Introduction potential of GPS navigation technology for supervision control at capital construction, reconstruction and conversion projects

This article analyzes potential use of various navigation technologies to implement building supervision functions for capital construction, reconstruction and conversion projects. It indicates the basic prerequisites for the development of such technologies and describes the navigation physical principle applicable due to its properties for a certain range of supervision functions in the construction industry. The article also examines testing of corresponding software systems on the construction sites in Moscow in control operations by the Technical Customer’s engineers, and analyzes the potential of using adjacent navigation systems for similar purposes as compared with the main physical and technical characteristics of implementation in professional software packages.


Introduction
The following is the definition of the systems science that now offers additional possibilities of developing human activities in a number of areas including the construction industry. Navigation (Latin navigatio, from Latin navigo -'I go by boat') is a field of study that focuses on methods to determine velocity, location and orientation of moving objects; it has evolved as a result of the general ship navigation study development (Table 1). In the modern world, it is virtually impossible to imagine human life without the navigation technology -navigation systems enable safe cargo and passenger transportation by air, sea and land; coordination of space devices and rescue operations; meeting the requirement of online tracking in large cities and heavy urban traffic, etc [1][2].

Methods
The Satellite Navigation System (Tables 2 and 3) is an integrated system consisting of equipment placed in space orbit and on the ground and designed to determine the coordinates and trajectory parameters of an object. There is a group of satellites in space orbit with each of them emitting signals in the radiofrequency band [3][4]. Once the signal reaches an object on Earth and is processed, the distance from the object to the satellite is calculated using previously known data (such the location of the satellite). The distance is determined by calculating the formulas of wave propagation in the medium. The waves from the satellites propagate at the speed of light, and the lag between their emission in the space and receipt on Earth is directly proportional to the distance between the object and the satellite [5][6].  storms. This factor constitutes the main problem in precise determination of an object's location. However, the accuracy may be increased using signal phase measurement. The satellite's data transmission frequency is 1575.42 MHz. The data include: ephemeris -precise orbit and clock adjustment data for each satellite; almanac -location data of the satellite. There are 31 GPS satellites currently in orbit. Each satellite transmits its unique signature consisting of random sequence (Pseudo Random Noise (PRN) code) of 1,023 units of 0's and 1's. There are 2 types of PRN code: a Pcode processed by a GPS receiver with an accuracy of more than 10 m; and a C/A-code with an accuracy of approx. 20 m. The unique ID is added in the code to determine the signaltransmitting satellite and to measure the signal transit time. 6.
USSR (RF) GLONASS The GLONASS satellites are situated in the medium-altitude circular orbit at an altitude of 19,400 km with inclination of 64.8 degrees and orbital period of 11 hours and 15 minutes. These satellites continuously emit two types of navigation signals: a standard accuracy navigation signal in L1 band (1.6 GHz), and a high accuracy navigation signal in L1 and L2 bands (1.2 GHz). The system exploits frequency division of channels -each satellite generates a wave at its own carrier frequency. The GLONASS system exploits a differential movement model. It means determining the satellite coordinates at a given point in time requires a solution to a system of differential equations using numerical integration. 7.
France Doris Designed to meet geodesic and geophysical requirements 8.
EU (European  Union) GALILEO Provides a unique global Search and Rescue (SAR) service with an essential feedback function 9.
China Beidou Beidou operates in a test mode and offers positioning, navigation and time determination services for China and "some of its surrounding regions." 10.
Japan Quasi-Zenit The satellite segment includes 3 satellites in total. Their orbits will be chosen to ensure that their subsatellite points trace out identical trajectories on the surface with identical time intervals. At least one satellite will always be visible at an angular altitude of over 70 degrees in Japan and Korea.
The principle of satellite signal generation in the NAVSTAR (GPS) system is as follows: the necessary synchronizing pulses and frequencies are generated as derivatives of the resonant frequency of atomic clock. The pulses are generated by the generators of the carrier frequency at which the satellite signals are transmitted, as well as by the PRN code generator and data generator (Fig. 2) [7][8].
Due to large distances and limited power of the signal that the satellite is capable to generate, information is transmitted digitally as a binary code (bit stream) rather than as an analog signal. Accordingly, the initial analog signal is preliminarily digitized and then converted by modulation into a radio signal with a certain frequency range capable of being received by on-ground devices (due to problems in recognizing LF signals, including background noise). This operation results in the frequency translation of digital signal into the HF range. This allows transceivers to ensure recognition of the required signal from the satellite at a certain frequency [9][10]. Thus, the modulation "lays" the information (digital signal) onto the L1 carrier frequency of a satellite (Table 3) -the information from the satellite is initially modulated by the C/A code (Table 3), then BPSK (binary phase-shift keying) performs modulation by a discrete signal of the L1 carrier frequency, at which the signal can be received by the devices (Figure 3 and 4).    To determine the object's coordinates, it is necessary to calculate the transit time for four satellites ∆ , ∆ , ∆ , ∆ . Distance from the satellite to the object is called the R-

Analog signal
Digital signal Radio signal range. At a given satellite location , the R-range is calculated for each satellite using the transit time [11][12]. Let us assume that a user's clock is not synchronized with UTC (Coordinated Universal Time). Therefore, additional error appears. The result of error allowance for the actual range is called the pseudo-range PSR.
Where: R is the actual range from satellite to user; c is the speed of light; ∆ R is the signal transit range from satellite to user; ∆ is the difference between satellite's and user's clock; PSR is the pseudo-range [13][14].
The actual range in the Cartesian coordinate system: Therefore, the pseudo-range is calculated using the formula: To determine the four unknown variables ( ∆ , " , " , " ), four independent equations are required.

Results
The following factors comprise the general error in the system: 10 ns time error of the satellite clock, error in the satellite orbit position, heterogeneity of propagation medium. The table reflects the effect of errors on data accuracy [15][16]. Troposphere effect 0.7 6.
Horizontal error (2 sigma (95,5%)HDOP=2,5) 20.4 Originally intended for military purposes only, GPS is used today for civilian applications such as surveillance, navigation (air, sea, and ground), positioning, speed measurement, time detection, control of stationary and moving objects, and so on. The system operator guarantees the standard civil consumer the following accuracy (Tables 5, 6) for 95% of the time: Table 5. Accuracy of GPS.

No.
GPS Accuracy Type Value in appropriate units
Time accuracy ~ 40 ns Table 6. Comparative analysis of the two main existing satellite systems.

Item
No. Despite the worldwide use of the GPS navigation system in various fields of science and technology (including the global construction industry), Analytical Table 6 shows that Russia's GLONASS system has a number of technical advantages resulting in better accuracy of both plane and high-altitude positioning. However, it is the worldwide coverage of GPS that makes it the most popular navigation equipment and software solution. As for the construction industry, let us review the main areas of application of a navigation system in tackling applied engineering, transport, management and qualimetry tasks (Table 7). Table 7. Practical application of navigation in the field of construction supervision and site survey.

No.
Application area Implementation effectiveness exemplified by a specific task solution 1.
Construction machinery Reduction of construction fleet hijacking rate (particularly truck mixers, self-propelled cranes, bulldozers, front loaders and excavators) by means of specialized GPS trackers 2.
Construction machinery Construction fleet route tracking (which also means fuel consumption control) and working time control by means of specialized GPS trackers 3.
Road and airfield construction Roadway condition survey; roadway composition control; road paving monitoring; maintenance vehicles work optimization; shunting management optimization 4.
Construction of engineering infrastructure High-precision laying of linear infrastructure (e.g. laying, inspection and monitoring of utility networks and systems) 5.
Inspection of buildings, structures and other facilities Measurement work; monitoring of buildings and structures using the navigation field of global navigation satellite systems (GNSS) 6.
Inspection of buildings, structures and other facilities Local flaw detection of construction objects, including generation of defect lists 7.
Construction supervision and operation of the Technical Customer services In-process quality control of construction products. Quality control of finished construction products. Verification of the on-site construction and installation work progress (factual completion, in some caseswork progress in numerical form). Control service engineer work optimization and automation. Generation of a defect database for a facility. 8.
Geodesic support of construction and inspection of buildings and structures Geodetic work using appropriate technologies; in-field positioning and object snapping; satellite geodesy methods in high-rise buildings construction 9.
Construction and installation works at industrial and civil construction projects Earthworks quality and volume control using machinery fitted with satellite signal receivers (e.g. bulldozers with 3D leveling system); relative movement control 10.
Cadastral work Measurement work 11.
Construction of underground mass transit facilities Geodesic and surveying work

Bridge construction Relative movement control
Geodesic methods based on satellite navigation are widely used in building supervision. They ensure a high accuracy, while on-line in-field positioning accelerates field work because there is no need to provide any extra geodetic control networks which involve reference points transfer. Based on the principles of global navigation satellite systems (GNSS), integrated software systems are being developed for the qualimetric needs of control procedures in the construction and inspection of existing buildings and structures; such systems include defect detection systems with a positioning function on extended objects (Fig. 6) and technical condition monitoring using GNSS.
Integrated construction supervision using GNSS may include the following operations:

Conclusions
Despite available high-precision advanced technologies, there are a number of difficulties related to establishing the maximum measurement accuracy in the matters of global satellite support in tackling engineering problems. Satellite navigation systems alone (neither GPS nor GLONASS, which is in fact more accurate) are incapable of providing sufficient accuracy for construction needs due to a number of specific physical and technical features (including those previously discussed in this article). For this reason there is a need for indirect geodetic instruments to ensure more accurate positioning. The use of satellite navigation basics in geodesy has significantly expanded the range of verification capabilities in construction control and monitoring of the technical condition of buildings and structures, from monitoring fluctuations in high-rise buildings to verifying the progress of construction and installation work at the stage of delivery of completed construction products by the General Contractor.