Guided Media — Copper and Fibre
What is inside the cable that carries our data?
- Identify UTP, STP, coaxial and fibre-optic cables
- Compare their speed, distance and cost
- Recommend a cable for a school lab
Overview
Guided media are cables — the signal is 'guided' along a physical path. Choosing the right cable decides how fast, how far, and how reliably data moves. In every school lab in PNG the choice is usually between twisted-pair copper (cheap, easy) and fibre (fast, long-distance, more expensive).
Twisted pair (UTP and STP)
Twisted-pair cable has pairs of insulated copper wires twisted together to cancel out interference. UTP (unshielded) is the everyday blue/grey cable behind every classroom PC — cheap, up to 100 m, gigabit speeds. STP (shielded) adds a foil wrap for noisy environments like factories. Category numbers (Cat 5e, Cat 6, Cat 6a) indicate speed grade.
Coaxial
Coax has a single copper core, an insulator, a braided metal shield and an outer jacket. It once ran early Ethernet and still carries cable-TV and long antenna feeds. In a school it usually shows up as the cable from the roof aerial to a TV or as the backbone of an old CCTV system.
Fibre-optic
Fibre carries light pulses through hair-thin glass. It is immune to electrical interference, secure (hard to tap), fast (10 Gbps+ common) and can run kilometres. Single-mode fibre is for long-haul (city to city, PNG NBN backbone); multi-mode is for shorter runs inside a building. Fibre is the reason your streaming works — the international traffic to PNG rides on undersea fibre.
Cable Show-and-Tell
- Examine the sample cables provided (UTP, coax, fibre).
- In a 3-column table, record: appearance, typical speed, typical use.
- Rank them from cheapest to most expensive per metre.
- Which cable is immune to electromagnetic interference?
Reveal answer
Fibre-optic.
- What is the maximum length of a Cat 6 UTP run?
Reveal answer
100 metres.
- Why is fibre used for undersea cables to PNG?
Reveal answer
It supports very high speeds over very long distances with low loss.
Trace the cable behind one school computer. What category is it (look for 'Cat 5e' or 'Cat 6' on the jacket)?