RCDD Optical Fiber Systems and Testing 3

Question 1

What does an OTDR 'ghost' event indicate?

Accepted Answer

A false reflection caused by high-reflectance events creating phantom signals further down the trace

Answer

OTDR ghosts are phantom events that appear further along the trace, caused by double reflections from highly reflective connectors or end faces bouncing back and forth.

Question 2

Why is a launch cable (also called a launch fiber or mandrel) used when performing OTDR testing?

Accepted Answer

To allow the OTDR to fully recover from the initial blind zone before measuring the first connector on the fiber under test

Answer

A launch cable allows the OTDR to pass its initial dead zone (caused by the strong Fresnel reflection at the output connector) so the first connector on the actual cable under test can be measured accurately.

Question 3

What is 'macrobending loss' in optical fiber?

Accepted Answer

Loss caused by bending the fiber cable below its minimum bend radius, causing light to escape the core

Answer

Macrobending loss occurs when fiber is bent beyond its minimum radius, causing the evanescent field to extend beyond the cladding and light to radiate out of the fiber core.

Question 4

Which standard defines the testing requirements for installed optical fiber cabling systems including insertion loss and return loss?

Accepted Answer

ANSI/TIA-526-14 (multimode) and ANSI/TIA-526-7 (single-mode)

Answer

ANSI/TIA-526-14 covers optical power loss measurement for multimode fiber, while TIA-526-7 covers single-mode; both are referenced by TIA-568 for acceptance testing.

Question 5

What is 'modal bandwidth' and why does it matter for multimode fiber?

Accepted Answer

The frequency range over which a multimode fiber can transmit; higher modal bandwidth supports faster data rates over longer distances

Answer

Modal bandwidth (MHz·km) describes how much information a multimode fiber can carry before intermodal dispersion causes adjacent pulses to overlap; higher bandwidth enables higher data rates over longer spans.

RCDD - Registered Communications Distribution Designer Practice Test

RCDD - Registered Communications Distribution Designer Practice Test

RCDD Optical Fiber Systems and Testing 3