Introduction to Data Communication

Hi, everyone!!! I'm back. Time passes so fast that we are already in week 3. Today is our third lesson for  telecommunication and networking class. The topic we learn today is 'Data Communication'. In today's lesson, I do obtain some input and gain extra knowledge on data communication. It's great to learn new things.

Okay, let's straight to the point!

What is the definition of Data Communication?

• Basically, Data Communication is simply means the collection and distribution  of the electronic representation of information FROM and TO remote facilities by electrical transmission system such as telephone lines, satellites or coaxial cable. *coaxial cable = a cable which has an inner conductor surrounded by flexible, tubular insulating layer with tubular conducting shield. It is used as the transmission line for radio frequency signals.

As illustrate on the diagram above, internet is collected in head office and distributed to regional office and remote/roaming users.

• Information appear in variety of format MUST BE DIGITIZED so that the information can be understood by the computer and convey the RIGHT message to the viewers.  

There are how many types of signal?

• 2 types :-   i) Analogue Signal  ii) Digital Signal

Analogue Signal
-  formed by continously varying voltage level that create a wave that can be grasped by an analogue transmitter like microphone.
- has features: frequency and amplitude

- Analogue signal is transmitted through PSTN (phone line).

Digital Signal

- Transmission of binary electrical ONLY in the the states of 0 and 1. e.g. bit, bytes, kilobytes, megabytes, gigabytes and terrabyte.

- Digital signal =) analogue signal to be transmitted through PSTN line.

How is the word 'MODEM' originated??? (MOdulator or DEModulator)

It is the process that converts data into electrical signals (analogue =) digital signal = MOdulation) that can be transmitted over the telephone and vice versa. (digital =) analog signal = )

DEModulation)

The continous conversion of signals

There are how many Data Transmission Mode???

• 2 types : - i) Parallel Transmission 

                          ii) Serial Transmission ~ Synchronous Transmission  

                                                                ~ Assynchronous Transmission

Parallel Transmission

A group of bits is transmitted simultaneously using a separate line for each bit.

Serial Transmission

Transmit all the bits one after another on a single line. This transmission is slower as compared to parallel trasmission.

i) Synchronous Tranmission - A large group of data is transmitted in blocks called FRAME.

ii) Assynchronous Transmission - Bits divided into small groups (bytes) and send independently.

                                                     - a group of bits send anytime and receiver unaware they arrive.

How many ways the data can flow?

Communication between 2 pieces of equipment in exchanging process can be done in three ways:

- simplex ( data is transmitted ONE direction only) e.g. radio station/TV

- half-duplex ( 2 direction BUT NEVER at the same time) e.g. Walkie-talkie

- full-duplex ( both station can transmit and receive simultaneously) e.g. phone call

Apart from that, MULTIPLEXING is a set of techniques that enable more than ONE DEVICE to combine and send their signals simulaneously through a single data link at the SAME TIME.

That's All From Me Today..Thank You for Reading!!!