What is Global Navigation Satellite System?

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What is Global Navigation Satellite System?

Global navigation satellite systems (GNSS) are inconspicuous bits of technology that people rely on without ever realizing it.

GNSS has an impact on everything we do every day, from communications systems to mobile navigation apps like Google Maps.

Understanding GNSS

A global navigation satellite system (GNSS) is a network of satellites that transmit time and orbital data for navigation and location measurements.

Satellites send out signals that report where they are and when they are there, and this information is utilized to establish where you are in the world.

Your technology computes your location based on your position in respect to at least four satellites via a sophisticated set of trilateration calculations.

GNSS is more than just satellites orbiting the Earth. Constellations are clusters of satellites that broadcast signals to master control stations and GNSS users all around the world.

These three parts — space, control, and user – are all included in GNSS. However, GNSS is most commonly used to denote satellites in space.

The GNSS constellations orbiting between 20,000 and 37,000 kilometers above the Earth are described in the space segment.

These satellites emit signals that identify which spacecraft is broadcasting, as well as the time, orbit, and state or health of the satellite.

Each of the four major constellations in orbit — GPS, GLONASS, Galileo, and BeiDou, as well as two regional systems, QZSS and IRNSS – is operated by a separate country.

The control segment is a global network of master control, data uploading, and monitoring stations. These stations receive a satellite signal and compare it to orbit models that show where the satellite should be.

Operators at these stations can regulate the satellites’ positions to correct or adjust their orbital courses, such as if a satellite has drifted or needs to be repositioned to avoid collision with debris.

This technique, along with monitoring a satellite’s health, maintains a baseline of GNSS location accuracy. The equipment that receives satellite signals and outputs a position based on the time and orbital location of at least four satellites is included in the user segment.

This component consists of the user’s antennae, which identify and receive high-quality signals, as well as high-precision receivers and positioning engines, which process the signals and correct potential timing mistakes.

History of GNSS

The use of satellites for navigation began in 1964 with the US Navy Navigation Satellite System, NNSS, which used the TRANSIT satellite system.

Other worldwide systems in the works include Europe’s Galileo and China’s COMPASS, now known as BeiDou-2 or BDS.

India’s IRNSS, currently known as NAVIC, and Japan’s QZSS are two regional systems. Unlike the aforementioned systems, these are operational but not fully operational yet.

Each manufacturer has been working on the core GNSS components for years and announced the first satellites in 2010. QZSS is one of three regional systems in operation and the only one that is fully operational.

In October 2016, its four satellites had a combined total launch mass of 648 kilograms while broadcasting 2,512 signals at a frequency of 10.75 gigahertz (GHz).

In comparison, NAVIC’s four satellites launched in April 2017 weigh in at a combined 529 kilograms and send out 4,548 signals. A new constellation of approximately 40 satellites is expected to be deployed as soon as 2020.

Types of global navigation satellite systems

Global positioning satellite systems (GPS) come in a variety of configurations.

The term “global navigation satellite system” (GNSS) refers to any of the satellite constellations that broadcast location, navigation, and timing data. There are four primary constellations and two regional constellations that are worth mentioning.

These constellations send their signals using radio frequencies in the L-Band; however, each constellation may select alternative frequencies and related labels for these transmissions.

GNSS positioning equipment normally receives at least two frequencies, with higher-end equipment capable of receiving additional L-Band signals.

These constellations send their signals using radio frequencies in the L-Band; however, each constellation may select alternative frequencies and related labels for these transmissions.

GNSS positioning equipment normally receives at least two frequencies, with higher-end equipment capable of receiving additional L-Band signals.

The types are:

Global Positioning System (United States)

GPS is managed by the United States Space Force, a branch of the United States Armed Forces. It was the first space-based constellation to be constructed, with the first satellite launched in 1978 and the first series of satellites completely operating by 1993.

The system now includes 31 satellites in orbit that support L1 (1575.42 MHz), L2 (1227.60 MHz), and L5 (1176.45 MHz) frequencies.

GLONASS (Russia)

GLONASS was developed in the Soviet Union to compete with GPS in the 1970s and is now operated by Roscosmos State Corporation for Space Activities, a Russian government department.

The first GLONASS satellite was launched in 1982, and the constellation now consists of 24 satellites in orbit. The constellation was fully launched and finished in 1995, with comprehensive satellite coverage across Russia attained in 2010.

GLONASS satellites transmit signals on the GLONASS L1 (1598.0625-1605.375 MHz), L2 (1242.9375-1248.625 MHz), and L3 (1202.025 MHz) frequency bands.

Galileo (European Union)

Galileo is a newer constellation that was launched in 2011. Galileo, which is managed by the European Global Navigation Satellite Systems Agency and is based in the European Union, currently has 26 satellites in orbit, with a goal of reaching 30 by 2021.

These satellites transmit on the L-Band band, with frequencies labeled E1 (1575.42 MHz), E5 (1191.795 MHz), E5a (1176.45 MHz), E5b (1207.14 MHz), and E6 (1207.14 MHz) (1278.75 MHz).

BeiDou (China)

BeiDou, which was launched in 2000 and is operated by the China National Space Administration, is based in China (CNSA). BeiDou has 48 satellites in orbit after 20 years.

Many signals are now transmitted by BeiDou satellites, including B1I (1561.098 MHz), B1C (1575.42 MHz), B2a (1175.42 MHz), B2I and B2b (1207.14 MHz), and B3I. (1268.52 MHz).

QZSS (Japan)

Japan’s Quasi-Zenith Satellite System (QZSS) was launched in 2010 by the Japan Aerospace Exploration Agency (JAXA). While the other constellations have offered worldwide coverage, QZSS continues to provide regional coverage between Japan and Australia.

As a regional constellation, QZSS currently has four satellites in orbit, with plans to add three more in the next years.

QZSS transmissions use the same frequency as GPS L1 (1575.42 MHz), L2 (1227.60 MHz), L5 (1176.45 MHz), and L6 (1176.45 MHz) (1278.75 MHz).

GNSS equipment

A variety of GNSS devices has been created to support various applications in a variety of settings. To use GNSS at its most basic, you’ll need an antenna and a receiver.

Antennas serve as a gatekeeper for satellite transmissions, accepting high-quality signals and rejecting low-quality signals.

A variety of antennas, including small antennas, fixed reference antennas, and high-performance low size and weight antennas, have been designed to better support various applications.

Receivers are offered as OEM receiver boards that users can put into their existing system or as GNSS enclosures that are ready to use.

Receivers demodulate satellite signals and compute the user’s position, navigation, or timing measures. Hexagon | NovAtel created smart antennas that already combine the two technologies into an all-in-one solution because users require both an antenna and a receiver.

There are various technologies that improve the performance of GNSS receivers depending on the application’s need for precision, signal resilience, and reliability.

These additional technologies, like as NovAtel’s GNSS and inertial SPAN technology, are frequently implemented within receiver enclosures.

Inertial navigation systems (INS) and its inertial measurement units (IMUs) combine heading, velocity, attitude, and heave motion measurements with GNSS readings to provide a completer and more three-dimensional picture of your location.

If users are working in areas where GNSS signals may be jammed or location, navigation, and timing coordinates falsified (also known as spoofing), they should invest in anti-jam technology.

NovAtel’s GPS Anti-Jam Technology (GAJT) protects customers’ antennas from being jammed or faked, allowing them to keep receiving GNSS satellite signals to their receivers.

Applications for Global Positioning Systems

To complete their tasks efficiently and accurately, GNSS applications rely on satellite signals. These applications span a wide range of industries, from agriculture to automotive to defense, but will generally fall into five broad categories:

  • Location – Determine your position in the world.
  • Navigation – Finding the best route from one location to another.
  • Tracking – Observing the movement of an object in the real world.
  • Mapping – process of creating maps of a specific geographic area.
  • Timing – the calculation of precise timing to billionths of a second.

Farmers, for example, require consistent routes across their fields in order to optimize seeding, fertilization, and harvesting. They rely on GNSS for equipment tracking and location. Farmers may use GNSS to map their fields prior to planning routes in some cases.

Vehicles use GNSS for navigation and location in the automotive industry. When a vehicle is self-driving, tracking becomes even more critical in order to continuously monitor potential hazards in the environment.

The Global Navigation Satellite System (GNSS) is used in aerospace for location, navigation, tracking, and timing – the US Federal Aviation Administration uses GNSS timing information to synchronize hazardous weather reports across the country.

The seventh episode of our Introduction to GNSS webinar series delves deeper into how GNSS is used in various applications.

FAQs

What is Global Navigation Satellite System?

The term “global navigation satellite system” (GNSS) refers to any satellite constellation that delivers positioning, navigation, and timing (PNT) services on a global or regional scale.

How do global navigation satellites work?

The GNSS satellite circles the Earth once every 11 hours, 58 minutes, and 2 seconds at a medium-orbit altitude.

When the receiver knows its precise position in relation to each satellite, it converts it into an Earth-based coordinate system, yielding the result in latitude, longitude, and height.

What is the American system of Global Navigation Satellite System?

GPS. The Global Positioning System (GPS) of the United States is made up of up to 32 medium Earth orbit satellites in six different orbital planes.

What is difference between GPS and GNSS?

GPS is commonly used to refer to the North American global positioning system, also known as the satellite positioning system.

The International Multi-Constellation Satellite System is referred to as GNSS. As a result, GPS, GLONASS, Baidu, Galileo, and any other constellation system are often included under GNSS.

What are navigation satellites used for?

Artificial satellites can serve as the foundation for all-weather, long-term navigation systems that can calculate the geodetic position, speed, and direction of a surface vehicle or aircraft, as well as the north reference and vertical reference, with pinpoint accuracy.

What is GLONASS and Galileo?

Global positioning systems (GPS), GLONASS, and Galileo are all examples of global navigation satellite systems. The United States owns GPS, Russia owns GLONASS, and the European Union owns Galileo.

That is the simplest method to distinguish the three systems, but all of the other features are significantly more crucial in real-world use.

Why do we need DGPS?

DGPS (Differential GPS) is essentially a technology that corrects GPS signals for position. To reduce pseudo-range inaccuracies, DGPS employs a fixed, known position to adapt real-time GPS signals. It is vital to note that DGPS corrections only increase the accuracy of position data.

How many navigation satellites are there?

24 GPS now has a 33-satellite constellation, with 31 of them in orbit and active. The US Air Force maintains it and is committed to keeping at least 24 operational GPS satellites operational. GPS has launched 72 satellites to date.

What does a global positioning system do?

The Global Positioning System (GPS) is a United States-owned utility that offers positioning, navigation, and timing (PNT) services to customers. This system is divided into three sections: the space section, the control section, and the user section.

Is Galileo GPS fully operational?

Galileo and GPS are entirely compatible, and their combined use will provide numerous benefits to the end user. Galileo satellites will provide more usable satellites, which will result in more accurate and dependable positioning and timing synchronization for end users.

What is the biggest source of error in DGPS?

Atmospheric interference is the most common source of GPS positional error. Errors in computation and rounding Data errors due to ephemeris (orbital path).

Which is the first navigation satellite in India?

IRNSS-1A is the first navigational satellite in geosynchronous orbit in the Indian Regional Navigation Satellite System (IRNSS) family.

Who can use Galileo?

Qualcomm and Mediatek As a result, several smartphones, including BQ, Samsung, Huawei, Apple, Asus, Google, LG, Meizu, Motorola, Nokia, OnePlus, Sony, and Vernee, already support Galileo. By visiting www.useGalileo.eu, you can easily determine whether your smartphone is Galileo-compatible.

What is the advantage of GLONASS over GPS?

When compared to GPS, one notable advantage of GLONASS is that its orbit inclination is 65°, which is 10 degrees higher than the GPS orbit inclination.

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