9.1 Communication Flashcards
What is a symbol in relation to communication?
A particular pattern of bits represented by a signal.
Define baud rate?
the number of signal changes in the medium per second.
Define bit rate?
The numbers of bits that are transmitted over the medium per second. Usually measured in bits per second (Bps)
What is the formula containing bit rate, baud rate and number of bits per signal?
Bit rate = baud rate * number of bits per signal
Define bandwidth?
Bandwidth is expressed in hertz and relates to the range of frequencies that a communication medium is capable of transmitting.
Define latency?
Often measured in milliseconds, it is the difference in time between an action being initialised and its effect being noticed.
Define protocol?
Set of rules relating to communication between devices.
What are the two different ways that computers can transmit data between their different components?
Serially or parallel
How does serial data transmission work?
Data is sent on bit at a time over one communication line.
When is serial data transmission usually used?
Transmitting data over medium to long distances such as peripherals like mice and keyboards to your computer.
How does parallel data transmission work?
Uses numerous parallel communication lines in order to send multiple bits between components in a computer simultaneously. The more lines that are used the more data can be transferred simultaneously. Each of the communication lines that forms part of a parallel communication medium will have slightly different electrical properties, meaning transfer time will differ from line to line, causing the bits to be received at different times which is referred as a skew.
What is bad about parallel data transmission?
Over long distances and extreme cases skews can lead to bits from different pulses overlapping causing the corruption of data. They are also more expensive than serial wires.
When is serial transmission?
Used over short distances like between parts of the processor and within RAM.
What are the advantages of serial data transmission?
Doesn’t suffer from skew or crosstalk meaning it’s a more reliable communication method especially over long distances. they are also cheaper than parallel.
How does synchronous transmission work?
a clock signal, which is shared by both the send and the receiver, is used to time when signals are sent. the signals are sent at regular intervals are received in the same order that they are sent. Making it good for real-time systems.
When is synchronous transmission used?
Within buses of a computer’s fetch-execute cycle.
How asynchronous transmission work?
Using start and stop bits. The start bit can be a 0 or 1 and the stop bit is the opposite of the start bit. The sender and receiver must the same baud rate and need only synchronise their clocks for the duration of data transmission.
what does the start bit do?
A “start bit” in serial communication acts as a signal to the receiving device that a new data transmission is about to begin
what does a stop bit do?
A Stop Bit is a part of the serial communication protocol used to signify the end of a data packet or byte. It ensures that the receiver has time to process each byte before receiving the next one.
