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EXFO FTB-5600 User Manual Download Page 139

Optimizing Measurements

Distributed PMD Analyzer

133

Use an Appropriate Spatial Smoothing Filter Value

If a 2000-m filter is applied to the curve, you can see a noticeable 
improvement. The noise level is much lower, yet the PMD variations are 
still there. This is the best filter value for such a trace.

Summary of Contents for FTB-5600

Page 1: ...User Guide Distributed PMD Analyzer for FTB 500 FTB 5600...

Page 2: ...y EXFO for its use nor for any infringements of patents or other rights of third parties that may result from its use No license is granted by implication or otherwise under any patent rights of EXFO...

Page 3: ...nd Connecting Optical Fibers 18 Installing the EXFO Universal Interface EUI 20 Setting up General Acquisition Parameters 21 Setting up the Graph Display 23 Setting up Storage Options 25 Displaying PMD...

Page 4: ...nters Worldwide 109 A Technical Specifications 111 B Distributed Cumulative PMD Measurement Theory 113 C Acquisition Data 117 D Optimizing Measurements 121 Basic Verification Steps 121 Use a Larger Nu...

Page 5: ...ompliance verification tests are systematically performed on most EXFO equipment Information Electronic test equipment is subject to the EMC Directive in the European Union The EN61326 standard prescr...

Page 6: ...rol and Laboratory Use Part 1 General Requirements EN 61326 1 2006 Electrical Equipment for Measurement Control and Laboratory Use EMC Requirements Part 1 General requirements EN 60825 1 1994 A2 2001...

Page 7: ...correction of the link by replacing faulty sections The results include A cumulative PMD curve and an OTDR trace A PMD section table that provides the PMD for each section identified by the instrumen...

Page 8: ...displays it This step only takes a few seconds At this point you should inspect the trace to see if there are any problems Then the instrument measures the SOPs This will take more or less time depen...

Page 9: ...zation Light that is not polarized In the case of the FTB 5600 we use this term to define zone on the fiber where the instrument cannot perform a measurement since light is entirely depolarised For mo...

Page 10: ...ther along the fiber but results in a lower resolution A shorter pulse width provides higher resolution but a smaller distance range RS POTDR Random scrambling tuneable polarization sensitive OTDR Sen...

Page 11: ...njury Do not proceed unless you understand and meet the required conditions CAUTION Indicates a potentially hazardous situation which if not avoided may result in minor or moderate injury Do not proce...

Page 12: ......

Page 13: ...urce Note Label shown for information purposes only It is not affixed to your product WARNING Do not install or terminate fibers while a light source is active Never look directly into a live fiber an...

Page 14: ......

Page 15: ...B 500 so that its right panel is facing you CAUTION Never insert or remove a module while the FTB 500 is turned on This will result in immediate and irreparable damage to both the module and unit WARN...

Page 16: ...t the right of the retaining screw hole 4 Insert the protruding edges of the module into the grooves of the receptacle s module slot 5 Push the module all the way to the back of the slot until the ret...

Page 17: ...s 7 While applying slight pressure to the module turn the retaining screw clockwise until it is tightened This will secure the module into its seated position When you turn on the unit the startup seq...

Page 18: ...it ToolBox and turn off your unit 2 Position the FTB 500 so that the left panel is facing you 3 Turn the retaining screw counterclockwise until it stops The module will be slowly released from the slo...

Page 19: ...Getting Started with your FTB 5600 Distributed PMD Analyzer 13 Inserting and Removing Test Modules 5 Hold the module by its sides or by the handle NOT by the connector and pull it out...

Page 20: ...0 Distributed PMD Analyzer module can be configured and controlled from its dedicated ToolBox application Note For details about ToolBox refer to the FTB 500 user guide To start the application 1 From...

Page 21: ...ted PMD Analyzer 15 Starting the Distributed PMD Analyzer Application The main window shown below contains all the commands required to control the Distributed PMD Analyzer Data display and control ce...

Page 22: ...y application that is not currently being used helps freeing system memory To close the application from the main window Click in the top right corner of the main window OR Click the Exit button locat...

Page 23: ...ed level you must have a solid knowledge on how OTDRs function This includes Interpreting OTDR traces Understanding the effect of the pulse on a trace Understanding the contents of an event trace Mani...

Page 24: ...ends as follows 2a Gently wipe the fiber end with a lint free swab dipped in isopropyl alcohol 2b Use compressed air to dry completely 2c Visually inspect the fiber end to ensure its cleanliness IMPO...

Page 25: ...tor features a key ensure that it is fully fitted into the port s corresponding notch 4 Push the connector in so that the fiber optic cable is firmly in place thus ensuring adequate contact If your co...

Page 26: ...plate indicates that it is for APC type connectors To install an EUI connector adapter onto the EUI baseplate 1 Hold the EUI connector adapter so the dust cap opens downwards 2 Close the dust cap in o...

Page 27: ...surement manually You can set the default spatial smoothing filter in meters The spatial smoothing filter helps improving the measurement results in filtering the cumulative PMD curve The default valu...

Page 28: ...ed PMD Analyzer 22 FTB 5600 Setting up General Acquisition Parameters 2 Select the General tab 3 Modify the parameters as desired under General setup 4 Press Apply to use the new settings or OK to use...

Page 29: ...are displayed You can display or hide the grid You can use the high contrast view if the lighting quality prevents you from seeing the graph properly glare from the sun darkness You can show or hide...

Page 30: ...ibuted PMD Analyzer 24 FTB 5600 Setting up the Graph Display 2 Select the Display tab 3 Modify the parameters as desired under Graph display setup 4 Press Apply to use the new settings or OK to use th...

Page 31: ...an autonaming scheme to facilitate and speed up your work You can also decide to keep the intermediate data while performing acquisitions This option should be used when there is a problem with your...

Page 32: ...Setting up and Operating your Distributed PMD Analyzer 26 FTB 5600 Setting up Storage Options To set up the storage options 1 From the main window select Setup 2 Select the General tab...

Page 33: ...ed PMD Analyzer 27 Setting up Storage Options 3 Under Storage setup enter the paths for the default save folder and the reporting template You can also use the Browse button to open a standard navigat...

Page 34: ...will see a preview of the next file name at the bottom of the window Note If your acquisition is set to continuous the autonaming feature is automatically selected and you cannot change this setting...

Page 35: ...MD Related Columns in the Main Window You can decide to hide or display the following columns in the main window PMD2 Cumulative PMD2 PMD coefficient Note If you decide to hide or display those column...

Page 36: ...FTB 5600 Displaying PMD Related Columns in the Main Window 2 Select the Display tab 3 Under PMD sections display setup select which column or columns you want to display 4 Press Apply to use the new s...

Page 37: ...r 31 Setting up Cable Information Setting up Cable Information The cable information is useful to help you differentiate your various acquisitions It will also appear in reports you generate for your...

Page 38: ...Distributed PMD Analyzer 32 FTB 5600 Setting up Cable Information 2 Select the Cable Information tab 3 Enter the information as needed 4 Press Apply to confirm the information or OK to confirm the inf...

Page 39: ...the general test mode All you have to set is the accuracy and sensitivity levels This mode is selected by default when you open the application To perform a standard acquisition see Performing a Stand...

Page 40: ...is will take more or less time depending on the accuracy and sensitivity requested The remaining time and SOPs to measure are indicated in the status bar of the application After measuring about 10 SO...

Page 41: ...he instrument This will improve the dynamic range The link length the range value may be updated with the link length seen on the trace This reduces the size of the file and accelerates both processin...

Page 42: ...ting up and Operating your Distributed PMD Analyzer 36 FTB 5600 Performing an Acquisition To perform a Quick Check acquisition 1 From the main window under General select the Quick Check acquisition m...

Page 43: ...ess Start The acquisition starts You can see the remaining time in the status bar Performing a Standard Acquisition The acquisitions are more optimized for characterizing the link correctly rather tha...

Page 44: ...three resolutions Setting the sensitivity to medium will improve the dynamic range and means an acquisition of about 30 minutes with three resolutions Setting the sensitivity to high will give you th...

Page 45: ...D Analyzer Distributed PMD Analyzer 39 Performing an Acquisition To perform a standard acquisition 1 From the main window under General select the Standard acquisition mode 2 Set the accuracy of the m...

Page 46: ...asurement by selecting a value in the list 4 Select the PMD resolution that can best fit the minimum measurable value for your PMD scale Note The PMD resolution will influence the acquisition time the...

Page 47: ...tive PMD curve A higher number of averages decreases the noise and increases the acquisition time EXFO recommends a value of 500 averages use more if the measurement range is too small A value below 5...

Page 48: ...ved Consider the following to improve your dynamic range Note You can obtain the dynamic range of the trace by subtracting the backscatter level at the fiber end from the injection level accepted rang...

Page 49: ...nts in links with high PMD you should use a value between 0 4 and 1 ps For low PMD measurements use a value around 50 ps and at least 100 SOPs For faster measurements of small PMD values use a lower s...

Page 50: ...anging this range unless you want to perform a very specific test 3 Set the distance range in kilometers from the list of available values or you can enter your own manually Reducing the range to the...

Page 51: ...Analyzer 45 Performing an Acquisition 4 Under Advanced select the number of SOPS from the list of available values You can also type in a value directly 5 Select the number of averages for the measure...

Page 52: ...Setting up and Operating your Distributed PMD Analyzer 46 FTB 5600 Performing an Acquisition 7 Select the pulse width in ns 8 Select the sensitivity level...

Page 53: ...he more difficult it is to measure weak PMD variations Using a measurement coming from each end of the link you want to characterize and combining the two measurements into one bidirectional trace fil...

Page 54: ...nal File Creator To create a bidirectional file 1 From Windows select start then All Programs EXFO Programs OR From ToolBox select the Applications tab then P OTDR Bidirectional File Creator 2 Select...

Page 55: ...up and Operating your Distributed PMD Analyzer Distributed PMD Analyzer 49 Using the Bidirectional File Creator 3 Select the trace file you want to use for the B A side by using the corresponding Open...

Page 56: ...g the Bidirectional File Creator 4 If the two traces do not allow the automatic calculation of the length of the link for example they do not cover the same distance or if you want to specify a length...

Page 57: ...buted PMD Analyzer Distributed PMD Analyzer 51 Using the Bidirectional File Creator 5 If you want to specify an estimation of the PMD on the link select the corresponding option 6 Click Generate to st...

Page 58: ...Setting up and Operating your Distributed PMD Analyzer 52 FTB 5600 Using the Bidirectional File Creator The resulting traces appear on screen once the application is done creating the file...

Page 59: ...ibuted PMD Analyzer 53 Using the Bidirectional File Creator To save the created bidirectional trace 1 Select Save as then select a name and location for your file 2 Select Save Note For information on...

Page 60: ...Using the Bidirectional File Creator To open the created trace in the P OTDR application to analyze it Once the trace was created and saved select Open in P OTDR Note A bidirectional file is always id...

Page 61: ...at you can access through ToolBox The offline application is identical to the online application except that you cannot make acquisitions with it therefore you will see that the Start button as well a...

Page 62: ...To access the offline application 1 From ToolBox select the Applications tab Note Depending on which applications are installed on your platform the Applications tab may look different 2 Select P OTD...

Page 63: ...File If you are working with the offline mode of the application or want to open a file you have previously acquired you can either open it and modify it as needed or open it as a read only file to av...

Page 64: ...Managing Results 58 FTB 5600 Opening an Existing File 2 Select the file you want to open If you want the file to open in read only mode select the corresponding option 3 Press Open...

Page 65: ...g file that you have opened IMPORTANT Since acquisition files can be extremely large they are directly sent to the storage location and are not kept in memory to optimize the operation speed of the un...

Page 66: ...Managing Results 60 FTB 5600 Saving a File To save a file using the autonaming scheme From the main window press Save...

Page 67: ...Managing Results Distributed PMD Analyzer 61 Saving a File To save a file using a personalized name 1 From the main window press Save As 2 Enter a name for the file then press Save...

Page 68: ...n a specific area by selecting the button and defining the zoom area with the stylus or your finger a rectangle with dotted lines will appear to help you define the area Once you release the stylus th...

Page 69: ...quare root difference of the PMD cumulative curve section s last value and the PMD cumulative curve section s first value Several indicators in the cumulative PMD table will help you with your measure...

Page 70: ...cific section of the cumulative PMD of a link Since PMD adds up to the square the contribution is computed in squares The percentage of contribution values are provided in square since it is mathemati...

Page 71: ...a linear scale it would fall from 11 18 ps to 5 ps You must therefore always remember that the contribution is computed as square values Section Status You can view the status of the section at all t...

Page 72: ...he section has a PMD value that is too high according to the selected PMD range A significant portion of the cumulated PMD curve for the section is too high according to the selected PMD scale Select...

Page 73: ...e imprecise The beating length the local variations that have to be measured is a lot shorter than the size of the pulse Therefore the polarizationfluctuation measured by the unit vanished through the...

Page 74: ...sections occur when on the link the polarization moves at a speed faster than the acquisition time of a wavelength s step This phenomenon can occur mainly when measuring aerial links when there are s...

Page 75: ...marker just after the end of the transition Note When you position the markers for the PMD you will see that they might not fit exactly with the automatically detected OTDR events on the trace Working...

Page 76: ...he OTDR automatic detection event algorithm Since most OTDR events do not coincide with PMD events you may find that the table contains events that are irrelevant to your test You may want to edit som...

Page 77: ...Managing Results Distributed PMD Analyzer 71 Editing Sections Trace after treatment...

Page 78: ...isting segment in two This could help you pinpoint events that are more relevant to your analysis than those automatically detected To split a fiber section 1 From the main window select the Section E...

Page 79: ...Managing Results Distributed PMD Analyzer 73 Editing Sections 2 Select the section you want to edit by pressing on it once 3 Press Split...

Page 80: ...o click drag the cursor to the desired location The new segment you are creating is indicated in red in the table You will also see the two segments in gray on the graph Note If you had comments in th...

Page 81: ...events To merge a fiber section to another 1 From the main window select the Section Edition tab 2 Select the section you want to merge by pressing on it once The section is always merged with the on...

Page 82: ...with Previous The selected section is merged with the one above it and you can see the results on screen Note If there were comments in either section they will be merged as well 4 Press Apply to acce...

Page 83: ...another section to improve the section table measurements To edit a fiber section length 1 From the main window select the Section Edition tab 2 Select the section you want to edit by pressing on it o...

Page 84: ...rrow buttons to move the right end of the segment to its new location You can also click drag the cursor to the desired position The other surrounding segments are updated accordingly 5 Press Apply to...

Page 85: ...add comments to each fiber section to include important information or details on the events that could be helpful in later analyses To add comments to a segment 1 From the main window select the Sec...

Page 86: ...Managing Results 80 FTB 5600 Editing Sections 3 Press Edit Comments 4 Type in the comment you want to add then press Apply to keep the comment or Cancel to leave without adding a comment...

Page 87: ...with two cursors cursor A indicates the beginning of the measurement and cursor B indicates the end On screen you will see the positions of the markers as well as the PMD cumulative values The applic...

Page 88: ...Using Markers to Measure PMD Differences Delta PMD Tab To move the markers 1 Select the PMD tab 2 Select which cursor to move 3 Use the arrow buttons to move the cursor You can also click drag the cu...

Page 89: ...ction itself This is done by modifying one or some strong PMD sections of the link to analyze By modifying the PMD value or the coefficient of the section in those links you can see the simulated cumu...

Page 90: ...rom the main window select the Estimation tab 2 Select the row for which you want to change a value by pressing on it once 3 Modify the PMD or PMD coefficient values as desired 4 Press Apply to se the...

Page 91: ...m the Trace Info tab you can also change the cable and job information reanalyze a trace and change the spatial smoothing filter Note You can find more information about the spatial smoothing filter i...

Page 92: ...Managing Results 86 FTB 5600 Viewing Trace Information To view the trace information From the main window select the Trace Info tab...

Page 93: ...is that of both measurements The maximum wavelength is that of both measurements The maximum number of SOPs is that of both measurements The number of averagings is the maximum value of both measureme...

Page 94: ...Managing Results 88 FTB 5600 Viewing Trace Information To change the cable and job information 1 From the main window select the Trace Info tab 2 Press Settings 3 Select the Information tab...

Page 95: ...ed some information in the Cable Information window as explained in Setting up Cable Information on page 31 it will already be in the corresponding boxes 5 Press Apply to use the new information then...

Page 96: ...Managing Results 90 FTB 5600 Viewing Trace Information 3 Select the Analysis tab 4 Press Reanalyze 5 Press Close to return to the application...

Page 97: ...anaging Results Distributed PMD Analyzer 91 Viewing Trace Information To change the spatial smoothing filter 1 From the main window select the Trace Info tab 2 Press Settings 3 Select the Analysis tab...

Page 98: ...Managing Results 92 FTB 5600 Viewing Trace Information 4 Change the filter value to the desired value in the list 5 Press Apply to use this new value then Close to exit the window...

Page 99: ...ting Reports Generating Reports Once your trace is cleaned up and that your measurements are optimized you can generate a report This report can then be printed or saved for future consultation To gen...

Page 100: ...ect what you want to do Press Save to store the file A standard Save As window opens to let you select a name and location Press Print to send the document to your printer A standard Print window open...

Page 101: ...erature in a clean and dry area Keep the unit out of direct sunlight Avoid high humidity or significant temperature fluctuations Avoid unnecessary shocks and vibrations If any liquids are spilled on o...

Page 102: ...ule 2 Moisten a 2 5 mm cleaning tip with one drop of isopropyl alcohol alcohol may leave traces if used abundantly 3 Slowly insert the cleaning tip into the EUI adapter until it comes out on the other...

Page 103: ...that the connector and ferrule are perfectly dry 6d Verify connector surface with a portable fiber optic microscope for example EXFO s FOMS or fiber inspection probe for example EXFO s FIP 7 Put the E...

Page 104: ...l unless this has been previously agreed upon with the customer Validity of specifications depends on operating conditions For example the calibration validity period can be longer or shorter dependin...

Page 105: ...to an European Union member state with legislation regarding Directive 2002 96 EC Except for reasons of safety or environmental benefit equipment manufactured by EXFO under its brand name is generally...

Page 106: ......

Page 107: ...the following Obtaining Online Help An online version of the FTB 5600 Distributed PMD Analyzer user guide is available at all times from the application Note You will also find a printable PDF version...

Page 108: ...o Friday 8 00 a m to 7 00 p m Eastern Time in North America For detailed information about technical support visit the EXFO Web site at www exfo com To accelerate the process please have information s...

Page 109: ...unction tab Transportation Maintain a temperature range within specifications when transporting the unit Transportation damage can occur from improper handling The following steps are recommended to m...

Page 110: ......

Page 111: ...calibration during the warranty period and found to meet all published specifications EXFO will charge standard calibration fees THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES EXPRESSED IMPLIED OR...

Page 112: ...hall be responsible for any failure in the performance of other items to which the product is connected or the operation of any system of which the product may be a part EXFO shall not be liable for d...

Page 113: ...EUI used with EXFO products are not covered by this warranty This warranty excludes failure resulting from improper use or installation normal wear and tear accident abuse neglect fire water lightnin...

Page 114: ...conditions under which it was observed 5 Return the equipment prepaid to the address given to you by support personnel Be sure to write the RMA number on the shipping slip EXFO will refuse and return...

Page 115: ...683 0155 USA and Canada Tel 1 418 683 5498 Fax 1 418 683 9224 quebec service exfo com EXFO Europe Service Center Omega Enterprise Park Electron Way Chandlers Ford Hampshire S053 4SE ENGLAND Tel 44 23...

Page 116: ......

Page 117: ...Web site at www exfo com Temperature Operating 0 C to 40 C 32 F to 104 F Storage 40 C to 70 C 40 F to 158 F Relative humidity 0 to 93 non condensing f Size H x W x D 96 mm x 75 mm x 281 mm 3 3 4 in x...

Page 118: ......

Page 119: ...l width of 4 GHz FWHM The OTDR pulses are routed by a circulator C and a polarization beam splitter PBS serving as a polarization analyzer before passing through an input and output state of polarizat...

Page 120: ...pair must be the same they are generally different from one pair to another For each pair of P OTDR traces a corresponding local transmission difference Tk zn can be calculated at each distance point...

Page 121: ...uted as the second order joint moment of the repeated differences thereby eliminating this noise offset In order to attain a maximum dynamic range and to minimize the coherence noise in the backscatte...

Page 122: ...45 is a saturated value of the ms difference when PMD and dT 15 is a proportional constant when 0 When the PMD is obtained from a single measurement at a given time the cumulative PMD curve PMD zn wi...

Page 123: ...h of the two traces in each pair is acquired twice consecutively in time thus producing a repeated pair having a difference T k zn which may differ somewhat from Tk zn The P OTDR traces Pj zn as a fun...

Page 124: ...figure below Note Each P instance represents an OTDR trace In order to settle up an acquisition you will note that since the acquisition consist of OTDR traces you must set the OTDR trace parameters...

Page 125: ...uist sampling criteria A sampling rate that is too high will result in a measurement that is too noisy The figure below gives an example of a correct step and of a step which is too large to measure t...

Page 126: ...residual PMD need to be set Note The PMD sampling steps overlap by 3 In the example below the chosen scale is 8 ps and the residual PMD of 60 fs We can see each scales with their saturation level and...

Page 127: ...nt to another because of a PMD theoretical uncertainty due to a finite wavelength range being used thereby a better accurate measurement may be achieved by using a maximum available wavelength range f...

Page 128: ...surement accuracy for RMS DGD in the available wavelength range A maximum wavelength range and as many SOPs as possible for the acquisition will reduce the uncertainty of a measurement that is to achi...

Page 129: ...er test if there is no very high PMD fiber s from there By combining two sided measurements together you can have a better and clearer cumulative PMD picture with a less measurement uncertainty Perfor...

Page 130: ...should be of 10 ps and if a total PMD of an FUT is of 22 ps an appropriate PMD scale is of 20 ps Note Make sure not to select a PMD scale that is too high when measuring low PMD To use an appropriate...

Page 131: ...s and are not interested in low PMD values for example 1 ps then you should select a residual PMD that is just smaller than 1 ps On the other hand if you are interested in measuring PMD the value of f...

Page 132: ...PMD for the Acquisition The figure below shows an example of a link having a low PMD measured with bad PMD scale and high PMD resolution A better setting for this acquisition would have been a PMD sca...

Page 133: ...ld a windy environment or any other reason that causes SOPs to vary over a time period when acquiring each individual P OTDR trace on an FUT using a lower number of averagings may be helpful in improv...

Page 134: ...ed in the field fibers a short pulse length for example 50 ns may be used to reduce the depolarization effect and improve SNR so as to ensure an acquired signal level that is larger than a coherent no...

Page 135: ...surements the sharp transition position will not be changed by the filter An anti causal filter has the property to remove the delay of the filter from the filtering effect of the signal This means th...

Page 136: ...a cumulative PMD curve you must take into account the behavior of the filters You might have to adjust the positions of the markers after you have applied a filter In the figure below you can see how...

Page 137: ...tributed PMD Analyzer 131 Use an Appropriate Spatial Smoothing Filter Value In the case of the large step the median curve jump almost straight to the top of the step whereas the moving average will s...

Page 138: ...elow is an example of applying different filter values to a same trace The first curve has a filter of 100 m applied to it The noise is quite visible and the PMD changes are sharp Attempting to take m...

Page 139: ...133 Use an Appropriate Spatial Smoothing Filter Value If a 2000 m filter is applied to the curve you can see a noticeable improvement The noise level is much lower yet the PMD variations are still the...

Page 140: ...causal filter has an effect on the PMD curves it will cause them to end before the actual end of the fiber With a correct dynamic range the cumulative PMD curve ends halfway through the actual fiber...

Page 141: ...al hazard 5 of product hazard 5 certification information v cleaning EUI connectors 96 fiber ends 18 front panel 95 columns in table displaying 29 connectors cleaning 96 contact information EXFO 103 c...

Page 142: ...ne user guide 101 optimized PMD scale 124 optimizing measurements 121 OTDR pulse 114 128 P PDF see online user guide PMD averaging 123 columns displaying 29 cumulative theory 113 residual 125 resoluti...

Page 143: ...equirements 95 symbols safety 5 T technical specifications 111 technical support 102 103 temperature for storage 95 theory cumulative PMD 113 transportation requirements 95 103 two sided measurements...

Page 144: ...363 2006 X Indicates that this toxic or hazardous substance contained in at least one of the homogeneous materials used for this part is above the limit requirement in SJ T11363 2006 SJ T11363 2006 Pa...

Page 145: ...MARKING REQUIREMENTS Product Environmental protection use period years Logo This Exfo product EXFO 10 Batterya a a If applicable 5...

Page 146: ...Swee Road 03 29 Manhattan House SINGAPORE 169876 Tel 65 6333 8241 Fax 65 6333 8242 EXFO CHINA No 88 Fuhua First Road Central Tower Room 801 Futian District Beijing New Century Hotel Office Tower Room...

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