long time to wait for a sufficient number of bit errors Characteristic Description Real time supported Equivalent time feature supported feature Constellation Diagram Constellation diagram accuracy including intradyne and demodulation X X error can be measured by the RMS error of the constellation points divided by the magnitude of the electric field for each polarization signal Constellation Elongation Ratio of constellation height to width X X Constellation Phase Angle Measure of transmitter IQ phase angle X X Constellation and Q Bias Measure of average symbol position relative to the origin X X Constellation Mask User settable allowed EVM level Symbols violating the mask are X X counted Eye Decision Threshold Q factor The actual Q achieved will depend on the quality of the data signal the X X signal amplitude and the oscilloscope used for digitalization Using the Tektronix DPO73304D oscilloscope 4 Ch a Q factor of 20 dB is achievable at 40 GBaud 12 www tektronix com OM1106 Characteristic Description Real time supported Equivalent time feature supported feature Decision Threshold Q plot Displays BER vs decision threshold for each eye opening The Q value X X at optimum decision threshold is the Q factor Signal Spectrum and Laser Spectrum Display of signal electric field vs
28. rmation about the signal provided by the user together with acquisition data from the oscilloscope and passes them to the MATLAB workspace shown in Figure 3 A series of MATLAB scripts are then called to process the data and produce the resulting field variables The OUI then retrieves these variables and plots them Automated tests can be accomplished by connecting to the OUI or by connecting directly to the MATLAB workspace The user does not need any familiarity with MATLAB the OUI can manage all MATLAB interactions However advanced users can access the MATLAB interface internal functions to create user defined demodulators and algorithms or for custom analysis visualization OUI MATLAB OUI e Write analysis parameters to MATLAB workspace e Clock recovery e Plot results eyes constellation diagrams e Polarization Poincare sphere estimation e Acquire oscilloscope data e Phase estimation e Report bit errors e Report Q factors constellation e Ambiguity resolution e Write data to MATLAB workspace e 2nd phase estimate parameters e Count bit errors e Calculate constellation parameters Vblock SigType Freq Window etc zXSym ZYSym ZX ZY DecTh etc OUI MATLAB data flow Signal processing approach For real time sampled systems the first step after data acquisition is to recover the clock and retime the data at 1 sample per symbol at the symbol center for the polarization separation and following algorit
29. rrors disp Estimated uncertainty num str Uncertainty Q factor scope const params record PatXRei2 PRBSGens 4 6 7 9 NENOOS PattXiIm 2 PRBSGens 4 6 7 9 us E field LJ LJ pHyb 1i 0 0 00 1i ClockRetime ApplyPhase EgFiti 1 dt 1 scope sample rate N x symbol rate gt gt gt Corect Fhase tue Data flow through the Core Processing engine CoreFrocessingCommands Signal processing customization pHybinUse l Eq FitInUse The OM1106 software includes the MATLAB source code for the CoreProcessing engine certain proprietary functions are provided as plot z Sym Values compiled code You can customize the signal processing flow or insert or remove processes as desired Alternatively you can remove all Tektronix k processing and completely replace it with your own By using the existing variables defined for the data structures you can then see the results of analysis processing using the rich visualizations provided by the OUI This pe s i Gi r C ram Fi l ications ore Processi oreProcessing m j a allows you to focus your time on algorithms rather than on tasks such as ___ _ _ _ ae acquiring data from the oscilloscope or displaying constellation diagrams DGe sBO6 SB Medh H OL BAM BB suclex ff Oe S dao 11 x 37 end 438 SSOPEstiT toc m Dynamic MATLAB integration ai l nitial phase estimate Tae
30. tePhase estimates the phase of the optical signal The algorithm used is known to be close to the optimal estimate of the phase The algorithm first determines the heterodyne frequency offset and then estimates the phase The phase reported in the Values field is after the frequency offset has been subtracted ApplyPhase multiplies the values representing a single or dual polarization parameters vs time by a phase factor to give a resulting set of values AlignTribs performs ambiguity resolution The function acts on variable which is already corrected for phase and state of polarization but for which the tributaries have not been ordered AlignTribs uses the data content of the tributaries to distinguish between them AlignTribs processes the data patterns in order according to the modulation Supported measurements and display tools format starting with X I For each pattern it tries to match the given data pattern with the available tributaries of the signal If the same pattern is used for more than one tributary the relative pattern delays will be used to distinguish between them The use of delay as a secondary condition to distinguish between tributaries means that AlignTribs will work with transmission experiments that use a single data pattern generator which is split several ways with different delays The delay search is performed only over a limited range of 1000 bits in the case of PRBS patterns so this method of distingu
31. the two signals are displayed on a circular plot representing one face of the Poincar sphere States on the back side are indicated by coloring the marker blue The degree of orthogonality can be visualized by inverting the rear face so that orthogonal signals always appear in the same location with different color So Blue means back side negative value for that component of the Stokes vector X means X tributary O means Y tributary and the Stokes vector is plotted so that left down blue are all negative on the sphere InvertedRearFace Checking this box inverts the rear face of the Poincar sphere display so that two orthogonal polarizations will always be on top of each other nalysis Parameters qq gt x PSphere Poincar Sphere window 8 www tektronix com Impairment measurement and compensation When studying transmission implementations it is important to be able to compensate for the impairments created by long fiber runs or optical components Chromatic Dispersion CD and Polarization Mode Dispersion PMD are two important linear impairments that can be measured or corrected by the OM4000 software PMD measurement is based on comparison of the received signal to the back to back transmitter signal or to an ideal signal This produces a direct measure of the PMD instead of estimating based on adaptive filter behavior The user can specify the number of PMD orders to calculate Accuracy for 1st order PMD
32. these algorithms Using these APIs to provide a substantial feature set is the OM Series User Interface OUI The OUI provides a complete coherent optical tool suite allowing any user to conduct detailed analysis of complex modulated optical signals without requiring any knowledge of MATLAB analysis algorithms or software programming The flexibility of the OM1106 software allows it to be used in a number of different ways You can make measurements solely through the OUI you can use the programmatic interface to and from MATLAB for customized processing or you can do both by using the OUI as a visualization and measurement framework around which you build your own custom processing www tektronix com 1 Datasheet OM series user interface OUI The common thread through the Tektronix OM series products is the OM series user interface OUI software that controls the acquisition and display of data This OUI can be ordered separately without the OM4000 series optical modulation analyzer for analysis purposes with another coherent receiver system The data capture and analysis only version of the OUI software is called OM1106 The OUI provides the user to display all the standard coherent optical visualizations such as eye diagrams constellation diagrams Poincar spheres and so on The OUI also provides a complete measurement suite to numerically report key measurements Constellation measurements include elongation real and imagin
33. timatePhase z f 460 zXSym ApplyPhaseBoundValsi Alerts ApplyPhase zXSym Theta v CoreProcessingAF Ln 1024 Col 1 OVR www tektronix com 11 Datasheet CoreProcessing functions The following are some of the CoreProcessing functions used to analyze the coherent signal Full details on these functions their use in the processing flow and the MATLAB variable used are available in the OM1106 user manual EstimateClock determines the symbol clock frequency of a digital data carrying optical signal based on oscilloscope waveform records The scope sampling rate may be arbitrary having no integer relationship compared to the symbol rate ClockRetime forms an output parameter p representing a dual polarization signal vs time from four oscilloscope waveforms V The output p is retimed to be aligned with the timing grid specified by Clock EstimateSOP reports the state of polarization SOP of the tributaries in the optical signal The result is provided in the form of an orthogonal rotation matrix RotM For a polarization multiplexed signal the first column of RotM is the SOP of the first tributary and the second column the SOP of the second tributary For a single tributary signal the first column is the SOP of the tributary and the second column is orthogonal to it The signal is transformed into its basis set the tributaries horizontal vertical polarizations by multiplying by the inverse of RotM Estima
34. ure Measurements 4 pb Mean Min Max StdDev Xconst Symbol Std Dev O 0886 mwW 0 0886ymwW 0 0833VmwW 0 0912imwW 0 00208 mw 19 Xconst Symbols Displayed 3942 4101 3905 4268 132 19 Xconst Mask Violations 6 6 6 7 0 19 Xconst EVM Average 88 8 6 8 2 8 9 0 23 19 Xconst Magnitude 1 482VmW 1 4395vmW 1 373vmv 1 505imwWw 0 03873 mW 19 Xconst Phase Angle 94 deg 90 deg 85 deg 94 deg 3 2 deg 19 Xconst Bias Imag 0 12 0 12 0 13 0 12 0 0029 19 Xconst Bias Real 0 011 0 011 0 012 0 011 0 00028 19 Xconst IQ Imbalance 0 9946 0 9976 0 9534 1 046 0 02677 19 X I Undershoot 0 79 0 75 0 72 0 79 0 023 19 X I Overshoot 0 86 0 86 0 82 09 0 022 19 X I Falltime 45 ps 47 ps 45 ps 49 ps 1 3 ps 19 X I Risetime 49 ps 47 ps 45 ps 50 ps 1 5 ps 19 X I Skew 0 027 ps 0 028 ps 0 027 ps 0 029 ps 0 00082 ps 19 X I Crossing Point 50 50 48 52 14 19 X I Rail 1 Std Dev 0 0873imwW 0 0904y mWw 0 0863imwW 0 0949 mWw 0 00244ymwWw 19 X I Rail 0 Std Dev 0 0838vmwW 0 0868imwW 0 0828imwW 0 0911ymWw 0 00234y mWw 19 X I Eye Height 2 04 mW 2 02 mW 1 96VmW 2 114mW 0 053Vmw 19 X I Q Factor 21 dB 21 dB 20 dB 22 dB 0 61 dB 19 X Q Undershoot 0 71 0 73 0 69 0 76 0 021 19 X Q Overshoot 0 85 0 87 0 83 0 91 0 025 19 X Q Falltime 47 ps 47 ps 45 ps 50 ps 1 3 ps 19 X Q Risetime 47 ps 48 ps 45 ps 50 ps 1 3 ps 19 X Q Skew 0 054 ps 0 056 ps 0 054 ps 0 059 ps 0 0014 ps 19 X Q Crassinn Paint 49 y AN a AR
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