Digital Communication Flashcards
What are the ways in which devices communicate
- Satellite
- Broadcast
- Wired
- Wireless
Why should we increase speed of data transfer in the future
Because as the world develops, more data is being transferred via networks. Due to this increase in the volume of data, the speed of data transfer should also increase, otherwise, the transfer times will also increase.
How does Streaming work
When streaming a video, all of the video data is not downloaded at once. Instead, a portion of the video is downloaded into an area of temporary storage called a buffer.
Then when there is a sufficient amount of video data in the buffer, the video will start playing and the buffer will get emptied.
After the video data has been emptied from the buffer, more data will be filled in.
If there is no data in the buffer, the video will pause until more data is downloaded.
The rate of filling the buffer should always be higher than the rate of emptying the buffer.
What is latency
Latency is the amount of time it takes data to travel through a connection between two or more digital devices.
What happens when you ping a domain
This sends a data packet to a web server connected to the Internet. Then this packet of data is immediately returned by the server.
Factors affecting latency and bandwidth
- Interference from other devices can interfere and degrade the wired or wireless signal
- Distance in the connection, because signals will spread out the further they travel, which makes the signal weaker as it travels further.
- Blockages from furniture or walls. This degrades the signal and makes it weaker.
- The method of data transfer. Wired data transfer methods have a higher frequency and bandwidth of data transfer.
How does bandwidth and latency affect user experience when gaming
Latency is the amount of time it takes data to travel through a connection.
Bandwidth is the number of bits that can travel through a connection in one second.
If the latency increases and the bandwidth is low, the signal will take a longer time to reach the webservers. this will cause gaming lag, reducing the user experience, because online gaming requires a high bandwidth and low latency connection.
What are the types of networks
- LAN
- WAN
3, PAN - Tethering
What are LANs
These are networks that are spread across a small geographical area. Ex : Office network, school network
What are WANs
These are networks spread across a large geographical area and often contain many LAN connections that are linked together.
WANs are often slower due to their wider reach.
They also use 3rd party telecommunications connectivity
What are PANs
These are network that have connected devices that are all near an individual user. Ex: smartwatch connected to smartphone, connected to sound system
What is tethering
This is when devices are connected to a host device with a mobile broadband connection, which is shared by the host device to the devices connected to it.
How do devices on earth receive satellite signals
Satellites orbiting the Earth send radio signals to earth, which is picked up by the antenna of digital devices.
What type of signals do satellites transmit
Radio Signals
What are the advantages and disadvantages of satellite communication
Advantages:
+ Number of satellites available means that the service is always available, 24/7.
+ Satellites are not affected by power shortages.
Disadvantages:
- Satellite Radio signals cannot pass through solid object, so the service will not be available in underground areas or in cities with a lot of buildings.
- Satellite Radio signals are also affected by weather, causing signal degradation and weakening of signal.
How does GPS work
Satellites send GPS signals to devices on earth.
This is picked up by the device using its antenna.
Then the devices will calculate the location using the GPS data.
What are the types of satellite communication
- Television
- Telephone
- GPS
- Military
How does DVB-S work
The broadcaster sends a video signal from Earth to one or more satellites using a large antenna.
The satellites then broadcasts the signal back down to earth.
The antenna in people’s homes then picks up the signal and the signal is then sent to a STB.
The STB then converts the source signal to a signal that can be sent to the TV and one that the TV can understand so that images and video can be displayed.
How does analogue television and Radio Work
The transmitters in the television station broadcast a signal, which is picked up by antenna in people’s homes. The antenna then send the signal to the television or radio receiver, which converts the signal into video and audio.
What is DVB-T
This stands for Digital Video Broadcasting Terrestrial. This is when the transmitter of the television or radio signal are based on Earth instead of being in orbit around Earth.
However, users are able to use the same antenna in order to receive the signal.
What are the wired connectivity methods that are used
- USB
- Ethernet
- Minijack
- S/PDIF
- HDMI
- Firewire
- AV
- Molex
- Coaxial
What increases as newer revisions of wired connectivity are developed
The speed of data transfer increases.
What is Wi-Fi
Wi-Fi is a wireless connectivity standard that is used to connect devices together in a network. This network can then be connected to the Internet in order to allow devices in the network to connect to the Internet.
What improves in every development of the Wi-Fi specification
The speed of data transfer
The distance in which device can be connected in.
