Just How Many Different Types of Satellites are There?

Line of sight propagation requires that the sending and receiving antennas be locked on to each other’s location at all times that is one antenna must have the other in sight. A satellite that moves faster or slower than the earth’s rotation is useful only for short periods of time. To ensure that the satellite has constant communication, it must move at the same speed as the earth. This allows it to seem to remain fixed above a certain spot, when in actuality it is moving at the same speed as the earth.

We can call such satellites geosynchronous. Because orbital speed is based on distance from the planet, only one orbit can be geosynchronous. This orbit occurs at the equatorial plane and is approximately twenty two thousand miles from the surface of the earth. The only downside to the geosynchronous satellite is that only one cannot cover the whole earth. It will take many to be able to cover the entire surface of the earth.

One satellite in orbit has line of sight contact with a vast number of stations but the curvature of the earth still keeps much of the planet out of sight. It takes a minimum of three satellites equidistant from each other in geosynchronous earth orbit to provide full global transmission. Medium earth orbit satellites are positioned between the two Van Allen belts. A satellite at this orbit takes approximately six hours to circle the earth.

One example of medium earth orbit satellites system is the global positioning system orbiting at an altitude about eighteen thousand kilometers above the earth. The system consists of twenty four satellites and is used for land and sea navigation to provide time and locations for vehicles and ships. The global positioning system is not used for communication. It is becoming need of time to assure one's exact position in space and time in a authentic way. This can be achieved by use of satellites.

Satellites are radio navigation system, which are launched by the various space Agencies. These satellites are worldwide system which ensures reliable service with the current Global positioning system. Science is making advancements everyday. Now a day daily new things are invented. Satellite radio navigation technology is one of the advanced technologies in the market these days. This technology is based on the emission of signals from satellites indicating the time extremely accurately. In this way a person can easily determine his or her position. Positioning of any stationary as well as moving object can be located with satellite radio navigation system. Global positioning system is based on principle of triangulation. Low earth orbit satellites have polar orbits. The altitude is between five hundred to two thousand kilometers with a rotation period of ninety to one twenty minutes. The satellite has a speed of twenty thousand to twenty five thousand kilometers per hour. A low earth orbit system usually has a cellular type of access similar to the cellular telephone system.

Tymon Hytem has worked in the electronics feild for the past 15 years. He enjoys helping people decide on electronic gadgets from telephones to XM Radio and choosing the perfect XM Satellite Radio system for their needs.