Satellite Communications
« Previous EntriesMicrowaves And Satellite Communication
Saturday, February 20th, 2010
Author: Kyle Newton
Micro is a unit for measurement of length. As the name suggests microwaves are the portion of the electromagnetic spectrum where the wavelength falls between about one millimeter and thirty centimeters that is micrometers.
Frequency of microwave bands extends from about one gigahertz to three hundred gigahertz and is useful for short range, high reliability radio and television links. Systems which use microwave frequencies are radar, mobile radio, satellite communications, terrestrial line of sight and troposphere links.
Resource Controller
Sunday, January 3rd, 2010Resource Controller-The Resource Controller will maintain the Control Station Database that provides SATCOM assignments to users based on input from communications managers and user requests. It will directly interface to communications managers through their Network Management Stations, allowing creation and maintenance of user networks. It will also interface with Resource Controllers at other control stations to support worldwide networks and to maintain redundant capacity, should one station fail.
Satellite Footprints
Wednesday, November 11th, 2009The area of coverage on the earth’s surface that is effectively irradiated by a satellite’s antenna is called its “footprint.” This footprint is also the earth coverage area from which a satellite’s antenna can effectively collect signals transmitted to it. Theoretically, like the beam from a flashlight, a footprint should be circular. However, the earth’s terrain is uneven, the thickness of the atmosphere changes, and different satellite antennas may have differently shaped beam patterns. The footprint, in reality, usually has an irregularly shaped beam pattern with signal intensity strongest in the central parts of the projected ground coverage pattern and tapering off towards the edges of the pattern.
SPACE SYSTEM SEGMENTS
Saturday, October 31st, 2009Satellite Systems are not just launched and then left to perform their missions. They are complex pieces of equipment, which cost millions of dollars to design and launch. To keep a satellite functioning over its expected life span requires constant attention through a complex network of equipment and people.
Space Segment: There are two parts to the space segment: the satellite platform (the basic frame of the satellite) and the payload. The payload’s functions and capabilities are the reasons a satellite is placed in orbit. The payload provides space-based capabilities to the users and distinguishes one type of satellite from another.
THE SPACE ENVIRONMENT DEFINITIONS AND EFFECTS
Tuesday, July 28th, 20091) Perturbation-irregularity in the motion of a satellite caused by an outside force, creates degradation of signal or total loss of communications
a)Lunar/Solar effects, earth triaxiality, solar winds
2) Solar Conjunction-A phenomenon that occurs when the earth, satellite and sun are in alignment. The earth terminal antenna is pointing directly at, or very near the sun. Communications can be degraded for 2 to 15 minutes total communications blackout can last for up to 5 minutes.
3) Van Allen Radiation Belts-The dynamo action of the Earth generates a magnetic field known as the Magnetosphere. Energetic particles from the Sun’s Solar Wind leak into the Magnetosphere and become concentrated in an area known as the Plasmasphere.
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