[...]The INTELSAT Organization was established in 1964 to handle the myriad of technical and administrative problems associated with a world wide telecommunication system. The international regions served by INTELSAT are divided in to the Atlantic Ocean region (AOR), the Pacific Ocean Region (POR), and the Indian Ocean region (IOR). For each region , satellites are positioned in geo-stationary orbit above the particular Ocean, where they provide a transoceanic telecommunication route. In addition to providing trans oceanic routes, the INTELSAT satellites are used for domestic services within any given country and regional services between countries. Two such services are vista for telephony and Intelnet for data exchange.
[...]DOMSAT
Domestic satellites are used to provide various telecommunication services, such as voice, data, and video transmission (T.V channels), with in a country. Satellite cell phones allow global travelers and those in remote areas to avoid landlines and terrestrial cell phone services entirely. Satellite cell phones relay your call to a satellite and down through a hub to the end user. This means that most of the earth's geographical area is now accessible by a satellite cell phone! Third party providers of satellite cell include Satcom Global, Roadpost Satcom, Online Satellite Communications, and others.
[...]SARSAT
SARSAT is one type of Polar orbiting satellites.
Polar-orbiting satellites orbit the earth in such a way as to cover the north and south polar-regions. Infinite number of polar polar satellite orbits are possible
Polar satellites are used to provide environmental data, and to help locate ships and aircrafts in distress .This service known as SARSAT, for search and rescue satellite.
[...].Definitions And Related Terms Of Earth-Orbiting Satellites
Apogee. The point farthest from earth.
Perigee. The point of closest approach to earth.
Line of apsides. The line joining the perigee and apogee through the center of the earth.
Ascending node. The point where the orbit crosses the equatorial plane going from south to north.
Descending node. The point where the orbit crosses the equatorial plane going from north to south.
Line of nodes. The line line joining the ascending and descending nodes through the center of the earth.
Inclination. The angle between the orbital plane and the earth's equatorial plane.
Prograde orbit. An orbit in which the satellite moves in the same direction as the earths rotation.
Retrograte orbit. An orbit in which the satellite moves in a direction counter to the earth's rotation.
Argument of perigee. The angle from ascending node to perigee, measured in the orbital plane at the earth's center in direction of satellite motion.
Mean anomaly. Mean anomaly M gives an average value of the angular position of the satellite with reference to the perigee
True anomaly. The true anomaly is the angle from perigee to the satellite position, measured at the earth's center. this gives the true angular position of the satellite in the orbit as a function of time.
4.Satellite system
A satellite communication system can be broadly divided into two segments, a ground segment and a space-segment. The space system includes Satellite.
Satellite system consist of the following systems.
[...]A satellite that is normally in geo-stationary will also drift in latitude, the main perturbing forces being the gravitational pull of the sun and the moon . the force cause the inclination to change at the rate of about 0.85 deg./year. if left uncorrected, the drift would result in a cycle change in the inclination going 0 to 14.67deg in 26.6 years and back to zero , when the cycle is repeated. To prevent the shift in inclination from exceeding specified limits, jets may be pulled at the appropriate time to return the inclination to zero. Counteracting jets must be pulsed when the inclination is at zero to halt that change in inclination.
[...] Antenna sub system
The Antennas carried abroad a satellite provide the dual functions of receiving the up link and transmitting the down link signals. They range from dipole-type antennas, where omni directional characteristics are required, to the highly directional antennas required for telecommunications purposes and TV relay and broadcasting.
[...] Determination of the Azimuth and Elevation angles (Look Angles)
Figure-1 shows spherical triangle bounded by points N, ES, and SS.
Here ES denotes the earth station. The point s denotes the satellite in geostationary orbit, and point SS the sub satellite point. To solve this triangle we have to use Napier's rules. By solving we get following results.
Let lE represents the latitude of the earth station, fE represents the longitude and of the earth station, fS the longitude of sub satellite point, and observing the sign convention stated previously, the angle B is given by
B can not exceed a theoretical limit of 81.3° , set by horizon. Napier's rules can then be used to show
Once angle A is determined, the azimuth angle AZ can be found. Four situations must be considered, the results for which can be summarized as follows:
(a) lE<0;B<0:AZ= A
(a) lE<0;B>0:AZ= 360°-A
(a) lE>0;B<0:AZ= 180°+A
(a) lE>0;B>0:AZ= 180°-A
These do not take into account the case when the earth station is on the equator. Obviously, when the sub-satellite, the elevation is 90° and Azimuth is irrelevant. When the west (B >0 ), the azimuth is 270°.
To find the range and elevation, it is necessary first to find side c of the quadrantal spherical triangle, and then use this in the plane triangle shown in fig. side c is obtained using the rule.
The equatorial radius RE= 6378.14 km, and geostationary height h = 35,786 km. Because of the flattening of the earth at the poles, the radius R varies with latitude. An equation that gives R to a close approximation is
Here RE is the earth's equatorial radius and R is the radius at the earth station.
The plane triangle shown in fig-2 can be solved using the plane trigonometry. Applying the cosine rule gives the distance d as.
The elevation angle is denoted by EI deg in fig . Application of the sine rule to the plane triangle gives
Ref; https://www.tutorialsweb.com/satcom/fundamentals-of-satellite-communications.htm
[...]DOMSAT
Domestic satellites are used to provide various telecommunication services, such as voice, data, and video transmission (T.V channels), with in a country. Satellite cell phones allow global travelers and those in remote areas to avoid landlines and terrestrial cell phone services entirely. Satellite cell phones relay your call to a satellite and down through a hub to the end user. This means that most of the earth's geographical area is now accessible by a satellite cell phone! Third party providers of satellite cell include Satcom Global, Roadpost Satcom, Online Satellite Communications, and others.
[...]SARSAT
SARSAT is one type of Polar orbiting satellites.
Polar-orbiting satellites orbit the earth in such a way as to cover the north and south polar-regions. Infinite number of polar polar satellite orbits are possible
Polar satellites are used to provide environmental data, and to help locate ships and aircrafts in distress .This service known as SARSAT, for search and rescue satellite.
[...].Definitions And Related Terms Of Earth-Orbiting Satellites
Apogee. The point farthest from earth.
Perigee. The point of closest approach to earth.
Line of apsides. The line joining the perigee and apogee through the center of the earth.
Ascending node. The point where the orbit crosses the equatorial plane going from south to north.
Descending node. The point where the orbit crosses the equatorial plane going from north to south.
Line of nodes. The line line joining the ascending and descending nodes through the center of the earth.
Inclination. The angle between the orbital plane and the earth's equatorial plane.
Prograde orbit. An orbit in which the satellite moves in the same direction as the earths rotation.
Retrograte orbit. An orbit in which the satellite moves in a direction counter to the earth's rotation.
Argument of perigee. The angle from ascending node to perigee, measured in the orbital plane at the earth's center in direction of satellite motion.
Mean anomaly. Mean anomaly M gives an average value of the angular position of the satellite with reference to the perigee
True anomaly. The true anomaly is the angle from perigee to the satellite position, measured at the earth's center. this gives the true angular position of the satellite in the orbit as a function of time.
4.Satellite system
A satellite communication system can be broadly divided into two segments, a ground segment and a space-segment. The space system includes Satellite.
Satellite system consist of the following systems.
[...]A satellite that is normally in geo-stationary will also drift in latitude, the main perturbing forces being the gravitational pull of the sun and the moon . the force cause the inclination to change at the rate of about 0.85 deg./year. if left uncorrected, the drift would result in a cycle change in the inclination going 0 to 14.67deg in 26.6 years and back to zero , when the cycle is repeated. To prevent the shift in inclination from exceeding specified limits, jets may be pulled at the appropriate time to return the inclination to zero. Counteracting jets must be pulsed when the inclination is at zero to halt that change in inclination.
[...] Antenna sub system
The Antennas carried abroad a satellite provide the dual functions of receiving the up link and transmitting the down link signals. They range from dipole-type antennas, where omni directional characteristics are required, to the highly directional antennas required for telecommunications purposes and TV relay and broadcasting.
[...] Determination of the Azimuth and Elevation angles (Look Angles)
Figure-1 shows spherical triangle bounded by points N, ES, and SS.
Here ES denotes the earth station. The point s denotes the satellite in geostationary orbit, and point SS the sub satellite point. To solve this triangle we have to use Napier's rules. By solving we get following results.
Let lE represents the latitude of the earth station, fE represents the longitude and of the earth station, fS the longitude of sub satellite point, and observing the sign convention stated previously, the angle B is given by
B can not exceed a theoretical limit of 81.3° , set by horizon. Napier's rules can then be used to show
Once angle A is determined, the azimuth angle AZ can be found. Four situations must be considered, the results for which can be summarized as follows:
(a) lE<0;B<0:AZ= A
(a) lE<0;B>0:AZ= 360°-A
(a) lE>0;B<0:AZ= 180°+A
(a) lE>0;B>0:AZ= 180°-A
These do not take into account the case when the earth station is on the equator. Obviously, when the sub-satellite, the elevation is 90° and Azimuth is irrelevant. When the west (B >0 ), the azimuth is 270°.
To find the range and elevation, it is necessary first to find side c of the quadrantal spherical triangle, and then use this in the plane triangle shown in fig. side c is obtained using the rule.
The equatorial radius RE= 6378.14 km, and geostationary height h = 35,786 km. Because of the flattening of the earth at the poles, the radius R varies with latitude. An equation that gives R to a close approximation is
Here RE is the earth's equatorial radius and R is the radius at the earth station.
The plane triangle shown in fig-2 can be solved using the plane trigonometry. Applying the cosine rule gives the distance d as.
The elevation angle is denoted by EI deg in fig . Application of the sine rule to the plane triangle gives
Ref; https://www.tutorialsweb.com/satcom/fundamentals-of-satellite-communications.htm
