In circumstances where running a SmartLoop test is not possible, a user may want to test a single strand of fiber in both directions using a separate OTDR at each end, and then also perform bi-directional averaging of the results. This article outlines the steps necessary to accomplish this. We will refer to the tester being used at End 1 as “Tester #1”, and the tester being used at End 2 as “Tester #2”.
- Equipment Needed:
In order to use this test method, you will need to have two separate Versiv mainframes, each with it’s own OptiFiber Pro (OFP-QUAD) module. You will also need to ensure that you have two OTDR launch cords that match the type of fiber that will be tested, as well as the correct port adapters for your testers. A list of part numbers for launch cords and port adapters can be found on the OptiFiber Pro product page in the “Accessories” section.
- Create the Projects and Test Setups on both testers:
The project name and test setup must be identical on both testers. For the test setup, this includes the Test Type, Fiber Type, and Test Limit.
- Create Cable ID Sets on both testers:
Each tester will need to have identical Cable ID sets, apart from the setting for “End 1” or “End 2”. The ID set on Tester #1 will be set exclusively to End 1, and the ID set on Tester #2 will be exclusively End 2. In our example we set up for OM3 Multimode fiber, which looked like this:
Note that the only difference between the two is “End 1” compared to “End 2”. The Project name, Test Setup, and Cable ID must be identical.
Set Launch Compensation
Next, we need to set launch compensation as “Launch + Tail” for each tester by using the same two launch cords, but in opposite directions. This means that the launch fiber that is the “Tail” for Tester #1 will be the “Launch” for Tester #2 and vice versa, as seen in these images:
Launch + Tail Compensation for Tester #1:
Launch + Tail Compensation for Tester #2:
Run the OTDR Autotests
When running the tests each tester and launch cord will stay at only one end of the fiber link under test. There is no need to move the launch cord(s) or tester(s) to the far end of the link under test.
Obs.: The End 1 and End2 tests are not run simultaneously. Test from one end first using the first test set, then test from the other end with the second test set. Below are examples of what this would look like.
Once the tests have been run and the results saved, you should see only results marked with on Tester #1, and only results marked with on Tester #2:
Import and Merge / Average the Results
Now that we have the results on each tester, we need to import them to the LinkWare PC software. Once the results have been imported from both testers, we should see two records for each cable that was tested, one for End 1 and one for End 2:
First, we need to merge the separate records for End 1 and End 2 for each record by using the “Fiber Record Merge” option found in the Utilities menu:
After the records have been merged, you will see a new record for each cable ID appended with (M) to indicate that it a merged fiber record. Next, we need to use the “Average Bi-directional OTDR Results” option found in the same Utilities menu. After the merged records have been averaged, there we be yet another new record for each cable ID, but this time with (M-B) appended to indicate that the record is both merged and averaged:
- Notes on tester calibration
If the two OFP-QUAD modules being used have differing calibration dates, please note that the primary calibration date listed for each merged result will be the earlier or “older” of the two dates. A standard LinkWare PC test report will show the calibration date for each OFP-QUAD module used.