- Is the very simply, the collection & distribution of the electronic representation of information from & to remote facilities another by means of electrical transmission system likes telephone lines, satellites or coaxial cables.
- The information can appear in a variety of formats, data, text, voice, pictures,, graphics & video.
- Prior transmission, the raw information must be digitised.
- There are 2 type of signal which are analogue signal & digital signal.
- Analogue signal - those used by conventional telephone systems, represent data with continuous waves.
2. Digital signal - Which data is represented by only two discrete states 0s & 1s.
*Digital data to be sent using analogue signal (such as computer data sent over a converted into analogue form before it can be transmitted)
FIGURE 1 : Picture of digital & analogue signal.
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Data Transmission
Data transmission has 2 types :
- Parallel transmission - The message is sent at least one byte at a time, with each bit in the byte taking a separate path.
- Serial transmission - Data is sent one bit at a time, one after the other along single path.
There are 3 serial transmission modes which are Synchronous transmission, Asynchronous transmission & Isochronous transmission.
- Synchronous transmission - data is organized into group / blocks of data, which are transferred at regular, specified intervals.
- Asynchronous transmission - data is sent when it is ready to be sent, without being Synchronous transmission. To identify the bits that belong in each byte, a start bit & stop bit are used at the beginning & end of the byte.
- Isochronous transmission - data is sent at the same time as other related data to support certain types of real-time applications that require the different types of data to be delivered at a proper speed for that applications.
FIGURE 2 : Picture of parallel & serial transmission.
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https://www.youtube.com/watch?v=PJ_bS7meE7s
Data Flow / Data Move
- Simplex transmission - data travels in a single direction only (like doorbell). Relatively uncommon in data transmission because most devices that are mainly on-directional, e.g, printer.
- Half-Duplex transmission - data can travel in either direction, but only in one direction at a time, e.g, walkie-talkie.
- Full-Duplex transmission - data can move in both directions at the same time, e.g, telephone.
FIGURE 4 : Picture of simplex, half-duplex & full-duplex.
There is the video that you can watch.
HOPE YOU WILL ENJOY WITH THIS NOTE :)
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