Data Transmission Flashcards
How is serial data received
Is received in order in which it is sent
Can be slow as it takes time for each individual bit to be transmitted
What is serial transmission
When you move data one bit at a time through a single wire
What is parallel transmission
Moving data many bits at a time along multiple wires
How is parallel data received at other end
Data can be received out of order as is transmitted along multiple wires.
But is faster than parallel as many bits of data are transmitted at once
What is simplex transmission
When the bits can travel one way only across wire
What is the difference between full duplex and half duplex
In full duplex data can travel in both directions at same time but in half duplex it can only travel one direction at a time but in both directions
What is bit rate
Bit rate is the speed at which one bit of data is transmitted
What is baud rate
Speed of which a symbol is transmitted
Likely to be less than bit rate as symbol is made up of many bits
What might cause data to be become corrupt during transmission
Distance in parallel may cause it to arrive in different order
A degradation if signal might occur over a large distance
Line noise or interfearance
What are the 3 ways if checking data
Echoing back
Check sums
Parity check
How does echoing back work
Sender issues original data
Receiver returns copy of original data
Ender checks if correct
Send s signal back confirming/ deconfirming data
How does check sums work
Additional data sent which has been calculated from known algorithm based on original data
Recover completes identical algorithm based on data received, if same same check sum is calculated then it is correct
What is parity check
Where aditional bit is sent to make entire byte hold even or odd number
Called odd or even parity
What is a parity byte
Along with normal bytes (contain parity bits) a parity byte is sent which is a vertical redundancy check making it more accurate to see where error has occurred.
What us meant by the term protocol
The term protocol is used when a there is a establishment of a set of rules with the data transfer
What needs to be agreed upon in the protocol (4)
Serial/parallel
Speed of transfer
Error checking method
Size of the data packets
What is handshaking
When rules are agreed between devices at outset
What is the importance of handshaking
Transfer signals to confirm if ready
What data check process will be used
Without it may cause confusion between devices and signals may be misinterpretated.
What are the 2 types if elements in transfer protocol
Physical and logical elements
Name four physical elements
Linking of hardware
Serial or parallel
Simplex or duplex
Wireless frequency
Name three logical elements
Agreed software protocol
Baud rate at which they will communicate
What characters will be used (ASCII act…)
What does data transfer within a network use
Packets
What is switching
Switching is the ways in which packets are transferd
What are packets
Packets is what data is broken into when being transferd
Packets are a standard size
