What is Data Communication?
How does a message travel from one device to another?
- Define data communication
- Identify the five basic components of any communication system
- Give a Papua New Guinean example of each component
Overview
Every time you send a WhatsApp message, tap a card on an EFTPOS machine, or click a link, data is moving between two devices. Data communication is the process of exchanging digital information between a sender and a receiver over some kind of medium, following an agreed set of rules. In this first lesson we break that process into five simple parts that appear in every network — from a two-can string telephone to the global Internet.
The five components
Any data communication system has the same five parts. Learning them once means you can analyse any technology — cable, radio or satellite — with the same mental model.
The five components:
- Sender: The device that generates the message (your phone, a card reader, a sensor).
- Receiver: The device the message is meant for (a friend's phone, the bank server).
- Message: The information itself — text, numbers, image, audio, video.
- Medium: The physical path the message travels along — copper wire, fibre, air (radio).
- Protocol: The rules both sides agree to follow so they understand each other (e.g. TCP/IP, HTTP, SMS).
Why protocols matter
Two devices that speak different 'languages' cannot communicate, even if the wire between them works perfectly. Protocols are the shared rules — how to start a message, how to acknowledge it, how to handle errors. Without protocols, the Internet would be 5 billion devices shouting past each other.
PNG examples
Digicel SMS between two students (sender + receiver = phones, medium = radio waves, protocol = GSM). A Kina Bank EFTPOS transaction (sender = card reader, receiver = bank server, medium = mobile data, protocol = ISO 8583). A radio station in Port Moresby (sender = transmitter, receivers = every radio in range).
Label the System
- In pairs, pick any everyday technology (radio, ATM, Facebook message, VSAT dish).
- Draw the system and label the five components on it.
- Present your diagram to another pair; check each other's labels.
- Name the five components of a data communication system.
Reveal answer
Sender, receiver, message, medium, protocol.
- Why do we need protocols?
Reveal answer
So that both devices agree on how to send, receive, and check the message.
- In an SMS, what is the medium?
Reveal answer
Radio waves (the mobile phone network).
Ask a family member how they sent messages before mobile phones (radio call, letter, HF radio). Which components changed, and which stayed the same?