Global satellite system communication

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INTRODUCTION

To make a satellite phone call today from a location that does not offer terrestrial wireline or wireless coverage requires the use of a large, costly terminal, and entails very high per minute charges. Further, the quality of service is relatively poor because of annoying echoes, large transmission delays, overtalk associated with satellite communications using geostationary satellites. The next generation of satellite communication systems will use advances in satellite systems, wireless technologies, and miniaturization, to provide global mobile satellite services that will make calls between any two locations on earth much easier, much more affordable and much more user friendly.


Mobile Satellite Communication System by the Geostationary Satellite
The geostationary satellite is the artificial satellite which looks stationary from the ground. 3-4 geostationary satellites can cover almost the entire surface of the earth. Most of the artificial satellites actually used for communications or broadcasting are geostationary satellites.
• i. Altitude: about 36,000km
• ii. Orbit: the circle orbit cycle on the equator is the same as the earth's autorotation time.
• iii. Number of Satellites: four (service areas are duplicated.)
• iv. Principle Satellite System: Inmarsat Communication System, N-STAR Communication System, Omunitrucks Communication System
2. Mobile Satellite Communication System by the Quasi-Zenith Satellite
The quasi-zenith satellite is an artificial satellite of the satellite system where one satellite always stays near the zenith in Japan by positioning at least three satellites synchronously on the orbit inclined at 45 degrees from the geostationary orbit. As the ground surface orbit draws the shape of number 8, it's also called "Number 8 Orbit Satellite". It can obtain a high elevation angle to reduce the influence of buildings and so forth (blocking.)
• i. Altitude: about 36,000km
• ii. Orbit: circle orbit crossing with the equator by the angle of 45 degrees
• iii. 3 as the minimum
• iv. The research and development of the satellite communication system is in progress
3. Mobile Satellite Communication System by the Non-Geostationary Satellite
This is roughly divided into three kinds of orbits: highly elliptic orbit, medium earth orbit, and low earth orbit. The medium and low earth orbits have lower satellite altitudes to shorten the radio transmission delay, enabling more speedy and smooth communication. Specifically, the highly elliptic orbit can obtain a higher elevation angle. It is currently being researched and developed.