Differences among Global Positioning System, Geographic Information System and Global Navigation Satellite System

This question can be referred to this forum http://bbs.manbu.cc gps, which uses satellite navigation. GPS is a global positioning system, which is usually used for navigation. That is, in official website, where Nokia is a satellite navigator, you can find Nokia's GPS wireless modules LD- 1W and LD-3W, which belong to Bluetooth GPS. This is what you should see. 2500 yuan should include the package of genuine navigation software, right = = = = = = = The details are as follows: 1. The global positioning system (GPS) was developed in the United States in 1970s, which lasted for 20 years and cost 20 billion dollars. 10. After nearly 10 years of application in China's surveying and mapping departments, it shows that GPS has won the trust of the majority of surveying and mapping workers with its remarkable characteristics of all-weather, high precision, automation and high efficiency, and has been successfully applied to geodesy, engineering survey, aerial photogrammetry, vehicle navigation and control, crustal movement monitoring, engineering deformation monitoring, resource investigation, geodynamics and other disciplines, bringing a profound technological revolution to the field of surveying and mapping. With the continuous improvement of the software and hardware of GPS, the application fields have been continuously explored, which have spread all over the national economy and gradually penetrated into people's daily lives. The GPS system includes three parts: the space part-GPS satellite constellation; Ground control part-ground monitoring system; User equipment part --GPS signal receiver. 2. Satellites and Constellations The GPS satellite constellation consisting of 2 1 working satellite and 3 in-orbit standby satellites is called (2 1+3)GPS constellation. These 24 satellites are evenly distributed on six orbital planes, with an orbital inclination of 55 degrees, and the orbital planes are separated by 60 degrees, that is, the orbital right ascension is separated by 60 degrees. The elevation distance between satellites in each orbital plane is 90 degrees, and the satellites in one orbital plane are 30 degrees ahead of the corresponding satellites in the adjacent orbital plane in the west. At an altitude of 20,000 kilometers, for stars, when the earth rotates once, they will make a circle around the earth, that is, the time to make a circle around the earth is 12 sidereal time. In this way, for ground observers, they will see the same GPS satellite four minutes in advance every day. The number of satellites above the horizon varies with time and place. At least 4 satellites can be seen, and at most 1 1 satellite can be seen. When using GPS signals for navigation and positioning, in order to determine the three-dimensional coordinates of the site, four GPS satellites must be observed, which is called positioning constellation. The geometric position distribution of these four satellites in the observation process has certain influence on the positioning accuracy. At a certain time in a certain place, even the exact point coordinates can't be measured. This time period is called "gap period". But this time difference is very short, which does not affect the all-weather, high-precision, continuous and real-time navigation and positioning measurement in most parts of the world. The number of GPS working satellites is basically the same as that of test satellites. 3. Navigation and positioning of ground monitoring system, GPS satellite is a dynamic known point. The position of the constant star is calculated according to the ephemeris transmitted by the satellite, which describes the motion and orbit parameters of the satellite. The ephemeris broadcast by each GPS satellite is provided by the ground monitoring system. Whether all kinds of equipment on the satellite work normally and whether the satellite has been running along the predetermined orbit should be monitored and controlled by the ground equipment. Another important function of the ground monitoring system is to keep all satellites in the same time standard-GPS time system. This requires the ground station to monitor the time of each satellite and find out the clock difference. Then it is sent to the satellite by the ground injection station, and the satellite sends it to the user equipment through the navigation message. The ground monitoring system of GPS working satellite includes a main control station, three injection stations and five monitoring stations. 4. User equipment 4. 1 GPS signal receiver The task of the GPS signal receiver is to capture the signals of the satellites to be measured according to a certain cut-off angle of satellite height, track the operation of these satellites, transform, amplify and process the received GPS signals, thus measuring the propagation time of the GPS signals from the satellites to the antenna of the receiver, interpreting the navigation messages sent by the GPS satellites, and calculating the three-dimensional position, orientation and even three-dimensional speed and time of the platform in real time. In static positioning, the GPS receiver is fixed in the process of capturing and tracking GPS satellites. The receiver measures the propagation time of GPS signal with high precision, and calculates the three-dimensional coordinates of the receiver antenna position by using the known on-orbit position of GPS satellite. Dynamic positioning is to measure the trajectory of a moving object with a GPS receiver. The moving objects where the GPS signal receiver is located are called carriers (such as sailboats, planes in the air, walking vehicles, etc.). The antenna of the GPS receiver on the carrier moves relative to the earth in the process of tracking the GPS satellite, and the receiver measures the state parameters (instantaneous three-dimensional position and three-dimensional speed) of the moving carrier in real time by using GPS signals. Hardware and software of receiver and post-processing software of GPS data.