GLOBAL NAVIGATION SATELLITE SYSTEMS AND THEIR APPLICATIONS
GLOBAL NAVIGATION SATELLITE SYSTEMS AND THEIR APPLICATIONS
Aitmambetov Zhassulan
“Geokurs” LLP, Director of the branch in Karaganda,
Kazakhstan, Karaganda
Aldikeshev Alibek
“Geokurs” LLP, Director of the branch in Kostanay,
Kazakhstan, Kostanay
Akhmetov Marat
“Geokurs” LLP, Director of the branch in Uralsk,
Kazakhstan, Uralsk
Introduction. For the past several decades, the Global Positioning System (GPS) has been the number one positioning tool in a number of surveying and geophysical applications. Emerging regional and global navigation satellite systems can expand positioning and non-positioning capabilities. The modernization of GPS from two-frequency to three-frequency signals has recently been complemented by the Global Navigation Satellite System (GLONASS), Galileo and BeiDou Navigation Satellite System (BDS), and the Quasi-Zenith Regional Satellite System (QZSS) and Indian Constellation Navigation (NavIC). By 2024, humanity is expected to have access to more than 110 satellites in the multi-GNSS model transmitting their signals on different frequencies. This will greatly improve current two-frequency GPS positioning as well as non-positioning applications such as atmospheric modeling and timing applications. However, rigorous models and algorithms are needed to link and integrate such multi-frequency signals from multiple GNSS with the estimated parameters of interest.
Global Navigation Satellite Systems and Their Applications. GNSS consists of three main satellite technologies: GPS, Glonass and Galileo. Each consists essentially of three segments: (a) the space segment, (b) the control segment, and (c) the user segment. These segments are almost identical in the three satellite technologies that all together make up GNSS. Today, the complete satellite technology is GPS technology and most of the world's existing applications are related to GPS technology.
The U.S. Department of Defense developed Navstar GPS, which is an all-weather, space-based navigation system to meet the needs of the U.S. military and accurately determine their position, speed, and time in a common reference frame anywhere on or near the Earth on a continuous basis [1].
GPS has had a significant impact on virtually all positioning, navigation, timing, and monitoring systems. It provides specially encoded satellite signals that can be processed in a GPS receiver, allowing it to estimate position, speed, and time [2].
GLONASS (GLObal NAvigation Satellite System or "Global Navigation Satellite System") is almost identical to GPS. The GLONASS satellite radio navigation system provides users with positioning and time information. It is operated by the Ministry of Defense of the Russian Federation [3].
The Glonass space segment consists of 24 satellites evenly distributed in three orbits spaced o 120 in the equatorial plane. The orbital altitude of the satellites is about 19,130 km above the ground. This results in an orbital period of 11:15:44, which corresponds to 8/17 side days.
Galileo segments are almost similar to GPS, but with some changes. The main extension of Galileo over GPS is the introduction of a global/regional segment to monitor the integrity of monitoring. The goal is to help safety-critical aircraft navigation as well as locating and guiding railroad trains [4].
Wide Area Differential GNSS (WADGNSS) is a scheme that will allow the user to perform differential positioning and obtain reliable positioning with high accuracy in real time over a significant area. WADGNSS consists of a main control station and several local or global monitoring stations and a communication link.
The monitoring stations collect data from the GNSS satellite, then send it to the main control station. station. The main control station evaluates the ionosphere, troposphere, satellite. ephemeris and clock errors. All these corrections are transmitted to the user via the Internet, wireless or satellite communications.
The Wide Area Augmentation System (WAAS) is a new addition to the U.S. Department of Defense Global Positioning System (GPS). U.S. Department of Defense Global Positioning System (GPS), which is designed to improve the integrity and accuracy of basic GPS capabilities.
WAAS uses geostationary satellites to acquire data measured from multiple ground stations and sends information to GPS users for position correction. Because WAAS satellites are of the geostationary type, the Doppler frequency caused by their motion is very low. Therefore, the signal transmitted by WAAS can be used to calibrate the sampling frequency in the GPS receiver.
The European Geostationary Navigation Overlay Service (EGNOS) is being developed by the European Space Agency (ESA), for aeronautical safety (Eurocontrol). EGNOS will complement GNSS systems. It consists of three transponders mounted on geostationary satellites and a ground network of 34 positioning stations and four control centers, all interconnected. EGNOS, like WAAS, transmits differential corrections to GNSS users via geostationary satellites in the European region and beyond.
Similar to WAAS and EGNOS, the Japanese satellite augmentation system MTSAT (MSAS) is used to transmit differential corrections for GNSS users.
The RTK network concept is similar to that of WADGNSS, but the reference stations are generally distributed over a regional area, and the network control center is responsible for transmitting data. distributed over a regional area, and the network control center is responsible for transmitting the phase correction to the GNSS user (rover receiver). Mobile wireless networks (GSM, GPRS, EDGE, CDMA2000 and UMTS) are commonly used in this type of application because of the need for duplex communication, where the rover receiver must initially send the approximate position to the network data center. The network data center calculates the VRS observation data and sends it to the user [5]. This scheme is widely used in many systems around the world due to its economic and accuracy advantages.
Conclusion. Global Navigation Satellite Systems (GNSS) technology has become vital for many applications from engineering planning and urban zoning to military applications. It has been widely accepted worldwide by governments and organizations. Multibillion-dollar investments and intensive research activities are being made in this field worldwide. Impressive progress in wireless communications and networking has played a major role in increasing interest in GNSS and creating favorable methodologies and mechanisms. All 3G and future generations of cellular phones are expected to be equipped with GNSS chips. GNSS technology dominates outdoor navigation, providing accuracy ranging from a few meters to 10 meters with the single-point positioning method or from sub-meters to several meters with the differential GNSS (DGSS) method. Recently, various methods have been developed for indoor positioning. They offer absolute or relative positioning capabilities with acceptable accuracy [6]. Combining these technologies with GNSS provides a more reliable and stable solution for positioning.
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