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How Satellite System Work

How satellite system works- Geostationary Orbit (GEO)



Today we will be talking how the satellite system works, we do see their light from at night, some people will be thinking how is it possible for those satellites to be there, and didn't fall back to earth or lost in space. today will explore your knowledge how the system works.

most of the world's communication satellite and some weather satellites are placed in the geostationary orbit a circular orbit in the same plane as the Earth equator since satellite GEO Circle the Earth in exactly the same time it takes the Earth to turn on axis to (24hrs) they appear to be stationary compared with the Earth this means that crustacean to not have to scan across the sky to track the satellites and its allies can be given orbit o0  position related to the line of the longitude above which day are stationed (e.g 19 W, 26 E). Geostationary orbit is commonly abbreviated to GEO or sometimes GSO (for geostationary satellite orbit or simple stationary orbit) The term geosynchronous in fact GEO  is a special type of geosynchronous orbit (i.e equatorial with a 24-hour period).

Geostationary orbit parameters

HIght ( above Earth's surface) 35,786 km (22,237 miles)
Radius ( from earth center) 42,168 km (26,200 miles)
Circumference 264,924 km (164,624 miles).
Each one-degree slot of orbital space is about 736 km wide ( 457 miles)

Other Orbits 
Low Earth Orbit (LEO)
several proposed constellations of satellites for mobile telecommunications service will occupy variety of low- attitude orbits. Some scientific satellite and all current manned space vehicles are launched to LEO. LEOs tend to be circular and up to about 1000 km in altitude. they're are not confined to the equatorial plane and they have any inflation from zero to 90 degrees (the higher inclination orbits are termed polar orbits) and may also be elliptical. Satellites in LEO tend circle the Earth in about 100 minutes

Medium Earth Orbit (MEO)

MEOs lie between LEO and GEO typically at altitudes between about 5, 000 km and 25,000 km. Circular MEOs are also referred to as intermediate circular orbits (ICOs)

Sun-Synchronous Orbit (550)

An orbit used particularly by Earth observation satellites, SSO is high inclination 'polar' orbit synchronized with the sun so that lightning condition are the same for each successive Pass over giving area SSOs have an attitude of 600-800 km

Molniya and Tundra Orbits

Molniya Orbits is a high-elliptical, near-polar orbit used by Russian Molniya communications satellites. typically perimeters inclination 63.4' period 12 hours apogee 39,00 km; perigee 1,500 km. A related Orbit is the elliptical Tundra Orbit (apogee 36,000 km; perigee 20,000 km). It is similar to Molniya Orbit in that it covers high latitude and similar to GEO in that it has a period of 24 hours, which gives it one apogee instead of the Molniya's two.


Some Potential Problem that affects a satellite 

Atmospheric Attenuation: 

All radio signals is transmitted by satellite or by terrestrial station subjected to atmospheric attenuation, in other words, their power is diminished by passing through the Earth's atmosphere there are two aspects of atmospheric pressure which affect satellite communication.

1. Oxygen and water Vapour Attenution 
This is caused by an interaction between the radio wave and atmospheric molecules which result in some of the energy being absorbed by the molecules.  The degree of attenuation is dependent on the radio frequency and greater at ku band (11/14 GHz), for example, than it is at C-band (416 GHz). Attenuation is also dependent on the elevation angle of the satellite from earth station because the atmospheric path is longer for the satellite near the horizon than for those overhead (the same factor causes stars near the horizon to twinkle), the left-hand figure shows how attenuation varies with frequency and elevation angle.

2. Rainfall Attenuation

This occurs because individual raindrops absorb radio energy and because some energy is scattered out of the propagation path, Rain attenuation also causes depolarization. The right-hand figure shows how attenuation varies with frequency and elevation angle.

Interference

As with telecommunication service interference between two or more radio frequency (RF) signals can have serious practical and commercial consequences in the telecommunication system there are three main factors used:
The allocation of different frequencies ( frequency separation), the use of opposite polarization and allocation of widely-spaced orbital positions (angular separation).

With the general increase in Satellite system, it has become increasingly difficult to find sufficient frequency-space to avoid interference not only between the Satellite system but also between the satellite and terrestrial system (such as microwave networks) this has led to the growth of technology and equipment for used at the higher frequency band. It is also proving difficult to find some short orbital position and spacing between systems operating in the same band has been gradually reduced this athletic Asian interference between which have usually been solved amicably however has a number of the computing system in growth areas such as Asia-pacific region increases interference problems are likely to increase.





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