Applications of Satellite Positioning

        The main uses of GPS: ① land applications, mainly including vehicle navigation, emergency response, atmospheric physical observation, geophysical resource exploration, engineering surveys, deformation monitoring, crustal movement monitoring, municipal planning and control, etc.; ② marine applications, including the determination of optimal voyage routes for ocean-going vessels, real-time scheduling of vessels and navigation, marine rescue, marine treasure hunting, hydrogeological measurements and marine platform positioning, Sea level rise and fall monitoring, etc.; ③ Aerospace applications, including aircraft navigation, aviation remote sensing attitude control, low orbit satellite orbiting, missile guidance, aviation rescue and manned spacecraft protection detection, etc.

Specific applications are as follows:

1、Ships ocean navigation and into the harbor water diversion

2、Aircraft route guidance and approach landing

3、Autonomous automobile navigation

4, ground vehicle tracking and urban intelligent traffic management

5、Emergency life-saving

6、Personal travel and wild adventure

7, personal communication terminals (integrated with cell phones, PDA, electronic maps, etc.): electric power, post and telecommunications, communications and other networks of time synchronization: the accurate time of granting in, the accurate frequency of granting in

8、Surveying and mapping related: road and all kinds of line sampling, underwater topographic survey, crustal deformation measurement, dams and large buildings deformation monitoring

9, GIS applications: engineering machinery (tire cranes, bulldozers, etc.) control, fine agriculture

Application in road engineering

The application of GPS in road engineering is mainly used to establish various road engineering control networks and determine the external control points of aerial survey. With the rapid development of high-grade highway, it puts forward higher requirements for the survey technology. Due to the long line and few known points, it is not only difficult to lay the network with conventional survey means, but also difficult to meet the requirements of high precision. China has gradually used GPS technology to establish the first level of high-precision control network of the line, and then encrypted with conventional methods of laying wire. Practice has proved that the point position error within dozens of kilometers is only about 2 cm, which achieves the precision that is difficult to achieve by conventional methods, and at the same time, it also greatly advances the construction period.GPS technology is also applied to the control measurement of very large bridges. Since no pass-through is required, it can form a stronger net shape and improve the point accuracy, and at the same time, it is also very effective in detecting the pivot point of conventional measurements.GPS technology also has a wide range of application prospects in tunnel measurements.GPS measurements do not require pass-through, which reduces the intermediary links of the conventional methods, and therefore, it is fast and accurate, and it has obvious economic and social benefits.

Application in car navigation and traffic management

Three-dimensional navigation is the primary function of GPS, which can be utilized by airplanes, ships, ground vehicles, and walkers. Car navigation system is a new technology developed on the basis of global positioning system GPS. The car navigation system consists of GPS navigation, auto-navigation, microprocessor, speed sensor, gyro sensor, CD-ROM drive, LCD display.GPS navigation system combined with electronic maps, radio communication network, computer vehicle management information system, can realize vehicle tracking and traffic management and many other functions.

Map Query

(1) The destination location can be searched on the operation terminal;

(2) Location information can be recorded and retained, or shared;

(3) Fuzzy query of various information near a certain location.

Route Planning

(1) The GPS navigation system will automatically plan a route based on the starting point and destination set by the user.

(2) The planning route can be set whether or not to pass through certain way points.

(3) The planning route can be set to avoid highways and other useful functions.

Automatic navigation

(1) Voice navigation:

Providing the driver with driving information such as intersection steering and the status of the navigation system in advance by voice is one of the most important functions in navigation, so that the user can arrive at the destination safely through voice prompts without watching the operation terminal.

(2) Screen navigation:

On the operation terminal, driving information such as map, vehicle position, traveling speed, distance to destination, planned route tips, intersection turning tips, etc. will be displayed.

(3) Re-planning route:

When not traveling according to the planned route, or taking the wrong intersection, the GPS navigation system will re-plan a new route according to the user's position.

Satellite Receiver

There are many types of GPS satellite receivers. According to models, they are divided into geodesic, total station, timing, handheld and integrated; according to applications, they are divided into vehicle-mounted, ship-mounted, airborne, star-mounted and bullet-mounted.

1, according to the use of receiver classification

(1) Navigation receiver

This type of receiver is mainly used for the movement of the carrier's navigation, it can give the carrier's position and speed in real time. This type of receiver generally use C / A code pseudo-distance measurement, single-point real-time positioning accuracy is low, generally ±10m, SA influence for ±100m. This type of receiver is inexpensive, widely used. According to the different areas of application, such receivers can be further divided into:

Vehicle-mounted —— for vehicle navigation and positioning;

Marine type —— — for ship navigation and positioning;

Aviation type —— for aircraft navigation and positioning. Due to the fast speed of the airplane, therefore, the receiver used in aviation requires to be able to adapt to high-speed movement.

Star-carried type —— for satellite navigation and positioning. As the satellite speed up to 7km / s or more, so the receiver requirements are higher.

(2) Geodesic receiver

Geodesic receiver is mainly used for precision geodesy and precision engineering measurements. This type of instrument mainly uses the carrier phase observation value for relative positioning, high precision, complex instrument structure, more expensive. According to the use of purpose and accuracy, it is divided into static (single-frequency) receiver and dynamic (dual-frequency) receiver, that is, RTK.

(3) Timing type receiver

This type of receiver mainly uses GPS satellites to provide high-precision time standards for timing, commonly used in observatories and radio communications in time synchronization.

According to the receiver's carrier frequency classification.

(4) single-frequency receiver

Single-frequency receiver can only receive L1 carrier signals, the determination of carrier phase observations for positioning. Because it can not effectively eliminate the delayed ionospheric effects, single-frequency receivers are only suitable for short baseline (<15km) precision positioning.

(5) Dual-frequency receiver

Dual-frequency receiver can simultaneously receive L1, L2 carrier signal. The use of dual-frequency delay of the ionosphere is not the same, you can eliminate the ionosphere on the delay of electromagnetic wave signals, so dual-frequency receivers can be used for up to several thousand kilometers of precision positioning.

2, according to the number of receiver channel classification

GPS receiver can receive multiple GPS satellite signals at the same time, in order to separate the signals received from different satellites, in order to realize the satellite signal tracking, processing and measurement, with such a function of the device called antenna signal channel. According to the type of channel the receiver has can be divided into multi-channel receiver, sequential channel receiver and multiplexing channel receiver.

3, according to the receiver working principle classification

(1) Code correlation type receiver

Code correlation type receiver is the use of code correlation technology to get the pseudo-distance observation value.

(2) square type receiver

Square type receiver is the use of carrier signal square technology to remove the modulating signal to restore the integrity of the carrier signal through the phasor meter to determine the receiver generated by the carrier signal and the phase difference between the received carrier signal to determine the pseudo-range of the observed value.

(3) Hybrid Receiver

This instrument is a synthesis of the advantages of the above two receivers, both the code phase pseudorange can be obtained, but also the carrier phase observations.

(4) Interferometric Receiver

This kind of receiver is to use GPS satellite as a radio source, using interferometric method to determine the distance between two stations.

After more than 20 years of practice has proved that the GPS system is a high-precision, all-weather and global radio navigation, positioning and timing multifunctional system. gps technology has developed into a multi-field, multi-mode, multi-purpose, multi-model international high-tech industry.

Early Warning Device

GPS early warning device is through the GPS satellite in the GPS early warning device to set the coordinates to complete, for example, encountered an electronic eye, and then through the relevant equipment in the electronic eye directly below the establishment of a coordinate, so that makes loaded with the coordinate point of the data of the early warning device in the first 300 meters before reaching the coordinate point or so will begin to early warning, to play a role in early warning.