Satellite communications have become a mainstay within everyday life and work. Broadcast television has benefited greatly from the use of satellite signals, providing continuous service for subscribers throughout the world. This article will cover how these "eyes in the sky" operate within our world of communication.
Technically, a satellite is any object that orbits another object; like when the Moon obits the Earth, or the Earth orbits the Sun. Both of these are natural satellites. In the case of television broadcasting, satellites are specialized machines that receive signals from broadcast centers and transmit them back to Earth from space. Each one is launched into space and positioned at 22,200 above the Earth. They 're programmed to track the Earth's rotational movement so that each one remains in the exact same position in respect to where it was placed. This is called a geosynchronous orbit pattern, which is why satellite customers only have to mount and position their disks once, as the broadcast will always come from the same position in space. The signal received by the dish is then read by your receiver box so that it appear on the television screen.
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It's the satellite dish mounts we see on so many rooftops that transmit and receive the radio signals sent out by satellites. Broadcast programming is coordinated by direct providers, such as the DISH Network, and DirecTV. Program selections are determined by the providers and sold to subscribers in packages. All programming is done in digital format making for a clearer picture and sound transmission onto subscriber's TV sets. The actual channels which broadcast our TV programs come from programming source providers. They, in a sense, rent out these channels to direct service providers, after having purchased the rights to be a programming source from network content providers. Some of the larger network content providers would be ESPN and HBO.
The initial idea for satellite TV came in the form of an article written in "Wireless World Magazine" in 1945 by a scientist named Arthur C. Clarke. Clarke is also known for authoring the book, "2001, A Space Odyssey." In his article, Clarke presented his idea of placing space platforms within special orbits that coincided with the Earth's equator. Russia's space exploration program was the first to follow-up on Clarke's idea with their launch of Sputnik in 1957. Soon after, the United States launched Explorer I in 1957. It was soon realized that these space stations were able to tap into the Earth's magnetic radiation belts, situated some 22,300 miles above the equator. International private companies began to invest in research projects to further understand this discovery. It wasn't until 1976, that Home Box Office (HBO) actually put the idea into use with the first satellite program broadcast featuring "The Thriller From Manila" in 1976.
Broadcast signals are transmitted by a series of satellites positioned in geosynchronous orbit above the equator line. Each one is positioned at a specific longitudinal point in space. Point positions determine which signals the satellites are able to receive. Direct service providers sell different levels of service to their subscribers. Subscriber packages vary according to programming selection, and different packages require the use of a certain type of dish. Subscribers can choose between three dish types depending on the package purchased, and the type of receiver they have. Standard dish sizes range from 18 to 36 inches. Dish components include a filter, called the Low Noise Blocker Receptor (LNB) which blocks out extraneous signal noise and outputs lines that run straight to the receiver. Dishes can come equipped with as many as three LNB's and four output lines. A dish with four outputs can broadcast to as many as four television receiver boxes.
Satellite television communications are just one way satellites are put to use. There are actually three types of satellites in use today. - Research - Weather - Navigational Research satellites are employed by NASA to study characteristics of outer space. They measure and record properties of space related to magnetic field, celestial objects, and cosmic rays. The weather satellites are responsible for the up-to-date information we receive regarding weather patterns. Cloud coverings and atmospheric conditions are tracked and measured and sent back to weather stations on a continuous basis. The navigational satellites are what provide us with the GPS systems used in automobiles. These same systems are also used by the military aircraft and ships to track their positions.