Hi all, it's time for the second reflective journal!
As usual, I am going to share my understanding towards the second lesson of Telecommunication & Networking.
Wednesday, 7th March 2012
It was a lecture regarding Data Communication. It sounded easy to understand, but in fact, it was too abstract for me to figure out.
Basically, we had been taught on these few topics :
1.0) Data Communications
1.1) Data Representative : Analogue & Digital Signal
1.2) Data Representative : Binary Digits
2.0) Data Transmission Mode
2.1) Parallel Transmission
2.2) Serial Transmission
2.2.1) Synchronous Transmission
2.2.2) Asynchronous Transmission
3.0) Data Flow Styles
Why I arranged those topics into point forms? This was because this method enabled me to have an overall idea on the knowledge that I had learnt. To me, it is quite useful especially when I need to memorise piles of notes. It enables me to have a clear idea on the contents.
So, let's start our sharing. ^^
At first, we had been introduced to the definition of Data Communication. This is all about how the data/information is being collected and also transmitted to other places including remote area. How could these processes be done? After Dr. Dayang’s explanation, I knew that those processes are done through electrical transmission system. It is simply a system that enables data to transmit through it and send to other communication media like computer. The examples of this system are telephone lines, satellites or coaxial cable.
Let's move on to the next point - Data Representative.
Last week I did mention that I couldn't understand the meaning of Analogue Signal and Digital Signal. Fortunately, these two terms were taught in this lecture.
Basically, I understood that these two terms are different forms of data representatives. The information below are the summary of Analogue Signal and Digital Signal.
Analogue Signal - Represent data with continuous waves
Digital Signal - Represent data in the form of 1’s and 0’s (Binary Digits Coding
Later on, I was introduced to the word MoDem. Most of us know that modem is needed for Internet access. In fact, there are other functions of MoDem. This hardware possesses components that are able to convert Analogue to Digital Signal (Modulation) and also Digital to Analogue (Demodulation). That’s why this hardware is named MoDem.
To illustrate the conversion, let us take recording by MP3 audio player as an example.
1.) Human voice (represent by Analogue Signal) is the input of the MP3 player. Recording is started.
2.) Analogue-to-Digital Converter (ADC) inside the MP3 receives the Analogue Signal and converts the Analogue Signal to Digital Signal (combination of 1’s and 0’s).
3.) Conversion is completed. Human voice in digital form is saved in the memory of MP3.
4.) During playback of the human voice, digital signals are converted back to Analogue Signals through the Digital-to-Analogue Converter (DAC).
5.) Human voice in analogue form is transmitted through the speaker system.
6.) Human voice can be heard.
Coming up next is the introduction of Byte. It sounded familiar right? What about Kilobytes or kB?
Through my understanding, I knew that Byte is actually the smallest unit of data capacity. We always ask data storage device like pen-drive or thumb-drive are printed with units like kB, MB, GB and so on.
So, here is the relationship of Byte and Binary Digits.
Let say I key in the alphabet “A” into the computer.
“A” is represented by a series of digits 1100 0001 in computer.
Thus, we can say that
1 alphabet/character = 8 digits = 1 byte
· Prefixes like Kilo- , Mega- , Giga- and Terra- are representing the different amount/size of the data.
After exposing to the basic ideas of data communication, I was able to understand the Data
There are two different modes of transmission that can be illustrated by the diagram below.
Serial Transmission : Bits are transmitted one by one in a single line.
Two type of Serial Transmission ( Let text as the example for the explanation) :
o Synchronous Transmission – Words (Data) are transmitted in groups
o Asynchronous Transmission – Transmission done through alphabet (1 byte)
by alphabet (1 byte)
· Parellel Transmission : Bits are transmitted in bytes in separated paths.
From the above figure, I can imagine that Serial Transmission is slower than Parallel Transmission as there is only 1 path for 8 digits to transmit through.