A Brief History of Satellites
In the late 1950s, Russia launched a satellite named Sputnik, and soon after the United States countered by launching Explorer 1. However these two satellites were not communications satellites. A few years later on July 10, 1962, AT&T launched Telstar 1, the world’s first active communications satellite. Although at that time the US and Russia were in heavy competition, AT&T was more interested in the communications aspect of satellites in order to broadcast TV, radio, and phone signals.
Why did satellites come when they did?
Television broadcasting was in its infancy during this time and currently there was no way to broadcast TV signals overseas. The goal of AT&T with the Telstar satellite was to establish a world communications network. However, people were able to receive radio and phone signals between the US and Europe for the past fifty years. With the introduction of TV broadcasting signals, current transoceanic cabling was unable to accommodate the extra bandwidth required for television broadcasts. Another way of transmitting radio signals great distances is by sending the signals from one radio station tower to another. For instance, a radio tower in North America can send a signal to Europe in this way. The trajectory of the signal is not direct, but it travels upward into the atmosphere and bounces back to the earth where the receiver can get them. However, this does not work with television signals.
The difference between radio signals and television signals is that television signals operate at a much higher frequency than radio signals. Typical radio signal range in the frequency of 500 kilohertz to almost 100 megahertz. Video signals operate above the 150-megahertz range. Because of the higher frequency of video signals, they are able to penetrate the earth’s atmosphere; therefore the traditional radio broadcast towers cannot be used to transmit video signals. In order to transmit video signals over long distances, there needed to be some kind of device that can rebroadcast signals to almost all over the globe. This is exactly what a communications satellite achieves.
In essence, satellites and satellite communications came about because there was no way to transmit video signals around the world using the current technology of the time. Today, satellites are mainly used for television and video broadcasting.
