Use of global positioning system technology

GPS was originally established to provide accurate positioning for the military, and it is still controlled by the US military. Military GPS products are mainly used to determine and track the coordinates of soldiers and equipment traveling in the field, provide navigation for warships at sea, and provide position and navigation information for military aircraft.

At present, the application of GPS system will be very extensive. We can use GPS signals to carry out guided geodesy, precise positioning, time transmission and speed measurement of sea, land and air navigation missiles. In the field of surveying and mapping, GPS satellite positioning technology has been used to establish a high-precision national geodetic control network to determine global geodynamic parameters; It is used to establish land and marine geodetic datum and carry out high-precision island-land joint survey and marine surveying and mapping; Used to monitor the motion state of the earth plate and crustal deformation; Used in engineering survey has become the main means to establish urban and engineering control network. The rapid mapping of aerial survey with little or no ground control through the camera position used to determine aerial photography time has led to the technological revolution of geographic information system and global environmental remote sensing monitoring.

Many commercial and government organizations also use GPS devices to track the position of their vehicles, which usually requires the help of wireless communication technology. Some GPS receivers integrate radios, wireless phones and mobile data terminals to meet the needs of fleet management.

Due to the emergence of diversified space resource environment, systems such as GPSGLONASSINMARSAT have navigation and positioning functions, forming a diversified space resource environment. This diversified space resource environment has prompted the formation of a consistent international strategy, that is, on the one hand, making full use of existing systems, on the other hand, actively building civil GNSS systems. By 20 10, a purely civil GNSS system will be built all over the world, which will form a three-legged trend of GPS/GLONASS/GNSS, fundamentally get rid of the dependence on a single system, and form an internationally available and internationally shared security resource environment. The world can enter the highest application realm of satellite navigation as a single navigation means. In turn, this international and non-governmental strategy has influenced and forced the United States to make more open adjustments to its GPS use policy. In a word, the establishment of diversified space resources and environment has created an unprecedented good international environment for the development and application of GPS.

The first trend of the development of vehicle-mounted GPS technology is frequency diversity technology, which is actually carried out in the process of replacing aging satellites with the second generation GPS system. After completion, the modern satellite constellation will provide three new positioning signals for civil users. In addition, the Galileo project launched by the European Union in March 2002 also adopted this technology. The second trend is to overcome radio frequency interference (RFI). The power of GPS broadcasting is extremely low, generally at 10 ~ 16 watts, which is easily interfered by the surrounding radio frequency signals and cannot work normally. The GPS receiver will penetrate the noise by matching the phase of the received ranging code with the locally stored replica code. When the phases are consistent, the receiver can use the timing signal as an accurate reference, so it can accurately locate. The third trend is to install a comprehensive mechanical system to ensure that the positioning error is less than a certain value. Using differential GPS technology, the system will obtain the latest error correction information from geosynchronous orbit communication satellites, and the correction data will come from the ground reference receiver. In the past, the error of GPS was 2 meters, but now it will be smaller.