ISO 24246:2022

Space systems — Requirements for global navigation satellite system (GNSS) positioning augmentation centers

This document specifies requirements for GNSS positioning augmentation centres that distribute correction data to provide higher accuracy and integrity information for positioning users in the civil and commercial market. The GNSS positioning augmentation centres cover the following types of positioning: a) real-time sub-meter to decimetre-level positioning; b) real-time centimetre-level positioning; c) post-processed geodetic positioning. This document also specifies roles of the following stakeholders and functions of the software present at GNSS positioning augmentation centres: — role of planner; — role of designer; — role of administrator; — function of software.

Titre manque

General Information

• Status: Published
• Publication Date: 27-Jun-2022
• ICS: 49.140 - Space systems and operations
• Technical Committee: ISO/TC 20/SC 14 - Space systems and operations
• Drafting Committee: ISO/TC 20/SC 14/WG 1 - Design engineering and production
• Current Stage: 6060 - International Standard published
• Start Date: 28-Jun-2022
• Due Date: 25-Jun-2022
• Completion Date: 28-Jun-2022

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 24246
First edition
2022-06
Space systems — Requirements for
global navigation satellite system
(GNSS) positioning augmentation
centers
Reference number
ISO 24246:2022(E)
© ISO 2022
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ISO 24246:2022(E)
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© ISO 2022

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ISO 24246:2022(E)
Contents Page

Foreword ..........................................................................................................................................................................................................................................v

Introduction .............................................................................................................................................................................................................................. vi

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ..................................................................................................................................................................................... 1

3 Terms and definitions .................................................................................................................................................................................... 1

3.1 Space-based positioning and navigation ......................................................................................................................... 2

3.2 Positioning quality .............................................................................................................................................................................. 2

3.3 Terrestrial reference system ..................................................................................................................................................... 4

3.4 Positioning results .............................................................................................................................................................................. 6

3.5 Cyber security ......................................................................................................................................................................................... 7

4 Abbreviated terms ............................................................................................................................................................................................. 8

5 System overview .................................................................................................................................................................................................. 9

6 Universe of discourse ......................................................................................................................................................................................9

6.1 General ........................................................................................................................................................................................................... 9

6.2 Scope of users ....................................................................................................................................................................................... 10

6.3 Service type ............................................................................................................................................................................................ 10

6.4 Service area ............................................................................................................................................................................................ 10

6.5 Service time ........................................................................................................................................... ................................................. 10

6.6 Sponsoring organization ............................................................................................................................................................ 10

7 Requirements for augmentation services .............................................................................................................................11

7.1 General ........................................................................................................................................................................................................ 11

7.2 Standard augmentation service ........................................................................................................................................... 11

7.3 Precise augmentation service ................................................................................................................................................12

7.4 Geodetic service ................................................................................................................................................................................. 13

7.5 Performance factors ....................................................................................................................................................................... 13

7.5.1 General .....................................................................................................................................................................................13

7.5.2 Communicable correction factors.................................................................................................................... 13

7.5.3 Receiver-dedicated correction factors ........................................................................................................ 14

7.5.4 Other correction factors ........................................................................................................................................... 14

7.6 Integrity information .................................................................................................................................................................... 14

8 Requirements for verification ............................................................................................................................................................15

8.1 General ........................................................................................................................................................................................................ 15

8.2 Distinction of accuracy and precision ............................................................................................................................ 15

8.3 Verification ...................................................................... ........................................................................................................................ 16

8.3.1 Principle .................................................................................................................................................................................. 16

8.3.2 Horizontal .............................................................................................................................................................................. 16

8.3.3 Vertical ..................................................................................................................................................................................... 16

8.4 Calibration ............................................................................................................................................................................................... 16

8.5 Evaluation period .............................................................................................................................................................................. 16

8.6 Convergence time .............................................................................................................................................................................. 17

8.7 Quality control items ..................................................................................................................................................................... 17

9 Requirements for maintenance ........................................................................................................................................................17

9.1 General ........................................................................................................................................................................................................ 17

9.2 Continuous performance monitor ...................................................................................................................................... 17

9.3 Cyber security ...................................................................................................................................................................................... 17

9.4 User service ............................................................................................................................................................................................ 17

Annex A (informative) Cross-border data exchange .......................................................................................................................18

Annex B (informative) GNSS constellations and systems ...........................................................................................................19

Annex C (informative) Transmission of augmentation data ...................................................................................................20

iii
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ISO 24246:2022(E)

Annex D (informative) Positional reference for precise navigation ...............................................................................21

Annex E (informative) Meaconing in radionavigaion .....................................................................................................................24

Annex F (informative) Approaches to evaluate positioning quality ...............................................................................25

Bibliography .............................................................................................................................................................................................................................26

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ISO 24246:2022(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www.iso.org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to

the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see

www.iso.org/iso/foreword.html.

This document was prepared by Technical Committee ISO/TC 20, Aircraft and space vehicles,

Subcommittee SC 14, Space systems and operations.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www.iso.org/members.html.
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ISO 24246:2022(E)
Introduction

In the initial decades of the 21st century, several countries provide their constellations of global

navigation satellite system (GNSS) such as U.S. GPS, Russian GLONASS, European Galileo, Chinese BDS,

Indian NavIC, Japanese QZSS and SBASs; and they have been utilized as an international public service.

GNSS positioning applications have been expanding in each region across the world.

In order to maximize the capability of these GNSS constellations, the respective regions have deployed

GNSS positioning augmentation centres with continuously operating reference station (CORS) network.

These facilities generate different types of corrections to mitigate atmospheric propagation errors

and satellite errors, as well as providing integrity information. The application of these augmentation

functions helps to achieve higher performance for GNSS positioning.

Along with the development of the GNSS constellations, GNSS reference stations have been established

across populous and economic areas of the world. Industrialized countries have adopted precise

positioning thanks to this integrated GNSS infrastructure in global, regional and national areas.

Positioning users in other parts of the world require similar GNSS infrastructure.

This document is intended to resolve the issue that the users in other areas of the world need similar

infrastructure and aims to provide high-performance GNSS standards for users around the world.

ISO TC 20 has published "ISO TC 20 business plan 2015" (https://www.iso.org/committee/46484. html).

In 2.1.2 of the business plan, TC 20 has specified that “Space systems are defined as Space segments,

Ground Segments and services (or applications)”; namely, space systems are defined to include the

service or application.

In the past ten years, ISO TC 20/SC 14/WG 1 has discussed the standardization of space-based services

based on "ISO TC 20 business plan 2015", because space systems provide a huge merit for the economy

and society in each country today and space-based services contribute to people’s quality of life across

the world. Space systems should be utilized furthermore in the world industry also after this time.

Today, the market has required precise navigation for automated craft and vehicles. One of the most

important requirements is the safety of navigation. In response to this requirement, the space systems

community is determined to take leadership of the use of space systems such as GNSS, for other

downstream areas of application and service. ISO TC 20/SC 14 and its WG1 collaborate and cooperate

with TC 20/SC 13, other ISO TCs, IEC TCs and harmonize the standards by international organizations

in the GNSS-relevant area shown as Figure 1.
Figure 1 — Standardization of space-based services (GNSS-relevant area)
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ISO 24246:2022(E)

The GNSS project of ISO has respected the International Committee on Global Navigation Satellite

Systems (ICG) and the Global Geospatial Information Management (GGIM) of the United Nations (UN)

and its achievements. The UN’s recommendations are reflected in this document.

This document is applicable in the civil and commercial market. Because these markets increasingly

require high accuracy positioning utilized in automated flight, driving and navigation, it is necessary to

standardize GNSS positioning augmentation centres in this document.

ISO TC 20/SC 14 already published ISO 18197, which specified the total matters of system engineering,

On the other hand, this document has focused on GNSS positioning augmentation centres as one element

of GNSS centimetre class positioning. For the realization of the actual infrastructure, both ISO 18197

and this document should be used.

GNSS applications are emerging industry. Space systems appears to be reaching to incorporated other

activities beyond space and aircraft platform for navigation. High performance positioning which is

described in this document contributes the safety of navigation after this time.
vii
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INTERNATIONAL STANDARD ISO 24246:2022(E)
Space systems — Requirements for global navigation
satellite system (GNSS) positioning augmentation centers
1 Scope

This document specifies requirements for GNSS positioning augmentation centres that distribute

correction data to provide higher accuracy and integrity information for positioning users in the civil

and commercial market.

The GNSS positioning augmentation centres cover the following types of positioning:

a) real-time sub-meter to decimetre-level positioning;
b) real-time centimetre-level positioning;
c) post-processed geodetic positioning.

This document also specifies roles of the following stakeholders and functions of the software present

at GNSS positioning augmentation centres:
— role of planner;
— role of designer;
— role of administrator;
— function of software.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

ISO 18197, Space systems — Space based services requirements for centimetre class positioning

ISO 19161-1:2020, Geographic information — Geodetic references — Part 1: International terrestrial

reference system (ITRS)

Annex ICAO, 10 – Aeronautical Telecommunications – Volume I – Radio Navigation Aids.

3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminology databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
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ISO 24246:2022(E)
3.1 Space-based positioning and navigation
3.1.1
radiodetermination

determination of the position, velocity, timing and/or other characteristics of an object, or the obtaining

of information relating to these characteristics, by means of radio waves
[SOURCE: IEC 60050-725:1994, 725-12-48, modified — “timing” has been added.]
3.1.2
satellite radiodetermination
radiodetermination (3.1.1) which makes use of a satellite system
[SOURCE: IEC 60050-725:1994, 725-12-49]
3.1.3
radionavigation

radiodetermination (3.1.1) used for the purpose of navigation, including obstruction warning

[SOURCE: IEC 60050-725:1994, 725-12-50]
3.1.4
satellite radionavigation
satellite radiodetermination (3.1.2) used for radionavigation (3.1.3)
[SOURCE: IEC 60050-725:1994, 725-12-51]
3.1.5
universe of discourse
view of the real or hypothetical world that includes everything of interest
[SOURCE: ISO 19101-1:2014, 4.1.38]
3.1.6
positioning augmentation centre

centring system that augments the function of another infrastructural positioning system

Note 1 to entry: An administrator of positioning augmentation centre is a person or a organization who operates,

maintains, and responds to users on the service of the above centre.
3.2 Positioning quality
3.2.1
accuracy

closeness of agreement between a test result or measurement result and the true value (3.2.5)

Note 1 to entry: In practice, the accepted true value (3.2.6) is substituted for the true value.

Note 2 to entry: The term “accuracy”, when applied to a set of test or measurement result, involves a combination

of random components and a common systematic error or bias (3.2.2) component.
Note 3 to entry: Accuracy refers to a combination of bias and precision (3.2.3).

[SOURCE: ISO 3534-2:2006, 3.3.1, modified — In Note 1 to entry, "accepted reference value" has been

changed to "accepted true value"; in Note 3 to entry, “trueness” has been changed to “bias”.]

3.2.2
bias

difference between the expectation of a test result or measurement result and a true value (3.2.5)

Note 1 to entry: Bias is the total systematic error as contrasted to random error. There may be one or more

systematic error components contributing to the bias. A larger systematic difference from the true value is

reflected by a larger bias value.
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ISO 24246:2022(E)

Note 2 to entry: The bias of a measuring instrument is normally estimated by averaging the error of indication

over an appropriate number of repeated measurements. The error of indication is the: “indication of a measuring

instrument minus a true value of the corresponding input quantity”.

Note 3 to entry: In practice, the accepted true value (3.2.6) is substituted for the true value.

[SOURCE: ISO 3534-2:2006, 3.3.2 modified — In Note 3 to entry, "accepted reference value" has been

changed to "accepted true value".]
3.2.3
precision

closeness of agreement between independent test/measurement results obtained under stipulated

conditions

Note 1 to entry: Precision depends only on the distribution of random errors and does not relate to the true value

(3.2.5) or the specified value.

Note 2 to entry: The measure of precision is usually expressed in terms and imprecision and computed as a

standard deviation of the test results or measurement results. Less precision is reflected by a larger standard

deviation.

Note 3 to entry: Quantitative measures of precision depend critically on the stipulated conditions. Repeatability

conditions and reproducibility conditions are particular sets of extreme stipulated conditions.

[SOURCE: ISO 3534-2:2006, 3.3.4]
3.2.4
integrity

measure of the trust that can be placed in the correctness of the information supplied by a navigation

system and that includes the ability of the system to provide timely warnings to users when the system

should not be used for navigation
[36]
[SOURCE: 2019 Federal Radionavigation Plan, DOT-VNTSC-OST-R-15-01, A.1.10]
3.2.5
true value

value which characterizes a quantity or quantitative characteristic perfectly defined in the conditions

which exist when that quantity or quantitative characteristic is considered

Note 1 to entry: The true value of a quantity or quantitative characteristic is a theoretical concept and, in general,

cannot be known exactly.
[SOURCE: ISO 3534-2:2006, 3.2.5, modified — Note 2 to entry has been deleted.]
3.2.6
accepted true value
value that serves as an agreed-upon reference for comparison
Note 1 to entry: The accepted true value is derived as:
a) a theoretical or established value, based on scientific principles;

b) an assigned or certified value, based on experimental work of some national or international organization;

c) a consensus or certified value, based on collaborative experimental work under the auspices of a scientific or

technical group;

d) the expectation, i.e. the mean of a specified set of measurements, when a), b) and c) are not available.

[SOURCE: ISO 3534-2:2006, 3.2.7, modified — The term has been changed from "accepted reference

value" to "accepted true value".]
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ISO 24246:2022(E)
3.2.7
state space

space defined by the state variables as axes of a vector space, in which every vector represents a state

of the system
Note 1 to entry: A vector space is defined in IEC 60050-102:2017, 102-03-01.

Note 2 to entry: “space” is this term is a mathematical vector space, and if different from “space” of a physical

universe.

[SOURCE: IEC 60050-351:2013, 351-41-09, modified — Notes 1 and 2 to entry have been added.]

3.3 Terrestrial reference system
3.3.1
coordinate
one of a sequence of numbers designating the position of a point

Note 1 to entry: In a spatial coordinate reference system (3.3.3), the coordinate numbers are qualified by units.

[SOURCE: ISO 19111:2019, 3.1.5]
3.3.2
coordinate system

set of mathematical rules for specifying how coordinates (3.3.1) are to be assigned to points

[SOURCE: ISO 19111:2019, 3.1.11]
3.3.3
coordinate reference system
coordinate system (3.3.2) that is related to an object by a datum (3.3.4)

Note 1 to entry: Geodetic and vertical datums are referred to as reference frames.

Note 2 to entry: For geodetic and vertical reference frames, the object will be the Earth. In planetary applications,

geodetic and vertical reference frames may be applied to other celestial bodies.
[SOURCE: ISO 19111:2019, 3.1.9]
3.3.4
datum

parameter or set of parameters that realize the position of the origin, the scale, and the orientation of a

coordinate system (3.3.2)

Note 1 to entry: “Reference frame” is an alias of “datum” in the field of geodesy (see SOURCE). But in space

systems area, “reference frame” means a platform-fixed coordinate system of a spacecraft or a space station.

Therefore, “reference frame” is not used as an alias of “datum” in this document.

[SOURCE: ISO 19111:2019, 3.1.15, modified — The alternative preferred term “reference frame” has bee

deleted; note 1 to entry has been added]
3.3.5
coordinate operation

process using a mathematical model, based on a one-to-one relationship, that changes coordinates

(3.3.1) in a source coordinate reference system (3.3.3) to coordinates in a target coordinate reference

system, or that changes coordinates at a source coordinate epoch to coordinates at a target coordinate

epoch within the same coordinate reference system
[SOURCE: ISO 19111:2019, 3.1.8]
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ISO 24246:2022(E)
3.3.6
coordinate transformation

coordinate operation (3.3.5) that changes coordinates (3.3.1) in a source coordinate reference system

(3.3.3) to coordinates in a target coordinate reference system in which the source and target coordinate

reference systems are based on different datums (3.3.4)

Note 1 to entry: A coordinate transformation uses parameters which are derived empirically. Any error in those

coordinates will be embedded in the coordinate transformation and when the coordinate transformation is

applied the embedded errors are transmitted to output coordinates.

Note 2 to entry: A coordinate transformation is colloquially sometimes referred to as a 'datum transformation'.

This is erroneous. A coordinate transformation changes coordinate values. It does not change the definition

of the datum. In this document, coordinates are referenced to a coordinate reference system. A coordinate

transformation operates between two coordinate reference systems, not between two datums.

[SOURCE: ISO 19111:2019, 3.1.12]
3.3.7
ellipsoid
reference ellipsoid

geometric reference surface embedded in 3D Euclidean space formed by an ellipse that is

rotated about a main axis

Note 1 to entry: For the Earth the ellipsoid is bi-axial with rotation about the polar axis. This results in an oblate

ellipsoid with the midpoint of the foci located at the nominal centre of the Earth.

[SOURCE: ISO 19111:2019, 3.1.22]
3.3.8
mean sea level

average level of the surface of the sea over all stages of tide and seasonal variations

Note 1 to entry: Mean sea level in a local context normally means mean sea level for the region calculated from

observations at one or more points over a given period of time. To meet IHO, standards that period should be one

full lunar cycle of 19 years. Mean sea level in a global context differs from a global geoid (3.3.9) by not more than

2 m.
[SOURCE: ISO 19111:2019, 3.1.41]
3.3.9
geoid

equipotential surface of the Earth’s gravity field which is perpendicular to the direction of gravity and

which best fits mean sea level (3.3.8) either locally, regionally or globally
[SOURCE: ISO 19111:2019, 3.1.36]
3.3.10
vertical datum

datum describing the relation of gravity-related heights (3.4.5) or depths (3.4.6) to the Earth

Note 1 to entry: In m
...