Types of Digital Communications

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Types of Digital Communications

Big idea: every digital device — whether it's talking over a mile-long wire or a 10cm Bluetooth link — sends its data as electrical, light, or radio signals down some kind of "channel," and the type of channel you pick depends on how far the data has to travel, how fast it needs to get there, and how much power/security you can afford.

Summary — the whole chapter in one scan

Satellite communication bounces radio waves between ground stations and orbiting satellites — always available, but weather and solid objects can block it.
Digital TV/radio (DVB-T, DAB) broadcasts from earth-based transmitters straight to your aerial — no satellite involved.
Wired methods (HDMI, S/PDIF, mini-jack, Ethernet, USB) are each built for a specific job — video, audio, networking, or general devices.
Wireless methods (Wi-Fi, Bluetooth, Infra-red, NFC, 4G/5G) trade the convenience of no cables for lower speed, shorter range, or weaker security.
Networks come in three sizes: PAN (a few metres, e.g. Bluetooth), LAN (one building, under a mile, fully owned by you), and WAN (multiple LANs joined across the world, using hardware you don't own — like telephone lines).
Wi-Fi vs Bluetooth is a classic exam comparison: Wi-Fi = faster, longer range, more devices; Bluetooth = lower power, simpler pairing, shorter range.
GPS uses satellites + radio frequencies to pinpoint an object's exact location — needs a direct line of sight to work.
3G/4G/5G are generations of mobile data network, each generation faster and handling more users than the last.
Infra-red is short-range, line-of-sight only, used in remote controls — sunlight and walls can disrupt it.
NFC is super short-range (touching distance), used for contactless payments and data-swapping — can be passive or active.
Tethering lets one device (usually a phone) share its internet connection with others nearby.

1. How Digital Devices Communicate

Satellite Communication

Think of satellite communication like a game of catch played across space. A ground station on Earth throws a radio-wave "ball" up to a satellite orbiting the planet. The satellite catches it, amplifies it (because the signal has weakened over such a huge distance), and throws it back down to another ground station — which then passes it, via an antenna, into your TV, phone, or sat-nav.

Because satellites orbit so high up, a single satellite can "see" — and therefore serve — a huge chunk of the Earth's surface at once. That's why satellite service is described as always available: as long as you're in that satellite's line of sight, you're covered, even in the middle of an ocean or desert where no cables reach.

But that same reliance on a clear line of sight is also its weakness. Weather (heavy rain, thick cloud) can scatter or absorb the radio waves before they reach the satellite — this is called "rain fade." And because radio waves used for satellite links can't pass through solid objects like buildings, mountains, or even your roof, anything blocking that direct path breaks the connection.

Key Process — Satellite TV (DVB-S) decodes

Memory hook

S T

Practice Question

TV & Radio (DVB-T and DAB)

DVB-T DAB

wires

better picture/sound quality more channels/stations

Common mix-up

Wired Communication Methods

2. Networks

LAN

desktop PCs

WAN

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Also in the full note

3. Wireless Communications (Deep Dive)
What to Memorise
Concepts Checklist
Exam Tips
Wireless Communication Methods (Overview)
Local Area Networks (LANs)
Wide Area Networks (WANs)
Personal Area Networks (PANs)

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Types of Digital Communications