Chapter_4_(Digital_communication) Flashcards
What does the speed at which devices can transfer data depend on?
It depends on the bandwidth of the connection.
What is bandwidth?
The number of bits that can be carried by the connection in one second.
What does higher bandwidth mean?
Higher bandwidth means more data can be transferred every second, making download and uploads faster.
What is buffer?
An area of memory used to temporarily store data, especially in video streaming.
What happen if the buffer is empty when playing a video?
There will no more videos to play and it will pause until more data is downloaded.
How to avoid the buffer becoming empty?
Data must be downloaded into the buffer constantly, filling it up at a rate faster than it is emptied.
How can you identify the latency?
By pinging a domain
What is latency?
The amount of time it takes to send data between devices.
What is domain?
The name used to identify the web server.
Wireless method has to work on an unlimited amount of frequency.
False
Which carry more frequencies, copper cable or wireless method?
Copper cables
What interfere with wired and wireless signals?
Other electromagnetic signals
How can cabled connection be done to prevent interference?
They can be shielded.
What reduce the available bandwidth of wireless signals?
Walls and furniture reduce the strength of wireless signals.
What reduce the strength of wired and wireless signals?
The more distance reduce the strength of wired or wireless signals.
What is LAN?
LAN is a network that connects digital devices that are in a small geographical area.
What is WAN?
WAN is a network that is spread over a large geographical area.
What does WANs use?
It often use connectivity provided by a third party telecommunications company, often linking LANs together through the internet.
WANs have _____ transfer speeds than LANs.
Slower
What is PAN and WPAN?
PANs is a group of connected devices that are all near an individual user.
WPAN (Wireless Personal Area Network)
What is tethering?
Tethering is connecting a host device that uses a mobile broadband connection with other devices, so that they can use the host’s broadband connection.
What are some common methods that digital devices use to share data?
- Satellite
- Broadcast
- Wired
- Wireless
What does digital devices use to receive radio signals that satellites transmit?
Antenna
What are the benefits and disadvantage of satellite communication?
- It has number of satellites meaning the system is always available and can’t be affected by power shortages
- Satellite signals does not pass through solid objects meaning they might not be available in some places
Which communication does GPS use?
Satellite communication
From where do GPS signals send from and how many satellites is required to calculate the accurate location of digital device?
GPS signals are sent from a network of 24 satellites orbiting the earth and only four is required to calculate the accurate location.
What is DVB?
Digital video broadcasting is the internationally accepted standard method of broadcasting digital television.
What is DVB-S?
Digital video broadcasting satellite is a type of DVB which a video signals from broadcaster is transmitted using a large antenna on earth to one or more satellites which thenbroadcasted signals back to earth, received by antenna.
What decodes the signals received from satellite and send it to television?
set-top box
What are other things that satellite communication allows?
It is used for people in remote areas to place voice calls using satellite telephones.
What broadcast television and radio signals that are received by viewer’s antenna?
Transmitter
What is DVB-T?
Digital video broadcasting (terrestrial) is a method of DVB where transmitters are based on earth, rather than in orbit as they are in DVB-S.
What is DVB-T2?
DVB-T2 is a newer standard that provides more functionality, such as HDTV and interactive services.
What is DAB?
Digital Audio Broadcasting which is broadcast in the same way as DVB, and it provides more radio stations and can also carry text data that DAB receivers can display.
What is ethernet?
A network connectivity standard that provides a way for computers to communicate.
What are the connection types and their uses?
- HDMI - digital video connections
- S/PDIF - Digital audio connections
- Minijack - Personal headphones
- USB - Storage transfer
- Ethernet - networking
What does ethernets allow?
It allow user to connect to wired networkers?
What is the maximum length of ethernet cable which can carry signals without lose of quality?
100meters
What is WI-FI?
Wi-Fi is a wireless technology used to connect devices to a network which are connected to the internet.
Which specification of standards does Wi-Fi for wireless communications?
IEEE 802.11
What is Bluetooth?
Bluetooth is a type of wireless connectivity that lets devices connect over short distance.
Which can carry more data Wi-Fi or Bluetooth?
Wi-Fi
What is Bluetooth used?
It is used to transfer small files between devices.
What are difference between Wi-Fi and bluetooth?
- Wi-Fi has long range
- Wi-Fi has higher bandwidth
- Wi-Fi has higher power consumption
- Wi-FI has higher security
- Wi-Fi can connection multiple simultaneously while Bluetooth is limited
What are 3G and 4G used?
They are used to provide internet access to mobile devices.
What does G in 3G and 4G stands for?
Generation
What does Infra-red transmitters should have?
It must have a clear line of sight to receivers because this allows signal to travel in a straight line between them?
What does NFC (near field communication) use?
It use close proximity RFID chips.
What are the advantages and disadvantages of Wired and wireless connectivity?
Wired
- Cables are cheap for small number
- Risk of tripping over cables
- Faster than wireless
- Less affected by interference than wireless
- Not portable and may need signal booster
- Can look untidy
- Most secure
- Using cables and ports long time may damage them
Wireless
- may need wireless access point
- Slower than wired
- Affected by obstacles
- Portable within signal range
- Tidy
- Less secured
What is ISP?
A company that provides customers with access to the internet. (internet service provider)
What does ISP use?
Fibre optic cable or copper cable network
What does mobile broadband provide?
High-speed wireless connectivity using 3G or 4G
