DCI Testing & Troubleshooting 5

Question 1

Which reference method for fiber insertion loss testing includes the loss of the launch cord in the measurement?

Accepted Answer

One-cord (Method B)

Answer

The one-cord reference method sets a reference using only the launch cord, so the launch connector's loss is included in the final link measurement.

Question 2

A copper channel test fails for ELFEXT (Equal-Level Far-End Crosstalk). At which end of the cable is ELFEXT measured?

Accepted Answer

The far end, opposite to the signal transmitter

Answer

FEXT (and ELFEXT, which normalizes for attenuation) is measured at the far end of the cable, opposite to where the disturbing signal is injected.

Question 3

A technician suspects a high-resistance fault on a copper pair. Which test parameter would best confirm this?

Accepted Answer

DC loop resistance

Answer

DC loop resistance measures the total resistance of the conductor loop and will be elevated if there is a poor connection, corrosion, or a partial break in the conductor.

Question 4

When using a visual fault locator (VFL) on a fiber, a bright red glow is visible through the jacket. What does this indicate?

Accepted Answer

A tight bend, break, or macro-bend causing light to escape at that location

Answer

A VFL emits visible red light; if it escapes through the jacket it means the fiber is losing light at that point due to a bend, break, or mechanical fault.

Question 5

What does it mean when a copper cable tester reports 'PASS*' (pass with an asterisk)?

Accepted Answer

The cable passed but one or more measurements were within the tester's measurement uncertainty margin

Answer

A PASS* result means the cable technically passed all limits but at least one parameter fell within the uncertainty band of the test instrument, indicating a marginal link.

(DCI) Data Cabling Installer Practice Test

(DCI) Data Cabling Installer Practice Test

DCI Testing & Troubleshooting 5