11 Communication Flashcards
(20 cards)
What is serial transmission?
The data packets are sent one after the other
What is parallel transmission?
All data packets are sent at once along different wires
List 4 advantages of serial transmission
- Requires fewer wires therefore cheaper
- Easy to set up as cable is flexible and thin
- Not much interference
- Doesn’t suffer from skew
List 2 advantages of parallel transmission
- Fast over short distances
- Data doesn’t need to be ordered before sending
Where is parallel transmission used?
Used in short range high speed applications e.g. data buses (used to be in printers)
Where is serial data transmission used?
Used over long distances e.g. the internet
What is synchronous transmission?
Data is transferred at regular intervals
The data is synchronized by a clock pulse
It allows large block of data to be sent continuously
Where is synchronous transmission used and why?
Used in real time applications e.g. video chat
Because it is extremely fast
What is asynchronous transmission?
One packet (8 bits) is sent at a time with a start and stop and parity bit
The computer starts reading at the start bit and stops at the stop bit
What is asynchronous transmission used for
Lower speed transmissions e.g. WAN
What are idling bits?
They are bits that fill in space until the next set of data arrives when no data is being sent in asynchronous transmission
What is the difference between asynchronous and synchronous transmission
Asynchronous - data is sent in small packets at intervals
Synchronous - data is constantly being sent & changing this synchronized with a clock pulse
What is bandwidth?
Bandwidth is a measure of how much information a channel is capable of carrying per second (bits per second)
(The maximum capacity)
What is a channels baud rate?
The number of signal changes it is capable of per second
What is baseband?
When a channel can only represent one bit per signal change
How do you calculate bit rate?
Bit rate = Baud rate * bits per signal
What is latency?
Latency is the delay between an action being started and the computer responding
What is a protocol?
A strict set of rules for data transmission
What is a handshake?
When two computers exchange signal in order to create a communication link
How does handshaking work?
A - requests to transmit data
B - sends back acknowledgement
A - sends data to B
If no acknowledgement is received A will resend request
