User Guide EPC1000 Endless Polarization Controller Novoptel
Contents
1. cccceeeeeeeeeeeeeeeceeeeeeeeeeeeeeeaeees 7 Operation of the instrument using Novoptel Software ceceeeeeeeeeeeeeeeteeeeeeeees 8 Installing the WS BIS ct incacinetscectihecncnsin eines tic ecie neds eit eid cassandra 8 Connect the MVSTMTIS NR sassatasscrtaiieuie newinticadondaise del evel dvlvadsigerelscxietieavadelvedegadeiievedevevceadevedeiiey 8 Installing the Novoptel Software ceeeeeeccccceeeeeeeeeeeeeeeeeeeeeeeeeeeeeseeaaeeeeeeeeeeeeeeeas 8 First steps with the Novoptel Software ccccceeeeeeeeeeeseeeeeeeeeeeeeeseesneeeeeeeeees 8 Operation of the instrument using Matlab ccccccceeeeeeeeeeeeneeeeeeeeeeeeeeeesneeeeeeeees 11 Access the USB OV SES aicticd cesses aecrin tic Goumesesdsemee se acnaaeihyupanctdeummceaheumasecdatnasiadearaueae 11 Mranster PROVO COM icsseesns ee helen tree ce ere eet ete E tare meee 11 USB registers ccc snd cdies cence dag uap wtp ened ceded eancemedenndensseias enneenien emeedaesssenedenenwonten 12 Operation of the instrument using other programs ceeseeeeeeeeeeeeeeeeeeeeeneeeeeeeeees 13 Operation of the instrument USING SPI eeeeeeeecceeeeeeeeeeeeeeeeeeeeeeeeeeeeeseeseeeeeeeeees 14 Novoptel 3 of 14 EPC1000_UG_0 1 5 docx Novoptel EPC1000 User Guide Operation of the instrument using the front control panel Power the instrument with the provided power supply and switch it on The controller firmware provides a cyclic men2. Novoptel 10 of 14 EPC1000_UG_0 1 5 docx Novoptel EPC1000 User Guide Operation of the instrument using Matlab The USB driver CDM20814 Setup exe has to be installed on your system and the polarization controller needs to be connected using a USB cable Access the USB driver Matlab needs a header file like ftd2xx h from FTDI to access the driver In the provided version matftd2xx h we have modified the data types to be compatible to Matlab You will find help about communicating to a driver at http www mathworks com help techdoc ref loadlibrary html The different functions of the driver can be seen from the header file Information about each function is provided at http www ftdichip com Support Knowledgebase index html Transfer Protocol The polarization controller is controlled by reading from and writing to USB registers The register address line is 12 bits wide while each register stores 16 bits All communication is initiated by the USB host e g the Matlab program Writing to a register uses a 9 byte data packet Each byte represents an ASCll coded character The packet starts with the ASCll character W and ends with the ASCII code for carriage return Send write data packet The 12 bit register address A is sent using 3 bytes each containing the ASCII character of the hexadecimal numbers 0 to F which represents the 4 bit nibble The character of the most significant nibble is sent first The 16 bit
3. Novoptel Application note 1 Error signals for polarization control N Novoptel EPC User Interface Create Diagnosis Report Record Histogram Novoper M rame For this mode a new form will be opened to observe and modify appropriate control parameters It also shows the calculated error signal e g the sum of the weighted power in the analyzed harmonics instead of the pure ADC signal N Novoptel EPC Harmonics Detection aT 000 3 Harmonics Eror Signal Weight Constraint none New Weights 0 216 0 338 0 446 Average Power 0 453 0 407 0 139 Novoptel 9 of 14 EPC1000_UG_0 1 5 docx Novoptel EPC1000 User Guide The new form allows to enable a PWM signal also described in Application note 1 at the BNC output The average powers in the three detected harmonics are displayed Detection of harmonics 1 2 3 or harmonics 2 3 4 can be selected For each of the two sets suitable weights are being proposed To meet a specific transmitter configuration the weights can be modified manually or via predefined weight constraints The weight constraint 0 1 means that the weight for the lowest harmonic is zero The weight constraint 0 25 0 75 means that the weight for the highest harmonic is 3 times the weight for the lowest harmonic and so on Weight Constraint mA New Weights 05 Average Power 1 Click on the button labeled Set to load the modified weights to the EPC
4. of the instrument using Novoptel Software The instrument communicates by a USB I C FT232R from FTDI Future Technology Devices International Limited http www ftdichip com The software is compiled on a Microsoft XP 32Bit system with NET Framework 3 5 SP1 installed but also tested with Windows 7 32 Bit and Windows 7 64 Bit Installing the USB driver Execute the installation program of the provided USB driver CDM20814_Setup exe You will find more detailed information about the driver at http www ftdichip com Support Documents InstallGuides htm Connect the instrument After the driver is installed successfully connect PC and instrument using the provided USB cable Power the instrument with the provided power supply and switch it on Wait until Windows has recognized the USB device and shown an acknowledgement message before proceeding Installing the Novoptel Software Execute setup exe in the folder EPC 1000_GUI Follow the instructions of the installation dialogue First steps with the Novoptel Software The software launches automatically after installation If you want to launch the software later manually select Programs Novoptel EPC 1000 from the Windows Start Menu Select one of the attached instruments If you have attached only one Novoptel polarization controller the software automatically selects this one If you have attached more than one polarization controller select the desired instrument from the dr
5. 07 6 5 12 us 31 us 1 379 7 10 24 us 62 us 696 3 8 20 48 us 123 us 349 9 9 40 96 us 246 us 175 3 10 81 92 us 492 us 87 78 11 163 84 us 984 us 43 92 12 327 68 us 1 967 us 21 97 13 655 36 us 3 933 us 10 99 14 1 310 72 us 7 865 us 5 49 15 2 621 44 us 15 729 us 2 75 16 5 242 88 us 31 458 us 1 37 17 10 485 76 us 62 915 us 0 69 Default value is ATE 0 This value is needed to achieve the specified endless polarization tracking speed The value ATE 11 will increase averaging time by a factor of 2048 and the control time constant by a factor of 900 Note that ATE values gt 11 are only supported by EPC firmware gt 1 0 4 1 Novoptel 5 of 14 EPC1000_UG_0 1 5 docx Novoptel EPC1000 User Guide Swap Channels Use the LEFT or RIGHT button to switch to the orthogonal polarization channel Only applicable with interference detectors Load Save Restore Settings Settings can be saved in and loaded from a non volatile RAM Restore will apply the factory settings Novoptel 6 of 14 EPC1000_UG_0 1 5 docx Novoptel EPC1000 User Guide External Error Signals Depending on configuration the EPC supports external error signals In case of supported electrical external error signal the unit will provide two SMA connectors at the backside of the desktop case The electrical error signal is differential with a typical common mode voltage of Vcm 0 9 V From rear view the left connector is for voltages V2sVcw the right connector is for VizVcm Max
6. User Guide Novoptel EPC1000 Endless Polarization Controller Novoptel GmbH EIM E Warburger Str 100 33098 Paderborn Germany www novoptel com Revision history Version Date Remarks Author 0 1 1 28 01 2012 Draft version B Koch 0 1 2 07 12 2012 Definition of averaging time exponent ATE B Koch 0 1 3 28 02 2013 Description of Detector Mode selection B Koch new section External Error Signals 0 1 4 20 12 2013 Support of ATE gt 11 B Koch 0 1 5 12 03 2014 Harmonics Bessel line detection B Koch Table of contents Operation of the instrument using the front Control panel ccccceeeeeeeeeeeeteeeeeeeees 4 Detection Mode reen r stead ceo SA A AA 4 Control ModE nose cheetah arte cei tec aaae eae a aee e aae A aaea 4 Dither Amplitude seeeooenennneneeeeeeeeentnnrtereerrrtttnnntrneertttttnnntnssertrrrtnnnnnnseeenrtnnnn nenene 4 ASOT ON GaN sae E E E eneauaaeequmacnquuscene 4 Feedback Delay c cicccnssssccncecenccsneesssecsseoneneneeenendaceecs none ntneesneeeccecetsentenneesnnesccecnenendnens 5 Averaging Time Exponent ccccceceeeeeeeeeeeceeeeeeeeeeeeeeeaaaeeeeeeeeeeeesseecaaeeeeeeeeeeeeeneea 5 Swap Channels sessirnir e Ea aa eE aaea 6 Load Save Restore Settings ecsoieinccsecutwnectcetwnntisntuancdeetecedbstenn sbdetvecbbiitwerssdeaucabbentins 6 fess 21g rl lg 0 abe gs oe ne eee en ee eee 7 Verifying control by internal optical detector
7. data which should be written into the register is sent with 4 bytes using the same coding as the register address Reading data from a register requires the host to send a request data packet to the instrument The packet starts with the ASCll character R followed by the register address coded the same way as in write data packets Send request data packet R aajao aofo fo or fo ror After receiving the request data packet the instrument sends the requested data packet to the host Novoptel 11 of 14 EPC1000_UG_0 1 5 docx Novoptel EPC1000 User Guide rapopo USB registers For register information please refer to EPC1000 Data Sheet Novoptel 120f14 EPC1000_UG_0 1 5 docx Novoptel EPC1000 User Guide Operation of the instrument using other programs The USB vendor http www ftdichip com Support Knowledgebase index html provides examples for USB access using other programs for example LabVIEW Novoptel 13 of 14 EPC1000_UG_0 1 5 docx Novoptel EPC1000 User Guide Operation of the instrument using SPI All control registers can also accessed by SPI The SPI interface allows much faster communication than USB The SPI connector at the backside of the device provides the following connection Connector notch For SPI timing please refer to EPC1000 Data Sheet Novoptel 14 of 14 EPC1000_UG_0 1 5 docx
8. gain increases tracking errors even at low polarization changing speeds For an interference detector which provides two minima the optimum control gain can be calculated by Novoptel 4 of 14 EPC1000_UG_0 1 5 docx Novoptel EPC1000 User Guide Gain 100 dither signal_range where dither is the dither amplitude factor and signal_range is the difference between maximum and minimum feedback signal divided by the full ADC range For example at 100 dithering and a feedback signal which uses half of the ADC range the optimum control gain is 100 1 0 5 200 For intensity detectors only one global minimum 100 has to be replaced by 400 in the above formula Feedback Delay Error signal delay deadtime risetime given as multiples of 20 ns Default value corresponds to optimum value for given error signal detector Only external feedback signals might require increasing the default value Averaging Time Exponent Noisy or slow feedback signals may require averaging The averaging time can be set by increasing the averaging time exponent ATE Averaging time influences the control time constant and hence the tracking speed Averaging Time f Control Time Exemplary Trackin Exponent pweraging Time Constant en ari j 0 0 08 us 1 1 us 40 000 1 0 16 us 1 6 us 27 692 2 0 32 us 2 5 us 17 143 3 0 64 us 4 4 us 9 730 4 1 28 us 8 3 us 5 217 5 2 56 us 16 us 2 7
9. imum ratings are OVSV1 2s2V and OVsV1i V2s0 8V Neglecting a small offset the analyzed relative feedback signal is proportional to the input voltage difference V1 V2 1 4 V1 v2 a M V1 V2 Volt foe a4 o D P 0 2 0 4 0 6 0 8 1 Relative Feedback Signal The use of a differential feedback signal is highly recommended However if control has to be tested with a single ended signal the connector for V2 can be terminated to ground Neglecting an offset the analyzed relative feedback signal is then proportional to the input voltage 0 lt V1 lt 0 8V 0 8 V1 V1 V2 Volt jo a 0 0 2 0 4 0 6 0 8 1 Relative Feedback Signal Verifying control by internal optical detector Desktop units of EPC with external electrical error signal also provide an optical feedback input connector in order to enable function verification of the EPC independent from the user supplied error signal To do so connect the optical controller output to the optical input at the backside of the unit using a single mode fiber patch cord If the unit does not provide an internal PBS Polarization Beam Splitter a PBS or polarizer has to be included in the light path externally Optical power at the optical feedback input should be lt 10 dBm to avoid error signal overflow unless otherwise specified Novoptel 7 of 14 EPC1000_UG_0 1 5 docx Novoptel EPC1000 User Guide Operation
10. op down menu N Novoptel EPC User Interface Device Tools Help Connects gt EPX1000 40 10 XL ia ia Sela Control Enable _Novoptel Maximize If the software is not able to connect to an instrument it may be blocked by a former program instance that has not been terminated correctly In this case terminate the former program instance by the Windows task manager Subsequently you can launch further instances of the software and connect them to further instruments Novoptel 8 of 14 EPC1000_UG_0 1 5 docx Novoptel EPC1000 User Guide Change Control Settings Control value can be typed in the four fields shown below and applied by clicking X Current values are displayed beside the fields 4 Dither Amplitude 100 Control Gain 24 Error Signal Delay 0 Averaging Time Exp For parameter information refer to the previous chapter Detector Switch 1 C Detector Switch 2 Depending on the ordered detector type two switches allow for switching between different detector modes e g interference detection optical power detection and external electrical error signal Detect Harmonics Bessel Lines If supported by the connected EPC module the software allows enabling the harmonics detection mode In this mode selected harmonics Bessel lines in the feedback signal will be analyzed and minimized instead of the feedback signal itself For detailed information about harmonics detection please refer to
11. u which is shown on the LCD display The menu structure is Welcome Screen Control ON OFF Show Feedback Signal Select Detection Mode optional Select Control Mode Set Dither Amplitude Set Control Gain Set Feedback Delay Set Averaging Time Exponent ATE Swap Channels Save Settings Load Settings Restore Default Settings The control buttons UP and DOWN let you to navigate through the menu The control buttons LEFT and RIGHT changes a selected setting Detection Mode For the EPC units that provide different detection modes two detector switches allow to select a specific feedback signal e g optical input detection or electrical input detection Control Mode This menu point lets you temporarily maximize the feedback signal This is required to determine the feedback signal range and calculate the optimum control gain Polarization tracking using signal maximization is not recommended Dither Amplitude Small dither is recommended if error signal is of good quality Large dither is needed if error signal is noisy Register determines percentage of nominal dither amplitude Default value is 0004h 100 0000h 50 0001h 62 0002h 75 0003h 87 0004h 100 0005h 112 0006h 125 0007h 150 Control Gain Optimum control gain depends on detector type dither amplitude and feedback signal range Too low control gain reduces tracking speed whereas a too high
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