ISO 18197:2015
(Main)Space systems — Space based services requirements for centimetre class positioning
Space systems — Space based services requirements for centimetre class positioning
ISO 18197:2015 defines the requirements for the wide area centimetre class positioning system by broadcasting augmentation data through satellites as follows. - Centimetre class positioning According to the progress of requirements for positioning services such as automatic farming, mapping and others, centimetre class positioning is very useful. - Wide area positioning It is quite effective to broadcast augmentation data through satellites for users over wide area such as a square, more than 1,000 km each side, anytime and anywhere. Even if this area is short of data network, additional ground network facilities are not needed. In addition, as ranging signal and augmentation data can be received from satellite broadcasting at the same time, it is unnecessary for user terminals to receive the signal such as transmitted by ground network. - Real-time property The user terminals need to resolve the ambiguity in real-time, using augmentation data broadcast from satellites or other means, for the realization of centimetre class positioning. On the other hand, the provider sides have to broadcast augmentation data such that the terminal sides are able to resolve the ambiguity in real-time.
Systèmes spatiaux — Exigences de services fondés sur l'espace pour le positionnement de la classe centimètre
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Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 18197
First edition
2015-05-01
Space systems — Space based
services requirements for centimetre
class positioning
Systèmes spatiaux — Exigences de services fondés sur l’espace pour le
positionnement de la classe centimètre
Reference number
ISO 18197:2015(E)
©
ISO 2015
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ISO 18197:2015(E)
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ISO 18197:2015(E)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms . 2
5 Positioning augmentation system overview . 2
5.1 System configuration . 2
5.2 Classification of augmentation satellites . 3
5.3 Positioning augmentation centres . 4
5.3.1 Functions and conditions of the positioning augmentation centres . 4
5.3.2 Message structure . 4
5.3.3 User operational support service . 5
5.4 Operation . 5
5.4.1 Simultaneous operation . 5
5.4.2 Various fields of application . 5
6 Requirements for positioning augmentation system . 5
6.1 Requirements for augmentation satellites. 5
6.2 Requirements for augmentation satellites control stations . 6
6.3 Requirements for ground reference points . 6
6.4 Requirements for positioning augmentation centres . 8
6.4.1 Requirements for some parameters . 8
6.4.2 Requirements for augmentation information . 8
6.5 Requirements for user terminals . 8
6.5.1 Requirements for input parameters . 9
6.5.2 Requirements for the user terminal pre-processing . 9
6.5.3 Requirements for user terminal output .11
6.6 Requirement for processing .11
6.6.1 Requirement for mathematical models .11
6.6.2 Requirement for physical constants .12
7 Requirements for verification and evaluation .12
7.1 Evaluation plan .13
7.1.1 Evaluation procedure.13
7.1.2 Evaluation items .13
7.1.3 Data .13
7.1.4 Evaluation matters .13
7.1.5 Time of verification .13
7.2 Verification conditions .14
7.2.1 Period .14
7.2.2 Place .14
7.2.3 Satellites .14
7.2.4 Reference points . . .14
7.2.5 Augmentation data . .15
7.2.6 Positioning objects .15
7.3 Evaluation criteria .15
7.3.1 Accuracy and convergence of augmentation data.15
7.3.2 Accuracy and convergence of positioning results .15
7.4 Verification methods .15
7.4.1 Estimation process .15
7.4.2 Verification method .16
7.4.3 Research for the cause of malfunction .17
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ISO 18197:2015(E)
Annex A (informative) Verification calculation of bias .18
Annex B (informative) Verification calculation of device specification .19
Annex C (informative) Verification calculation of dependence on place or time .20
Annex D (informative) Orbit constellation for augmentation satellites .21
Annex E (informative) Ground track and antenna coverage of augmentation satellite .23
Annex F (informative) Data volume and transmission rate of augmentation data .27
Annex G (informative) Applications required for centimetre accuracy positioning .29
Bibliography .31
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ISO 18197:2015(E)
Foreword
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The committee responsible for this document is ISO/TC 20, Aircraft and space vehicle, Subcommittee
SC 14, Space systems and operations.
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ISO 18197:2015(E)
Introduction
Nowadays, applications such as civil engineering, automatic farming, traffic control, and disaster
monitoring system need centimetre class positioning. This centimetre class positioning is deeply
concerned with various fields of our daily life.
Especially the positioning system of applications for the construction and civil engineering, surveying
and mapping, and water level measuring for river or ocean, requires certifying the reliability of
positioning system. Also, the case of automatic vehicle driving, ship control, and snowplow on the road
demands the centimetre class positioning capability which is available in real-time and over wide area.
This International Standard intends to standardize the system requirements and verification criteria
for centimetre class positioning over a wide area by broadcasting augmentation data through satellites,
in order that we can enhance the availability of related applications and improve our daily life.
The services broadcasting augmentation data through satellite or satellite-based augmentation system
(SBAS), such as WAAS, EGNOS, and MSAS, are currently in operation for aviation. This SBAS claims the
positioning accuracy of meter level and focuses on high integrity. Also, the SBAS is mainly operated by a
state agency for the sake of human life and internationality of aviation.
On the other hand, the services in this International Standard such as precise point positioning (PPP) require
the positioning accuracy at centimetre level. There are now a number of providers supplying different
sets of PPP corrections. At the same time, this PPP covers different markets such as civil engineering,
automatic farming, and automatic driving. PPP began to outpace SBAS for some applications requiring
higher precision. Therefore, it is inevitably essential to ensure and certify the reliability of the PPP system.
As stated above, from the viewpoint of benefit, it is clear that PPP services continue to evolve and
[7]
become more and more sophisticated to match the growing complexity of customer applications. On
the other hand, in view of rationale, there have been some great strides in overcoming the convergence
time challenge and there are currently some successful real-time PPP applications both academic and
[8]
commercial. The objective of this International Standard is to establish the space based services
by broadcasting the augmentation data for centimetre class positioning over wide area. Also, this
International Standard defines the requirements for verification and evaluation of the guarantee of
quality of the services, and therefore, this International Standard plays a role of the recognition for the
certification of these services as well.
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INTERNATIONAL STANDARD ISO 18197:2015(E)
Space systems — Space based services requirements for
centimetre class positioning
1 Scope
This International Standard defines the requirements for the wide area centimetre class positioning
system by broadcasting augmentation data through satellites as follows.
— Centimetre class positioning
According to the progress of requirements for positioning services such as automatic farming,
mapping and others, centimetre class positioning is very useful.
— Wide area positioning
It is quite effective to broadcast augmentation data through satellites for users over wide area such
as a square, more than 1,000 km each side, anytime and anywhere. Even if this area is short of data
network, additional ground network facilities are not needed. In addition, as ranging signal and
augmentation data can be received from satellite broadcasting at the same time, it is unnecessary
for user terminals to receive the signal such as transmitted by ground network.
— Real-time property
The user terminals need to resolve the ambiguity in real-time, using augmentation data broadcast
from satellites or other means, for the realization of centimetre class positioning. On the other hand,
the provider sides have to broadcast augmentation data such that the terminal sides are able to
resolve the ambiguity in real-time.
2 Normative references
No normative references cited in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
fixing
determining the integer number of carrier phase waves when calculating the position by use of carrier
phase measurement
Note 1 to entry: This should be distinguished from the case of determining the desired value by convergence of
continuous quantities when calculating the position by use of pseudorange measurement.
3.2
sustainability
measurement anomaly at some reference point should make no influence on the augmentation data
generation
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ISO 18197:2015(E)
4 Abbreviated terms
BDS BeiDou Navigation Satellite System
CEP Circular Error Probable
DOP Dilution of Precision
ECEF Earth-Centred Earth-Fixed
ECI Earth-Centred Inertial
GEO Geostationary Earth Orbit
GLONASS Global Navigation Satellite System
GNSS Global Navigation Satellite System
GPS Global Positioning System
IGSO Inclined Geosynchronous Satellite Orbit
IOD Issue Of Data
IRNSS Indian Regional Navigational Satellite System
ITRF International Terrestrial Reference Frame
ITS Intelligent Transportation System
LEO Low Earth Orbit
MEO Medium Earth Orbit
NED North East Down
NRTK Network Real-Time Kinematics
RTK Real-Time Kinematics
QZS Quasi-Zenith Satellite
QZSS Quasi-Zenith Satellite System
5 Positioning augmentation system overview
5.1 System configuration
Figure 1 shows the typical view of positioning augmentation system of centimetre class. Here, this
International Standard does not deal with the ranging signal broadcast from GNSS.
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ISO 18197:2015(E)
Ranging Signal BroadcastingAugmentation Data Broadcasting
Augmentation Satellites
GNSS (GPS, GLONASS, Galileo,
䠄 GEO, IGSO, MEO/LEO 䠅
BDS, QZSS, IRNSS)
Augmentation
Augmentation Data
Data
( Satellite clockerror,
Satellite orbit error,
Ionospheric delay,
Others )
Ranging Signal,
Navigation Data
Augmentation
Augmentation
Satellites
Data Uplink
Control Stations
User Terminals
Positioning
Ranging
Ground
Signal Augmentation Centers
Reference
Calculation of Position
Receiving
Points
Augmentation Data
Generation
Observables
NOTE Bold: facilities, italic: primary functions, normal: signal/data.
Figure 1 — Typical augmentation satellite system for centimetre class positioning
This typical system is configured mainly by the following components:
a) GNSS;
b) augmentation satellites;
c) augmentation satellites control stations;
d) ground reference points;
e) positioning augmentation centres;
f) user terminals.
Each component is explained below.
5.2 Classification of augmentation satellites
An augmentation satellite broadcasts augmentation data, uplinked from the positioning augmentation
centres for users over wide area. Augmentation satellites are classified into the following:
a) geostationary earth orbit satellite (GEO);
b) inclined geosynchronous satellite orbit (IGSO);
c) medium or low earth orbit satellite (MEO/LEO).
The overview and features of various augmentation satellites is shown in Table 1.
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ISO 18197:2015(E)
Table 1 — Overview and features of various augmentation satellites
Observed time
Satellites Orbit height Available
No. per satellite Features
class (km) region
(hr)
Restricted to Operational with one satel-
1 GEO 36 000 24
low latitude lite
Several satellites are needed
Available for
to hand over several times a
2 IGSO around 36 000 8 low, middle, and
day for users to receive the
high latitude
signal continuously
A lot of satellites are needed
Available for
to hand over more frequently
3 MEO/LEO < 36 000 <8 low, middle, and
for users to receive the sig-
high latitude
nal continuously than IGSO
5.3 Positioning augmentation centres
The augmentation centres make augmentation data using the observation data at the ground reference
points. The system sustainability is taken into account when making augmentation data. Some remarks
are described below about the functions and conditions, message structure, and user operational
support service.
5.3.1 Functions and conditions of the positioning augmentation centres
The functions and conditions of the positioning augmentation centres are as follows.
a) Augmentation data generation
The augmentation centres make augmentation data using the observation data at the ground
reference points.
b) Monitoring of operation and measures
The augmentation centres monitor the system operational conditions by analysing data received
from augmentation satellites and reference points so as to detect ionosphere disturbance or others.
Based on the result, this International Standard should assess the influence on ranging signal or
communication link and takes proper measures to recover the situation.
c) Detection of satellite signal anomaly
The augmentation centres calculate the predicted error using observation data at the ground
reference points. The signal analysis is provided to specify the malfunction satellite.
5.3.2 Message structure
Figure 2 shows the example of message structure of augmentation data broadcast from the
augmentation satellite.
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ISO 18197:2015(E)
Error
Header Contents of data
Co rrection Code
NOTE The header contains preamble, satellite number, station number, and message number. The contents of
data correspond to the corrections, that is, satellite clock error, satellite orbit error, ionospheric delay, the status
parameters, and ancillary data, such as those listed in Table F.1. The message format contains the error correction
code, such as a cyclic redundancy code, so as to decode the message correctly.
Figure 2 — Message structure
5.3.3 User operational support service
The system should provide useful information for user terminals as follows.
a) Estimation of positioning error.
b) Condition of ionosphere, such as disturbance of ionosphere.
c) Condition of troposphere, such as anomaly of water vapour as caused by local rainfall, resulting in
the positioning error due to tropospheric delay mismatch.
5.4 Operation
Some remarks on the operation of positioning augmentation system are as follows.
5.4.1 Simultaneous operation
The centimetre class augmentation data can also be used as the meter class augmentation data at the
same time. Therefore, this system enhances the operational variation.
5.4.2 Various fields of application
A variety of industrial fields required for centimetre class positioning is illustrated in Annex G.
6 Requirements for positioning augmentation system
6.1 Requirements for augmentation satellites
Requirements for augmentation satellites of various orbits are described below.
a) Orbit constellation
b) Numbers of satellites
c) Antenna coverage
This means a part on the earth where the transmission signal from the augmentation satellite
can be reached.
d) Transmission signal characteristics
Over the targeted area, under the condition of the minimum elevation angle of the augmentation
satellite, this International Standard establishes the requirements for orbit constellation (satellite
number/orbit plane/phase difference between orbit planes).
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ISO 18197:2015(E)
The examples of orbit constellation of augmentation satellites are shown in Annex D. Corresponding to
the respective orbit constellation, the ground track and the antenna coverage are shown in Annex E.
6.2 Requirements for augmentation satellites control stations
Augmentation satellite control stations shall track and control the augmentation satellite so that it
might broadcast augmentation data for users correctly. Requirements for satellite control stations are
described as follows.
a) Allowable broadcasting latency of augmentation data
The allowable broadcasting latency of augmentation data shall be determined for the following
parameters:
Latency from ground reference points to positioning augmentation centre d1[sec]
Latency from positioning augmentation centre to satellites control station d2[sec]
Latency from satellites control station to augmentation satellite d3[sec]
Latency from augmentation satellite to user terminals d4[sec]
–––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––
Total latency time d1+d2+d3+d4 [sec]
For typical example, d1, d2, d3, and d4 are 1 s, 1 s, 2 s, and 2 s, respectively.
b) Switch of augmentation data between satellites
In the case of switching augmentation satellites which broadcast the augmentation data for the
prescribed area, the procedure for the handover of the augmentation data between relevant
satellites shall be established.
c) Preparation for anomaly in space
The satellites control station shall detect anomaly in space environment or satellite orbits and
embed the alert message or disabled satellites data into the broadcasting signal.
6.3 Requirements for ground reference points
The functions and conditions required for ground reference points shall be shown as follows.
a) Requirements for output signal
— Pseudorange
— Carrier phase
— Signal strength
The information such as data acquisition rate cycle slip, multi-path, shall be used as effectiveness
criterion for augmentation data generation. The following data can be used for verification of the
correctness of augmentation data, which is an optional service that is not necessarily operated by
the ground reference point:
— augmentation data;
— positioning results;
— S/N of ranging signal;
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ISO 18197:2015(E)
— number of ephemeris;
— DOP value
b) Geometrical allocation
— Regular allocation
The ground reference points shall be selected so that they are located regularly or in grid type.
— Irregular allocation
The density of ground reference points varies according to the necessity of the respective regions.
c) Objectives of ground reference points
— Determination of satellite clock error
— Determination of satellite orbit error
— Determination of ionospheric delay
— Determination of tropospheric delay
— Determination of signal biases
— Determination of integer biases
d) Case of distinction between primary and secondary reference points
Augmentation data shall be defined for the primary reference points. But, in some cases, the
augmentation data can be made by use of not only primary reference point data, but secondary
reference point data.
— Reason for the necessity of secondary reference points
e) Case of improper allocation
The method for application of augmentation data shall be clarified in the following cases.
— Case of positioning over ocean
The case should be remarked where no ground reference points are found in the neighbourhood of
the user terminal.
— Case of height difference influence
It should be remarked that augmentation data like tropospheric delay depends on the height
above sea level.
f) Location of reference points
The highly accurate location of all the reference points for augmentation data generation shall be
clarified beforehand.
The ground reference networks in Japan, Germany, France, Europe, United States, China, Latin America,
and the whole world can be referred in Reference [9] to Reference [16], respectively.
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ISO 18197:2015(E)
6.4 Requirements for positioning augmentation centres
6.4.1 Requirements for some parameters
The following parameters shall be determined for the positioning augmentation centres configuration.
a) Data transmission rate
Each correction value shall be updated by its data transmission rate. The correction value shall be
predicted forward using the last correction data. Therefore, the accuracy of the correction value
depends on the data transmission rate.
b) Data fo
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