All About Satellites
What is satellite :
Satellites are objects consist of several electrical devices like antennas, cameras, solar arrays, magnetometer, which has been forced in to the orbit on the earth by some machines made by human beings.
Uses Of Satellite :
Use of satellite in communication:
Most of the communication satellites are operated in microwave frequency range in C band. The 500 MHz bandwidth is divided into 12 separate channels each 36 MHz wide. For each channel a separate transponder is used. A single satellite contains 12, 24 or more transponders. The uplink frequencies are in the range 5.925 to 6.425 GHz range and the download frequencies are in 3.7 to 4.2 GHz range.
One typical transponder can handle up to 1000 one way analog telephone channels as well as one full color television channel. A single transponder can handle digital data at rate up to 60 MB per second. Frequency reuse and spatial isolation techniques can be used to increase the bandwidth and signal carrying capacity of the satellite.
Use of satellite for monitoring earth :
For studying the weather condition and observing earth Meteorological satellites are used. These satellites take photographs of cloud cover and the picture are send back to earth. These pictures are used for determining and predicting the weather. More accurate and more detailed maps can be created by using observation satellite.
Satellite can monitor the status of the earth resources like land oceans water level. They can observe crops, forests, lake and rivers. They can spot diseased crop areas, mineral resources and sources of pollution.
Use of satellites in surveillance :
On board film cameras in military satellite takes photographs which are received on the earth. Television cameras can take picture and send them back to earth as electrical signal. Infrared sensors detect heat sources and small radars can profile earth features. Intelligence satellite collects information about enemies. They allow monitoring for the purpose of proving implementation with nuclear test ban and missile treaties and many more.
Use of satellite for Global positioning system (GPS) :
Global positioning system GPS is a network of 24 low earth orbit satellites spaced equally around the world in overlapping patterns. At least four among these 24 is always visible at any point on the earth to show your position on the earth. Each satellite transmits a signal back to the earth on low microwave frequencies. Receivers on the earth pick up transmission from four satellites simultaneously. In a microprocessor the exact position of the receiver on the earth is computed. The receiver output is a display giving the latitude, longitude and altitude of the receiver.
Global positioning system can be used by military, individuals and industry for general navigation purposes. We can know our position on earth at any time by using GPS device. It shows accuracy about 100 meters from the actual location.