Communications means sharing or transmitting informations, ideas, or feeling from one person to another. If you tell some one what you think or want, you are transferring that information from your mind to his.
Communications is a basic necessity of all living creatures. Life without communications would just be unimaginable. If it suddenly disappeared, our whole way of life would disintegrated. Communications is familiar with us in our daily life. It also protects us.
Exchanging information is not only among human beings but also among animals. Animals since the start of their life make sounds to communicate its arrival in the world. Growing older, they would bark, chirp make movements with parts or their body, and they like to communicate.
Communications is made in a variety of ways : with gestures, sign, facial expressions, speech, sound, etc. Nodding of head indicates agreement, while shaking means no. Similarly, a newly born baby cries to announce its coming into the world. The crying of the baby is to inform that it is hungry, feels cold or warm, fells sick or uneasy, and so on. The baby would smile to tell people around it that it feels happy, comfortable and content. A child standing its feet on the ground is trying to force its will to its mother or to others. Facial expressions may communicate sympathy, anger, fear, happiness, disgust and others. Humans being have bigger and complicated brains than animals. Human beings use mainly their brain and senses. Animal brains are much simpler than human brains but they use their senses very well. They cannot speak a language. Human being can speak a language. There fore communication among them is continuously developing.
Communications developed very rapidly between the development of the alphabets about 1500 BC, and the beginning of printing from movable metal type about A.D. 1440.
The development if the electronic compulere have enable engineers to design machines that run other machines. Scientist can feel information and problems into compulers and receive answers.
On October 1, 1965, United State scientist set a record the communications distance.
They sent a radio signal 191 millions miles to the Mariner IV spacecraft and received a return signal. Mariner IV was farther from the earth than Mars was at that time.
Monday, July 23, 2007
COMMUNICATIONS
THE INTERNET
The internet is sometimes called “the net”. It is a worldwide system of computer networks a network of network in which users at any computer can get information from any other computer through either private or public telephone connection. The Internet sometimes enable a user to talk directly to user at other computers. Individually, the network component is managed by government agents, universities, commercial agents, and volunteers as well.
At present, however, most universities in the world have already been directly or indirectly connected with the network.
Meanwhile, many business groups join up for different reasons. Some want to make us of the efficiency and cheap services of the international communications system, and some others want to advertise their products, merchandise or services. There are also people such as political parties, influential groups, charity institutions who want to get access to the abundant on-line data, however, there are millions of individuals who connect their computers at home to one of the providers or companies that provide Internet services.
The first thing you should do before getting access to the internet is to connect your computer network to the internet. There are two ways to get the access. First, via the local computer network, and second, by joining compuserve or MSN.
PC User group, one of the many providers, can give you both, access to the Internet anf many kinds of services. However, we only need one of its telephone numbers to have on-line connection, you should have a “terminal” in your house. This will need :
a. A computer of any kind.
b. A modem, a device to connect your computer to the telephone line.
c. A telephone connecting socket which is placed near your computer.
d. Communications software which enable you to make a connection between your computer and other computers in overseas countries.
When you’ve got the access to the Internet, you can do the following activities :
1. Sending a letter to your friend wherever he / she is. Your letter will only need a few seconds to reach the receiver and it costs as much as the telephone charge for the connections to the Internet.
2. Participating in a computer group discussion.
3. Getting special fun, hobby, or obsession via one of the news groups in which people from all over the world changes ideas, opinions, advice and files.
4. Downloading files, e.g. text, graphs, or even programmers from the public data bank kept at the computer host owned by an academy or commercial institutions.
5. Getting information from electronics libraries by using key-words to obtain papers containing reference about the topic you need.
6. Getting information from reference books, such as Webster Dictionary and Britain Encyclopedia.
7. Watching video clips on museums and art exhibitions.
8. Getting the latest national and international news, including weather report, prices in the exchange market , financial report, etc.
9. Playing games with other players , and so on.
Internet with all its facilities has made the world become small. It can eliminate time and distance. However, in taking advantage of the Internet facilities, a users should bear in mind to evade high cost to himself as well as to receivers by using the Internet lengthily. More over users should intelligently select the right information from the numerous sources provided by the Internet.
COMMUNICATIONS SATELLITES
Advanced Technology has brought great changes in communications. Man has been successful in launching an artificial earth satellite into satellite into orbits around the earth. The communications satellites make it possible to send radio messages, telephone calls, and television programmers between distant parts of earth. Rockets boast it into orbit, and the force of gravity keeps it fro flying off into space.
This artificial earth satellite is used to send radio, telephone, television, or other electronic communications to any part of the world. Transmitting stations on earth bounce television signals to the satellite by means of special antennas. The satellites send the signals back to the earth. Communications by the satellite is more reliable than by ordinay short wave radio and it has better quality.
There are two kinds of communications satellites. They are passive or active depending on the way it sends signals back to the earth.
Passive communications satellites simply reflect signals, as a mirror reflect light. The signals send to passive satellites must be strong because radio waves weaken as they travel to a satellite and back to the earth. The satellite must be large to reflect the radio energy back to the ground or receiving stations on another continent or thousand of miles from the sending station.
Active communications satellites are equipped with a radio receiver and transmitter. They receive signals from the earth, ampifly (strengthen) them, and than transmit them back to the earth. Therefore, they do not need to be so large as passive satellites. Most active satellite are less than 3 meters high. The electric equipment gets its power from sunlight by means of solar batteries.
Television signals are sometimes blocked by mountains, by the earth’s curvature, or even by tall buildings. Therefore, they have to be relayed from one transmitter to another in order to tunnel long distances.
The first message transmitted by satellite was sent in 1958. It was a Christmas greeting by President Dwight D. Eisenhower. The first television pictures were relay to many parts of the world by satellite in 1969 from Apollo II astronauts on the moon.
