BDS Fiber Optic Systems and HFC Architecture

Question 1

What does HFC stand for in cable broadband architecture?

Accepted Answer

Hybrid Fiber-Coaxial

Answer

HFC (Hybrid Fiber-Coaxial) refers to the network architecture that uses optical fiber from the headend to neighborhood nodes, and coaxial cable from the nodes to subscriber homes.

Question 2

What is the primary function of a fiber node in an HFC network?

Accepted Answer

To convert optical signals to RF signals for the coaxial distribution plant

Answer

The fiber node contains an optical receiver that converts the downstream optical signal to RF, and a laser transmitter that converts upstream RF signals back to optical for transport to the headend.

Question 3

What is the typical wavelength used for downstream optical transmission in an HFC network?

Accepted Answer

1550 nm

Answer

The 1550 nm wavelength is widely used for downstream transmission in HFC networks because it offers lower fiber attenuation and is compatible with EDFA optical amplification.

Question 4

Which fiber optic connector type is most commonly used in the cable broadband industry for node and headend connections?

Accepted Answer

SC/APC

Answer

The SC/APC (Subscriber Connector / Angled Physical Contact) connector is the dominant connector in HFC networks due to its low back-reflection, snap-lock design, and compatibility with industry standards.

Question 5

What is optical return loss (ORL) and why is it important in HFC systems?

Accepted Answer

The ratio of reflected optical power to incident power; excessive reflections degrade laser performance

Answer

Optical return loss measures reflections back toward the laser transmitter; high reflections can destabilize the laser, increase relative intensity noise (RIN), and degrade CNR in the RF system.

BDS - Broadband Distribution Specialist Practice Test

BDS - Broadband Distribution Specialist Practice Test

BDS Fiber Optic Systems and HFC Architecture