A satellite can surround the earth on two basic types of orbits. The first and most obvious is a circular orbit at that distance from the Earth remains constant. The second type of orbit is elliptical orbit. When a satellite orbiting the Earth orbit is circular or elliptical, describes a plan.
It passes through geocenter. The rotation around the Earth also has two variants. It can be in the same direction as the Earth’s rotation, in which case it is said to be direct or reverse rotation of the Earth, in which case it is said to be retrograde. Speed is an important factor. For a circular orbit it is always the same. For an elliptical orbit this is no longer true because speed changes depending on the position in orbit.
Speed is an important factor. For a circular orbit it is always the same. For an elliptical orbit this is no longer true because speed changes depending on the position in orbit. Speed is highest when the moon is closest to Earth and must defeat gravity is the largest and highest minimum remoteness from Earth. For an elliptical orbit Earth’s center is in one of the foci of the ellipse.
A satellite can rotate around the Earth in different planes. The angle of inclination of the orbit is the angle between a line perpendicular to the right orbit and passing through Earth’s poles. This means that an orbit that is located in the equatorial plane has an inclination of 0 ° or 180 °, and one passing over the poles would have a slope of 90 °. Those seeking orbits over the equator are called equatorial orbits, and that passing over the poles are called polar orbits.
Another important factor on the position of the satellite elevation angle.
This is important because it can communicate with the satellite earth station when it has direct visibility to it. The elevation angle is the angle at which the satellite appears to the horizontal. If the angle is too small, the signals can be masked by objects surrounding the antenna is placed high enough. For the satellite to be used for communication earth station must be able to follow to receive signals and transmit to him. Obviously, communication will be possible only when there is direct visibility and, depending on orbit, visibility may exist only for a short period of time.
However, switching from one satellite to another introduce more complexity into the system, as well as the need for and the launch of 3 satellites. The most common option is to launch a satellite in a geostationary orbit. Using this orbit, the satellite rotates in the same direction as Earth and has a rotation period of 24 hours. As a result, he remains in the same position relative to Earth. Because the forces involved to balance and satellite remain in a geosynchronous orbit, it must turn over the equator at an altitude of 35 860 km.
Geostationary orbits are used, because once the earth station satellite was oriented, it can remain in the same position and normally do not require a follow-up to the satellite. This greatly simplifies the design and construction of the antenna. For direct broadcasting satellites means that users who have antennas placed outside the house must not settle after being targeted once by satellite. Many satellites are placed on geostationary obit and a method to achieve this is based on the transfer of Hohmann.
This is the method used when it launches satellites into space using a ship bearing. Using this system, the satellite is placed on a low earth orbit (http://www.gpsphone-tracker.net/) at an altitude of around 290 km. After correct positioning this orbit missiles that are started to put the satellite into an elliptical orbit, with perigee and apogee low-Earth orbit to geosynchronous orbit. When the satellite reaches final altitude, rockets are again switched to stabilize the geostationary satellite orbit at the right speed. Sometimes when using rockets Ariane launch vehicle, the satellite is launched directly elliptical transfer orbit. When the satellite reaches maximum altitude missiles that are turned on to transfer to geostationary orbit desired, with appropriate speed.