23
1 INTRODUCTION
Themaritimesectorwasoneofthefirstcommunities
that recognized and exploited the opportunities and
advantages provided by GNSS systems. In fact, the
introductionofGNSSrepresented agreat revolution
inthemaritimefield.
GNSS positioning has progressively acquired
moreandmorerelevanceinallshipssailing around
theglobe.Atthebeginning,GNSSwasonlyusedasa
way to know the current position, but toda
y GNSS
receivers are connected and integrated with other
differentfunctionssuchasIntegratedBridgeSystems,
ECDIS,ARPA,GMDSS,AIS,LRITorVDR.
It is recognised that Global Navigation Satellite
Systems (GNSS)havebecome the prima
ry means of
obtaining Position, Navigation and Timing (PNT)
information at sea. Most of the ships in the world
(even in the recreational and leisure field) are
equipped with GNSS receivers (SOLAS carriage
requirement). And nowadays these users take
advantageofdifferentaugmentationsystemssuchas
DGNSS or SBAS/EGNOS, as they provide an
adequat
eanswer,especiallyintermsofaccuracyand
integrity.
Thequestionis:howmanyoftheGNSSonboard
equipmentareSBASready?Toanswerthisquestion,
thispaperpresentstheresultsofthesurveythathas
been done among a large set of approved maritime
devicesincludingaGNSSreceiver.
1.1 WhatisEGNOS?
Sat
ellitenavigationsystemsaredesignedtoprovidea
positioningandtimingserviceovervastgeographical
areas (typically continental or global coverage) with
high accuracy performance. However, a number of
SBAS/EGNOS Enabled Devices in Maritime
M.López
GSA,EuropeanGlobalNavigationSatelliteSystemsAgency,Prague,CzechRepublic
V.Antón
ESSP,EuropeanSatelliteServicesProvider,Madrid,Spain
ABSTRACT:Nowadays,itisafactthatGlobalNavigationSatelliteSystems(GNSS)havebecometheprimary
meansofobtainingPosition, NavigationandTiming(PNT)informationatsea.Mostoftheshipsintheworld
are equipped with GNSS receivers. And currently these users take adv
antage of different augmentation
systemssuchasDGNSSorSBAS/EGNOS,astheyprovideanadequateanswer,especiallyintermsofaccuracy
andintegrity.
To take advantage of this improved accuracy, direct access to EGNOS in vessels can be achieved through
EGNOS‐enablednavigationreceiversandEGNOS‐enabledAIStransponders.Therefore,thenaturalquest
ion
is:ArethoseGNSSreceiversSBAS(EGNOS)enabled?Inmostcasestheyare;SBASisbeingused.Thispaper
provides an analysis of the number of onboard devices, mainly devoted to navigation purposes and AIS
transponders,whichareSBAScompatible.
http://www.transnav.eu
the International Journal
on Marine Navigation
and Safety of Sea Transportation
Volume 12
Number 1
March 2018
DOI:10.12716/1001.12.01.01
24
eventsmayleadtopositioningerrors.Satellite‐Based
Augmentation Systems (SBAS) are designed to
augment the navigation system constellations by
broadcasting additional signals from geostationary
(GEO) satellites. EGNOS (European Geostationary
Navigation Overlay Service) is the European SBAS
providing an augmentation service to the Global
PositioningSystem(GPS).
EGNOShasbeen
designedtobroadcastaGPS‐like
rangingsignalinEuropewithembeddedcorrections,
providing improved performances over GPS. With
EGNOS, all navigation receivers will benefit from
enhanced accuracy, availability and continuity over
GPS.
TheEGNOScoverageareaisWesternEurope,but
could be readily extended to include other regions
within
the broadcast area of the geostationary
satellites,such asAfrica. EGNOSisthefirstelement
of the European satellite‐navigation strategy and a
major stepping‐stone towards Galileo, Europeʹs own
globalsatellitenavigationsystemforthefuture.
In addition to EGNOS, there are other SBAS
around the world with similar
characteristics and
compatible among them. Figure 1 presents the
coverageofthedifferentSBASsystemsintheworld.
Figure1.ExistingandplannedSBASsystems
The main objective of the EGNOS Open Service
(EGNOSOS)istoimprovetheachievablepositioning
accuracybycorrectingseveralerrorsourcesaffecting
theGPSsignals.Thecorrectionsfreelytransmittedby
EGNOSgeostationarysatellitescontributetomitigate
the ranging error sources related to satellite clocks,
satellitepositionandionosphericeffects.The
EGNOS
OS minimum accuracy is specified in the following
table[1].
Table1.EGNOSOSHorizontalandVerticalAccuracy
_______________________________________________
Accuracy DefinitionValue
_______________________________________________
Horizontal Correspondstoa95%confidence 3m
boundofthe2‐dimensionalposition
errorinthehorizontallocalplanefor
theWorstUserLocation
Vertical Correspondstoa95%confidence 4m
boundofthe1‐dimensionalunsigned
positionerrorinthelocalverticalaxis
fortheWorstUser
Location
_______________________________________________
Accuracy Definition Value
2 ONBOARDGNSSRECEIVERS‐SOLAS
CONVENTION
To have a picture of what kind of navigation
equipment can be found onboard vessels, SOLAS
Convention [2] must be consulted. The SOLAS
Conventionisconsideredasthemostimportantofall
international treaties concerning the safety of
merchantships.ChapterVwithinSOLAS
Convention
deals with safety of navigation; it identifies
navigationsafetyserviceswhichshouldbeprovided
by Contracting Governments and sets forth
operational provisions applicable in general to all
shipsonallvoyages.OfspecialinterestisRegulation
19 within chapter V, which establishes the carriage
requirementsforshipbornenavigationalsystemsand
equipment.
2.1 SatelliteNavigationEquipment
AccordingtothatRegulation,allshipsirrespectiveof
size are required to be fitted with a GNSS receiver.
This will probably be a GPS receiver using the US
GlobalPositioningSystemwhichmayormaynotbe
equippedtoprovidedifferentialcorrections,sincethe
carriage
of a DGPS receiver or an SBAS enabled
receiver is not mandatory. The question is: Does a
simpleGPSreceiverfulfiltheIMOrequirementsinall
navigationphases?
Themostcommonsystemusedasprimarymeans
of navigation is GNSS, however currently available
GNSS do not fulfil IMO requirements in regards
to
accuracy and integrity in all the navigation phases.
AccordingtoResolutionA.915(22)[3]onthe“Revised
maritimepolicyandrequirements forafutureGlobal
Navigation Satellite System (GNSS)” GPS (and
GLONASS) has been recognized as a component of
theWorldWideRadionavigationSystem
1
(WWRNS)
for navigational use in waters other than harbour
entrancesandapproachesandrestrictedwaters.That
is,GPSalone,withoutaugmentationisnotenoughin
thesesituations.
A.915(22) recognises that differential corrections
canenhanceaccuracy(inlimitedgeographicareas)to
10 m or less (95%) and also offer external integrity
monitoring. In this sense, this Resolution mentions
the following techniques that can improve the
accuracy and/or integrity of GPS and GLONASS by
augmentation
2
:
Differential correctionsignals fromstationsusing
the appropriate maritime radionavigation
frequency band between 283.5 and 325 kHz for
localaugmentation.
Craftorreceiverautonomousintegritymonitoring.
Integrated receiverscombiningsignals fromGPS,
GLONASS, LORAN‐C and/or Chayka (a Russian
1
InMay2016,theIMOrecognisedalsoGalileoaspartof
theWorldWideRadioNavigationSystem.
2
TotakeintoaccountthatResolutionA.915(22)wasadopt‐
edon29November2001andconsequentlyitisnotupdat‐
ed.Someofthesystemshavebeendecommissioned,forin‐
stanceLORAN‐C,andtechnologicaladvancesarenot
considered.
25
terrestrial radionavigation system, similar to
LORAN‐C).
Wideareaaugmentationsystemsusingdifferential
correction signals from geostationary satellites
suchasEGNOSforEurope,WAASfortheUnited
StatesandMSASforJapan.
Amore recentIMOResolution,A.1046(27)[4]on
the “Worldwide Radionavigation System” refers to
ChapterV of
theSOLAS Convention,Regulation13,
whentalkingaboutnavigationinharbour entrances,
harbourapproaches andcoastal waters.Atthesame
time, IMO Res. 1046 establishes that: where a
radionavigationsystemisusedtoassistinthenavigation
of ships in such waters, the system should provide
positionalinformationwithan
errornotgreaterthan10m
with a probability of 95%. It is important to note that
this is a requirement to be accomplished by the
radionavigationsystem.
The provision of differential corrections,
understood as aids to navigation to be provided by
maritimeauthorities,isnotmandatory.Itisupto
the
Contracting Governments to decide to provide this
servicebasedonthevolumeoftrafficandthedegree
ofrisk. Hence,whennavigating inwaterswithouta
maritime DGNSS service, it is of specialinterestthe
accesstoSBAScorrectionsorevenasabackupwhen
thisDGNSSserviceis
provided.
2.2 AISonboarddevices
Automatic Identification System (AIS) is an
autonomous and continuous broadcast system,
operating in the VHF maritime mobile band. The
objectiveof AISis toexchange navigationdatasuch
as vessel identification, position, course, speed, etc.
betweenparticipatingvesselsandshorestations.
Section 4.1.1 of the IALA
Guideline 1082 [5] is
devotedtoshipborneAIS,thatis,ClassAandClassB
devices. According to that Guideline and the AIS
Technical Standards (ITU‐R M.1371), Class A
equipment complies with the IMO AIS performance
standards. Whilst the Class B are compatible with
Class A, they are not
fully compliant with IMO
requirementsandreportlessfrequentlythanClassA.
AIS uses an absolute referencing system to
determineposition.Thispositionisnormallyderived
fromaGNSSreceiver.AISClassAdevicescanobtain
positioninformationfroman internalGNSSreceiver
orfromthevessel’sprimaryGNSSreceiver.However,
Class Bequipment only uses theAIS internal GNSS
sensortoobtainthepositioninformation.
AccordingtotheSOLASConvention,AIScarriage
(ClassA)ismandatoryforshipsof300grosstonnage
and upwardsengagedon international voyages and
cargo ships of 500 gross tonnage and upwards not
engaged on
international voyages and passenger
ships irrespective of size. In addition, EU Directive
2002/59/EC[6]statesthatfishingvesselswithalength
ofmorethan15metresoverallshallbefittedwithan
AIS(ClassA)whichmeetstheperformancestandards
drawnupbytheIMO.
3 SURVEYRESULTS
Asurvey has
been doneto havean overviewof the
percentageofonboardGNSSdeviceswhichareSBAS
enabled. The statistical analysis took as basis the
satellite navigation equipment and AIS devices
approved to be used in SOLAS and non‐SOLAS
vessels. As a starting point, the list of receivers and
their
characteristicssheetsweregathered.
Thereceiverequipment andAIS deviceslisttook
as reference was extracted from the data base
publishedbytheSpanishMerchantMarine,ascanbe
found in the Spanish Ministry of Transport website
[7].ThisinventorycataloguesSOLASandnon‐SOLAS
authoriseddevicesincludingbrand,modeland
dates
ofhomologationandexpirationforeachequipment.
The analysis of the characteristics sheets,
brochures, owner’s manuals, webpages or technical
specificationsof thelisted receiversand AIS devices
hasledtoknowifthedeviceisSBAScompatibleand,
among the SBAS compatible ones, if EGNOS is
explicitlymentioned.
3.1
SatelliteNavigationEquipmentSurvey
3.1.1 SOLAS
24 satellite navigation devices authorised for
SOLAS vessels were analysed, from 7 different
brands,accordingtothepublishedlistbytheSpanish
MinistryofTransport.
It is important to note than a 100% of the
authorised manufacturers to provide SOLAS GNSS‐
based equipment have at
least 1 SBAS‐enabled
receiver and 71% mentioned their equipment was
EGNOScompatible.
The analysis yielded the following results:
Table2.SBAScompatibledeviceanalysis–SOLASsatellite
navigationequipment
_______________________________________________
SBAScompatibleequipment
Percentage
_______________________________________________
YES1875%
NO00%
N/A625%
_______________________________________________
EGNOSmentionedPercentage
_______________________________________________
YES1689%
NO211%
_______________________________________________
N/A:Navigationsystemtobeusedincombinationwith
externalantennas.ThecompatibilitywithSBASdependson
thechosenantenna.
3.1.2 Non‐SOLAS
432satellitenavigationdevicesauthorisedfornon‐
SOLAS vessels were analysed, from 27 different
brands,accordingtothepublishedlistbytheSpanish
26
Ministry of Transport. To be noted that 92% of the
authorised manufacturers to provide non‐SOLAS
GNSS‐basedequipmenthaveatleast1SBAS‐enabled
receiver and 83% mentioned their equipment was
EGNOScompatible.
Theanalysisyieldedthefollowingresults:
Table3. SBAS compatible device analysis – non‐SOLAS
satellitenavigationequipment
_______________________________________________
SBAScompatibleequipment
Percentage
_______________________________________________
YES32174%
NO10023%
N/A113%
_______________________________________________
EGNOSmentionedPercentage
_______________________________________________
YES24075%
NO8125%
_______________________________________________
N/A:Nobuilt‐inGPSornoinformationavailableonthese
models
3.2 AISEquipmentSurvey
3.2.1 SOLAS
There are 14 AIS devices authorised for SOLAS
vessels, from 12 different brands, according to the
published list by the Spanish Ministry of Transport.
The analysis of the specifications of these onboard
AISdevicesresultedasfollows:
Table4.SBAScompatibledeviceanalysis–AISSOLAS
_______________________________________________
SBAScompatibleequipment
Percentage
_______________________________________________
YES643%
NO857%
_______________________________________________
EGNOSmentionedPercentage
_______________________________________________
YES350%
NO350%
_______________________________________________
3.2.2 Non‐SOLAS
The characteristics sheets of 38 AIS devices
authorised for non‐SOLAS vessels were analysed,
from19differentbrands, accordingtothepublished
list by the Spanish Ministry of Transport. The
followingresultswereobtained:
Table5.SBAScompatibledeviceanalysis–AISnon‐SOLAS
_______________________________________________
SBAScompatibleequipment
Percentage
_______________________________________________
YES616%
NO3182%
N/A13%
_______________________________________________
EGNOSmentionedPercentage
_______________________________________________
YES583%
NO117%
_______________________________________________
N/A:Noinformationavailableonthesemodels
3.2.3 InlandAIS
There are 27 approved Inland AIS devices,
according to the “List of approved Inland AIS
equipment in accordance with the Rhine Vessel
Inspection Regulations” [8]. These devices were
analysedwiththefollowingresults:
Table6.SBAScompatibledeviceanalysis–InlandAIS
_______________________________________________
SBAScompatibleequipment
Percentage
_______________________________________________
YES933%
NO1556%
N/A311%
_______________________________________________
EGNOSmentionedPercentage
_______________________________________________
YES778%
NO222%
_______________________________________________
N/A:Noinformationavailableonthesemodels
4 CONCLUSIONS
Many GNSS receivers currently available on the
marketareabletoreceiveandprocessEGNOSsignals
and can be used to support numerous applications.
As a result of using EGNOS, a better position
performancecanbeobtained.
AccordingtotheEGNOSOSSDD[1],theEGNOS
OShorizontal
minimumaccuracy,correspondingtoa
95%confidencebound ofthe 2‐dimensionalposition
errorinthehorizontallocalplanefortheWorstUser
Location, is 3 meters. Therefore the accuracy
requirement established in IMO Res. 1046 about
navigationinharbourentrances,harbourapproaches
andcoastalwaters withan errornotgreater
than 10 m
with a probability of 95% is fulfilled by far when the
GNSSreceiverisEGNOSenabled.Itisalsoimportant
to remark that IMO Resolution A.915(22) considers
27
SBAS/EGNOS as one of the techniques that can
improvetheaccuracyofGPS.
To take advantage of this improved accuracy,
direct access to EGNOS in vessels can be achieved
through:
EGNOS‐enablednavigationreceivers:
75% of the GNSS-based equipment authorised to be
used in SOLAS vessels are SBAS/EGNOS compatible.
A similar percentage, 74%, of the GNSS-based
equipment authorised to be used in non-SOLAS vessels
are EGNOS compatible.
EGNOS‐enabledAIStransponders:
43% of the AIS devices authorised to be used in
SOLAS vessels are SBAS/EGNOS compatible. This
percentage is lower in the AIS non-SOLAS devices,
around 16%.
The analysis of the list of approved Inland
AIS
equipment in accordance with the Rhine Vessel
InspectionRegulationsresultsin9SBAS‐enabledAIS
transponders out of 27. Therefore a 33% of the
approved inland AIS transponders are EGNOS
compatible.
ChoosingSBAS/EGNOS‐enabledreceiversleadsto
accuratepositioninformation; thisis directly related
withanimprovementinsafety
innavigationandan
enhancement of those services based on position
information.
REFERENCES
EGNOS OS SDD: EGNOS Open Service (OS) Service
Definition Document v2.2 https://egnos‐user‐
support.essp‐sas.eu/new_egnos_ops/sites/default/
files/library/official_docs/egnos_os_sdd_in_force.pdf
SOLASConvention:InternationalConventionfortheSafety
ofLifeatSea(SOLAS)
IMO Resolution A.915(22) “Revised maritime policy and
requirements for a future Global Navigation Satellite
System(GNSS)”.Adoptedon29November2001
IMO resolution
A.1046(27) “Worldwide Radionavigation
System”.Adoptedon30November2011
IALA Guideline 1082 “An Overview of AIS” Edition 2.0
(June2016)
EU Directive 2002/59/EC: Directive of the European
Parliament and of the Council of 27 June 2002
establishingaCommunityvesseltrafficmonitoringand
informationsystem.
http://www.fomento.gob.es/MFOM.DGMM.RADIO.WEB/e
quipos.aspx(Asperdataavailable
inMarch2016)
“ListofapprovedInlandAISequipmentinaccordancewith
the Rhine Vessel Inspection Regulations” (February
2016) http://www.ccr‐zkr.org/files/documents/ris/
ais_apagrees.pdf
