What is ‘Positioning, Navigation and Timing’ (PNT)?
The three elements of PNT
PNT comprises three different components which, when combined, creates a powerful capability:
- ‘Positioning’ is the ability to determine the geographic location of a person, object or signal.
- ‘Navigation’ is the ability to calculate a route to a desired position from a current position. In other words, it is the ability to calculate a path from point A to point B.
- ‘Timing’ ties ‘Navigation’ and ‘Positioning’ together, enabling the ability to calculate the duration of travel between locations and to maintain precise time in accordance with time zone standards such as Coordinated Universal Time (UTC) or ‘Australian Central Standard Time’.
Global Navigation Satellite Systems (GNSS)
GNSS are systems comprised of a constellation of satellites that beam down positioning and timing information to GNSS receivers which analyse this data to establish location. The information collected by GNSS is relied on by military, governmental, commercial and other entities, including private citizens, for countless applications. GNSS provides global coverage of services.
There are a number of GNSS currently in operation:
There are also regional navigation satellite systems (RNSS) which, unlike GNSS, provide regional coverage only. Although there is a desire for countries to develop their own GNSS, almost all countries remain dependent on US GPS services.
RNSS in operation include:
- Quasi-Zenith Satellite System (QZSS) (Japan)
- Indian Regional Navigation Satellite System
(IRNSS)
Three segments of GNSS/RNSS:
Both GNSS and RNSS rely on three core ‘segments’ of operation to reliably deliver and access the services they provide.
- Space Segment – the space segment of GNSS/RNSS refers to the constellation of satellites orbiting the Earth.
- Control Segment – the control segment is comprised of monitoring stations or receivers established worldwide which track and maintain the satellites.
- User Segment – the user segment refers to the various entities which rely on GNSS/RNSS to support countless applications.
Satellite-Based Augmentation Systems (SBAS)
SBAS are systems which operate to improve the accuracy, integrity, continuity and availability of GNSS by correcting signal measurement inaccuracies; and provide operational data regarding GNSS signals.
A variety SBAS are currently in effect:
- European Geostationary Navigation Overlay Service (EGNOS)
- Wide Area Augmentation System (WAAS) (USA)
- MTSAT Satellite-based Augmentation System (MSAS) (Japan)
- GPS Aided GEO Augmented Navigation System (GAGAN) (India)
- Chinese Satellite Navigation Augmentation System (SNAS)
- System for Differential Corrections and Monitoring (SDCM) (Russia)
- Australian SBAS (in development)
Ground-Based Augmentation Systems (GBAS)
Similar to SBAS, GBAS improve the accuracy, integrity, continuity and availability of GNSS by correcting signal measurement inaccuracies, and by providing essential operational data. However, unlike SBAS, GBAS is based terrestrially — consisting of a network of ground stations installed across Earth’s regions to maximise coverage. GBAS conducts safety-critical activities such as monitoring air traffic control.
More information regarding GBAS may be found on the Federal Aviation Administration website.
Performance criteria for GNSS which can be improved by RNSS:
- Accuracy – the difference between a receiver’s measured and real position, speed or time.
- Integrity – a system’s capacity to provide a threshold of confidence and, in the event of an anomaly in the positioning data, an alarm.
- Continuity – a system’s ability to function without interruption.
- Availability – the percentage of time a signal fulfils the above accuracy, integrity and continuity criteria.
Australia’s National PNT Infrastructure
Australia does not possess any independent space-based GNSS or RNSS capability. Australia does however maintain a network of ground stations capable of accessing and monitoring GNSS and RNSS systems controlled by international partners. The Australian government is pursuing a ‘National Positioning Infrastructure’ (NPI) project which aims to maximise the value which can be derived from the GNSS currently in operation. In the 2019-20 Federal Budget, Geoscience Australia was awarded $64 million to complete the NPI project. The NPI project aims to deliver high accuracy positioning capabilities by upgrading current GNSS ground stations, establishing new GNSS ground stations, and ensuring ground station network integration.
Currently, GNSS services like GPS provide positioning accuracy to within 5 meters. Once the NPI project is completed, Australia’s ground-based positioning infrastructure will be able to track, verify and optimise data from global networks of satellites for more precise positioning across Australia, with an accuracy of 3-5 centimetres.
Precise positioning offers an exciting opportunity for all Australians. The ability to identify a location anywhere in Australia in real-time with a high degree of accuracy enables a range of activities to be conducted more efficiently. Australia’s infrastructure provides greater accuracy and productivity for a number of activities conducted in various industries such as the mining, construction, agriculture and transport industries. Improved services will also be available to the public, including emergency services, road safety management and enhanced smart-device functions. Entrepreneurs can also take advantage of the improved technology to develop their own applications.
For more information on Australia’s National Positioning Infrastructure, visit the Geoscience Australia website.
Legal rules applicable to GNSS
Recognising what laws apply to the use of GNSS and PNT data can be a difficult task. GNSS technology is a highly advanced tool which was developed to support an array of operations on Earth, in outer space and in the virtual sphere. The potential applications for GNSS technology and the ways in which PNT data can be used are virtually endless. Such applications have the potential to engage a broad spectrum of different legal regimes depending on their intended function and scope of operation.
When determining what legal rules apply to a given scenario, it will be necessary to identify what GNSS and services are being used and what they are being used for, in addition to any specific details of the particular case giving rise to legal issues. This will assist in identifying, on a general level, what legal or regulatory framework might be applicable to the circumstances. For example, if GNSS and their services are used in the context of aviation, international and national air law will apply (as well as any other body of law with regulatory implications or application to activities conducted in airspace). Additionally, legal obligations may arise under contract, or the law of tort — which covers negligence and fault-based liability. Due to the complexity of this issue, it is beyond the scope of this article to capture and explain all potential aspects of law that may possess some applicability to the use and access of GNSS services.
Seek legal advice:
The span of legal rules which could be applicable to the use of GNSS and PNT data/services is vast. It depends on what technology products and services are used and what the data is used for.
If you are uncertain if your activities may involve legal implications with respect to GNSS or PNT data, it is always good practice to seek legal advice to clarify and address your specific circumstances.
use case: Legal issues for GNSS user applications
ANGELS Aerospace is selected by several Remotely Piloted Aerial Systems (RPAS) to facilitate the use of various GNSS services by RPAS in Australian Airspace.
Space Law
When analysing to what extent space law has an impact on GNSS, it is appropriate to consider the following five elements of GNSS, identified by Dr Frans von der Dunk in his article Space Law and GNSS:
(1) Ground stations controlling by way of (2) radio signals (3) the satellites launched in and then operating in outer space, emitting (4) the positioning, navigation and timing (PNT) signals allowing (5) relevant receivers to calculate positioning and navigation information.
Elements (1) and (5) (relating to ground stations and receivers) are not usually considered to be subject to space law as ground stations and the information collected by receivers fall within the legal control of whichever state these facilities are located.
Elements (2) and (4) (relating to radio signals and PNT data), although travelling through outer space, are also governed by an international body of law dealing with all communications; the International Telecommunications Union (ITU). The ITU, operating on the basis of the ITU Convention and Radio Regulations, is the body responsible for regulating and coordinating frequency use and associated orbits. See our page on Spectrum Management for more information regarding frequency allocation and coordination.
Element (3) (relating to global and regional navigation satellites traversing through space) is the main feature of GNSS which is subject to space law. The most relevant treaties which affect the space segment of GNSS are:
- Treaty on Principles governing the Activities of States in the Exploration and Use of Outer Space including the Moon and Other Celestial Bodies (1967 Outer Space Treaty)
- Convention on International Liability for Damage Caused by Space Objects (1972 Liability Convention)
- Convention on Registration of Objects Launched in Outer Space (1975 Registration Convention)
From these treaties, there are several principles which apply to the space segment of GNSS and highlight the responsibility of relevant countries (referred to as ‘states’). These include:
- The freedom of use and exploration for the benefit of all mankind;
- the responsibility of states for national activities in outer space;
- the liability of states for physical damage caused by space objects;
- the registration of space objects by states involved in their launching; and
- possible state responsibility to mitigate space debris.
For a comprehensive overview of the international legal framework governing space, see our page on Space Law Fundamentals.
important to know:
Space law provides the initial structure for assessing liability for all activities conducted in space, including GNSS failures that cause damage or loss.
For more information relating to the assessment of liability in space activities, visit our page on Liability and Insurance.
International and national forums relevant to PNT
There are a number of international and national forums which regulate GNSS activities, address GNSS issues, and provide high-quality GNSS data and expertise. These forums should be of key interest to space entrepreneurs interested in GNSS data, products and services as they present an excellent opportunity to engage directly with GNSS regulators and providers.
The ITU facilitates communication networks worldwide by allocating and coordinating radio spectrum and satellite orbits. The ITU establishes global technical standards to ensure seamless connectivity between communication networks and technologies.
For more information, see the ITU website.
The ICG is a forum established under the United Nations which endorses voluntary cooperation on matters related to civil satellite-based PNT and value-added services. Through the establishment of the Providers’ Forum, the ICG encourages coordination among GNSS, RNSS and augmentation system providers to ensure ‘greater compatibility, interoperability, and transparency’.
For more information, see the United Nations Office for Outer Space Affairs website.
The IGS is a voluntary organisation of over 200 self-funded universities, agencies and research institutions from over 100 countries. The mission of the IGS is to ensure open access to high quality GNSS data, products and services in support of PNT and other applications such as Earth observation.
For more information, see the IGS website.
In addition to the international forums outlined above, there are other international organisations which regulate GNSS in the specific fields of aviation and maritime transport:
Geoscience Australia is responsible for maintaining Australia’s geospatial reference system and ensuring global access via positioning and geodetic infrastructure. Geoscience Australia chairs the Positioning, Navigation and Timing Working Group (PNT-WG) established under Australia’s Satellite Utilisation Policy (2013). The PNT-WG is the main coordination body for a number of roles and responsibilities, including sharing information relevant to Government PNT activities and coordinating advice on PNT policy, planning, standards and research.
Geoscience Australia is currently in charge of the National Positioning Infrastructure Project which involves upgrading Australia’s ground-based positioning infrastructure and exploring the feasibility of acquiring a satellite-based augmentation system. Geoscience Australia established a National Positioning Infrastructure Advisory Board (NPI-AB) to provide strategic guidance and advice on developing and implementing the NPI. The roles and responsibilities of the NPI-AB are provided in the NPI-AB Terms of Reference.
For more information regarding the National Positioning Infrastructure Project, visit the Australian Government’s information page here.
For general information regarding Geoscience Australia, visit the Geoscience Australia website.
Frequently Asked Questions (FAQ)
For more information tailored to both the general public and GPS professionals, you can visit gps.gov. There is also a helpful list of external links to federal agencies, GPS contractors and non-profit groups with additional information regarding GPS.
For GPS users looking for more resources, visit the
Navigation Center of Excellence website, established by the United States Department of Homeland Security.
You can find this information here, on the gps.gov website.
The technical documentation available is comprehensive and includes interface specifications and performance standards.
It depends on a number of factors.
According to gps.gov, GPS-enabled smartphones are usually accurate to within a 4.9m radius when the signal is not hindered by buildings, bridges and trees. Users can improve the accuracy of real-time positioning to within a few centimetres, and long-term measurements to within millimetres by using augmentation systems.
For more information, visit the GPS Accuracy webpage.
Yes. Almost 60% of all receivers, chipsets and modules currently available on the market support at least two GNSS constellations.
Multi-GNSS-constellation capability that includes GPS, Galileo, GLONASS and other GNSS services is rapidly becoming a standard feature across all market segments. GNSS providers, such as Galileo and GPS, work directly with chipset and receiver manufacturers to increase the level of their respective GNSS integration into manufacturers’ products.
For more information, particularly in relation to the integration of Galileo services, click
here.
The range of envisaged applications is enormous, spanning both public and private segments across numerous markets.
Applications include:
- The Internet of Things (IoT) (supporting the vast integrated network of connected devices across all sectors);
- location-based services;
- emergency, security and humanitarian services;
- science, environment, weather;
- transport;
- agriculture;
- fisheries;
- civil engineering;
- time-reference function (for communications, finance, banking, insurance, and the energy sector); and
- unmanned systems.