Question

Why, a fiber optic cable cannot be called as a transmission line? Also clarify what are the
primary conditions required for a transmission line.
(b)Why a structured cabling system is required? Describe the structure in a proper flow with a neat
diagram.

Answer 1

A) A transmission line is defined as a conductor or conductors designed to carry electricity or an electrical signal over large distances with minimum losses and distortion.These are the solid cables with as minimum resistance to the electricity as possible used for transmission of electricity from one part to another. It transmits the wave of voltage and current from one end to another. The transmission line is made up of a conductor having a uniform cross-section along the line. Air act as an insulating or dielectric medium between the conductors. The performance of the transmission line depends on the parameters of the line. The transmission line has mainly four parameters, resistance, inductance, capacitance and shunt conductance. These parameters are uniformly distributed along the line. Hence, it is also called the distributed parameter of the transmission line.

Whereas, a fiber optic is defined as a flexible, transparent fiber made by drawing glass (silica) or plastic to a diameter slightly thicker than that of a human hair. Optical fibers are used most often as a means to transmit light between the two ends of the fiber and find wide usage in fiber-optic communications, where they permit transmission over longer distances and at higher bandwidths (data transfer rates) than electrical cables. They are more actually concerned with the transmission of information in the form of light or electric pulse. They are the modes of communication of information and do not transmit electricity for its general use as a transmission line on the other end. Hence they are not considered as transmission lines.

B) In telecommunications, structured cabling is building or campus cabling infrastructure that consists of a number of standardized smaller elements (hence structured) called subsystems. Structured cabling components include twisted pair and optical cabling, patch panels, and patch cables. The importance of organized cabling systems will vary from business to business, but for the majority, it can ensure a highly reliable and cost-effective network infrastructure that will stand the test of time. Hence their importance is utmost.

The following diagram explains the proper flow of structured cabling.

Subsystems

Structured cabling consists of six subsystems:

• Entrance facilities are the point where the telephone company network ends and connects with the on-premises wiring belonging to the customer.
• Equipment rooms house equipment and wiring consolidation points that serve the users inside the building or campus.
• Backbone cabling is the inter-building and intra-building cable connections in structured cabling between entrance facilities, equipment rooms and telecommunications closets. Backbone cabling consists of the transmission media, main and intermediate cross-connects, and terminations at these locations. This system is mostly used in data centers.
• Horizontal cabling wiring can be standard inside wiring (IW) or plenum cabling and connects telecommunications rooms to individual outlets or work areas on the floor, usually through the wireways, conduits or ceiling spaces of each floor. A horizontal cross-connect is where the horizontal cabling connects to a patch panel or punch up the block, which is connected by backbone cabling to the main distribution facility.
• Telecommunications rooms or telecommunications enclosure connects between the backbone cabling and horizontal cabling.
• Work-area components connect end-user equipment to outlets of the horizontal cabling system.