Definition and Characteristics of Data Communication
Two machines, one conversation: what it takes for data to cross a medium and still mean the same thing.
You are sitting at the back of a lecture hall in Ilorin. You type "I'm outside, come and see me" and tap send. Two seconds later your friend's phone buzzes in Lagos. Between those two seconds, your words were turned into electricity, then light, then radio — and still arrived exact, in order, untouched.
A copper wire is not clever. A radio wave doesn't know your friend's name. So who is doing the work? A small cast of characters, each with one job. Let's meet them.
The word telecommunication comes from Greek tele, "far". Humans have always wanted to talk across distance — drums, smoke signals, town criers, letters. Data communication is the computer-age version of that very old wish.
Here is the precise definition, worth knowing word for word: data communication is the exchange of data between two devices via some form of transmission medium, such as a wire cable. And data itself means information presented in whatever form is agreed upon by the parties creating and using it.
Notice the three ingredients hiding in that sentence: two devices, a medium between them, and an agreement about form. Keep those in mind — they will come back as the five components in a moment.
How do we judge whether a communication system is doing its job? Four fundamental characteristics:
- Delivery — data must reach the correct destination, and only the intended device or user.
- Accuracy — data must arrive unaltered. A bank transfer of ₦5,000 that arrives as ₦50,000 is a disaster, even if it arrived on time.
- Timeliness — data must arrive on time. For video and voice, late data is useless data; this is called real-time transmission.
- Jitter — the variation in packet arrival time. If video packets are sent every 30 ms but some arrive after 30 ms and others after 40 ms, the picture stutters.
Pause & think
On a video call, every word arrives perfectly — but six seconds late. On another call, the delay is small but keeps changing: 20 ms, then 90 ms, then 30 ms, so voices sound choppy. Which characteristic is failing in each case?
Spotted a mistake?