Communication

Number of times a signal changes per second

Number of bits transmitted over a channel per second

Bit rate is baud rate multiplied by the number of bits per signal

Maximum rate of data transfer of a communication channel

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

The delay from the time that a signal is sent, to the time its received

A set of rules that determine the communication between devices

• 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

Streams of bits are transferred over a channel at a constant rate. Transmitter and receiver are synchronised using a common clock signal

There is no clock signal, so start and stop bits are used to control communication Data transmitted when available rather than specific intervals

• 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

Data bits are sent in a sequence over a single wire

Several bits are sent at the same time over their own dedicated wires. Only reliable over short distances

• 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

Occurs when electromagnetic interference between wires that are close Results in transmitting corrupted data that will need to be re-sent

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