Positioning of GPs in vehicle navigation system

The first purchase of the car navigation system has a GPS signal reception function, you can receive GPS latitude and longitude signal, and then the navigation terminal installed in the navigation map can be very detailed to display the specific latitude and longitude coordinates and figure information. The navigation terminal receives the free latitude and longitude signal of the satellite 24-hour uninterrupted transmission through the receiver, And then through the software system to display these latitude and longitude signals in the installed map corresponding to the latitude location, resulting in accurate positioning information. You can then know where you are at your current location by displaying the figure information on the map.

GPS is the United States from the 70 's development, lasted 20 years, costing $20 billion, completed in 1994, with a full range of sea, land and air in real-time three-dimensional navigation and positioning capabilities of the next-generation satellite navigation and positioning system. The use of surveying and mapping departments in China in the past 10 years shows that GPs has won the trust of surveying and mapping workers and successfully applied to geodetic surveying, surveying, aerial photogrammetry, vehicle navigation and control, crustal movement monitoring, engineering deformation monitoring, resource investigation, and other notable features such as 24x7, high precision, automation and efficiency Earth dynamics and other disciplines, thus bringing a profound technological revolution to the field of surveying and mapping.
With the continuous improvement of the global positioning System, hard, software, continuous improvement, the application of the field is constantly expanding, has been in various sectors of the national economy, and began to gradually deepen people's daily life.

　　The GPS system consists of three parts: The space part-gps satellite constellation, the ground control part-the ground monitoring system, the user equipment part-GPS the signal receiving machine.

　　2. Satellites and Constellations

The GPS constellation is composed of 21 working satellites and 3 in-orbit standby satellites, which are recorded as GPs constellations (21+3). 24 satellites are evenly distributed in 6 orbital planes, with an orbital inclination of 55 degrees, and a 60 degree distance between each orbital plane, that is, the ascending intersection of the orbit has a 60 degree difference from the Red meridian. The distance between the satellites in each orbital plane is 90 degrees from each other, and the satellites in one orbital plane are 30 degrees ahead of the corresponding satellites in the west adjacent orbital plane.

GPS satellites at 20,000 km altitude, when the Earth rotates for a star for a week, they orbit the earth for two weeks, that is, about 12 stars a week around the earth. In this way, for ground watchers, the same GPS satellite will be seen 4 minutes in advance of the day. The number of satellites located above the horizon varies with time and place, with a minimum of 4 visible and up to 11 capsules. In the GPS signal navigation and positioning, in order to settle the three-dimensional coordinates of the station, 4 GPS satellites must be observed, known as the locating constellation. The geometric position distribution of the 4 satellites in the observation process has a certain influence on the positioning accuracy. For some time in a place, even the exact point coordinates cannot be measured, and this time period is called "Clearance segment". However, this time gap is very short, and does not affect the most parts of the world around the clock, high-precision, continuous real-time navigation and positioning measurement. The GPS working satellite is basically the same number as the Test satellite.

　　3. Ground Monitoring System

For navigation positioning, the GPS satellite is a dynamic known point. The position of the star is based on the satellite-launched Ephemeris-the parameters that describe the motion of the satellite and its orbit. The Ephemeris broadcast by each GPS satellite is provided by the ground monitoring system. The equipment on the satellite is functioning properly, and whether the satellite has been running along a predetermined orbit is monitored and controlled by ground equipment. Another important function of the ground monitoring system is to keep the satellites at the same time standard-gps time system. This requires the Earth station to monitor the time of each satellite, to find the clock difference. The satellite is then sent by the ground injection station, and the satellite is then sent to the user device by the navigation message. GPS working satellite ground monitoring system includes a master station, three injection stations and five monitoring stations

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Positioning of GPs in vehicle navigation system