Global Navigation Satellite System (GNSS) and Satellite Navigation Explained
Abstract
Global Navigation Satellite System (GNSS) technology is a collection of satellite positioning systems with worldwide coverage. These systems aid in positioning, navigation, and timing (PNT) applications for commercial and military purposes. Due to its critical role in everyday life, it is vital to understand the system architecture. This paper examines the basic principles of GNSS and its role in developing precise navigation solutions. The sections outlined below include an introduction, an overview of the main functions, and a review of available satellite navigation (SATNAV) systems.
Section 1. Introduction to GNSS
Historically, humans have tried to solve the issue of global positioning and navigation in many ways, ranging from celestial navigation to modern-day satellites. In every system, the most significant hurdle is accuracy and dependability. To provide the best workable solution, satellite navigation systems must be exact, reliable even under harsh weather conditions, and user-friendly. Additionally, they must be able to compensate for delays caused by the ionosphere.
Modern GNSS systems are the most efficient and accurate answer to the question of reliable and exact navigation. GNSS technology has created a system for precise and updated global navigation information, including positioning and velocity information (Kaplan, 2017).
Global Navigation Information includes positioning and velocity information.
Section 2. Function of GNSS
GNSS signals are electromagnetic waves that use frequencies in the L-band portion of the radio spectrum, which is between 1.2 and 1.6 GHz. This range of signals allows for accurate measurements and can compensate for ionospheric delays (Teunissen et al., 2017). GNSS satellites send out navigation signals, which are tracked by the time it takes for the navigation signal to travel from the satellite to the receiver.
One feature of GNSS signals is the carrier, or harmonic radio wave, that is modulated to include pseudorandom noise (PRN) code. PRN code is a random mix of binary ones and zeroes transmitted between 1-10 MHz at a variable frequency. The PRN code has two main functions: it determines the signal transmission time to satellite antennae and is a distinct identifier for each satellite. This allows each satellite’s transmissions to be tracked independently (Teunissen et al., 2017).
The second main feature of GNSS signals is their use in navigation data, which is the collection of information on the position of satellites, time corrections, and other details. To understand how GNSS systems can do this, it is simpler to split them into three main parts: the space segment, the control segment, and the user segment. The space segment, which consists of navigation satellites, creates and emits the radio signals used for navigation. The control segment monitors and maintains the satellites. This is done by tracking their health, maintenance needs, and required updates. The user segment comprises the components needed for users to work with GNSS systems. This includes antennae, GNSS receivers, and a processing system (Ochin, 2021).
Section 3. GNSS Types
Four main satellite navigation (SATNAV) systems are at total operational capacity: GPS, GLONASS, Galileo, and BeiDou. Other systems of note are the QZSS and NavIC systems, which are regional GNSS systems. The section below outlines specific details for each SATNAV:
- Global Positioning System (GPS): Developed by the US Department of Defense (DoD) in the 70s, this is the first fully operational navigation system. The 31 satellites in operation for this system transmit signals in the L1 and L2 frequencies with a horizontal accuracy of 500 to 30 centimeters (Kumar et al., 2021).
- Global Navigation Satellite System (GLONASS): This is the Russian counterpart to GPS. It was officially completed in 1995 but did not have global coverage until 2011. Like GPS, satellites in this system transmit at L1 and L2 frequencies. Most modern receivers are compatible with both systems, but the GLONASS system only provides a horizontal accuracy of five to ten meters (Kumar et al., 2021).
- Galileo: Created via a collaboration between the European Space Agency and the EU, this system was officially completed just a few years ago in 2020. Unlike its previous two counterparts, this system consists of 30 satellites, with six serving as spares. This system was developed in two phases of implementation: In-Orbit Validation, IOV, a phase to ensure the concepts around the Galileo system were accurate, and Full Operational Capacity, FOC, which deployed the Galileo satellite system in full. At total operational capacity, Galileo provides services to users worldwide, in public and private iterations, with one-meter precision (Kumar et al., 2021).
- BeiDou Navigation Satellite System (BDS): This Chinese system provides users with several services, including radio navigation satellite service, Short Message Service (SMS) access, and wide-area differential services. It comprises 35 satellites, five geostationary, and can reach a horizontal accuracy of 2-3 meters for the public and 10 centimeters for encrypted use. (Teunissen et al., 2017).
- Quasi-Zenith Satellite System (QZSS): This is a regional Japanese system with only a few satellites serving the East Asian region. This system primarily uses L1, L2, L5, and L6 frequencies to serve phone communication services (Kumar et al., 2021).
- Navigation with Indian Constellation (NavIC): This autonomous system for the Indian region consists of seven satellites and three geostationary. This system services civilians and military officials, working in L5 and S-band frequencies with a horizontal accuracy of one meter for the public and ten centimeters for encrypted use (Kumar et al., 2021).
GPS suits users with accurate position, velocity, and time data.
Section 4. Applications of GNSS
GNSS technology has transformed many industries by permitting accurate positioning, navigation, and timing (PNT) data. Its applications cut across various sectors, providing needed information that helps improve efficiency and safety and drives innovations. Here is a list of some vital fields for the application of GNSS.
Transportation and Logistics
GNSS allows tracking on-road vehicles in real-time, perfect routing, and advanced fleet management. All of these result in lower fuel consumption, reduced operational costs, and, consequently, a higher level of safety on the road. That’s how important GNSS (global navigation satellite system) is in the cargo or air transport industry, which helps ships and other aircraft avoid collisions by providing precision navigational solutions and secure landing conditions, thus improving shipping routes.
Agriculture
GNSS Technology Plays a Key Role in Precision Agriculture for Improved Productivity and Sustainability GNSS: As we know, GNSS helps in activities like precision farming and land leveling… ensuring the most advanced technology on earth executes work with great accuracy. This, in turn, results in better resource management, lowered input costs, and a greater crop yield per unit area. Planting, fertilizing, and harvesting are carried out with little overlap and wastage with GNSS-enabled machinery.
Construction and Mining
For the construction and mining industries, advantageous site surveying, GPS on heavy equipment or machinery guidance, and earthwork quantity measurement also use GNSS technology. GNSS technology enables proper excavation, grading, and material placement to minimize rework while enhancing productivity. Systems based on GNSS make it easy to monitor the movement of materials and equipment, improve safety measures at site operations, and help adhere to project schedules.
Disaster Emergency Response System
GNSS supplies critical information to support response and recovery efforts in natural disasters or other emergencies. It plays a crucial role in identifying the affected areas, planning evacuating routes, and cooperating in rescue operations. In addition, with GNSS, we can monitor environmental changes such as landslides and floods so that action can be taken preemptively.
Telecommunications and Power Networks.
GNSS, the heartbeat of time-sensitive operations for wireless and electric utilities, provides a method for data transmission and power distribution while maintaining service reliability. It is used for network synchronization timing to allow efficient global communication systems and power grids.
Military and Defense
In the military, precise positioning is vital for GNSS to place troops, vehicles, and weapon systems. It increases the accuracy of targeting and navigation in complex environments. Another essential aspect of GNSS has been its use in surveillance, reconnaissance, and intelligence operations to provide real-time information for strategic decision-making.
Conclusion
This article outlines global navigation systems’ history, function, and types (GNSS). These systems have been developing for decades and still have room for technological advancements. As shown, GNSS technology is a vital part of everyday life for people all around the globe, both for public and military purposes.
References
[1] Kaplan, E. D. & Hegarty, C. J. (2017). Understanding GPS/GNSS: Principles and Applications (3rd ed.). Artech House
[2] Kumar, A., Kumar, S., Lal, P., Saikia, P., Srivastava, P. K., & Petropoulos, G. P. (2021). Introduction to GPS/GNSS technology. GPS and GNSS Technology in Geosciences, 3-20. https://doi.org/10.1016/B978-0-12-818617-6.00001-9
[3] Ochin, E. (2021). Fundamentals of Structural and Functional Organization of GNSS. GPS and GNSS Technology in Geosciences, 21-49. https://doi.org/10.1016/B978-0-12-818617-6.00010-X
[4] Teunissen, P. J. & Montenbruck, O. (2017). Springer Handbook of Global Navigation Satellite Systems. Springer International Publishing.
