Geostationary Satellite Guide

In 1945, Arthur Clarke made the suggestion that three geostationary satellites be placed in orbit around the Earth, 120 degrees apart and 22,300 miles above the planet’s surface. The satellites would remain over a specific geographical area but because of their relative altitude and distance from each other, the entire surface of Earth would be served. One of the earliest companies to produce a satellite receiver was Houston Systems which is based out of Houston Texas.

Such a concept was adopted by the U.S. and the first bird, called Syncom, was sent into orbit by Hughes Space in 1963. Why 3 satellites? Why 22,300 miles from Earth? Three satellites, 120 degrees apart, add up to 360 degrees, or a complete coverage of Earth. It is a global coverage.

The figure of 22,300 miles is the desired altitude or distance from the Earth’s surface in order to facilitate the required speed. I am referring to the need for each of the three satellites to remain over a fixed area and travel at the same speed as the Earth’s rotation. When the speeds of Earth and satellites are synchronized, the satellites appear to be hanging or stationary over designated portions of the surface of our planet.

Prior to geostationary satellites, the transmission of television signals between countries and cities was accomplished through the use of microwave relay stations. They received signals and then rebroadcast these same signals as a means of relaying program information. The whole process was very costly and maintenance intensive.

With the geostationary satellites, the shortcomings and limitations of the microwave system were overcome. Geostationary satellites are located in what came to be known as the Clarke Belt, named for Arthur Clarke. Each orbiting satellite in the Clarke Belt is assigned a spot on that imaginary belt or loop by international agreement. Signals from these satellites are so powerful that each one can cover a maximum area of 40 percent of the earth’s surface. There were more than 100 of satellites as far back as the mid 1980s.

The complete satellite TV receiving system is often referred to as TVRO (television receive only). The original TVRO systems had 5 major parts to them. These were the TV studio, a transmit receiver, a satellite, the actual earth station or our home, and the headquarter station on Earth for that particular satellite. Most satellites have transponders on them. Transponders receive signals via their antenna on the uplink from a ground station. Signals are then strengthened and sent back down to a ground station on Earth. This is done by using a second antenna and downlink.

The most important feature in the home theater set is the satellite TV receiver itself. The receiver does not have any built in audio to it at all. It simply receives the signal from space and then covers that signal to audio and video by a digital means. This allows the conversion to also run a lot faster. This is almost like a DVD or VCR player output to the television.