1、附录 GPS positioning technology in the engineering point of measurement Abstract Global Positioning System GPS is a global, all-weather, all-powerful advantage of the navigation and positioning systems, which can provide the advantages of three-dimensional coordinates is still not given full play. Thr
2、ough technical analysis, described the GPS positioning technology in the engineering survey of the advantages and disadvantages. Key words GPS positioning Engineering Surveying Discussion In the mapping field, with the total station on its popularity, the traditional theodolite, distance meter being
3、 replaced. In recent years, with the GPS measurement technology, engineering survey of working practices is a historic change took place. GPS measurements by receiving satellite signals emitted and processes the data, thereby seeking the spatial location of measurement points set, it has the all-pow
4、erful, global, all-weather, continuous and real-time three-dimensional precision navigation and positioning capabilities, but also has good anti- interference and confidentiality. Has been successfully applied to engineering measurements, aerial photography, surveying, engineering surveying, resourc
5、e survey and many other fields. 1 GPS mainly by the space satellite constellation, ground control stations and user equipment of three parts (1) GPS satellite constellation space for work by the 21 in-orbit satellites and three spare satellites. 24 satellites evenly distributed in six orbital planes
6、, the orbital plane with an inclination of 55 , the average height of satellite 2O200km, run the cycle for the 11 h 58 min. The two satellite radio with the L-band carrier to the user to send continuous navigation signals, satellite navigation and positioning signal containing the location informati
7、on, the satellite is known as a dynamic point. Any place on Earth, at any time, in high angle of 15 or more, an average of six satellites simultaneously observed up to nine. (2) GPS ground control station is primarily used by worldwide a master stations, three injection station and five stations. Th
8、e master station under various stations on GPS satellites of observational data, calculation of the satellites orbit and clock error parameters, etc, and these data compiled navigation message, transferred to the implanted station, then by the injection station master station to and from the navigat
9、ion message into the appropriate satellite storage. (3) GPS user equipment consists of the GPS receiver, data processing software and terminal equipment (such as a computer) and other components. GPS receiver can be captured by satellite height cutoff point selected satellite signal to be measured,
10、tracking satellites are running, and on signal switching, zoom in and processing, and then use the computer and the appropriate software, baseline solution, adjustment, find the GPS receiver Center (measuring site) of three-dimensional coordinates. 2 from the engineering survey of the implementation
11、 of applications, we can fully see the advantages of GPS measurements, fully demonstrated the high accuracy of satellite positioning technology and high efficiency (1) using GPS technology determination for the grid, and adaptable than conventional methods. Net-shaped structure is simple, point dens
12、ity and the flexibility to select the length of edge, even farther away from the known control point can connect, and control network location and orientation. In addition, it addresses the point and can not pass between the visual difficulties, site selection and flexible, do not need high standard
13、, but also outside the industry can guarantee Surveying protected from the weather. Test for large (long side) grid and communications, as conditions are particularly difficult, especially to show its superiority. GPS measurements by themselves, although not by-pass, as the conditions, however, gene
14、rally small-scale engineering survey measurements and by the cost of the project limits. Therefore, the actual engineering survey, still have to consider the use of total station, theodolite and other instruments commonly used and less investment. These commonly used instruments are generally a bit
15、and intervisibility between points, particularly in the layout control network Oclock, points and points can not pass, as will give the survey work has brought more trouble and Kunnan. Especially large bridge network, if the point and point barrier, as is bound to affect the networks strength and ac
16、curacy, thereby affecting the accuracy of the bridge itself. Therefore, in the Engineering Survey GPS control network layout when necessary, should try to make more points with each other through visual. (2) GPS box points high accuracy, errors of evenly distributed, not only to meet the regulatory
17、requirements, and has a large precision reserves. (3) The point position error of measurement accuracy as a indicator grid is feasible, with a relative error than the precision of indicators that are more reasonable. (4) method using GPS geodetic control network layout, because of its graphic intens
18、ity coefficient is high, can effectively improve point closer to the speed. Optimization of the more convenient. (5) use GPS-RTK survey building grid and routine measurement of efficiency can be improved when compared to more than doubled, and a significant reduction in the intensity of the workers.
19、 A reference station can have more than one mobile station operation, mobile stations, base station without the command of a single person can operate independently. 3 GPS technology with its unique and powerful features and benefits of fully demonstrated its superiority in the development of the fi
20、eld, as well as a bigger and wider space for development. But in that area, the actual construction and subsequent construction and monitoring also betrayed some disadvantages (1) GPS pinpoints the key lies on the satellite and the distance between the accurate calculation, in accordance with a fixed pattern: = speed ×； time, time after speed according to the velocity of propagation of electromagnetic waves. Well known electromagnetic waves in a vacuum of propagation velocity quickly, but the atmosphere is the signal to be ionosphere and tropospheric despite interference. GPS
