1.8 TOPOGRAPHIC SURVEY USING SATELLITE TECHNOLOGIES IN THE

Abstract

Abstract:

The article presents the main methods of topographic survey using satellite technologies for engineering and geodetic surveys and discusses the prospects for expanding their functionality.

Key words:

Engineering surveys, method of satellite geodetic measurements, topographic survey, methods of satellite definitions.

Engineering surveys a set of works carried out to obtain information necessary for the selection of economically feasible and technically sound location of the structure, to address the main issues related to the design, construction and operation of structures.

Tasks of engineering surveys complex study of natural and technogenic conditions of the territory (region, district, site, site, route) of construction objects, making forecasts of interaction of these objects with the environment, justification of their engineering protection and safe living conditions of the population.

Engineering surveys main types:

• engineering-geological and hydrogeological surveys;
• инженерно engineering and geodetic surveys;
• engineering and environmental surveys;
• engineering and hydrometeorological surveys.

When conducting engineering surveys, modern methods such as the method of satellite geodetic measurements are used [1.2.3.4.5].

To speed up the timing of survey work and improve their quality, the method of satellite geodetic measurements is used, which are especially effective in areas that are difficult to access for ground study (swampy lowlands, deserts, etc.). Methods of space shooting, for which special equipment has been developed, methods of decoding images, allowing to obtain high-precision and reliable information, are widely used in modern conditions.

Fig.1. Methods of decoding images

Work, but shooting the situation and terrain using satellite technology is designed for those cases of topographic and geodetic practice, when the conduct of such work using this technology is economically profitable, as well as technically justified. The technical possibility of conducting such works appears where natural and artificially created objects available on the ground allow for satellite observations [6].

Topographic survey using satellite receivers is usually used for fairly open areas in a wide range of terrain, it is possible in the presence of low buildings. It can be territories of one-storeyed civil and industrial building (garages, objects of trade and municipal services, warehouses, etc.), transport objects (Railways and highways, pipelines, canals, airfields), water areas, recreation areas, areas of the state border, etc.

The question of the technical capability of satellite observations to capture the situation and relief of a particular object is solved by studying the object on the map before the start of design work. In the process of this work on the object identify existing on the ground natural and artificially created objects that prevent the passage of radio signals from satellites and at the same time establish the technical possibility of conducting satellite observations.

Fig.2. Definitions of geodetic points

If the obstacles to the passage of radio signals from satellites, available at the site or in its immediate vicinity, greatly complicate the organization of observations of satellites, making shooting irrational, then at such an object to carry out shooting by satellite definitions is impractical.

If the obstacles to the transmission of radio signals from satellites are located only in the vicinity of the object, and they are such that they do not exclude the possibility of observing satellites on the object, or if there are no obstacles at all, in these cases, the survey can be designed.

In the process of designing survey work in accordance with the specified scale of shooting and the height of the relief section perform the following work:

• Select the method of satellite definitions to perform the binding (i.e., obtaining the data necessary to bring the survey results in the coordinate system and the heights of the points of the geodetic basis), as well as the method of this binding.
• Select the materials of topographic and geodetic study of the object of work points geodetic basis for reference. Develop a working program of zero work on the binding to the points of the geodetic basis.

Methods of satellite definitions, but the range and accuracy fundamentally provide the possibility of conducting survey work directly on the basis of the state geodetic and leveling network, which has the appropriate density. Therefore, the survey work by these methods eliminates the need to create and use geodetic networks of condensation, creation of survey justification and its condensation [7.8].

Fig.3. Scheme of observations using the method of satellite geodetic measurements

Geodetic basis used as a support for surveying the situation and terrain, must meet the requirements for the smooth and noise-resistant passage of radio signals.

As the starting points for the reference should be used all points of the geodetic basis, located within the object, and the closest to the object outside it, but not less than 4 points with known planned coordinates and not less than 5 points with known heights.

For the production of shooting the situation and terrain is recommended to use the method of "stand-go", which is a kind of kinematic method of satellite definitions.

For production of shooting of a situation and a relief as points of installation of base station it is necessary to design use of any points of a geodetic basis involved for binding with such calculation that distances from them to shooting pickets on which during works the mobile station is placed, were minimum. Thus it is necessary, using a map of object, to break object on the sites carried to certain points of a geodetic basis, with observance of this requirement.

When using satellite equipment to capture the situation and terrain before going to Iole produce preparatory work, which consists of the following actions:

1) comply with the requirements of operational documentation, but the preparation of equipment for work;

2) comply with the requirements of operational documentation, but the preparation of equipment for work;

3) performing operations on the prediction of the satellite constellation.

Prediction of the satellite constellation for surveying the situation and terrain should be carried out in accordance with the instructions supplied with the software packages.

According to the obtained as a result of forecasting the time periods optimal for observing satellites at each point of the geodetic basis and the survey area, the overlap zones are found and the time periods optimal for the session (when performing the binding) or the survey area are established. These data in the form of the date of work and the time of the beginning and end of the interval (period), in which the configuration parameters of the satellite constellation are optimal, are entered in the work program of zero works.

Field work when shooting the situation and relief on the object consists of the delivery of receivers and equipment to the points of geodetic basis, binding sessions in accordance with the work program and shooting the situation and relief in accordance with the work program of field surveys.

At the same time, carrying out binding, for implementation of "fast static "and" static " methods of satellite definitions on each point of the geodetic basis it is necessary to perform one reception, and implementing the occupation method-two receptions with an interval from 1 to 4 hours. Carrying out shooting on each site, the mobile station must perform the initialization reception and receptions on all shooting pickets, and the base station-one reception, covering all the time receptions performed by the mobile station.

Thus, when shooting at each site, the reception carried out by the base station should be performed during the entire time of work by the mobile station on this site.

When shooting, the work carried out by the mobile station should be carried out, guided by the operational documentation attached to the receiver. Since the use of the "stand-go" method requires continuous observation of the required number of satellites during the entire time of the survey on the site after each initialization, it is necessary to avoid communication losses both during the reception on the picket line and during the transition from picket to picket line. If there is a loss of connection during the survey, then to continue shooting, you must eliminate the causes of the loss of communication, repeat the initialization process and again make measurements on this site.

Performing field work when shooting must be combined with cameral processing of shooting materials, during which the following must be performed:

1) checking zero logs and drawing up a detailed binding scheme;

2) calculation of coordinates and heights of all pickets;

3) overlay on the tablet of points of the geodetic basis and picket points, drawing horizontal lines and drawing the situation.

These works are recommended to be performed on a computer, using the General recommendations for computational processing.

Summary:

• When conducting satellite imagery, the time spent on field work is reduced by 85% depending on the complexity of the topographic survey area, which significantly reduces the cost of work.
• Cameral works at the same time do not increase significantly, and the quality of the field material is improved.
• The accuracy of the obtained materials is not inferior to the works performed by the classical method of topographic or cadastral survey, and sometimes (when obtaining relief) and superior.

References

1. Penttinen T.J. The Telecommunications Handbook: Engineering Guidelines for Fixed, Mobile and Satellite Systems.Cambridge University Press. p. 150.  ISBN978-1-119-94488-1.
2. William H. Numerical Recipes 3rd Edition: The Art of Scientific Computing. Cambridge University Press. p. 959. ISBN978-0-521-88068-8. 
3. http://harveycohen.net/crcssArchived May 29, 2017, at the Wayback Machine "GPS Signal Science"
4. Abdualiyev E.B., Eshonov F.F. New uses of culvert Construction. Design Taxi, Issue 2, 2020 year 149-152p.
5. Abdualiev E. B., Embergenov A. B. /Case of waterproofing pipes on railways/ skills of the 21st century for professional activity /volume 2/Tashkent 2021/2/15/ 184-185 p.
6. Abdualiev E.B., Abdukarimov A.M. Increase of productivity and reliability of control of rails. Architectural and construction science and period materials of the Republican scientific and practical conference part №. 2 T.: 2017y. 24-26p.
7. Abdualiyev, E.B. (2019) "Research of surface condition of the rails rolling on sections of high-speed and high-speed train traffic, ," Journal of Tashkent Institute of Railway Engineers: Vol.15:Iss.2,Article14.Available at:https://uzjournals.edu.uz/tashiit/vol15/iss2/14
8. Abdualiyev, E.B. (2019) "Research of surface condition of the rails rollingon sections of high-speed and high-speed train traffic," Journal of Tashkent Institute of Railway Engineers: Vol.15:Iss.3,Article4. Available at: https://uzjournals.edu.uz/tashiit/vol15/iss3/4