06-04-2012, 02:32 PM
satellite communication
report.doc (Size: 3.75 MB / Downloads: 60)
Introduction
For 10,000 years (or 20,000 or 50,000 or since he was able to lift his eyes upward) man has wondered about questions such as “why holds the sun up in the sky?” , “Why doesn’t the moon fall on us?”, and “How do they (the sun and the moon) returns from the far west back to the far east to rise again each day?” Most of the answers which men put forth in those 10,000 or 20,000 or 50,000 years we now classify as superstition, mythology, or pagan religion. It is only in the last 300 years that we have developed a scientific description of how those bodies travel.
• Why Satellite for communication?
By the end of World War II, the world had a taste of “global communication” Edward R.Murrow’s radio broadcasts from London had electrified American listeners. We had, of course been able to do transatlantic telephone calls and telegraphs via underwater cables for almost 50 years. At exactly this time, however a new phenomenon was born. The first television programs were being broadcast, but the greater amount of information required transmitting television picture required that they operate at much higher frequencies than radio stations. For example, the vary first commercial radio station (KDKA in Pittsburgh) operated at 1020 on the dial. This number stood for 1020 KHZ the frequencies at which the station transmitted. Frequency is simply the number of times that the electrical signal wiggles 1 time/second.
TYPES OF SATELLITE
LOW EARTH- ORBITING COMMUNICATION SATELLITE
In 1960, the simplest communications satellite ever conceived was launched. It was called Echo, because it consisted only of a large (100 feet in diameter) aluminized plastic balloon. Radio and TV signals transmitted to the satellite would be reflected back to the earth and could be received by any station within view of the satellite.
COMPONENTS OF SATELLITE
Every communication satellite in its simplest form involves the transmission of information from an originating ground station to the satellite (the uplink), followed by a retransmission of the information from the satellite back to the ground (the downlink).
TRANSMITTERS
The amount of power which a satellite transmitter needs to send out depends a great deal on whether it is in low earth orbit or in geosynchronous orbit. This is a result of the fact that the geosynchronous is at an altitude of 22,300 miles. While the low earth satellite is only a few hundred miles.
The geosynchronous satellite is nearly 100 times as far away as the low earth satellite. We can show fairly easily that this means that higher satellite would need almost 10,000 times as much power as the low-orbiting one, if everything else were the same, (Fortunately, of course we can change some other thing so that we don’t need 10,000 times as much power).
report.doc (Size: 3.75 MB / Downloads: 60)
Introduction
For 10,000 years (or 20,000 or 50,000 or since he was able to lift his eyes upward) man has wondered about questions such as “why holds the sun up in the sky?” , “Why doesn’t the moon fall on us?”, and “How do they (the sun and the moon) returns from the far west back to the far east to rise again each day?” Most of the answers which men put forth in those 10,000 or 20,000 or 50,000 years we now classify as superstition, mythology, or pagan religion. It is only in the last 300 years that we have developed a scientific description of how those bodies travel.
• Why Satellite for communication?
By the end of World War II, the world had a taste of “global communication” Edward R.Murrow’s radio broadcasts from London had electrified American listeners. We had, of course been able to do transatlantic telephone calls and telegraphs via underwater cables for almost 50 years. At exactly this time, however a new phenomenon was born. The first television programs were being broadcast, but the greater amount of information required transmitting television picture required that they operate at much higher frequencies than radio stations. For example, the vary first commercial radio station (KDKA in Pittsburgh) operated at 1020 on the dial. This number stood for 1020 KHZ the frequencies at which the station transmitted. Frequency is simply the number of times that the electrical signal wiggles 1 time/second.
TYPES OF SATELLITE
LOW EARTH- ORBITING COMMUNICATION SATELLITE
In 1960, the simplest communications satellite ever conceived was launched. It was called Echo, because it consisted only of a large (100 feet in diameter) aluminized plastic balloon. Radio and TV signals transmitted to the satellite would be reflected back to the earth and could be received by any station within view of the satellite.
COMPONENTS OF SATELLITE
Every communication satellite in its simplest form involves the transmission of information from an originating ground station to the satellite (the uplink), followed by a retransmission of the information from the satellite back to the ground (the downlink).
TRANSMITTERS
The amount of power which a satellite transmitter needs to send out depends a great deal on whether it is in low earth orbit or in geosynchronous orbit. This is a result of the fact that the geosynchronous is at an altitude of 22,300 miles. While the low earth satellite is only a few hundred miles.
The geosynchronous satellite is nearly 100 times as far away as the low earth satellite. We can show fairly easily that this means that higher satellite would need almost 10,000 times as much power as the low-orbiting one, if everything else were the same, (Fortunately, of course we can change some other thing so that we don’t need 10,000 times as much power).