The evolution of technology over the years has allowed humans to reciprocate with expanding needs. Modern devices have made room for new possibilities in terms of high-tech products and advanced services. Satellite navigation systems, for instance, are one of such crucial developments providing autonomous geo-spatial navigation systems.

Positioning, navigation, and timing (PNT) technology plays a key role in a satellite’s functioning. PNT technology has a wide range of applications for governments, space agencies, autonomous vehicles, military and defense, large businesses, and other specific technologies like the global positioning system (GPS).

Currently, government agencies and private companies operating in the global satellite positioning, navigation, and timing (PNT) technology market are engaged in research endeavors to offer assured position, navigation, and timing (A-PNT) technology.

The global satellite position, navigation, and timing (PNT) technology market was valued at $961.7 million in 2020, and it is estimated to reach $8,817.3 million by 2031, at a compound annual growth rate (CAGR) of 22.45% during the forecast period 2021-2031.

The biggest factor driving the growth of this market is the demand for reliable navigation and positioning data for both commercial and defense-related applications.

Positioning

Positioning technology determines the geographical location of a person, object, or signal with high accuracy. The ’location’s orientation is usually two-dimensional or sometimes three-dimensional, as per the requirement. Its capability to measure small changes of the ’Earth’s atmosphere as well as on its surface with an unprecedented exactitude makes it a crucial discovery.

The positioning process is carried out by satellites that revolve around the Earth. They receive signals from different entities in the world, and these signals are then used to determine the position of the source with an accuracy of a few meters at a rapid rate.

The positioning technology is used in-
● Vehicle navigation systems
● Smartphones
● Land surveyors

Navigation

The navigation system is used to determine an object’s current position, route in between, and destination. It allows the autonomous positioning of satellites and aids in navigation. The navigation system uses a global network of satellites that handle the signals and dictate their transmission and reception.

The navigation technology has a wide range of applications in different sectors, such as the following

1) Road navigation: Saves time by avoiding traffic and finding the shortest distance between two points
2) Railways: For timely movement of automated trains
3) Space: ’Satellite’s movement in space
4) Aviation: For flight’s timely movements
5) Marine: For ’submarine’s underwater movement and cargo

Timing

Timing is the ability to acquire, maintain, and supply highly accurate time to synchronize complex systems. Timing binds the other two elements of positioning and navigation. It enables calculating the duration of travel between locations and also maintains precise time following a time zone standard such as Coordinated Universal Time (UTC).

Timing also includes the transferring of time. The satellite positioning system is highly dependent on the accuracy of time transfer. The satellites are equipped with atomic clocks based on a particular time zone standard; they transmit time signals toward E Earth, which are then used in the mechanism to indicate the satellite’s position.

Classifications of Satellite System

Based on the region of coverage, satellite systems can be broadly classified as-
● Global Navigation Satellite System (GNSS)
● Radio Navigation Satellite Service (RNSS)

Global Navigation Satellite System Global Navigation Satellite System (GNSS) is a constellation of satellites that use PNT technology to transfer information on a global scale. GNSS has a wide range of applications, and its services are available uniformly throughout the globe.

There are several GNSS currently being used by different countries, namely:

1. Global Positioning System

The global positioning system is one of the most prevalent navigation systems. It consists of 77 satellites in its constellation. It is owned by the U.S. and operated by the United States Space Force.

2. BeiDou Navigation Satellite System

The BeiDou Navigation Satellite System (BDS), previously known as Compass, is a Chinese GNSS. It was first launched on October 31, 2000, and now consists of 35 satellites.

3. Galileo

Galileo is a global navigation satellite system owned by the European Union (EU). It went live in 2016 and was made by the European Space Agency (ESA). ’Galileo’s constellation size is 30, comprising 24 active and six spare satellites.

4. GLONASS

The Globalnaya Navigazionnaya Sputnikovaya Sistema or global navigation satellite system is a Russian-based GNSS that provides an alternative for GPS. Its constellation size comprises 26 satellites.

Radio Navigation Satellite Service

Satellite systems like the radio navigation satellite service (RNSS) are used for radio navigation and have regional coverage. RNSS is used for critical navigation purposes on land, sea, air and is regarded as a safety-to-life service.

RNSS currently being used are as follows:

1. Quasi-Zenith Satellite System
The Quasi-Zenith Satellite System (QZSS), also known as Machibiki, is a regional navigation system of the Japanese government. It is operated by the QZS System Service Inc. (QSS) and has a constellation size of five satellites.

2. Navigation Indian Constellation

Navigation Indian Constellation (NavIC), also known as the Indian Regional Navigation Satellite System (IRNSS), is a regional satellite system that covers the Indian mainland. NavIC is operated by the Indian Space Research Organisation (ISRO) and has a total of eight satellites in its constellation.

Augmentation

Augmentation of satellites is a method of improving the basic characteristics of the navigation system such as reliability, accuracy, availability, and integrity by improving the connectivity, signal measurement inaccuracies, and providing adequate operational data.

Augmentation system can further be classified as-

1. Satellite-Based Augmentation System (SBAS)
2. Ground-Based Augmentation System (GBAS)
3. Aircraft-Based Augmentation System (ABAS)

Challenges Faced by Satellites Using PNT technology

PNT satellites hold huge significance in space technology and deliver serviceability in numerous practical applications, but it faces several limitations. Challenges that PNT technology needs to overcome encompasses the following demands-

● Availability
Availability issues are of deep concern as continuous positioning data is crucial regardless of the weather condition, time of the day, or any other factor.

● Coverage
The ’satellite’s range of coverage should surround the entire globe in order to deliver important information uniformly.

● Accuracy

Positioning and navigation systems need to accurately identify locations, vehicles, and other land features.

● Hardware and Tools
Hardware used in the ’satellite’s NPT system should be durable, have practical utility, and the tools used should be portable.

● Usability

Straightforward, apposite usability with fewer malfunctions allows persistent use of PNT satellites over a long time.

Satellites have become the cornerstones of positioning and navigation in modern technology. Innovation that has allowed PNT technology to integrate with map data has narrowed down the barrier of communication transportation and allowed several crucial developments in the military, civilian and commercial fields. Thus, PNT continues to hold a vital role in space development and modern science.