Data transmission is the sending and receiving of binary strings from one device to another via a wireless or wired connection using narrowband or broadband.
Narrowband is generally used for voice communication and refers to a channel of communication.
Broadband is a channel of communication that facilitates a much greater bandwidth, allowing much more data to flow at a greater speed from one device to another.
Asynchronous data transmission refers to data being transmitted in half-duplex mode (communication taking place in both directions but not at the same time), one byte at a time. The transmissions are accompanied by parity bits at the beginning and end of each byte, so that the receiver can separate the flow of data into a coherent sequence that can be understood. Asynchronous data transmission is a relatively slow because of the gaps between transmission of each byte of data. However, it is a cheap and effective form of serial transmission that is particularly well suited to low speed connections. Examples of asynchronous transmission include emails, forums and telephone transmissions.
In synchronous data transmission, data flows in a full duplex mode as a continuous stream of data. As there are no gaps in the data flow, synchronisation by way of an internal clock is required to ensure that the sender knows where each new byte starts. In this way, the receiver of the data can count up how many bits (1s and 0s) were sent and then reassemble them into bytes of data. Synchronous data transmission is a faster method of data transmission than asynchronous data transmission and is used for transferring large amounts of data (for example, in network communications). Examples of synchronous data transmission include Chat Rooms, Video Conferencing and telephone communication.
Before a normal data transmission can take place between a computer and another device, a protocol known as a handshake is required. This handshaking process establishes the rules for data transmission that are acceptable at both ends of the communication channel, for example information transfer rate, parity information and other protocol details.