How Digital Devices Communicate (Edexcel IGCSE Ict)
Satellite
Spec point —
2.1.1
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
Spec point —
2.1.1
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
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Transmitters are based on earth
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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
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The advantages of digital television and radio are:
- Improved video/audio quality
- Access to more channels/stations
Wired
Spec point —
2.1.1
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
Spec point —
2.1.3
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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