Application Note

WEBSITE: www.jdsu.com/fiberoptictest

By Geraldine Samier, Gregory Lietaert; Email: gregory.lietaert@jdsu.com

JDSU’s MTS/T-BERD platforms: Fully automated bi-directional

OTDR data acquisition and data analysis test instruments

From the beginning, JDSU has understood the need for developing a test instrument that reduces both the test-

ing time and the processing time of a large quantity of test results, maximizing quality assurance. With its 20

years of experience in OTDR measurement, JDSU has developed dedicated and powerful solutions in coopera-

Bi-directional analysis is a technique that is used to minimize the effect of back scattering coefficient differences

along a fiber link, which in turn causes erroneous OTDR splice measurements. It is used when accurate baseline

data is desired or during acceptance testing where splice measurements, often performed by subcontractors, are

required. Complete commission of a network can only be accomplished using bi-directional OTDR techniques,

taking into account the fiber section performance differences (core diameter, back scattering coefficient, etc.) on

the link. These tests require two technicians, one at each end of the fiber.

The traditional bi-directional OTDR process

For fiber characterization, two technicians are required with two OTDR units, one at each end of the fiber link.

Each technician measures and stores the results of all of the fibers. Then, the results of the two OTDRs are com-

piled in order to generate the acceptance report. In the event of problems, errors or incorrect results are usually

The drawbacks of the traditional bi-directional OTDR process

The traditional bi-directional OTDR process has the following drawbacks:

(1) Possible operator error

• Incorrect or different OTDR settings on one of the two units.

• No fiber continuity check, generating incorrect bi-directional testing from the technicians measuring two

different fibers.

• A mismatch between the fiber number and the stored data, resulting from a file management error.

(2) Inefficient use of time

• A meeting (or access to an Ethernet point) is necessary in order to exchange data.

• No real-time problem detection. e technicians must usually return to the test sites the following day, intro-

Testing time increases with the number of fibers. In order to expedite the installation phase or increase the

number of fibers tested within a given period of time, the importance of having fully automatic tools, such as

automated bi-directional OTDR testers, becomes clear.

JDSU now offers an automated bi-directional OTDR function in its MTS/T-BERD platforms that solves the

issues of traditional bi-directional OTDR analysis as previously described.

JDSU’s automated solution provides the following capabilities:

• Provides error-free operation by exchanging the master unit’s OTDR test configuration if it differs from the

remote unit’s OTDR test configuration.

• Performs a fiber continuity check to ensure that both units are testing the same fiber.

• Performs data acquisition on the remote unit and transfers the trace to the master unit.

the process in less than 50% of the time required for other traditional bi-directional OTDRs.