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ANSI/TIA-568-C testing LC to ST (Duplex Multimode) DTX-EFM2

This article is for the Encircled Flux compliant DTX-EFM2 modules, testing LC to ST duplex fiber links.

The Encircled Flux requirement can be found in ANSI/TIA-526-14-C April 2015.

You can learn more about Encircled Flux (EF) at http://www.brighttalk.com/webcast/727/62347, hosted by FOTC, TIA's Fiber Optic Consortium.
 
Any deviation from the test method below cannot be tolerated if you wish to remain Encircled Flux compliant. 
 
Items required in addition to a DTX CableAnalyzer:

            TIA LC to ST1 Jumper Reference - EFM2


Inspection is critical. You can use anything from a simple Fiber Viewer to a Video Scope such as the FiberInspector Mini shown above.
 
If you have no inspection equipment, you cannot proceed.
 
Let's define what is acceptable and not acceptable.

Fiber End Faces     

 

  1. Perfect. Test Reference Cords are required to be perfect.
     
     
  2. No scratches, but there are a few deposits on the end face and whilst they are not on the core, they could move to the core during referencing/testing. 
        
      
  3. Dirt is clearly covering the core. The hazy stripes across the ferrule indicates poor cleaning practices.
      
       
  4. The cladding has been chipped. This could cause damage to anything you insert it into, including the test equipment. 
                                   

 

 
The Test Reference Cords (TRCs) are critical to a successful measurement. To maintain Encircled Flux compliance, you MUST use one of the following two kits:

 

  •     MRC-50EFC-SCSTKIT:    Duplex MM 50 µm TRC kit for ST links (Two SC to ST EF-TRC cords and two ST to ST TRC cords) 
  •     MRC-50EFC-SCLCKIT:    Duplex MM 50 µm TRC kit for LC links (TwoSC to LC EF-TRC cords and two LC to LC TRC cords) 
  •     You will also need two 50 µm ST to LC TRCs, which Fluke Networks does not currently offer.
    or
  •     MRC-625EFC-SCSTKIT:  Duplex MM 62.5 µm TRC kit for ST links (Two SC to ST EF-TRC cords and two ST to ST TRC cords)
  •     MRC-625EFC-SCSCKIT:  Duplex MM 62.5 µm TRC kit for LC links (Two SC to LC EF-TRC cords and two LC to LC TRC cords)
  •    You will also need two 62.5 µm ST to LC TRCs, which Fluke Networks does not currently offer.

 

In this example, we're going to test a 100 m (328 ft) duplex 50/125 µm multimode fiber link with LC connectors at one end and ST connectors at the other end to ANSI/TIA-568-C whilst maintaining Encircled Flux compliance to ANSI/TIA-526-14-B Oct 2010. 

Setting up the DTX CableAnalyzer

 

  1. With the DTX-EFM2 fiber modules inserted into the DTX CableAnalyzer, power up the main and remote units.
    Sources will need at least five minutes to stabilize, longer in colder or hotter environments.
     
  2. Replace the SC Adapter on the main unit with the optional ST Adapter
     
  3. Replace the SC Adapter on the remote unit with the optional LC Adapter.
     
    Removing the SC Adapter
      
  4. Rotate the dial on the DTX CableAnalyzer to SETUP.
     
  5. Select Fiber Loss and press ENTER.
     
  6. Change the Test Limit to TIA-568-C Multimode.
     
  7. Change the Fiber Type to the cable you are testing.
    This setting changes the Refractive Index (n) value. The DTX uses n to calculate the length of the fiber. You can manually enter the n values in Tab 3 of the Setup. If you cannot find your cable in the DTX Cable Library, look to the cable vendor's website for their datasheet. Since the TIA-568-C Multimode limit is calculated based on length, it is important to get this value right.
     
  8. The Number of Adapters is going to be 2.
    This is always the number of adapters per fiber strand added after the reference has been set.
     
  9. Set the Connector Type to LC.
    This will not affect the outcome of the result. It only affects the help screens.
     
  10. Set the Test Method to 1 Jumper.
      
     Setting Test Method to 1 Jumper
      
     
  11. Inspect the TRCs. If needed, clean them and inspect again. You will not know if they are clean or not until you have visually inspected them.
     
  12. Connect the Output port on the main unit to the Input port on the remote unit as shown below.
      
    Connection of Output Port on Main Unit         

    EF-TRCs must be used. Failure to do so will result in non Encircled Flux compliance.
     
  13. Connect the Output port on the remote unit to the Input port on the main unit as shown below.
      
    Connection of Output Port on Remote Unit 
     
    EF-TRCs must be used. Failure to do so will result in non Encircled Flux compliance.
     
  14. Rotate the dial to SPECIAL FUNCTIONS.
     
  15. With Set Reference selected, press ENTER then TEST.
      
  16. You will then be presented with the results of the Reference.
     
    View Reference Result
     
    For 50/125 µm it should be better than -24.50 dBm where -23.50 dBm is better than -24.50 dBm.
    For 62.5/125 µm it should be better than -20.00 dBm where -19.50 dBm is better than -20.00 dBm.
     
    These values reflect the cleanliness of the Ports and TRCs. The fact that your reference values are better than the minimum stated above does not mean they are good/clean. 
     
  17. Press F2 OK.
     
  18. You can enter the length of your TRCs here. It does not affect the outcome of the test, but will be displayed on the test report.
     
    View Connections   Patch Lengths
     
  19. Press F2 OK when done.
     
  20. Rotate the dial to AUTOTEST and press TEST.
     
  21. We're looking to make sure the sources have stabilized, so with Loss (Remote  Main) highlighted, press ENTER.
     
    Loss Remote to Main Highlighted   Loss Remote to Main Source Stable Check
     
    If you see the loss deviate from 0.00 dB by more than 0.02 dB, your sources have not stabilized. This is an important step to avoid negative loss readings.
     
  22. Press EXIT and then highlight Loss (Main > Remote) followed by ENTER.
     
    Loss Main to Remote Highlighted   Loss Main to Remote Source Stable Check
      
    Again, if you see the loss deviate from 0.00 dB by more than 0.02 dB, your sources have not stabilized. This is an important step to avoid negative loss readings.
         
  23. Remove the ST and LC connectors from the Input Ports. Never disconnect from the Output Ports. Doing so invalidates the reference you just set. 
     
    Remove SC and LC Connectors from Input Ports
     
      
     
  24. Insert the ST to LC TRC' into the Input Port on the main unit.
     
    Insert SC to LC TRC Into Input Port
     
     
     
  25. Insert the LC to ST TRC into the Input Port on the remote unit.
     
    Insert Other SC to LC TRC into Input Port
     
     
     
  26. You are now ready to test the fiber link. There is no easy way to verify the TRCs so inspection is going to be critical. This method is far more precise thany any other method that may result in negative loss readings. You  could build yourself a reference link to verify your TRCs. 
      
  27. Connect the TRCs to the link you're testing.

    Connecting TRCs to Testing Link
     
     
  28. Press TEST.

The DTX CableAnalyzer will calculate the test limit (optical loss budget) for you.
 
Changing the number of adapters/splices will of course increase the test limit. Be sure the Number of Adapters is set correctly.
 
How often should I Set Reference?
The quick answer is; every time you begin to test a series of fiber links. It is critical to continually inspect the TRCs.