The Composition and Application of Global Positioning System

Global Positioning System is a medium-distance circular orbit satellite navigation system. It can provide accurate positioning, speed measurement and high-precision time standards for most areas (98%) on the earth's surface. The system is developed and maintained by the US Department of Defense, which can meet the needs of military users located anywhere in the world or in near-Earth space to continuously and accurately determine the three-dimensional position, three-dimensional motion and time. The system includes 24 GPS satellites in space; 1 master control station, 3 data injection stations and 5 monitoring stations on the ground, as well as a GPS receiver as a user terminal. At least 3 satellites are required to quickly determine the position and altitude of the user terminal on the earth; the more satellites that can be received and connected, the more accurate the decoded position will be.

The GPS satellite constellation consists of 24 satellites, of which 21 are working satellites and 3 are spare satellites. 24 satellites are evenly distributed on 6 orbital planes, that is, there are 4 satellites on each orbital plane. The satellite's orbital plane has an orbital inclination angle of 55° with respect to the earth's equatorial plane, and the ascension of the ascending node of each orbital plane differs by 60°. A satellite on one orbital plane is 30° ahead of the corresponding satellite on the adjacent orbital plane in the west. The purpose of this layout is to ensure that at least 4 satellites can be observed at any point in the world at any time.

 

The GPS satellite was developed by the Space Department of Rockefeller International Corporation. The satellite weighs 774 kg and has a service life of 7 years. The satellite adopts a honeycomb structure, the main body is cylindrical, and the diameter is 1.5m. Two double-leaf solar panels (BLOCK I) are installed on both sides of the satellite, with a total length of 5.33m and an area of 7.2 that receives sunlight. The solar orientation system controls the rotation of the two-wing battery windsurfing board so that the board is always aligned with the sun, continuously providing power to the satellite, and charging three sets of 15Ah nickel-cadmium batteries to ensure that the satellite can work normally in the shadow of the earth. A 12-unit multi-beam directional antenna is installed at the bottom of the star, which can transmit two L-band (19cm and 24cm waves) signals with an opening angle of about 30 degrees. Omnidirectional telemetry and remote control antennas are installed on both ends of the star to communicate with the ground monitoring network. In addition, the satellite is also equipped with an attitude control system and an orbit control system to keep the satellite at an appropriate height and angle and accurately align the satellite's visible ground.

1. Precise timing: widely used in astronomical observatories, communication system base stations, and television stations

2. Engineering construction: GPS equipment is widely used in the construction of roads, bridges and tunnels for engineering surveys

3. Exploration surveying and mapping: It is used in field exploration and urban planning

4. Navigation:

Weapon navigation:

Global Positioning System

Global Positioning System

Precision guided missiles, cruise missiles

Vehicle navigation: vehicle scheduling, monitoring system

Ship navigation: ocean navigation, port/inland water diversion

Aircraft navigation: route navigation, approach and landing control

Navigation: satellite orbit positioning

Personal navigation: personal travel and wild adventure

5. Positioning:

Vehicle anti-theft system

Mobile phone, PDA, PPC and other communication mobile equipment anti-theft, electronic map, positioning system

Anti-lost system for children and special groups

Precision agriculture: agricultural machinery navigation, automatic driving, high-precision land leveling

6. Provide time data: used to provide accurate synchronized clock sources for telecommunication base stations, TV transmitting stations, etc.

In addition to GPS being used for navigation, positioning, and measurement, because the precise clock on the space satellite of the GPS system can release time and frequency information, it is based on the precise clock on the space satellite and is monitored by the ground monitoring station. Accurate time and frequency are another important application of GPS. This function can be used to control precise time or frequency, which can serve many engineering experiments. In addition, according to foreign data, GPS can also be used to obtain meteorological data for certain experiments and engineering applications.

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