863

1 EGNOS L1 MARITIME SERVICE

International Maritime Organization (IMO)

Navigation, Communication, Search & Rescue

Subcommittee (NCSR), during its 7th session in

January 2020 [IMO, 2020a], considered the proposal

by Germany, Japan and Poland on a functional

approach and modular structure of performance

standards for shipborne equipment using radio

signals for the provision of information and data for

navigation, including an overview of a structure and

content of performance standards for maritime

radionavigation receivers. This action was based on

invitation from NCSR and MSC dating back to 2018

[IMO, 2018a].

NCSR 7 agreed that the work on the development

of performance standards for shipborne satellite

navigation system receiver equipment should

continue in the context of “satellite” navigation

receiver equipment only and invited interested parties

to progress the work intersessionally and submit

relevant proposals to NCSR 8 for finalization.

Following the invitation a non-formal intersession

correspondence group coordinated by Germany was

established and a proposal to NCSR 8 prepared [IMO,

2021].

NCSR 8 in April 2021 noted that the development

of generic performance standards would still require

further consideration and agreed this time to establish

a formal Correspondence Group (CG) to finalize a

draft MSC resolution by 2022 addressing, in

particular, the relationship with the existing

performance standards [IMO, 2021a].

NCSR 9 in June 2022 appreciated the proposal

developed by CG but noted that the work under this

agenda item consisted of consolidating existing

performance standards and, because no urgent action

was required regarding this matter, NCSR 9 agreed to

postpone consideration of the documents related to

CG work to 2023. The main motivation of the

Challenges Related to Standardization of GNSS/RNSS

Shipborne Equipment by International Maritime

Organization

(IMO)

P. Zalewski

, M. Bergmann

, R. Wawruch

& A. Weintrit

Maritime University of Szczecin, Szczecin, Poland

Bergmann Marine Consultants & Advisors, Germany

Gdynia Maritime University, Gdynia, Poland

ABSTRACT: In 2020 several member states initiated at IMO forum (NCSR subcommittee) a process to create a

single set of generic performance standards consolidating all existing performance standards for shipborne

satellite navigation system receiver equipment without creating any new requirements. After over 4 years the

resultant generic framework for GNSS/RNSS subsystems has not been adopted yet and awaits further

amendments. Analysis of the proposed standards with stress on harmonization issues of the existing, IMO

recognized, global and regional navigation satellite systems and the expected impact of these generic standards

of satellite navigation receivers on the maritime user are presented in this paper. Additionally the strengths,

weaknesses, opportunities, and threats awaiting maritime or shipborne GNSS/RNSS equipment standardization

process are outlined in the paper.

http://www.transnav.eu

the

International Journal

on Marine Navigation

and Safety of Sea Transportation

Volume 17

Number 4

December 2023

DOI: 10.12716/1001.17.04.

864

postponing, though not expressed directly in NCSR 9

report to MSC [IMO, 2022], was NSCR work overload

by other agenda items, and possible consensus issues

deemed hard to resolve during lengthy but restricted

to online form only meetings due to COVID-19

pandemic times.

Finally the documents related to NCSR agenda

item on “Development of generic performance

standards for shipborne satellite navigation system

receiver equipment”, provided by CG led by

Germany [IMO, 2022a] and by United States as

commentary [IMO, 2022b], were considered during

hybrid (stationary and online) NCSR 10 meeting in

May 2023 but with the outcome that can be recognised

as not satisfactory by many maritime stakeholders.

The evolution of maritime Global Navigation Satellite

System (GNSS) and Regional Navigation Satellite

System (RNSS) receivers’ performance standards have

been thoroughly described for interested readers in

[Zalewski et. al., 2022c]. In this paper the authors put

stress on the developed generic framework for

GNSS/RNSS subsystems performance standards,

issues of its acceptance and of harmonisation of the

existing standards.

2 IMO GNSS/RNSS OBLIGATORY INSTRUMENTS

IN FORCE

IMO resolutions on the worldwide radionavigation

system [IMO, 2011] and on performance standards of

shipborne GNSS receivers [IMO, 2000, 2000a, 2000b,

2000c, 2006, 2014, 2015, 2017, 2018, 2020] provide

manufacturers with obligatory parameters for

certification by IEC (International Electrotechnical

Committee) and classification societies, and inform

seafarers of proper receiver setup / choice to meet

PVT (position, velocity, time) data accuracy and

integrity in two designated maritime areas: 1) ocean

waters and 2) harbour entrances, harbour approaches,

and coastal waters. Contents of MSC resolutions on

various shipborne GNSS radionavigation receivers

include common structure of requirements:

The GNSS ”x” - subsystem receiver (display

presented in the fig. 1) should:

− be capable of receiving and processing the ”x”

positioning, velocity, and timing signals;

− provide position information in latitude and longi-

tude in degrees, minutes and thousandths of

minutes;

− provide time referenced to UTC;

− be provided with at least one output from which

PVT information can be supplied to other equip-

ment;

− have static accuracy such that the position of the

antenna is determined to within … m (95%);

− have dynamic accuracy equivalent to …;

− have timing accuracy such that …;

− have a minimum resolution of position, i.e. lati-

tude and longitude, of 0.001 minutes;

− be capable of selecting automatically the appro-

priate satellite-transmitted signals for determining

the ship’s position with the required accuracy and

update rate;

− be capable of acquiring satellite signals with input

signals having carrier levels in the range of … dBm

to … dBm. Once the satellite signals have been

acquired, the equipment should continue to

operate satisfactorily with satellite signals having

carrier levels down to … dBm;

− be capable of operating satisfactorily under nor-

mal interference conditions consistent with the

requirements of resolution A.694(17) [IMO, 1991];

− be capable of acquiring position to the required

accuracy, within … min, when there is no valid

almanac data;

− be capable of acquiring position to the required

accuracy, within … min, when there is valid al-

manac data;

− be capable of re-acquiring position to the required

accuracy, within … min, when subjected to a

power interruption of 60 s;

− generate and output to a display and digital inter-

face a new position solution at least once every 1 s

(for a craft meeting the HSC Code [IMO, 2000d] 0,5

s is recommended);

− provide the COG, SOG and UTC outputs with a

validity mark aligned with that on the position

output. The accuracy requirements for COG and

SOG should not be inferior to the relevant per-

formance standards for heading and speed and

distance measuring equipment (SDME) and the

accuracy should be obtained under the various

dynamic conditions that could be experienced on

board ships;

− have the facilities to process ”x” differential data or

augmentation data.

− should indicate whether performance of ”x” is

outside the bounds of requirements as specified in

A.1046(27) [IMO, 2011].

Figure 1. Example of a contemporary minimum keyboard

display or human-machine interface of GNSS shipborne

receiver.

The table 1 below covers references to IMO

performance standards and IEC standards met by the

exemplary GNSS multisystem shipborne navigation

receiver.

Table 1. Example of a GNSS shipborne receiver

manufacturer’s certificate confirming meeting the IMO and

IEC standards.

________________________________________________

Function IMO Per. Standard IEC Test Standard

________________________________________________

GPS MSC.112(73) IEC61108-1

GLONASS MSC.113(73) IEC61108-2

DGNSS MSC.114(73) IEC61108-4

MULTI(*) MSC.115(73) …

Alert Management MSC.302(87) IEC62923-1/-2

________________________________________________

* Combined GPS/GLONASS

3 GENERIC GNSS/RNSS PERFORMANCE

STANDARDS AT IMO NCSR 10

The document resultant from CG work, finalized in

the beginning of 2022 [IMO, 2022a], provides a

functional approach and modular structure for

performance standards for shipborne satellite

navigation system receiver equipment providing

position, navigation and time (PNT) data and

associated information to watchkeeping team and

865

shipboard applications, e.g. electronic chart display

and information system (ECDIS), automatic

identification system (AIS), integrated navigation

system (INS), global maritime distress and safety

system (GMDSS), long range identification and

tracking system (LRIT), ship security alert system

(SSAS), bridge alert management system (BAM),

voyage data recorder (VDR) and other equipment like

radar, echosounder, marine weather forecast system,

etc. The applicability of the approach was proved by

the exemplary implementation of a performance

standard for shipborne Quasi-Zenith Satellite System

(QZSS) and BeiDou Navigation Satellite System

(BDS), as well as Galileo receiver equipment, into the

proposed modular documentation structure.

The figure 2 presents structure of the proposed

generic performance standards for shipborne GNSS

receivers providing PNT data and associated

information.

Figure 2. Structure of the proposed generic performance

standards for shipborne GNSS receiver equipment (source:

[IMO, 2022a]).

Such a structure allowed for differences in

installed equipment and implementation options,

measurements principles, supported functionalities,

signal sources, scope of data as well as usability in

specific regions. Concurrently, the generic

performance standards provided a harmonized and

logically structured compilation of recommendations

for shipborne radionavigation receivers providing

position, velocity and time (PVT) data and associated

information by using radio signals from one or more

radio navigation services, according to the modular

concept. For these performance standards, a

radionavigation receiver is characterized as an entity

with the ability to carry out at least the following:

1. the conversion of radio waves into signals by

means of antennas and radio frequency front-ends;

2. the determination of PVT data and associated in-

formation by means of signal and data processing;

data management with other equipment and sys-

tems including input and output data, status in-

formation, configuration parameters, control data

and alerts;

3. if applicable, a human-machine interface (HMI) to

display the provided data for navigation and to

enable the configuration and control of the ship-

borne equipment. The HMI should either be inte-

grated with the equipment itself or be provided as

an external component, as part of a multi-

functional display.

The functional / technical architectures of the

expected three receiver’s configurations are presented

in the figures 3, 4, and 5. They comprise the following

elements:

− antenna with RF frontend;

− signal and data processing including PNT data

processing (PNT-DP), if applicable;

− increased accuracy, integrity monitoring and alert

management, if applicable;

− data management to facilitate the data exchange

for input/output messaging, configuration, con-

trolling, alerting, and status reporting, if applica-

ble.

They are categorised by a human-machine

interface (HMI). The HMI for input (configuration,

controlling) and output (data, alerts, status report) to

facilitate human-machine interactions can be either:

1. intrinsically built into receiver’s structure (figure 3)

2. with increased automation, the operational use of

HMIs for controlling, alerting or reporting, may be

rendered obsolete - therefore, the corre-sponding

architecture of the radionavigation re-ceiver would

not contain the HMI (figure 4) or

3. the modular arrangement of a radionavigation

receiver may result in a separation of the HMI

from the original receiver, as illustrated in the

figure 5.

A separation of the HMI from the original receiver

or architecture without HMI results in additional

recommendation that the receiver and the HMI

should be equipped with a standardised bi-directional

interface to exchange the output data and associated

information and to control alerting and reporting

from the receiver for proper operation.

Figure 3. Architecture of the shipborne GNSS receiver with

HMI included (source: [IMO, 2022a]).

866

Figure 4. Architecture of the shipborne GNSS receiver

without HMI (source: [IMO, 2022a]).

Figure 5. Architecture of the shipborne GNSS receiver with

separated HMI (source: [IMO, 2022a]).

If available, the radionavigation receiver may also

use data from augmentation and correction services to

improve the performance of PVT data and to provide

associated integrity and status information. Future

radionavigation receivers with changed functionality

should be represented by new functional groups.

The CG has also worked on satellite based

augmentation systems (SBAS) issue and prepared a

suggestion on how to include SBAS systems (e.g.,

WAAS, EGNOS) as additional annexes to this generic

performance standard. Additionally, United States in

their commentary document have added the

functionality to detect and indicate to the user by

signal to noise ratio (SNR) values the presence of

radio frequency interference from in-band emission

that could be experienced on board ships. This has

paved a way to possibility to include SBAS

functionality, SNR and integrity data processing

according to the current research [Zalewski, 2020].

Finally, it was agreed by the CG that these

performance standards have been developed under

the scope of the consolidation of existing and when

available future GNSS performance standards also

featuring capabilities of radionavigation receivers.

Existing recommendations of current single GNSS

and RNSS performance standards have been

integrated within these performance standards. The

performance recommendations are identical to those

given by the single system performance standards

and have been consolidated within the annexes of

these performance standards without raising new or

additional recommendations. The current single

GNSS or RNSS performance standard should remain

in force until it is superseded by the single GNSS or

RNSS performance standard adopted as a system-

specific annex of the new generic standard.

4 ISSUES IDENTIFIED AT IMO NCSR 10 AND MSC

107

Firstly, during the discussion at IMO NCSR 10 [IMO,

2023] not all but five out of the six recognized GNSSs

administrations supported the adoption of the new

draft performance standards, though all them were

involved in CG work and consented to these

standards when the report was submitted.

Secondly, the representative of one of the

recognized GNSSs noted that the draft resolution

setting out the framework without including

specifications of minimum functions to be achieved

by receivers could not be the performance standards,

hence merely giving the guidance and as such should

not be a resolution. If a guidance was developed, it

should be disseminated as a circular similar to the

Guidelines for shipborne position, navigation and

timing (PNT) data processing [IMO, 2017a], which

had been developed as associated guidelines to

resolution on Performance standards for multi-system

shipborne radio navigation receivers [IMO, 2015]. The

NCSR work group concluded that some additional

work to fully address this concern is necessary. In this

context, it was recalled that:

1. when this output had been discussed and agreed,

the intention was to create a single set of generic

performance standards consolidating all existing

performance standards for shipborne satellite nav-

igation system receiver equipment, without creat-

ing any new requirements;

2. to meet the current performance standards defini-

tions and ensure no unnecessary type approval are

required, the proposal developed by the CG ad-

dressed that by presenting a "framework" for fu-

ture development of general and specific recom-

mendations for shipborne radionavigation receiv-

ers providing PNT data and associated infor-

mation;

3. it was very important that the outcome of this work

is confirmed and agreed, in particular, by those

Member States that had established systems

already recognized by the Organization. This in-

cludes GPS (United Sates), GLONNAS (Russian

Federation), Galileo (European Commission), BDS

(China), IRNSS (India) and QZSS (Japan);

4. that it was also important to confirm the applica-

tion of any new resolution to be adopted in terms

of existing and new installations and whether this

would revoke or supersede previous resolutions

adopted by the Organization.

Thirdly, some other comments were expressed,

such as that the proposed performance standards

have covered also new stipulations for some systems

instead of consolidating only the current ones. For

instance the functionality of receiver autonomous

867

integrity monitoring (RAIM) was included for all

GNSS/RNSS receivers, but currently not all

performance standards require that the results of

RAIM should be used for the provision of status and

integrity information contributing to alert

management and an integrity warning of system

malfunction, non-availability or discontinuity, and

they should be provided to users within 10 sec.

Similar concern arises regarding SNR or

augmentation data needed by advanced RAIM

(ARAIM). The EUSPA research shows that maritime

users still have very basic knowledge of RAIM

algorithms in GNSS receivers and their interpretations

[EUSPA, 2021].

The discussion at NCSR finalized with request to

MSC for extension of the completion year to 2024 and

alteration of the scope of this output to develop a

framework document instead of strict performance

standards. Anyway, the MSC during its 107 session

noted that the urgency and possible implications for

existing performance standards of a change of scope

of the output (consolidation of performance

standards) had not been thoroughly considered by the

NCSR, and NCSR had too high current workload to

proceed with this output right away. Doubts if the

intended application of the new resolution would be

both for existing and newly installed receivers were

also expressed. So, the final decision was not to agree

to extend the target completion year of the

GNSS/RNSS performance standards output and to

move the output “Development of generic

performance standards for shipborne satellite

navigation system receiver equipment” to the post-

biennial agenda until a clear indication of the new

scope of the work is conducted and information on

the associated implications are provided by the NCSR.

5 DISCUSSION

Some of the concerns raised by the opposition to the

new generic performance standards for shipborne

satellite navigation system receiver equipment can be

mitigated rationally:

1. Developing a standard to combine all GNSS PS into

a single PS.

As described in the report of the CG, the CG

recognized that there are both common aspects for

all GNSS/RNSS, as well as certain aspects of the

individual PS which only apply to the individual

systems given their different technologies used. As

such the development of a single minimum PS

applicable for all GNSS/RNSS receivers would not

adequately address all system specific

requirements currently described and agreed to by

IMO in the individual PS. To resolve this issue the

CG developed the presented structure of the

Generic PS to contain the minimum PS aspects

applicable to all GNSS in the annex of the draft

MSC Resolution. But to also capture the aspects of

the individual GNSS PS only applicable to an

individual PS, appendices are suggested to contain

specific receiver requirements for any GNSS/RNSS

to be included in the new Generic GNSS/RNSS

receiver PS. This way a single MSC resolution is

suggested to address both generic as well as

individual PS components.

2. The Generic GNSS/RNSS PS should reduce the

administrative burden and avoid the need for type

new approvals for existing systems.

To address this concern the recommended new

MCS Resolution should include a numbering and

versioning schema for both the generic part

(Annex) as well as the individual parts per

GNSS/RNSS (Appendices). The type approval

would be executed with both the generic

specifications (Annex) as well as the applicable

individual parts (Appendix or, for multi receivers

Appendices). If a system is to be certified for BDS

as an example, it would be certified according to

version 1 of annex relevant part as well as version

x of relevant appendix. This way the addition of a

next appendix (for example for Galileo) will have

no affect to any BDS receivers, as well as any

changes to another appendix.

3. The current GNSS/RNSS system administrations

should individually be able to decide of the mi-

gration from the individual PS to the Generic PS.

The shifting of data from current individual

performance standards to the new generic

template is in sole discretion of GNSS/RNSS

system administration – the performance

standards in new format must be input to MSC,

adopted and the previous ones revoked. It is

recommended to perform this migration once an

update of the system PS is necessary, as then new

type approval is necessary anyhow. Member states

or organizatio

ns (like EC) who do not want to

switch to new template will have their standards

written as they are, until the time they decide to

suggest amendments to the PS of the GNSS/RNSS

they are responsible for.

4. The suggested PS doesn’t include an existing

GNSS/RNSS and as such is currently not appli-

cable to any system.

This is a correct statement, and it is intentionally

done this way. During the development of the

framework of this single generic PS all existing

GNSS/RNSS have been included as appendices.

This was done to ensure that all existing GNSS PS

can be merged into the suggested Generic

Standard. But to avoid unnecessary administrative

actions, like re-type approval, only a template has

been developed. The appendix FG-1-1 for QZSS,

FG-1-2 for Galileo and FG-1-3 for BDS have been

added for illustration purposes only. According to

stipulations in the proposed standard the

respective organization could decide when they

want to migrate.

5. The document with United States comments [IMO,

2022b] or other additional requirements.

Additional requirement for GNSS/RNSS

equipment could be added individually to a

system relevant appendix. New functional

requirement would not have to be applicable to

existing individual GNSS/RNSS PS or it can reduce

the administrative burden to the organizations as

by one simple addition to the generic part it

becomes applicable to all included GNSS/RNSS PS.

868

6 CONCLUSIONS

To outline some of the strengths, weaknesses,

opportunities, and threats awaiting maritime GNSS

standardization process, a SWOT analysis is

presented in the Table 2.

Concluding:

1. Adoption of generic GNSS/RNSS/SBAS receiv-ers

performance standards will be possible if common

consensus between IMO recognised GNSS/RNSS

administrations is reached.

2. IMO MSC agreed to include in its post-biennial

agenda an output on “Development of procedures

and requirements for the recognition of augmen-

tation systems in the World-wide radionavigation

system”, with one session needed to complete the

item; and an output on “Development of perfor-

mance standards for dual frequency multi-

constellation satellite-based augmentation systems

(DFMC SBAS) and advanced receiver autono-

mous integrity monitoring (ARAIM) in shipborne

radionavigation receivers”, with two sessions

needed to complete the item.

3. Inclusion of integrity, continuity and availability

parameters requires adoption of standard algo-

rithm of protection level calculation for high level

RAIM / ARAIM. There is a disagreement in mari-

time community over practical values of time

scope for continuity, availability and integrity.

4. Maritime users still have very basic knowledge of

RAIM algorithms in GNSS receivers and their in-

terpretations.

Table 2. SWOT analysis of maritime GNSS standardization

process.

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