A2.3.2 — Transmission Media

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Types of Media

Fibre-Optic Cable

Uses pulses of light through glass or plastic fibres to transmit data at very high speeds over long distances.

Twisted Pair Cable

Uses pulses of electricity through pairs of insulated copper wires twisted together.

  • UTP (Unshielded Twisted Pair): Most common in computer networking.
  • STP (Shielded Twisted Pair): Extra shielding reduces electromagnetic interference — used in high-EMI environments.
  • Cat 6 and above support higher speeds than older categories.

Wireless

Uses electromagnetic waves (radio frequencies, infrared, microwaves) to transmit data. No physical cables. Common technologies: Wi-Fi, Bluetooth, cellular networks.

Comparison Table

FactorFibre-OpticTwisted PairWireless
Bandwidth Extremely high — tens of Gbps Moderate — sufficient for home/office. Cat 6+ supports higher speeds. Limited — affected by connected devices, distance, environment.
Installation Complex — specialised tools and skills for splicing. Well understood — standard technicians can install without specialised skills. Simpler — set up access points and configure settings. No cable laying.
Cost High — cables and equipment expensive. Low — especially UTP. Widely available. Moderate equipment cost. No physical cable costs.
Range Excellent — long distances with minimal signal loss. Ideal for WAN. Limited — needs repeaters for longer distances. Limited — can be extended with hardware but adds cost and complexity.
Interference Immune to EMI — ideal for industrial or dense urban areas. Susceptible — especially over long distances or in high-EMI environments. STP mitigates this. Highly susceptible — interference from other devices, physical barriers, environmental factors.
Attenuation Very low — signal integrity maintained over long distances. Higher — needs signal boosters for longer runs. Significant — signal weakens with distance and through obstacles.
Reliability Very high — low latency, unaffected by weather. Generally reliable within limits — can be impacted by EMI. Variable — affected by interference, signal strength, and congestion.
Security Very secure — hard to intercept light signals without physical access. Secure — interception requires physical access to the cable. Vulnerable — susceptible to eavesdropping if not properly secured (encryption essential).