Testing installed optical fiber cables is the final step of any installation. But testing fiber can be done in five different ways, depending on what the standards require or what you need to know. How well do you know the options? Answers and explanations are in red.

1. All international standards require _______ testing to verify the cable plant installation.

A. Continuity

B. OTDR

C. Insertion loss

D. Reflectance

Insertion loss measured with a light source and power meter or OLTS is the only recognized test for verifying the performance of an installed cable plant. OTDR testing is permitted but not allowed in place of insertion loss testing.

2. Insertion loss testing is performed with a _______.

A. Light source and power meter

B. Light source and power meter and reference test cables

C. OTDR with a launch reference cable

D. OTDR with two reference test cables

Insertion loss testing uses a light source and power meter connected to the cable under test with reference test cables.

3. Insertion loss testing requires setting a “0 dB reference” in one of _______ ways.

A. Two

B. Three

C. Four

D. Five

Standards allow 3 ways to set a “0 dB reference,” using one, two or three reference cables between the meter and source.

4. The difference between the methods of setting a “0 dB reference” for insertion loss testing is _______.

A. The value of optical power chosen for the “0 dB reference”

B. The wavelength of light used for calibration and testing

C. The number of reference cables used when setting the “0 dB reference”

D. The range of the OTDR display

The three methods use different reference cables to allow adapting test equipment to the cable plant under test.

5. The loss measured using either of the methods to set the “0 dB reference” will be the same.

True

False

When setting the “0 dB reference” with one cable, no connections are involved, one connection is included in setting the reference with two cables and two connections when setting the reference with three cables. These connections will cause loss measurements to vary by the amount of the loss in the connections between the reference cables, so a two cable reference will be lower by the connection included in the reference measurement and a three cable reference will be lower by the two connections included.

6. TIA 568 requires insertion loss testing using Method B, which requires setting a “0 dB reference” using _______ reference test cable(s).

A. One

B. Two

C. Three

D. Four

TIA 568 calls for a Method B, once cable reference, but now notes that it may not be possible with some connector types, so other reference methods may be used as long as they are documented in the test results.

7. If the connector types being tested do not match those on the test equipment, insertion loss testing can use the _______ reference method.

A. Method A, two cable

B. Method B, one cable

C. Method C, three cable

D. Either method A or method C

Hybrid reference cables (matching the test equipment on one end and the connector on the cables to test on the other end) allow testing cables with connectors different from the test equipment.

8. If the connector types being tested are of the “plug and jack” style (MTP, MT-RJ) and do not match those on the test equipment, insertion loss testing must use the _______ reference method.

A. Method A, two cable

B. Method B, one cable

C. Method C, three cable

Only Method C will work with plug and jack connectors.

9. OTDRs are always used with launch cables, which allow measuring the loss of the first connector on a cable but do not measure the loss of the connector on the far end.

True

False

If nothing is connected to the far end connector, there will be no connection loss to measure.

10. In order to measure the loss of the connector on the far end of a fiber with an OTDR, you can _______.

A. Attach a reference cable to the far end of the fiber being tested

B. Test a second time with the OTDR at the far end of the cable

C. Either A or B

D. None of the above; the OTDR does not make that measurement

A reference cable connected to the far end of the fiber will allow the OTDR to measure the loss of the connector as will shooting the fiber in the opposite direction.

HAYES is a VDV writer and educator and the president of The Fiber Optic Association. Find him at www.jimhayes.com.