What is baud Rate
Number of times a signal changes per second
What is bit rate
Number of bits transmitted over a channel per second
Difference between bit rate and baud rate
Bit rate is baud rate multiplied by the number of bits per signal
What is bandwidth
Maximum rate of data transfer of a communication channel
Relationship between bit rate and bandwidth
They are directly proportional
The greater the amount of data that can be transmitted over a channel, the more bits that can be transferred per second
What is latency
The delay from the time that a signal is sent, to the time its received
What is a protocol
A set of rules that determine the communication between devices
Specify the details of the communication in the protocols
- types of transmission (sync or a-sync)
- types of interfaces (serial or parallel)
- the transmission channel (wired or wireless)
- speed of transmission (bit or baud rate)
- error checking techniques
- format of transmitted data
What is synchronous transmission
Streams of bits are transferred over a channel at a constant rate.
Transmitter and receiver are synchronised using a common clock signal
What is asynchronous transmission
There is no clock signal, so start and stop bits are used to control communication
Data transmitted when available rather than specific intervals
Difference between sync vs a-sync
- a-sync uses a start and stop bit to mark beginning and end of transmission, stop signal typically longer than 1 bit so receiver has time to reset
- sync uses clock signal, no need for start and stop bit, commonly used with parallel transmission
What is serial transmission
Data bits are sent in a sequence over a single wire
What is parallel transmission
Several bits are sent at the same time over their own dedicated wires.
Only reliable over short distances
Advantages of serial over parallel transmission
- Parallel experiences skew and crosstalk over longer distances
- Parallel is only efficient over shorter distances and with a lower bitrate
- cheaper as less wires are used
What is crosstalk
Occurs when electromagnetic interference between wires that are close
Results in transmitting corrupted data that will need to be re-sent
What is skew
Happens when bits that are transmitted across parallel links travel at different speeds
In sync transmission, this results in data falling out of sync with clock signal, leading it to not be read correctly
