OSP Fiber Optic & Copper Cabling Systems 2 — Questions and Answers
Question 1: What is the primary advantage of using loose-tube construction in outdoor fiber optic cables compared to tight-buffered construction?
- Lower cost per foot
- Better resistance to temperature extremes and moisture ingress (Correct answer)
- Easier to splice in the field
- Higher fiber count capacity
Correct answer: Better resistance to temperature extremes and moisture ingress
Loose-tube construction allows fibers to float in gel or dry water-blocking material, providing superior protection against temperature cycling and moisture ingress in outdoor environments.
Question 2: When performing an OTDR trace on a fiber span, a reflective spike followed by a loss event typically indicates:
- A clean mechanical splice
- A fusion splice with high loss
- A fiber connector or open end reflection (Correct answer)
- Macro-bending loss
Correct answer: A fiber connector or open end reflection
A reflective spike (Fresnel reflection) on an OTDR trace is characteristic of a connector, cleaved end, or mechanical splice where there is an air gap causing back-reflection.
Question 3: Which copper cable configuration is MOST susceptible to cross-talk interference in a dense multi-pair outside plant environment?
- Direct burial twisted pair with individually shielded pairs
- Aerial self-supporting cable with central strength member
- Unshielded twisted pair with identical twist rates across all pairs (Correct answer)
- Filled gel copper cable with armor
Correct answer: Unshielded twisted pair with identical twist rates across all pairs
Pairs with identical twist rates run parallel to each other for long distances, creating maximum coupling and cross-talk between pairs; varying twist rates reduce this interference.
Question 4: In a fiber optic OSP design, the term 'optical budget' refers to:
- The total cost of fiber and hardware
- The maximum allowable power loss between transmitter and receiver (Correct answer)
- The number of fiber strands available in a route
- The wavelength range supported by the cable
Correct answer: The maximum allowable power loss between transmitter and receiver
Optical power budget is the difference in dB between the transmitter output power and the minimum receiver sensitivity, representing the maximum tolerable link attenuation.
Question 5: A central office engineer needs to run a new copper cable through an existing conduit that already contains a filled cable. What is the primary concern?
- Dielectric interference between cables
- Exceeding conduit fill ratio and heat buildup from increased cable mass (Correct answer)
- Magnetic interference from adjacent pairs
- Corrosion from gel compound interaction
Correct answer: Exceeding conduit fill ratio and heat buildup from increased cable mass
Conduit fill ratio limits must be respected to maintain cable pulling tension limits and prevent overheating from reduced airflow around cables.
Question 6: What type of fiber splice provides the lowest insertion loss and is preferred for permanent OSP connections?
- SC connector splice
- Mechanical splice using index-matching gel
- Fusion splice (Correct answer)
- Cleave-and-crimp splice
Correct answer: Fusion splice
Fusion splicing melts fiber ends together, eliminating air gaps and producing insertion losses typically below 0.1 dB, far better than mechanical methods.
Question 7: Which attenuation specification applies to standard single-mode fiber (OS2) at the 1310 nm window per TIA-568?
- 0.1 dB/km
- 0.4 dB/km (Correct answer)
- 1.0 dB/km
- 3.5 dB/km
Correct answer: 0.4 dB/km
TIA-568 specifies a maximum attenuation of 0.4 dB/km at 1310 nm for OS2 single-mode fiber used in OSP applications.
OSP Fiber Optic & Copper Cabling Systems 2
What is the primary advantage of using loose-tube construction in outdoor fiber optic cables compared to tight-buffered construction?