How Do Satellites Work

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Satellites

Satellite is called “Eyes in the sky”. A satellite is a tin can spinning through space. The word “satellite” is more general than that it means a smaller, space-based object moving in an orbit around a larger object. The Moon is a natural satellite of Earth because gravity locks it in orbit around our planet (earth). satellites are actually artificial satellites that move in precisely calculated paths, circular or elliptical (oval), at various distances from Earth, usually well outside its atmosphere. satellite doing great work.  If you want to make a phone call from the North Pole, you can fire a signal into space and back down again, using a communications satellite as a mirror to bounce the signal back to Earth and its destination.

Satellite Communication Basics

Satellite Communication Basics

The process begins at an earth station an installation designed to transmit and receive signals from a satellite in orbit around the earth.The  Earth stations send information in the form of high powered, high frequency (GHz range) signals to satellites which receive and retransmit the signals back to earth where they are received by other earth stations in the coverage area of the satellite. The area which receives a signal of useful strength from the satellite is known as the satellite’s footprint. The transmission system from the earth station to the satellite is called the uplink, and the system from the satellite to the earth station is called the downlink.

Satellite Frequency Bands

The three most commonly used satellite frequency bands are the C-band, Ku-band, and Ka-band. C-band and Ku-band are the two most common frequency spectrum used by today’s satellites.

  • L-band (e.g. Inmarsat Swift Broadband): pretty slow, max 422kbps per channel per airplane
  • Ku-band (e.g. Panasonic, Global Eagle, and Gogo): tops out at around 20-40Mbps per airplane. Speeds depend on how many airplanes are in the satellite’s transponder “footprint” (aka spot beam)
  • Ka-band (near future, satellites launching soon): promises even higher speeds.
  • C-band satellite transmissions occupy the 4 to 8 GHz frequency range

 

C-band Satellite Antenna

Ku-band Satellite Antenna

Geosynchronous Earth Orbit (GEO) Satellites

As the height of a satellite increases, so the time for the satellite to orbit increases. At a height of 35790 km, it takes 24 hours for the satellite to orbit. A geosynchronous orbit is a high Earth orbit that allows satellites to match Earth’s rotation. Located at 22,236 miles (35,786 kilometers) above Earth’s equator, this position is a valuable spot for monitoring weather, communications and surveillance

 

 

 

 

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