1. space

This space is a part of the work of 24 GPS satellites [1]. It is located on 20 200km surfaces and evenly distributed on 6 orbital planes (4 per orbital plane), with an orbital inclination of 55. In addition, there are four star-orbiting satellites actively backed up. The distribution of satellites anywhere in the world at any time can be observed above 4, and the accuracy of satellite positioning geometric image can be maintained. This provides continuous global navigation skills. GP S satellite generates two groups, one is called Morse code (C/A coarse/acquisition code 1 1023MHz), and the other is called P code (Procise code 10 123MHz). P code is affected by its high frequency, no interference and high accuracy. C/A code is deliberately used mainly to the public as a measure to reduce accuracy.

2. Ground control

The ground control station consists of 1 master station, 5 global stations and 3 ground control stations. There is a precise station clock and a visible satellite receiver for continuous measurement of cesium. The data obtained by the satellite observatory, including ionospheric and meteorological data, will be sent to the main station after preliminary processing. The master station calculates the orbit and clock parameters from the tracking data of each station and satellite, and then transmits the results to three ground control stations. The ground control station runs on each satellite, sending the instructions and data of navigation and main station to the satellite. Inject each GPS satellite, and inject it at a fixed distance from the satellite station before each injection. If there is a ground fault, the information stored in satellite navigation can be used for a while, but the navigation accuracy will gradually decrease.

3. User equipment components

The user equipment part is the GPS signal receiver. Its main function is to select and track these satellites and satellites according to the cut-off time of capturing satellites at a certain angle. When the receiver captures the satellite tracking, the antenna can measure the demodulation data such as the pseudo-range and distance change with the satellite and the satellite orbit parameters after receiving it. Based on these data, the receiver can process the computer by positioning calculation method, and calculate the longitude and altitude of the user's location, geographical location, speed, time and so on. The hardware and software receiver in the GPS data post-processing software package constitute a complete GPS user equipment. The GPS receiver unit and receiving antenna unit are divided into two parts. Generally, the receiver is powered by mechanical plus two kinds of DC power supply. The purpose of setting up the machine is to change the power supply without interrupting continuous observation. The power battery of the machine will automatically charge during the use time. After shutdown, the machine battery supplies power to RAM and memory to prevent data loss. At present, various types of receivers are light in weight, small in size and light in weight, which is convenient for on-site observation.

Ground control system (now), the station is the control station (main), so now the antenna (ground), antenna control station, Springfield, Colorado (yes). The ground control station is responsible for collecting information through satellites and correcting the satellite data of Alex relative to the stars from the atmosphere. Secondly, the existing users' receivers are two-frequency and two-frequency. Due to the price factor, ordinary users buy more single-frequency receivers.

Aiming at the application of GPS in road engineering

The application of GPS in road construction is mainly used to establish various road engineering control networks and measure the electricity quantity of control points. With the rapid development of expressway, higher requirements are put forward for measurement technology. Because of the long lines and few known points, it is not only difficult to measure the network with conventional measurement methods, but also difficult to meet the requirements of high precision. At present, China has gradually adopted GPS technology to establish lines, and then laid out high-precision control networks by conventional methods. Practice has proved that the point error in the range of tens of kilometers is only 2 cm, which reaches the accuracy achieved by conventional methods and is greatly advanced. GPS technology is also applied to the control survey of large bridges. Since it is unnecessary to poke, a firm net can be formed and the accuracy of inspection can be improved. It is effective to measure through the conventional fulcrum. GPS technology has a broad application prospect in tunnel survey. Using GPS reduces the intermediate links that need to pass through conventional methods, so it has high speed, high precision and remarkable economic and social benefits.

Application of GPS Navigation and Traffic Management in Automobile

Three-dimensional navigation is the main function of GPS, and pedestrians in ships, planes and ground vehicles can use GPS navigation devices to navigate. Car navigation system is a new technology developed on the basis of Global Positioning System (GPS). The car navigation system consists of GPS navigation, autonomous navigation and microprocessor, speed sensor, gyro sensor, CD-ROM drive and LCD. The combination of GPS navigation system with electronic map, radio communication network and computer vehicle management information system can realize many functions such as vehicle tracking and traffic management.

The application of a GPS in long-distance passenger vehicle management (for example),

Taking the first set of professional long-distance GPS vehicle management system and long-distance communication GPS intelligent management system as an example, it combines satellite positioning technology, GPRS/CDMA communication service, GIS, image acquisition technology, computer network technology and database to construct a passenger control system (combining C/S structure and B/S structure) and another control system for the branch, public security bureau and various departments in Yun Guan. An all-weather and all-round driver and vehicle tracking management platform is established, which consists of four parts: control center system, wireless communication system platform (GPRS/CDMA), global positioning system (GPS) and roadside equipment. The system can realize the functions of vehicle dynamic tracking, monitoring and registration, taking photos, driving records, management, data analysis and so on, and monitor the operation of vehicles on electronic maps. And display the vehicle running track data, the operating terminal can choose the internal network or Internet server to access, and integrate the data analysis (B/S structure) of the passenger management control system through the online IE browser provided by the center, and the capacity of the system software can be greatly expanded according to the hardware configuration of the center and the maximum capacity of the operating terminal server. The network car can not only be 500,000 vehicles, but also be a social vehicle such as passenger vehicles. Moreover, the system can also use grouping management, and different types of vehicles are divided into different groups for easy operation and management.

Application example of GPS technology in navigator

The international leading brand of GPS navigator: Ahada YiHang (of)-from Silicon Valley, now landing in China!

Core product features:

1) map query

Saving a penny is to get a penny in the operation of searching your destination location at the terminal.

You can record where you always want to go, keep the information, and share the location information with others.

Pay for what you pay for. Fuzzy query about your connection or the station, hotel, ATM and so on near a certain location.

2) Route planning

The GPS navigation system will automatically program the route according to the set starting point and ending point.

Whether the planning route can be set in some ways.

Saving one point means earning one point to plan whether the route can avoid the high speed and so on. Function.

3) Automatic navigation

A penny saved equals a penny earned;

Provide drivers with intersection traffic information such as voice and navigation conditions in advance, and tell you how to drive to your destination in a way that understands the guide. One of the most important functions in navigation makes you need to watch the voice prompts of the operating terminal to reach your destination safely.

A penny saved is a penny earned.

Finally, the operation map and the current position, driving speed, route destination, planning and crossing tips of the car will be displayed.

A penny saved is a penny earned. Redesign the series:

When you have planned the route, or took the wrong road when crossing, the GPS navigation system will plan a new route for you to reach your destination according to your current position.

global positioning system

The basic principle of GPS navigation system is to measure the distance between the satellite and the user receiver with known position, and then the position of the receiver can be known by synthesizing the satellite data. In order to achieve this goal, the position of the satellite can be found in the calendar according to the clock time recorded on the satellite.

It can be seen that GPS navigation system is a part of satellite continuous launching navigation. However, because the user's clock is not synchronized with the satellite clock, a δt, that is, the difference between the satellite and the receiver, may be introduced in addition to the user's 3d coordinates X, Y and Z, so four equations are used to link these four unknowns. So if you want to know, there are at least four satellites where the receiver can receive the signal.

The GPS receiver can receive the GPS clock, which can be used to accurately adjust two levels of second time information, to predict the approximate position of the satellite prediction star Alex in the next few months, and to calculate the position of the satellite radio star Alex, whose coordinates range from several meters to tens of meters with different accuracies, meters (variable) satellites, GPS system satellites and other information.

The GPS receiver can get the distance of the satellite receiver by measuring the code, because the distance to the clock includes the satellite transmission error and atmospheric error of the receiver, which is called pseudo-range. The measured pseudorange of 0A code is called UA code pseudorange, and its accuracy is about 20 meters of that of P code. The measured pseudorange of ds code is called P code pseudorange, and its accuracy is about 2 meters.

After the signal received by GPS receiver, decoding technology or other information on carrier modulation is deleted, the carrier can be recovered. Strictly speaking, the carrier phase should be called the carrier frequency phase, which is the phase difference oscillation between the satellite signal received by the beat receiver and the signal generated by the beat machine. Generally, when the Bell receiver measures the epoch, the satellite signal keeps timing, which can track the change of the recorded phase. However, when the receiver and satellite oscillator are started, the observed values do not know the initial phase of the epoch, nor the integer of the phase, that is, the ambiguity, which can only be used as a parameter in data processing. The accuracy of phase observation is very high, which is millimeter level, but the premise is a whole week, so phase observation can only be used in fuzzy relative positioning and continuous observation, and only phase observation can be used to achieve excellent positioning accuracy.

According to the positioning mode, GPS positioning and relative positioning are divided into single point positioning (differential). Single point positioning is to determine the position of the receiver according to the observation data of the receiver. It only uses pseudo-range observation and can be used as an outline of vehicle navigation and positioning. Relative positioning (differential) is an observation method to determine the relative position according to the observation data of more than two receivers. It can adopt pseudo-range observation or phase observation, and geodetic survey or engineering survey should obtain the phase observation value for relative positioning.

Satellite and receiver in GPS observation include clock, atmospheric propagation delay, multipath effect, etc. When calculating the positioning error, it is affected by the relative positioning error of satellite radio star Alex. When most common positioning errors are cancelled or weakened, the positioning accuracy will be greatly improved. Therefore, the dual-frequency receiver can cancel the main errors of the atmosphere and ionosphere according to the observations of two frequencies. When the distance accuracy between receivers is high (the air difference is significant), the dual-frequency receiver should be selected.