Data Transmission Flashcards
data is broken down into _______ in order to be transmitted
packets
structure of data packet
header, payload, trailer
what does the header contain
- Sends IP address
- Receiver’s IP address
- Packet Number
what does the payload contain
Data/part of message
what does the trailer contain
Bits to show end of packet
what is a packet
small unit of data that can be transmitted from a sender to a receiver through a network communication protocol
what is packet switching
method used to efficiently transmit data from th sender to the receiver
steps of packet switching
- data is broken down into packets
- headers info is used by router to determine source and destination of packet
- packets take different routes and so arrive out of order
- payload carries the actual data
- trailer tells receiver that the end of the packet has ben reached
- once arrived, packets are reordered
advantages of packet switching
take different routes which ensures data will arrive despite route availability
- transmission errors can be detected
disadvantages of packet switching
- packets may be dropped if they move around a network for to long (they each have a TTL value)
- a single delayed packet can cause entire message to be delayed
which factors determine which method is best for transmission
number of bits, number of wires, direction of data
overall, transmission can be
serial or parallel
what is serial transmission
one single wire is used to connect, bits are transmitted one at a time
advantages of serial
- more reliable
- bits arrive in order so wont be mixed up
- chances of bits being lost is slim
- long distance
what is parallel transmission
multiple wires to connect sending with receiving, several bits are sent simultaneously
advantages of parallel
- faster than serial
disadvantages of parallel
- bits may arrive out of order
- expensive method to implement over longer distance because it requires multiple wires
- low reliability
- short distance
3 types of data direction in transmission
simplex, half-duplex, duplex
what is simplex
only one device can transmit data (one direction)
example of simplex
connection between computer and printer using USB cable
what is half-duplex
both sending and receiving device can transmit data but not at the same time
example of half-duplex
walkie-taklies
what is full duplex
both sending and receiving devices can transmit data at the same time
example of full duplex
telephone, video games
data synchronisation can be
synchronous or asynchronous
what is synchronous
Data as a string of bits, also containing timing signals, that are generated by an internal clock.
what is asynchronous
data is sent in groups in an agreed pattern
what does USB stand for
universal serial bus
what is USB
communication interface that has become standard for connecting devices to host controllers
what method does USB use
serial
examples of USB use
digital cameras, keyboard, printers
Newer USB-C is capable of
transferring data in both directions
what synchronisation does USB use
asynchronous
advantages of USB
- Device drivers are installed automatically
- USB interface is self-configuring
- The connectors can only be connected in a particular manner. This property makes sure the user does not connect it in an incorrect manner
- Several data transmission rates are supported
- Newer USBs are compatible with the older USB standard
how many pins is USB composed of and what ar their uses
4 pins - 2 for connecting wires that transmit data and 2 for wires that carry the power
steps to connecting USB to computer
- Device detected through change in voltage lines
- Speed, type, configuration determined by computer.
- Computer loads driver
- Computer prompts user to install required driver id not already available.
