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Appendix E: Equivalent-Time (ET) oscilloscope operation

Once connected and con

fi

gured, 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

fi

lter for phase recovery) (See

page 34.)

Receiver equalization

DC calibration (ET)

Although the OM4000 Series units use balanced detection, there is usually some
small offset voltage present at the signal outputs. Since the Common-Mode
Rejection Ratio (CMRR) is optimized for the signal input, the dc offset is almost
entirely due to the Reference (LO) input power. The presence of a dc offset causes
the recovered signal to be unstable.

To correct for dc offset when connected to an equivalent time oscilloscope, follow
this procedure:

130

OM4000D Series Coherent Lightwave Signal Analyzer

Содержание OM4006D

Страница 1: ...xx OM4106D and OM4006D Coherent Lightwave Signal Analyzer ZZZ User Manual P071316002 071 3160 02...

Страница 2: ......

Страница 3: ...OM4106D and OM4006D Coherent Lightwave Signal Analyzer ZZZ User Manual xx www tektronix com 071 3160 02...

Страница 4: ...ges reserved TEKTRONIX and TEK are registered trademarks of Tektronix Inc MATLAB is a registered trademark of The MathWorks Inc LabVIEW is a trademark of National Instruments Inc Intel and Pentium are...

Страница 5: ...taxes and any other charges for products returned to any other locations This warranty shall not apply to any defect failure or damage caused by improper use or improper or inadequate maintenance and...

Страница 6: ......

Страница 7: ...quirements 4 Power requirements 5 PC requirements 6 Software installation 6 Set the instrument IP address 8 Equipment setup 13 Operating basics 17 OM4000 controls and connectors 17 Software overview 1...

Страница 8: ...um 104 QDecTh 104 zSpectrum 106 Appendix A MATLAB variables used by core processing 107 Appendix B Alerts 109 Appendix C Calibration and adjustment RT oscilloscope 111 Calibration and adjustment RT 11...

Страница 9: ...settings 147 OUI settings for 2 oscilloscope operation 150 Appendix G The automated test equipment ATE interface 153 The LRCP ATE interface 153 The OUI4000 ATE interface 159 ATE functionality in MATLA...

Страница 10: ...vs Channel plot 74 Figure 13 Q vs Channel plot 75 Figure 14 Meas vs Channel table 75 Figure 15 When adjusting the middle slider watch the Y Eye and Y Const to minimize the signal in the Y polarizatio...

Страница 11: ...e 7 Software install oscilloscope 8 Table 8 OUI plots real time oscilloscopes 25 Table 9 Controls panel elements 30 Table 10 Record length and block interaction behavior 32 Table 11 OUI Analysis Param...

Страница 12: ...r maintenance or adjustment Before use always check the product with a known source to be sure it is operating correctly This product is not intended for detection of hazardous voltages Use personal p...

Страница 13: ...that there is damage to this product have it inspected by qualified service personnel Disable the product if it is damaged Do not use the product if it is damaged or operates incorrectly If in doubt a...

Страница 14: ...ce safety summary The Service safety summary section contains additional information required to safely perform service on the product Only qualified personnel should perform service procedures Read t...

Страница 15: ...duct DANGER indicates an injury hazard immediately accessible as you read the marking WARNING indicates an injury hazard not immediately accessible as you read the marking CAUTION indicates a hazard t...

Страница 16: ...Important safety information Front panel labels Item Description 1 Indicates the location of laser apertures 2 On inside cover of the instrument 3 x OM4000D Series Coherent Lightwave Signal Analyzer...

Страница 17: ...els Item Description 1 Instrument model and serial number label 2 Fuse safety information 3 COMPLIES WITH 21CFR1040 10 EXCEPT FOR DEVIATIONS PURSUANT TO LASER NOTICE NO 50 DATED JUNE 24 2007 OM4000D S...

Страница 18: ...electromagnetic field immunity IEC 61000 4 4 2004 Electrical fast transient burst immunity IEC 61000 4 5 2001 Power line surge immunity IEC 61000 4 6 2003 Conducted RF immunity IEC 61000 4 11 2004 Vol...

Страница 19: ...uipment for Measurement Control and Laboratory Use Part 1 General Requirements EN 60825 1 Safety of Laser Products Part 1 Equipment classification and requirements U S nationally recognized testing la...

Страница 20: ...humidity is controlled The area is protected from direct sunshine rain or direct wind Pollution degree 4 Pollution that generates persistent conductivity through conductive dust rain or snow Typical o...

Страница 21: ...appropriately This symbol indicates that this product complies with the applicable European Union requirements according to Directives 2002 96 EC and 2006 66 EC on waste electrical and electronic equ...

Страница 22: ...Compliance information xvi OM4000D Series Coherent Lightwave Signal Analyzer...

Страница 23: ...nt Lightwave Signal Analyzer OM1106 Coherent Lightwave Signal Analyzer stand alone software OUI included with OM4000 Series About this manual This manual contains the following sections Getting starte...

Страница 24: ...Preface xviii OM4000D Series Coherent Lightwave Signal Analyzer...

Страница 25: ...le real time burst mode constellation diagram display eye diagram display Poincar sphere and bit error detection A remote interlock for the laser located on the rear of the unit allows for remote lock...

Страница 26: ...cap for BNC interlock connector 131 8925 xx Power cord See page 3 International power cord options Varies by option Reply card Not orderable Cleaning swab Not orderable USB flashdrive case 016 2067 xx...

Страница 27: ...a lock mechanism except as otherwise noted Opt A0 North America power standard Opt A1 Universal EURO power Opt A2 United Kingdom power Opt A3 Australia power Opt A4 North America power 240 V Opt A5 Sw...

Страница 28: ...ON Damage to the instrument can occur if this instrument is powered on at temperatures outside the specified ambient temperature range Table 4 OM4000 environmental requirements Parameter Description O...

Страница 29: ...n to a grounded power source could result in serious electrical shock CAUTION Protective features of the OM4000 instrument may be impaired if the unit is used in a manner not specified by Tektronix Co...

Страница 30: ...lled Networking Gigabit Ethernet 1 Gb s or Fast Ethernet 100 Mb s Display 20 minimum flat screen recommended for displaying multiple graph types when using with the OM4000 Software Other Hardware 2 US...

Страница 31: ...bit either Matlab choice Power meter Software and drivers to communicate with the instrument optical power meter Install in the order listed Only required for use with the HRC software HRC ISSetupPrer...

Страница 32: ...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 b...

Страница 33: ...icating it is ready Press the front panel Power button to enable the network connection button light turns On 3 On a PC connected to the same network as the OM instrument start the LRCP program See pa...

Страница 34: ...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...

Страница 35: ...nt separately to change the IP address 1 On the PC with LRCP installed click Start Control Panel 2 Open the Network and Sharing Center link 3 Click the Manage Network Connections link to list connecti...

Страница 36: ...retained and are associated with the MAC address of each instrument 17 Enter the new IP address for the OM instrument in the AutoConfig screen that is compatible with your network For example 172 17 2...

Страница 37: ...copes See the following figure for how to connect the OM4000 instrument to take measurements with real time oscilloscopes Tektronix MSO DSO70000 series Figure 1 Real time RT oscilloscope setup diagram...

Страница 38: ...ignal for ET oscilloscopes The TX reference signal is picked off before the modulator using a PM fiber cable with a total path length equal to the path from the splitting point to the Signal Input on...

Страница 39: ...eping main front panel switch off 4 RF connections the four coaxial cables from OM4000 instrument to the oscilloscope 5 Fiber optic PM patch cable connection from Laser 2 to Reference if needed 6 Fibe...

Страница 40: ...e same subnet to communicate You should now have three devices on a localized Ethernet network computer oscilloscope and OM4000 instrument This little network may be connected to your corporate networ...

Страница 41: ...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...

Страница 42: ...I Sets up measurement parameters for the OM4000 Takes input from the OM4000 oscilloscope and LRCP Processes data to display a wide assortment of plots NOTE The OUI requires the LRCP software to take m...

Страница 43: ...n the local network It also provides a Windows Communication Foundation WCF service interface allowing Automated Test Equipment ATE to interact directly with the controllers and lasers while LRCP is r...

Страница 44: ...allow for easy identification Lasers are numbered and once the controller is brought online the laser panels will populate with the laser manufacturer and model number Once the user presses the button...

Страница 45: ...tered to be accepted by the application CAUTION LRCP does not save the state of any hardware settings The hardware keeps the settings until that hardware is turned off After turning on the hardware ag...

Страница 46: ...ical power to the laser module This should only be needed to reset the laser to its power on state or to save electrical power if a particular laser is never used Emission Click to turn on or off fron...

Страница 47: ...Clicking and dragging a panel title tab opens a positioning guide Hold down the left mouse button to position the window onto the positioning guide then release to organize the plots You can rescale...

Страница 48: ...needed less often Click on the double arrow on a tab displays or hides the contents of that tab The graphics windows can be docked or free floating To move a graphics window click and hold over the ta...

Страница 49: ...ymbol center values are shown in blue Symbol errors are shown in red Right click for other color options 3d Eye for X or Y signal polarization This plot can be scaled and rotated to view on a 2d or 3d...

Страница 50: ...rage shown in red is an average of each logical transition The calculation is enabled in the Analysis Parameters tab and is used for calculating transition measurements The Power Eye shows the compute...

Страница 51: ...3d Poincar shows polarization of each symbol center value Click and drag to rotate the sphere The Decision Threshold Q Factor is an ideal signal quality measurement based on measured BER values The h...

Страница 52: ...lculated 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 ei where is the recovered lase...

Страница 53: ...ription 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 Multicarrie...

Страница 54: ...e Sets the number of points that are processed at one time For record lengths up to 10 000 or even 50 000 points it makes sense to process everything at once This will happen if Blk Size is greater th...

Страница 55: ...s each block is processed By default raw data electric field values and other time series data are not aggregated over all blocks in a record greater than 1 000 000 samples See page 53 Managing data s...

Страница 56: ...into blocks for processing Only BER and other summary measurements are aggregated block to block Raw data and time series variables are erased when next block is processed Need to save workspace of in...

Страница 57: ...plots Apply limiting function Some signal distortions may cause the clock component of the signal to be weak so that the eye diagram is shifted in time or the clock recovery fails wrong frequency rep...

Страница 58: ...hich is removed by EstimatePhase Phase estimation time constant parameter Alpha After removing the optical modulation from the measured optical field information what remains is the instantaneous lase...

Страница 59: ...oblem if you choose a block size small enough that peak to peak frequency wander is on the order of the laser linewidth For the lasers supplied with the OM4000 instruments a block size of 50 000 point...

Страница 60: ...e is faster when disabled but must be enabled for the linear average to be displayed in the X vs T diagram Calculate subsequence average Controls computation of the subsequence averaging Refresh rate...

Страница 61: ...se calibration from offline file When selected applies calibration data hybrid equalization calibration taken from offline file When not selected applies calibration data loaded from disk at OUI start...

Страница 62: ...e processing applies an FIR filter defined in a variable UserFilter If the variable does not exist or if it is not valid then core processing continues without applying a filter and an Alert is issued...

Страница 63: ...at is not one of the standard patterns provided in the drop down list you can assign the PRBS polynomial directly in the MATLAB Engine Command Window in the OUI The acceptable PRBS polynomials are of...

Страница 64: ...y to keep calculations fast when using non PRBS patterns longer than 215 and if using record lengths long enough to capture at least as many bits as in the pattern is to simply use the SyncFrameEnd fi...

Страница 65: ...es 0 PattYImM imag zYSymUI Values 0 6 To get a single full pattern delete the extra data as follows in this case for 32 767 bits For QPSK PattXReM PattXReM 1 32767 PattXImM PattXImM 1 32767 For dual p...

Страница 66: ...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 Constella...

Страница 67: ...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 symbol expressed as a...

Страница 68: ...ntinue processing See page 104 QDecTh Offset modulation formats Both polarization and quadrature offset formats are available To properly display polarization offset formats select Home Constellation...

Страница 69: ...his mode helps reveal patterns not readily apparent in monochrome Persistence can be cleared or set from the Right Click menu as well Figure 4 Color Key constellation Color Key Constellation Points is...

Страница 70: ...Computed from 20 Log10 of the linear decision threshold Q factor of the eye Eye Height The distance from the mean one level to the mean zero level units of plot Rail0 Std Dev The standard deviation of...

Страница 71: ...ization menus and hovering the mouse shows a list of available selections The field options are the as measured electric field components plotted as green lines The symbol options draw blue dots at th...

Страница 72: ...e different transitions between levels 0 0 1 1 0 1 and 1 0 The transition parameters listed in the X Trans Y Trans and Pow Trans sections of the Measurements table are derived from the transition aver...

Страница 73: ...on for example if there is a reflection from a length of RF cable inside the transmitter then the linear average eye diagram will clean up once the impulse response length is made long enough to captu...

Страница 74: ...ailable in the MATLAB workspace The table shows the following measurements X Eye Y Eye These are the measurements related to the decision based Q factor method Sweeping the decision threshold value wh...

Страница 75: ...ee of orthogonality can be visualized by inverting the rear face so that orthogonal signals always appear in the same location with different color Thus Blue means back side negative value for that co...

Страница 76: ...form The method used is described in the research paper by Taylor 1 The PMD measurement works with dual polarization signals Two kinds of measurement are possible reference based and non reference bas...

Страница 77: ...y setting the Blk Size to something between 10 000 and 200 000 Typically 50 000 is a good balance between speed of progress updates and overall processing time When operating in this mode only the num...

Страница 78: ...the Clk string with the month 2 day 3 year 1 hour 4 minute 5 and second 6 the save was executed Clk clock save Test num2str Clk 2 _ num2str Clk 3 _ num2str Clk 1 _ num2str Clk 4 _ num2str Clk 5 _ num...

Страница 79: ...ge significantly between the time of calibration and the time of using the calibration data then you will not get optimal results It is still possible to assume ideal receiver properties To use a rece...

Страница 80: ...performance of transmitters and optical communication links It uses fixed calibration parameters to remove uncertainties Deployed receivers will run algorithms to correct in real time for skew gain a...

Страница 81: ...oscilloscopes running the Scope Service No Yes Software required on oscilloscope LAN server Scope Service Utility or ET Scope Service Utility Real time oscilloscope compatibility Any real time Tektro...

Страница 82: ...arization Quadrature In the case below we disable two channels and set the other two to Channel 1 and Channel 3 since these can be active channels in 100Gs s mode The disabled channels must still have...

Страница 83: ...l the proper version of SSU for either real time or equivalent time ET oscilloscopes See installation guide Once the SSU is installed on the oscilloscope start the Socket Server and the TekScope oscil...

Страница 84: ...Connection Dialog box reports 0 Scopes Found you will have to type in the IP address manually This happens when connecting over a VPN or when network policies prevent the IP broadcast When typing the...

Страница 85: ...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 1...

Страница 86: ...he 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 w...

Страница 87: ...be independently driven by a distinct source though all sources must be tuned to the same ITLA channel or at least to the same wavelength While no phase locking of the sources is necessary the beatno...

Страница 88: ...y get ET processing you can use CoreProcessingET in the window instead of CoreProcessingCommands Similarly you can use CoreProcessing in the Engine Window if you want to be sure you only get real time...

Страница 89: ...the plots you want either using the stored Layout button or by clicking on the particular display format icon in the Plot Tools bar Displays can be rearranged within the UI window or dragged and posi...

Страница 90: ...channels within a multicarrier signal at the same time The MCS option can scan automatically between channels Alternatively the scan may be performed manually and the OUI displays the results with the...

Страница 91: ...nition table has four columns The Channel column contains an integer identifying the channel The values in this column do not have to be consecutive The Frequency column contains the absolute channel...

Страница 92: ...tton The Scan Single button and Scan Run Stop buttons start single and continuous automatic scans respectively The OUI may take many acquisitions at each LO setting during the automatic scan according...

Страница 93: ...filter transfer function specified in Analysis Parameters A control is provided to adjust where the plot is placed since the units are relative not dBW Subsequence average Displays the power spectrum...

Страница 94: ...when a change is made to the Absolute Relative Autocenter choices Ref dBW Use the buttons to increase or decrease the power in dBW corresponding to the top of the plot dB Div Click the tall spectrum...

Страница 95: ...as tuned to channel number 1 the green spectrum was found When it was tuned to channel 2 it was the red spectrum Since the channels are close together relative to the optical bandwidth of the system t...

Страница 96: ...integer multiples of one over the difference in cable delays Since different cables are used on the X and Y inputs of the modulator the nulls do not perfectly align and so wash out when looking at the...

Страница 97: ...ms are accessed by clicking on the Eye icon button on the Home tab These plots behave in a similar fashion to the existing eye plots except that there are regions reserved for each channel The layout...

Страница 98: ...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 channel...

Страница 99: ...tatistics table except that only the most recent value is shown so that data from every channel can be displayed in one plot As with the Measurement Statistics plot it is necessary to make sure the de...

Страница 100: ...Taking measurements 76 OM4000D Series Coherent Lightwave Signal Analyzer...

Страница 101: ...latform The references listed below all describe this kind of measurement Although the approach has been used to date to demonstrate optical communications systems it can also be used to record the el...

Страница 102: ...Tsukamoto K Katoh K Kikuchi Coherent detection of optical quadrature phase shift keying signals with carrier phase estimation IEEE J Lightwave Technol vol 24 no 1 p 12 21 2006 K Kikuchi Phase Diversi...

Страница 103: ...ATLAB workspace The order of processing for each acquisition is as follows 1 OUI launches MATLAB engine 2 OUI writes variables to MATLAB workspace corresponding to settings in the OUI Analysis Paramet...

Страница 104: ...A variable representing a quantity that varies with time is a structured variable having at least three fields t0 time of first element in seconds dt time separation between elements Values actual val...

Страница 105: ...iable containing status information typically warnings and error messages accumulated from all the functions called so far See page 88 Alerts management The other variables contain the actual inputs a...

Страница 106: ...e same folder as CoreProcessing m has been prepared in this way to process single polarization QPSK signals It can be called by replacing the line in the MATLAB Commands Window CoreProcessing with Cor...

Страница 107: ...If the phase angle deviates from 90 or if the polarizations are not perfectly orthogonal that is included in pHyb and corrected within CoreProcessing The main output of EstimateClock is SymClock whic...

Страница 108: ...function ApplyPhase At this point zXSym appears as a conventional QPSK signal four clusters of constellation points on the corners of a square Align signal tributaries with data content Although the...

Страница 109: ...ampled from the oscilloscope record The correct polarization rotation is applied to pSym and the X component assigned to zXSym At this point zXSym can be thought of as the four state QPSK constellatio...

Страница 110: ...per symbol timed at the center of the symbol The various eye diagrams and constellation diagrams in the OUI contain traces that appear as smooth lines over time The final task in CoreProcessing is to...

Страница 111: ...mples A user wishing to customize the core processing software does not have to be concerned about block processing unless large record sizes have to be processed The complete steps of interaction bet...

Страница 112: ...ter for the whole oscilloscope record The function Aggregate is called many times in EngineCommandBlock It is a multipurpose function that aggregates the latest block result of a variable into the UI...

Страница 113: ...is by convention declared as the final parameter at both input and output MATLAB sometimes requires it to have a different name at input and output in the function declaration depending on how the fun...

Страница 114: ...ime core processing is executed or after entering clear all at the MATLAB prompt an error is generated if two calls to RegisterAlerts anywhere in the core processing software have the same alert code...

Страница 115: ...alerts accumulated before executing function PattXReOut data pattern of real part of X polarization including synchronization parameters PattXImOut data pattern of imag part of X polarization includi...

Страница 116: ...a row vector of logical values 0s and 1s The other acceptable form for the pattern variable is an empty variable which is used if the data sequence is not known AlignTribs then does not attempt to sy...

Страница 117: ...tXReOut PattXImOut PattYReOut and PattYImOut The PRBSGens or Values field of the input pattern variable is copied to each corresponding output pattern variable Additional fields are set to the output...

Страница 118: ...ing execution of function This function multiplies X Values by a phase factor to give Y Values X may be a single or dual polarization representation There is no requirement that Theta has the same tim...

Страница 119: ...s raised during execution of function 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 w...

Страница 120: ...ats the result is given as complex numbers where each value refers to power in one arm i power in other quadrature arm The optical power in one output arm single ended detection is reported if Balance...

Страница 121: ...lock frequency may be located Low low frequency limit High high frequency limit NonlinFunc string containing instruction for nonlinear function used in clock recovery BoundValsIn structure of boundary...

Страница 122: ...en it may be better to use Y sqrt abs X 1 2 abs X 2 2 If the edges of the signal have excessive ringing then that may cause the clock phase reported by EstimateClock to be offset compared to the true...

Страница 123: ...ndValsOut structure of boundary values to be passed to next block AlertsOut structure of alerts including any alerts raised during execution of function The EstimatePhase function estimates the phase...

Страница 124: ...escription of optical signal at symbol center times t0 time of first symbol dt symbol duration Values 2xN array row of Jones vectors symbol center signal values SigType integer value indicating signal...

Страница 125: ...field values single polarization vs time with fields t0 time of first symbol dt symbol duration Values 1xN array row vector of complex values symbol center signal values SeqRe bit sequence correspond...

Страница 126: ...re of alerts accumulated before executing function Seq sequence of logical values BoundValsOut structure of boundary values to be passed to next block AlertsOut structure of alerts including any alert...

Страница 127: ...s not a structure It is a variable containing a row vector of logical values and does not have t0 and dt fields Jones2Stokes Y Jones2Stokes X X 2xN array row of Jones vectors Y 3xN array row of Stokes...

Страница 128: ...produced by LaserSpectrum does not represent the behavior of the transmit laser alone instead it displays the convolved power spectral density of the local oscillator and the transmit laser The resolu...

Страница 129: ...te of Q factor the output signal to noise ratio even if there are no bit errors or if it would take a long time to wait for a sufficient number of bit errors The actual signal vs time including noise...

Страница 130: ...the spectrum of the signal as follows 1 The signal is downsampled by an integer rate to the slowest rate faster than the sampling rate of the digital oscilloscope to avoid unnecessary processing 2 Th...

Страница 131: ...polarization offset QPSK 13 offset polarization QPSK 14 single polarization 8 ary phase shift keying 8 PSK 15 dual polarization 8 PSK 16 single polarization 8 QAM 17 dual polarization 8 QAM PattXRe P...

Страница 132: ...Appendix A MATLAB variables used by core processing 108 OM4000D Series Coherent Lightwave Signal Analyzer...

Страница 133: ...lization filter coefficients by placing the supplied file EqFiltCoef mat in the ExecFiles folder 10 CoreProcessing DC Calibration may be needed Click DC Calibration on Calibration tab 20 CoreProcessin...

Страница 134: ...use length NumBitsVar Values less than PRBS length 412 GenPattern Generating random data values because NumBitsVar less than PRBS length 413 GenPattern Patt t0 has a different clock phase from BoundVa...

Страница 135: ...ncompensated dc offset in the system this will be evident by a smearing out of the constellation point groups If the offset is large enough the point groups will begin to look like donuts Perform a dc...

Страница 136: ...Q channels have unequal delay there will be a phase offset proportional to the difference frequency between the reference and signal laser oscillation frequencies This phase offset will turn a straig...

Страница 137: ...putting the following statements before CoreProcessing Vblock 3 Values Vblock 3 Values 0 001 Vblock 4 Values Vblock 4 Values 0 001 In either case it is good to adjust the fiber somewhat to maximize th...

Страница 138: ...stellation to see the signal going into the wrong polarization This should just be noise when the middle slider is set properly 12 The delay calibration is done if there is only noise in eye plots exc...

Страница 139: ...serial number is correct then you have the proper file The following procedure can be used to verify and correct the calibration at a single wavelength using a minimum of external hardware This proce...

Страница 140: ...gle block BlockSize 20 000 2 Display the MATLAB Engine Window the X Constellation Window and the Y Constellation Window Close other windows 3 Put DispCalEllipses in the MATLAB Engine Window of the OUI...

Страница 141: ...hat the ellipses are displayed on the Constellation plots Right now only the Y constellation has signal The green trace should line up with the blue circle in the Y constellation plot 5 If the green t...

Страница 142: ...the input fiber until there is signal on all four channels 5 Click Run The green trace should now be circular in both constellations 6 The pHyb statement in step 3 is the final output that is correct...

Страница 143: ...d a clock frequency equal to twice the offset between the signal and LO frequencies This will display two clusters of points and the Magnitude measurement will provide the average signal strength Lase...

Страница 144: ...ET mode Equivalent Time captured signals can be equalized to see the corrected waveshape when using small enough time resolution or time step to emulate a real time captured waveform A number of filte...

Страница 145: ...does not have to be perfectly biased Adjust the vertical gain on the oscilloscope so that the signal is filling up at least 50 of the oscilloscope screen Adjust the signal polarization as needed to ge...

Страница 146: ...Appendix D Automatic receiver deskew 122 OM4000D Series Coherent Lightwave Signal Analyzer...

Страница 147: ...put Four coaxial cables connect the OM4000 Series to a high speed sampling oscilloscope An Ethernet connector will connect the receiver via a router to a computer and to the oscilloscope An IEC power...

Страница 148: ...same network Connections list ET OM4000 Series Complex Modulation Receiver Power cable Ethernet cable BNC shorting cap for interlock 4 Dust covers for optical inputs not in use 4 SMA caps to protect...

Страница 149: ...ies User Interface OUI software and the Laser Receiver Control Panel LRCP software Monitor plus cable Mouse and keyboard Power cables Ethernet cable An Ethernet switch or hub plus a router running DHC...

Страница 150: ...page 4 Environmental operating requirements Computer and software requirements Make sure that your controller computer PC or oscilloscope meets minimum requirements See page 6 PC requirements Make sur...

Страница 151: ...the module s Trigger Output to the Direct Trigger input and choose Pattern Sync Setup Vert tab Use Channels 1 4 or Channels 5 8 Also set the channels used in the ET Scope Service Utility SSU applicati...

Страница 152: ...enu NOTE Be sure that Matlab is available and properly licensed since the OUI will attempt to launch a Matlab Command Window and will appear to stall if Matlab is not available Connecting to the oscil...

Страница 153: ...ecting over a VPN or when network policies prevent the IP broadcast When typing the address in manually do not include ET or RT on the end Click Connect After connection map the channels to the physic...

Страница 154: ...error in the hybrid Laser linewidth factor choosing the correct filter for phase recovery See page 34 Receiver equalization DC calibration ET Although the OM4000 Series units use balanced detection t...

Страница 155: ...on which is assumed when using the software in equivalent time mode creates special difficulty for dc offset measurement since a homodyne signal can have an important dc component This is why the Inpu...

Страница 156: ...lation and signal on Q Eye for 28 Gbps BPSK Note that the sliders control the 1 2 delay the 1 3 delay and the 3 4 delay or 5 6 5 7 7 8 if right hand mainframe slots are chosen These are the most conve...

Страница 157: ...hould only be noise 6 Shut down the RX X polarization by again moving the polarization state of the signal and disabling channels the RX X polarization channels Now only the bottom slider will matter...

Страница 158: ...Constellation to see the signal going into the wrong polarization This should just be noise when the middle slider is set properly 11 The delay calibration is done if there is only noise in eye plots...

Страница 159: ...bCalib file by connecting to an oscilloscope typing pHybInUse in the MATLAB Engine Window and clicking Single Similarly EqFiltInUse shows the equalization filter in use if any The information statemen...

Страница 160: ...ast 3 1 ratio between X I and Y I This is most easily done with a polarization controller 9 Tape the fiber down so that you continue to get most signal on X I and X Q 10 Click Single on the oscillosco...

Страница 161: ...get most of the signal on RX channels Y I and Y Q Tape it down 2 Click Single on the Oscilloscope 3 Click Run on the OUI 4 Observe that the ellipses are displayed on the Constellation plots Right now...

Страница 162: ...and X Y relative gain 2 Replace the DispCalEllipses statement with CoreProcessingCommands for normal operation Keep the pHyb statement as it is correcting the calibration Laser linewidth factor Refer...

Страница 163: ...ock 1 Values through Vblock 4 Values using a 100 tap FIR filter Equalization provides a challenge when working in ET mode Equivalent Time captured signals can be equalized to see the corrected wavesha...

Страница 164: ...e TX Reference signal is picked off before the modulator using a PM fiber cable with a total path length equal to the path from the splitting point to the Signal Input on the OM4000 Receiver Use a SMF...

Страница 165: ...ths differences up to 2 m can be tolerated Matlab Engine file ET You can configure MATLAB to perform a wide range of mathematical operations on the raw or processed data using the Engine window Normal...

Страница 166: ...d window results in two files saved per block plus one final save DebugSave 0 or empty suppresses mat file saves Taking measurements ET Click Single in the OUI and observe that the oscilloscope takes...

Страница 167: ...icient Assume Orthogonal Polarizations Is not yet implemented for ET mode 2nd Phase Estimate Is not yet implemented for ET mode Phase estimation time constant parameter The parameter used in phase est...

Страница 168: ...faster when disabled Calculate linear average vs time Controls computation of the average signal vs time Refresh rate is faster when disabled Calculate transition average Controls computation of the t...

Страница 169: ...ity running on each oscilloscope You can connect one receiver polarization to each oscilloscope However with the recommended hardware configuration shown below it is possible to use the SkewControl fu...

Страница 170: ...onnect the standard USB cable between one of the ports on the scopes and the Sync Board This cable is simply used to power the board RF cabling Connect rear panel BNC connections Ref Out on the master...

Страница 171: ...e unused Sync Board outputs must be terminated in 50 ohms Connect the IQ signal inputs Connect X I on the OM4000 to Ch3 on Oscilloscope 2 lower oscilloscope Connect X Q on the OM4000 to Ch1 on Oscillo...

Страница 172: ...trigger which arms the system and the B trigger from the Sync Board which provides the low jitter trigger relative to the slave scope Both master and slave need to react immediately to the B trigger s...

Страница 173: ...Make sure that the Slave Scope Trigger Holdoff is set to minimum time Slave oscilloscope trigger settings The slave uses the Reference signal from the master via the rear panel BNC The Ch 4 trigger s...

Страница 174: ...ond IP address Find the two oscilloscopes and decide which one is the Master The Master oscilloscope is the one receiving the external trigger The Slave scope is the one triggering on the sync board o...

Страница 175: ...ntrol 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 h...

Страница 176: ...Appendix F Configuring two Tektronix 70000 series oscilloscopes 152 OM4000D Series Coherent Lightwave Signal Analyzer...

Страница 177: ...B NET Both services expose most of the functionality that is available through the LRCP s user interface The basic service implemented using a wsBasicHTTPBinding exposes the same subset of commands as...

Страница 178: ...tive controller takes offline Controller Types All Example Connect Obj Returns ans true bool GetActualCavityLock classname Description Returns the actual cavity lock state for the active controller la...

Страница 179: ...14 5 double GetCalculatedFrequency classname laserusagetype Description Searches all of the connected controllers for the first laser of the specified laser usage type and returns the calculated frequ...

Страница 180: ...ans 196 25 float GetPhotoCurrent classname Description Returns the photocurrent in mA of the receiver in the active controller Controller Types 4006 4106 Example GetPhotoCurrent Obj Returns ans 11 034...

Страница 181: ...for the specified usage type was selected False No lasers found on running controllers for the specified usage type bool SetDesiredCavityLock classname bool_desiredCavityLock Description Sets the des...

Страница 182: ...Description Sets the desired grid spacing in THz of the active laser Can only be set if the active laser is NOT emitting Returning true Successful Controller Types 4006 4106 2210 2012 Example SetDesi...

Страница 183: ...edFrequency Description Sets the channel and fine tune frequency of the currently selected laser to the specified frequency Controller Types 2210 2012 void TogglePolarization classname Description Tog...

Страница 184: ...executed 2 Record Block data is retrieved from the scope and saved to vBlock 3 All commands in the MATLAB Engine Command window are executed against the acquired data record and all variables both sta...

Страница 185: ...ce interface function list Refer to The OM4000 user interface OUI See page 23 for more information on the OUI functionality of these functions both as exposed by the simple http binding and the Client...

Страница 186: ...v Xconst Symbols Displayed Xconst Mask Violations X I Chirp X I Crossing Point X I Eye Height X I Falltime X I Overshoot X I Q Factor X I Rail 0 Std Dev X I Rail 1 Std Dev X I Risetime X I Skew X I Un...

Страница 187: ...bool IsAcquiring classname Description Returns a boolean flag of the scope interface state True Data is being acquired from the scope Example IsAcquiring Obj Returns ans true bool IsCancelling classn...

Страница 188: ...ngth classname uint newRecordLength Description Sets the desired record length in the OUI as an unsigned integer for the next acquisition Example SetRecordLength Obj 10000 void Single classname int ti...

Страница 189: ...ns the real part of the specified complex number double GetArrayOfComplexImaginary string vname Description Returns an array of imaginary double values of the specified array of complex numbers void R...

Страница 190: ...s one or more MATLAB commands that get run before record processing occurs void BlockProcessed BlockProcessedEventArgs eventArgs Description Event Trigger that is executed when the OUI4006 application...

Страница 191: ...assFromWsdl Url obj Laser_ReceiverServiceBasic Where The first specifies the URL or path to a WSDL application programming interface API that defines the web service methods arguments and transactions...

Страница 192: ...OM4006Basic wsdl createClassFromWsdl Url obj WCFServiceOM4006Basic Where The first specifies the URL or path to a WSDL application programming interface API that defines the web service methods argume...

Страница 193: ...t that method WCF service background The OUI4006 application exposes functionality using several WCF services The OM4006ATEClient assembly uses two of those WCF services See page 160 Basic and advance...

Страница 194: ...f the computer is not local then replace localhost with the name of the remote machine for example DavesAsus Adding the XML below to your APP CONFIG file will define two service references running on...

Страница 195: ...ntLength 8192 maxArrayLength 16384 maxBytesPerRead 4096 maxNameTableCharCount 16384 reliableSession ordered true inactivityTimeout 00 10 00 security mode Message message clientCredentialType Windows n...

Страница 196: ...d it can be browsed to understand the available functionality Double click on the reference to bring up the Object browser Scroll down from Optametra OM4006 OM4006ATEClient and double click on OM4006A...

Страница 197: ...this method Values returned from the Get methods outside of this method will potentially be corrupt Private Sub EndOfBlockEvent ByVal sender As System Object ByVal e As System EventArgs Handles MyOM4...

Страница 198: ...cope and do a single acquisition Private Sub Form1_Load ByVal sender As System Object ByVal e As System EventArgs Handles MyBase Load My4006ATEClient RegisterForBlockUpate myBER My4006ATEClient Connec...

Страница 199: ...06ATEClient Serializable public class CustomerVariable MATLABVariableStructure public BER this MATLABVariableName MyCustomStructure BadBlocks new MATLABVariableDouble BadBlocks GoodBlocks new MATLABVa...

Страница 200: ...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 The information is accessed any time the a...

Страница 201: ...internal parts is not necessary Maintenance There are no user serviceable components or subsystems within the OM4000 Attempting any internal repairs will void your warranty Never remove the external...

Страница 202: ...Appendix H Cleaning and maintenance 178 OM4000D Series Coherent Lightwave Signal Analyzer...

Страница 203: ...figuration of experiments 77 Direct assignment of pattern variables 39 E Environmental operating requirements 4 Equipment setup connections 15 equivalent time ET oscilloscopes 14 140 real time RT osci...

Страница 204: ...Operating requirements 4 Optional accessories 2 Options CC two C band lasers 2 3 CL one C band one L band laser 2 3 instrument 2 international power cords 3 LL two L band lasers 2 3 software 3 P PC r...

Страница 205: ...Index W Waveform averaging 48 OM4000D Series Coherent Lightwave Signal Analyzer 181...

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