Data Transmission – GCSE Computer Science WJEC Revision

Basics of Data Transmission

Data Transmission: This is the process of transmitting data from one place to another. It can be between devices, networks, or databases.

Bit: The smallest unit of digital information. All data is broken down into bits for transmission.
Byte: A byte is equivalent to 8 bits. The speed of transmission is often measured in bytes per second.
Bandwidth: This is the maximum capacity of a network to transmit data. It’s measured in bits per second (bps).

Serial Transmission: In this method, bits are sent one after the other over a single line. It’s slower than parallel transmission but can be used for long distances.
Parallel Transmission: In this method, multiple bits are sent simultaneously over multiple lines. It is used for short distance data transmission, such as within a computer.
Simplex: Data flows in one direction only, like in a radio broadcast.
Duplex: Data flows in both directions but not at the same time, comparable to a walkie-talkie system.
Full Duplex: Data flows in both directions simultaneously, like in a telephone conversation.

Wired Transmission: Data is transmitted via physical cables such as Ethernet cables or fibre optics. It’s generally faster and more secure than wireless transmission.
Wireless Transmission: Data is transmitted without use of wires, using signals such as radio waves, microwaves or infrared. Examples are Wi-Fi and Bluetooth.
Infrared (IR): A form of wireless transmission often used by remote controls. Line-of-sight is required for transmission.
Radio Frequency (RF): Used by Wi-Fi and Bluetooth for their short-range wireless communications.

Error Detection: Networks use protocols to detect errors in data transmission, one common method is by using parity bits.
Parity Bits: These are used in error detection to ensure the number of bits with values of 1 in a set of data remains even or odd, depending on the system.
Error Correction: Some protocols can correct errors once they are detected, often by retransmitting the data.

Transmission Control Protocol/Internet Protocol (TCP/IP): This is a set of protocols used for transmitting data over the internet. It ensures the data packets are correctly assembled at the receiving end.
File Transfer Protocol (FTP): This is a protocol for transferring files between computers over a network.
Hypertext Transfer Protocol (HTTP): This protocol is used for transmitting hypertext over a network, and is the basis of any data exchange on the Web.