Digital communication : speed and volume of data transfer

what happens if we don’t figure out how to increase the speed in which we transfer data ?

transferring more data will mean that the transfer time will increase.

define bandwidth?

it is what the speed of data transfer depends

what is bandwidth ?

the number of bits that can be carried in one second

what a buffer ?

its is an area in memory used to temporairy store data, especially when streaming videos.

explain how a buffer works

you are streaming a video and a few seconds of it is stored in the buffer, the screen will show what is inside the buffer, as it is showing those few seconds more data is being place in the buffer.

if the buffer is empty there is no video showing.

what is latency ?

the amount of time it takes to send data between devices

how can you identify the latency ?

by ‘pinging’ a domain.

what is the ‘'ping’’ time ?

the amount of time it takes to make a return trip

how does pinging a domain work ?

when you ping a domain you send a packet of data to a server which immediately sends it back to the original device.

give an example of pinging a domian .

ping gov.uk

how does bandwidth impact the user experience ?

the higher bandwidth you have the faster the speed in which data is transferred, and the lower the speed the poorer the experience

the impact that latency has on the user experience ?

if they latency is high the events being represented in example television will delay (lag) the real time event and the playback

what is palyback

previously recorded sounds and moving images

what happens if a factor stops data from reaching its destination?

it has to sent again which slows down the transfer time.

give an advantage wired cables have over wireless ?

frequencies.

wireless methods have to work with a limited number of frequencies, copper cables can carry more frequencies then wireless, this means that cabled methods have more bandwidths available to them

what is a difference between some older wireless cables and newer ones.

some older wireless cables have less bandwidth than newer ones

explain interference in wireless signals

electromagnetic signals disrupt and interfere with wired and wireless signals, cabled connections can be shielded from interference by being wrapped in thin layer of metal.

what are some examples of things that interfere with signal.

wireless devices, wireless routes and appliances emitting electromagnetic fields like fridges and microwave ovens.

what is frequency ?

it is a waveband at which a radio signal is transmitted

what does blockage (eg, walls and furniture) of wireless signal do ?

they reduce the strength of the signal, which reduces the available bandwidth.

what happens to the strength of wired and wireless signals as the distance it has to travel increases ?

the strength reduces

what is device to device communication ?

it is when devices connect to each other directly by using wired and wireless methods

what is a minijack ?

a plug and socket widely used to analogue audio signals in portable devices

what does HDMI stand for ?

High-Definition Multimedia interface

what is a temperature sensor and an air conditioner connected by?

wired

what is a smartphone and headphones connected by ?

Minijack

what is a laptop and internal hard drive connected by ?

USD

what is a camcorder and monitor connected by ?

HDMI

what connects game controller and games console ?

bluetooth

how is a network formed ?

when two or more computer are connected

how many major types of networks are there ?

4

what are the 4 major types networks ?

LAN, WAN, PAN and Tethering

what does LAN stand for ?

LOCAL AREA NETWORK

what is LAN ?

it is a network that connects devices in a small geographical area

where could you find LAN ?

Schools, offices and homes

what does WAN stand for ?

Wide Area Network

what is WAN ?

its a network that spreads throughout a large geographical area

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where WAN used ?

they mostly used to connect different building owned national and international, law enforcement agencies, health and education organizations and government departments.

some organizations launch there own satellites to provide connectivity for there own global WAN.

which has a slower transfer speed WAN or LAN ?

often WANs has a lower transfer speed

which network type use connectivity provided by a third-party communication company ?

WAN they often link LAN together through the internet.

what is the biggest example of WAN ?

the internet

why WANs have a slower transfer speed than LANs (mostly) ?

because of the wide reach

what PAN stand for ?

Personal Area Network

what is PAN ?

it is a group of connected devices that are all near an individual user.

Explain PAN

its like the apple ecosystem, where their smartphone is could connected to their smartwatch, which connected to their laptop and home cinema speaker.

how are devices in PAN connected to each other ?

either directly or connected through access points.

what does WPAN stand for ?

wireless personal area network

what is WPAN ?

When a PAN only uses wireless connectivity. However PAN is general term for all PAN types.

what Tethering ?

connecting a host device that uses a mobile broadband connection with other devices so that they can use the host’s broadband connection.

Explain Tethering ?

the process of connection a host device, such as a smartphone or a tablet device, that uses a mobile broadband connection with one or more other device.

what does Tethering ?

it enables the other device or devices to share the host device’s broadband connection.

what is a service agreement ?

contract

what is part of the service agreement of mobile phone network providers ?

that they can enable or disable tethering

do some network providers charge more for tethering to be enabled ?

yes

give an example of a tethering network

A tethering strategy involves connecting one device without Wi-Fi to another device that has Wi-Fi connectivity. For example, a user could tether a laptop to a smartphone through cabling or through a wireless connection. This would allow for using the computer on a connected basis.

what are some methods that digital devices use to share data (and with what technology) and there uses ?

satellite : radio waves (GPS, television, telephone, military).

Broadcast : radio waves (television shows, radio shows)

Wired : electrical signals (networking, connecting peripherals)

Wireless : radio waves (networking, connecting peripherals)

what do satellites do ?

they transmit data (to) and receive data from digital devices.

how do digital devices receive the radio signals that satellites transmit ?

they use antennae.

What are the benefits of satellite communication ?

the number of satellites means that the system is always available & it is also not affected by power shorta

what are the drawbacks of satellite communication ?

satellites do not pass through solid objects (which means it will not work in areas with tall building or tunnel) & the signal can also be affected by atmospheric weather conditions (such as heavy snow or rain)

what is satellite communication often used for ?

GPS

how does navigation aids make use of GPS signals ?

to calculate the exact location of a device, 24 satellites orbiting the earth and GPS signals are sent from them, a device is at few of 12 at any time but only 4 are needed to calculate an accurate location.

what does DVB stand for ?

Digital Video Broadcasting

what is a DVB ?

an internationally accepted standard method of broadcasting television.

what is an example of DVB

DVB -S( digital video broadcasting -satellite)

how does DVB work ?

a video it send by a broadcaster on earth through their antenna to one or more satellites, which sends it back to earth were its received by a television viewers antenna which passes it to theset-top box and then finally sends it to the television

*some television have build in decoders so there is no need for a set- top box

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what sort of satellite communication is used by people in remote areas ?

satellite telephones

give examples of the satellite communication systems used by the military in some countries .

the global command and control system

they use satellites for communication

Analogue television and radio .

transmitters broadcast television and radio signals which are received by viewer’s antenna. the antenna send the signal through a wire to the television or radio receiver, which converts it to images and sound.

what does terrestrial mean ?

On the Earth

what does DVB-T stand ?

Digital video broadcasting - Terrestrial

the difference between DVB-S and DVB-T ?

DVB-S’s transmitter is located in the orbit (satellites), DVB-T’s transmitter is located on earth

what is needed to receive digital tv broadcasted by DVB-T ?

the same antenna that you would use for DVB-S

what is DVB-T2 ?

a new standard that provides new functionality, such as high definition television (HDTV) or interactive services (a service were the user can make choices electronically

in form do digital broadcasting station transmitters transmit digital signals in ?

binary

what does DAB stand for ?

Digital audio broadcasting

where is DAB used ?

in Europe and Asia pacific region

how is DAB broadcasted ?

the same way as DVB

benefits of DAB

• they provide more radio stations

• they can also carry text data that DAB receivers can display

what is Ethernet ?

its gives a way for computers to communicate, its the standard for network connectivity.

how can devices use cables to communicate with each other ?

via wired connections

Give 5 different connection types and there use .

connection type	use
HDMI	Digital video connection
Minijack	personal headphones

USD	storage transfer
Ethernet	Networking
S/PDIF	digital audio connection

how long long can ethernet cables be before they lose quality ?

100 meters

explain the difference between WI-FI and internet access

wi-fi allows you to connect to a network wirelessly, the network may or may not have internet access.

what is the first version of WI-FI ?

IEEE 802.11a

what is Wi-Fi used for ?

to connect devices to a network

how does a device get connected to the internet ?

the device connects to Wi-fi which connects its to a network, which can be be connected to the internet so that the network connected device can be connected to the internet.

what specification standard for wireless connection does Wi-Fi use ?

IEEE 802.11

what does each revised version of the specification aim to improve ?

the data transfer speed and the connection distance

what does Bluetooth do ?

it allows devices to connect over short distance’s

	Wi-Fi	Bluetooth
Range
Bandwidth

Power
Security
can connect multiple devices at once

	Wi-Fi	Bluetooth
Range	long	short
Bandwidth	high	low

power	high	low
Security	high	low
can connect multiple devices at once	yes	limited (usually have to be paired)

What are 4G and 3G referred to as ?

mobile broadband

what are 4G and 3G used for ?

to provide internet access to mobile devices when a Wi-Fi signal is not available

what does the G in 4G and 3G stand for ?

Generation, meaning that 4G is the 4th generation of mobile broadband technology

what are 3 drawback of Bluetooth ?

1.they cannot carry as much data as Wi-Fi

2.Bluetooth devices need to be paired before they can communicate

what future generations of mobile broadband technology planning to improve ?

the speed and availability of the signal.

what is the difference between 4G or 3G and WI-FI ?

4G or 3G connectivity are provided by mobile phone companies

what is infra-red ?

a type of electromagnetic radiation with a longer frequency but shorter wavelength than visible light.