At the beginning of the twentieth century, there were four powerful means of transmitting and receiving information over long distances: print, photography, telegraph and telephone. By the middle of the 20th century, both radio and television had become established means of transmitting sounds and pictures. In 1964, the Olympic Games in Tokyo became the first program to be transmitted via satellite.
In order to transmit an event such as the Olympics via satellite, television signals are first changed into radio waves, which are then sent from a station on earth to an orbiting satellite. The satellite receives the radio waves and sends them back to earth, where another station picks them up and changes them back into television signals. Because any form of sound or visual information can be changed into radio waves, satellites are capable of transmitting not only television broadcasts, but telephone calls and printed materials such as books and magazines.
The combination of satellites, which transmit information, computers, which store information, and television, which displays information, will change every home into an education and entertainment center. In theory, every person will have access to an unlimited amount of information.
Another important use of telecommunication satellite was demonstrated in 1974 when the "Teacher in Sky" satellite transmitted educational programs to classes in remote areas of the United States. In 1975, many people in India saw television for the first time as they watched programs about agriculture and health.
The most common use of telecommunication satellites, however, has been for transmitting telephone calls. Most of them travel 40,000 miles to a satellite and then back to earth. Twenty years ago, a satellite was capable of receiving and transmitting more than 33,000 telephone conversations. Now a single satellite is able to transmit over 100,000 conversations as well as several television channels—all at the same time.
Telecommunication can make information from around the world available to use quickly and easily, but some people worry that this may he a risk to our privacy; If personal information is stored in computers, then it may be easily transmitted via satellite to anyone who can pay for the service.
Another worry is that telecommunication system may separate people from each other. When people are able to buy things from their homes, do their banking without leaving the house, watch any movie they want on their television, as well as get any information they need, then there will not be as much contact between people.
It is important to realize that the same technology that helps us may also harm us, We can prevent this from happening by carefully controlling the new technology. As one telecommunication expert says, "We must remember that technology alone is not the answer... It is the good application of technology that will lead us to success." The television signals are transmitted in the form of ______.