GLOBAL NAVIGATION SATELLITE SYSTEMS AND THEIR ROLE IN PRECISION AGRICULTURE TECHNOLOGIES
Authors: Kholodyuk Oleksandr 
Published: September 2020

Today, global navigation satellite systems are being implemented in many structural units of the Ukrainian economic complex, many spheres of human activity, and every year they continue to develop. One of the main feature of these satellite systems is the requirements for high accuracy and speed of received data. They provide the opportunity to reduce operating costs and increase the efficiency of use of equipment and other resources.
Therefore, the use of navigation satellite systems for controlling machine units, establishing their location, monitoring soil condition and yield mapping is becoming increasingly relevant today.

The subject of study in this article were global navigation satellite systems NAVSTARGPS (USA), GLONASS (RF), GALILEO (EU), BEIDOU (China) and regional navigation systems NavIC (India) and QUASI-ZENITH (Japan).
The purpose of the work was to clarify and establish the main characteristics of global navigation satellite systems and their role in the implementation of precision agriculture technologies.
The task of the work was: to analyze the functional characteristics of global positioning satellite systems and their main elements; to find out principles of operation of systems: navigation, coordinates, time; to establish the accuracy of navigation systems; to substantiate the role of global positioning satellite systems in the effective implementation of precision agriculture technologies in agriculture.
The research methodology was based on the method of materialistic dialectics, methods of analysis and synthesis of both information from official sources and information from the works of other researchers.
Two major operators of satellite navigation systems the NAVSTAR GPS and GLONASS, which are similar in many respects, have been identified in the scientific work. Among the distinctive features there are the nature of the location, the motion of satellites in orbits and their total number, methods of encoding the CDMA and FDMA signals, the use of different coordinate systems WGS-84 and PZ90.11. As for the other two satellite navigation systems GALILEO and BEIDOU, they are developing rapidly with great ambition and potential. It is established that at the present time the accuracy of determining the coordinates of the GLONASS system is inferior to the performance of the American satellite navigation system GPS. GLONASS provides more accurate positioning in the northern latitudes and GPS in the middle.
It is noted that the positioning accuracy of machine units for the implementation of precision farming technologies can be improved (from 2 to 20 cm) due to differential signal correction with the help of free and commercial wideband satellite navigation subsystems. These services will allow to implement the tasks of precision driving, and therefore, to ensure the accurate implementation of sowing material, fertilizers and herbicides to spare them, accurate inter-row cultivation of industrial crops, accurate harvesting, etc., when performing agro-technological operations using ground vehicles and landless vehicles.