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Posted by ametya 2 comments Links to this post
Labels: currnet conditon
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Labels: currnet conditon
It is a microwave communication and hence requires Line Of Sight(LOS) to transmit and receive signal. LOS means the earth station in ground and satellite in sky could see each other. The frequencies that it utilizies falls on the category of GigaHertz(GHz). Among the several freq. band separation of microwave, C, Ku and Ka bands are allocated for commercial satellite communication.
To make satellite able to stay in space revolving round the earth, Rocket having the satellite equipment is required to launch to sky with velocity greater than escape velocity. Escape velocity means the velocity required against the earth's gravitation.
The 1st satellite ,sputnik1, was launched by Soviet Union in october 4, 1957 which again lauched the first living creature(sputnik2), a dog named Laika in to space on November 3, 1957. Explorer 1 was the first satellite of United States, launched in January 31, 1958. The early communication satellites were in relatively low altitude orbits(below 36000 km) and consequently sped around the earth in a few hours. This required the ground antennas to move constantly in order to beam signals to them.
The orbit in range of 36000 km above the earth surface is called geostationary orbit as the satellite in that orbit do round the earth in the same time that the earth takes to round in it's own axis, means 24 hours. So though both earth and satellite revolve, the satellite appears to be stationary from a particular earch surface. This provides easyness in work eliminating the need of ground antennas to move constantly regarding satellite movement.
Posted by ametya 1 comments Links to this post
Labels: my own
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Labels: career control
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Labels: career control
Posted by ametya 0 comments Links to this post
Labels: career control
The recent development in mobile are categorized broadly in terms of generation(G). The mobile in the decade of 60 were used to be 1G, totally analog based. The cellular constumer were used to be registered manually when moving from one cell to another.
2G came in 1990 with knowledge about digital concept. In actual mean mobile captured it's pace through this generation. Since 2nd Generation, hand off not only became easy and fast but also sophisticated too. Till the journey of 2G, Network Controlled HO(NCHO) has been turned in Mobile Assisted HO(MAHO). SMS (Short Message Service) is the most favourable service provided by it where two user (subscriber) can communicate through text. To reduce the burden of MSC, BSC blocks have been placed in between BS and MSC.
2.5G came in to existence with internet approach but it's speed fasten with the emergence of 3G. Broadband Integrated Service Digital Network (B-ISDN) in 3G made it capable of accessing voice, data, video simultaneously and HSPA(High Speed Packet Access) transferring data in fastest manner. Together with advanced modulation technique mobile technology is making itself more sophisticated than mentioned in words and languages.
The latest upgrades in mobile technology, 3.5G,4G, in highly developed countries are showing the truth that yet there is some more things to be innovated in mobile field.
Posted by ametya 1 comments Links to this post
Labels: my own