Second Footmark on 7 March

Introduction to Data Communication 

*My Word*

Time passed faster, it was the next lesson I had attended. Before that, I wondered to know what i would be going to learn. Would it be the new knowledge about devices or something else. However, this lesson was quite fascinating. My lecturer did prepare presentation to explain the lesson. I felt that it was fun because I could understand the meaning, but we need to memorize the specific name. 

*True knowledge exists in knowing that you know nothing.*

I was surprised when I learnt 3 operation styles of data flow, that are simplex, half-duplex and full-duplex. There make me more understand the way they process with example given.

For future information, u may go...

~( Link: http://www.camiresearch.com/Data_Com_Basics/data_com_tutorial.html   )~
 

Now, I would like to share the lesson I had learnt in my class:

♥Briefly,                                                                               

1.  What is Data Communications?

- is the collection and distribution of the electronic representation of information FROM and TO remote facilities by means of electrical transmission system such as telephone lines, satellites or coaxial cable.

For example:

2. 2 types of signal:  

Analogue Signal and Digital Signal

- An analog or analogue signal is any continuous signal for which the time varying feature (variable) of the signal is a representation of some other time varying quantity, i.e., analogous to another time varying signal. It differs from a digital signal in terms of small fluctuations in the signal which are meaningful. Analog is usually thought of in an electrical context; however, mechanical, pneumatic, hydraulic, and other systems may also convey analog signals.

3. Data Transmission Mode

- Parallel transmission and serial transmission

QUESTION~Do you know what is difference between parallel transmission and serial transmission?~

•       Ans: Parallel transmission: a group of bits is transmitted simultaneously by using a separate line for each bit while serial transmission: transmits all the bits one after another on a single line. This style is a bit slower compared to parallel.

 
4. 2 serial transmission MODE

a) Asynchronous Transmission Characteristics

Asynchronous transmission usually encapsulates individual characters in control bits called start and stop bits. The following graphic shows three eight-bit units of asynchronous data transmission. This transmission could be from a serial interface in a PC modem.

~The example of asynchronous~

b) Synchronous Transmission Characteristics 

Synchronous transmission uses more expensive clocking to operate at faster rates. It combines much more data into the information payload carried in the bit stream of each serial frame. The following graphic shows synchronous transmission. 

~The example of synchronous~

5. 3 operation styles of data flow:

      

*Simplex       *Half-Duplex       *Full Duplex 

Can you give the example of these operation styles?

a) The example of simplex:  TV

 b) The example of half-duplex: Walkie-talkie




c) The example of full-duplex: Phone call

6.  MULTIPLEXING

The latest technology of LINK = high-bandwidth media: coaxial cable, optical fiber, satellite microwaves




         *Faith is a knowledge within the heart, beyond the reach of proof.*               

 

                                                                Dreamers / Jack Savoretti