A satellite is a physical object that orbits, or rotates about, some celestial body. Satellites occur in nature, and our own solar system is a perfect example. The earth and other planets are satellites rotating about the sun. The moon is a satellite to the earth. A balance between the inertia of the rotating satellite at high speed and the gravitational pull of the orbited body keeps the satellite in place.
Satellites are launched and orbited for a variety of purposes. The most common application is communication in which the satellite is used as a repeater. In this chapter, we introduce satellite concepts and discuss how satellites are identified and explained. We summarize the operation of a satellite ground station and review typical satellite applications, with particular emphasis on the Global Positioning System, a worldwide satellite-based navigational system.
17-1 Satellite Orbits 17-2 Satellite Communication Systems 17-3 Satellite Subsystems 17-4 Ground Stations 17-5 Satellite Applications 17-6 Global Positioning System
Define the terms posigrade, retrograde, geocenter, apogee, perigee, ascending, descending, period, angle of inclination, geosynchronous, latitude, longitude, and meridian.
State the operative physical principles of launching a satellite and maintaining its orbit.
Draw a block diagram of the communication system in a communication satellite, give its name, and explain how it works.
List the six main subsystems of a satellite.
Draw a block diagram of a satellite ground station, identifying the five main subsystems and explaining the operation of each.
Name three common applications for satellites and state which is the most common.
Explain the concept and operation of the Global Positioning System. Draw a block diagram of a GPS receiver and explain the function of each component.