Digital communication 1 Flashcards
What are the two factors which affect the speed devices can transfer data
Bandwidth
Latency
Define bandwidth
The number of bits that can be carried by a connection in one second.
How can higher bandwidth impact the user experience?
Uploads and downloads are made faster
It is possible to do things that require lots of data to be transferred within short periods of time such as multiplayer online gaming and high definition video streaming.
How is streaming a video different from a downloading a video.
All of the data does not need to be downloaded before a video can start playing.
The data needed for the video isn’t permanently stored in you computer, but is instead temporarily stored on an area of memory known as a buffer and is cleared from the memory once the videos is stopped playing.
What happens to the video being streamed, if the buffer needed to store its data is empty?
It will stop playing until the buffer is filled with the remaining data again- a term known as buffering.
What must be done to prevent buffering?
Data must be downloaded into the buffer faster than the rate at which it is being emptied.
What does it mean for a buffer to be empty in terms of streaming a video?
The data to play a portion of the video which was temporarily stored on the area of memory has now been deleted as the that portion has already been played.
Define latency
The amount of time it takes to send data between devices.
What is one way of identifying latency?
By pinging a domain
Define ‘ping time’ -
The amount of time it takes for the packet of data which is sent from the computer to the server to make the return trip.
Define domain
The name used to identify a web server.
How will high latency impact the user experience when gaming. 2 ways.
When playing multiplayer online games, events in the game will lag.
the game will not seem responsive to user commands.
How will high latency affect the user when watching live television?
High latency will result in a delay between the real time events and the video being received for playback.
How does the transfer method affect the data transfer rate?
Some wired methods such as copper cables can carry more frequencies than other wireless methods which have to deal with a limited number of frequencies.
In other words cabled methods have more bandwidth available for the transfer of data than other wireless methods.
What is something you must keep in mind when comparing the bandwidth or wired and wireless methods of data transfer.
Older wired methods have less bandwidth available than new wireless methods.
How does interference occur?
When other electromagnetic signals disrupt or interfere with wired and wireless signals.
List some devices from which interference can be caused.
Other wireless devices, wireless routers, and appliances emitting electromagnetic fields like fridges and microwaves.
Can interference happen to both wired and wireless media
YES
What is one way that interference to signals carried by cabled connections can be blocked.
By wrapping the wires in a thing layer of metal.
Do blockages only affect wireless signals.
YES
How do blockages affect wireless signals-
Furniture and walls reduce the strength of wireless signals- this reduces the available bandwidth.
How does distance affect both wired and wireless media-
The strength of the signals of both wired and wireless media reduce if the distance it has to travel increases.
How does distance affect both wired and wireless media-
The strength of the signals of both wired and wireless media reduce if the distance it has to travel increases.
Define frequency-
The waveband at which a radio signal is transmitted.
Define device to device communication-
When devices connect to each other directly using wired or wireless methods.
Define device to device communication-
When devices connect to each other directly using wired or wireless methods.
How can a game controller be connected to a games console and what’s its purpose-
Through blue tooth
to control the game.
How can a camcorder be connected to a monitor and what’s its purpose?
Through HDMI
to operate as a security camera
How can a smart phone be connected to a headphone and what’s its purpose.
Through Mini Jack
to play the songs on the smart phone on the headphone
How can laptops be connected to an external hard drive and what’s its purpose?
Through USB cable
To transfer files
How can a temperature sensor be connected to a air conditioner and what’s its purpose?
Through a wired method to automatically turn on the air conditioning when the temperature is too high.
Define HDMI
High definition multimedia interface used to transmit video and audio data
Define HDMI
High definition multimedia interface used to transmit video and audio data
Define HDMI
High definition multimedia interface used to transmit video and audio data
Define minijack
A plug and socket widely used for analogue audio signals in portable devices
