How Digital Devices Communicate (Edexcel IGCSE ICT)
Revision Note
Written by: Robert Hampton
Reviewed by: James Woodhouse
Satellite
What is satellite communication?
Satellite communication uses radio waves for wireless communication
Signals are sent between satellites and ground stations on earth
Ground stations transmit the radio wave to antenna within or connected to a digital devices
The advantage of satellite communication is that the service is always available
The disadvantages of satellite communication is that the service can be interrupted by weather conditions and signals do not pass through solid objects
Satellite television
Digital Video Broadcasting (DVB) is the international standard for broadcasting digital television
Digital Video Broadcasting-Satellite (DVB-S) is an example of DVB
A video signal is sent from a broadcaster to a satellite, and sent back to earth to an antenna connected to a set-top box or directly to a television
The set-top box or television decodes the signal to make it watchable
TV & radio
What is digital television and radio?
Digital Video Broadcasting Terrestrial (DVB-T) and Digital Audio Broadcasting (DAB) are methods of transmitting video and audio signals from transmitters to an antenna
Transmitters are based on earth
Once received by the antenna, signals travel through wires to a television or radio receiver which decodes the signal and converts it into video and/or audio
The advantages of digital television and radio are:
Improved video/audio quality
Access to more channels/stations
Wired
What are wired methods of communication?
There are a number of wired methods of communication, some are designed to transmit a specific type of data and some are universal
Type | Use |
|---|---|
High Definition Multimedia Interface (HDMI) | High definition video and audio signals |
Sony/Phillips Digital Interface Format (S/PDIF) | Transmit digital audio streams between devices |
Mini-jack | 3.5mm jack commonly used to connect headphones, speakers and microphones to devices |
Ethernet | Networking standard for connecting devices to a local area network (LAN) |
Universal Serial Bus (USB) | Connecting and powering various devices such as printers, flash drives, keyboards, mice etc. |
Wireless
What are wireless methods of communication?
There are a number of wireless methods of communication, including:
Type | Use |
|---|---|
Wireless Fidelity (Wi-Fi) | A wireless method of connecting devices to a local area network (LAN) |
Bluetooth | Allows two devices to connect to each other over very short distances |
Infra-red (IR) | Transmits tiny amounts of data over very short distances |
Near Field Communication (NFC) | Use close proximity RFID (radio frequency identification) |
4G and 5G | Provides internet access to mobile devices |
Worked Example
Smartphones can be connected using wired or wireless methods.
A. Give two advantages of using a wired method to connect to a smartphone
[2]
B. Give two advantages of using a wireless method to connect to a smartphone
[2]
Answers
A. Any two from:
Faster / higher bandwidth / lower latency [1]
More stable connection [1]
Less interference (e.g. dropped packets, loss of data) / Not affected by physical obstructions (e.g. walls) [1]
More secure [1]
Password not needed [1]
B. Any two from:
Can move around (while transferring data) [1]
Does not have to waste time finding / connecting cables [1]
Cost of cables / cheaper [1]
Health and safety / no trailing wires [1]
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