Friday, 26 May 2017

WEEK 2 - Data Communication

Basically data is raw data that had been processed, arranged, stored and will be used to get information while data communication is a process of transferring information in a form of binary in between two or more devices using electronic delivery system and is transmitted via mediums such as wires, coaxial cables, fibre optics or radiated electromagnetic waves such as broadcast radio, infrared light, microwaves and satellites.

As I read more, data comes in variety styles such as text, videos and others and need to be converted into signal that can be understood by the communication media in order to transmit the data from one place to another. There analogue signal and digital data that can be read at the table below.

Now that there are two types of signal between analogue and digital, we know that digital has more advantages compared to analogue. There also types of transmission mode which are serial and parallel. Before that, before that we need to know that data needs to be digitized before it can be transmitted through the electrical transmission medium. As data entered through keyboard, it will be encoded into equivalent binary code that known as ASCII and EBCDIC


1. Synchronous Transmission 
• data transmitted into blocks called “framed” or groups and transferred at regular specified interval
• Both sending device and receiving device are operated simultaneously and are resynchronized after each few thousand data signals bits are transmitted 
• Only the start and end of the entire frame is mark with the start and stop bit 
• This type of transmission mode are more efficient as fewer control bits involves

2. Asynchronous Transmission 
• Used when the bits are divided into small group (bytes) and sent independently. 
• The group of bits can be sent at any time and the receiver never knows when they will arrive (e.g: keyboard) 
• Usually required a “start bit” to alert the receiver of incoming data and a “stop bit” to indicate the end of transmission

3. Isochronous Transmission
• data is sent at the same time as other related data to support certain types of real time applications e.g streaming voice, video and music
• Isochronous can be distinguished from asynchronous, which pertains to processes that proceed independently of each other until a dependent process has to "interrupt" the other process, and synchronous, which pertains to processes in which one process has to wait on the completion of an event in another process before continuing.

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