1. What is a Data Transmission Medium?
A Data Transmission Medium is the path through which data travels from a sender to a receiver.
Key Idea: Wired media use a physical path, Wireless media use air/space.
2. Two Categories of Media
- Guided/Wired Media, data travels through a physical medium
- Unguided/Wireless Media, data travels through air or space without a physical cable
3. Guided/Wired Media
A. Twisted Pair Cable
Two insulated copper wires twisted together.
- UTP (Unshielded Twisted Pair), flexible and inexpensive, suitable up to 100m
- STP (Shielded Twisted Pair), has extra shielding for better protection and transmission quality
B. Coaxial Cable
A central conductor surrounded by protective layers, innermost to outermost:
- Central Conductor, carries the signal
- Insulation, wraps the conductor
- Shielding, blocks interference
- Outer Cover, protects the cable
C. Fiber Optic Cable
Transmits data using light signals through glass fibers, innermost to outermost:
- Core, carries the light signal
- Cladding, reflects light back into the core
- Jacket, protects the fiber
Key Idea: Used in modern communication networks, supports high-quality, high-speed transmission.
4. Unguided/Wireless Media
A. Radio Waves
Data transmitted using radio signals.
Example: Wi-Fi, BluetoothB. Microwaves
Data travels in a straight line.
Key Idea: Requires line of sight between sender and receiver.
C. Satellite Communication
Uses microwaves to transmit data over very long distances.
Key Idea: Best suited for long-distance communication.
D. Infrared
Used for short-range wireless communication.
Example: TV remote controls, wireless keyboards, wireless miceQuick Memory Trick
- Twisted Pair, twisted copper wires
- Coaxial, layered cable
- Fiber Optic, light signals
- Radio Waves, Wi-Fi/Bluetooth
- Microwaves, line of sight
- Satellite, very long distance
- Infrared, short range
Summary
- Transmission medium, the path data travels through from sender to receiver
- Guided/Wired, Twisted Pair, Coaxial, Fiber Optic
- Unguided/Wireless, Radio Waves, Microwaves, Satellite, Infrared
Remember: Wired needs a physical path, Wireless travels through air or space.