Tuesday, March 13, 2012

Week 2~

week 2: Data Communications

my last post have been quite long huh? the days have been very busy and i completely forgot about my blog. i'll try and catch up very soon.

our second chapter is the DATA COMMUNICATION. it is a collection and distribution of the electronic representation of information. it uses electrical transmission systems. Eg: Telephone lines, satellites or coaxial cable.

first we learn about analog VS digital signal.

this is the analog and digital signal    
analog signals: signals like sound wave/image and it is continuous
Eg: Standard phones, fax machines and modems.

Digital signals: transmission of signals to a binary digit. It is also a series of on/off signals.

p/s : process of changing analogue to digital is called modulation. the process of turning back is called demodulation.

next, we will go to the data flow as known as the transmission directions.

A) Simplex
-one way communication (alarm, door bell, radio)

B) Half-duplex
-flow in two directions, but never in the same time. (walkie-talkie)

C)Full duplex
-can transmits and receive simultaneously (Internet connections, telephones)

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