221
1 INTRODUCTION
Navigation positioning systems are an important
elementinensuringthesafetyofland,marineandair
transportation. For each transport application
protected by such systems, the requirements for the
object position accuracy , the availability, reliability,
continuity and coverage of the positioning systems
should be specified globally and nat
ionally. A
legislative solution can be national plans for radio
navigation systems, such as European Radio
Navigation Plan (ERNP) 2004; General Lighthouse
Authorities Radio Navigation Plan (GLAs) 2007;
Swedish Radio Navigation Plan (SMA) 2009; US
FederalRadionavigationPlan(FRP)2012[19].These
actsnotonlydefinethestrictminimumrequirements
intermsofnavigationalpositioningsystemsimposed
on different forms of tra
nsport activity, but also
recommendthemforspecificsystems.
In the 1990s, the first Differential GPS stations
were launched. Within a few years, it became the
main positional system used in coastal navigation,
hydrographyandcoastalworks.ThesignalsofDGPS
reference stations cover coastal waters a
pprox. 100
nautical miles from the shore. Over the years, its
positioning accuracy was improving steadily – from
10to1‐2meters(2drms).Despitesuchhighaccuracy,
DGPS still does not meet the requirements for
hydrography, coastal works, natural resources
exploitation, or marine construction in the coastal
zone.
Figure1.Coverageareas ofDGPSreferencestations in the
GulfofGdańsk
Evaluation of Positioning Functionality in ASG EUPOS
for Hydrography and Off-Shore Navigation
J
.Rogowski,C.Specht&A.Weintrit
GdyniaMaritimeUniversity,Gdynia,Poland
W.Leszczyński
InstituteofMeteorologyandWaterManagement,Warsaw,Poland
ABSTRACT: The paper discusses the ASG EUPOS services. It assesses the possibility of using this system
selectedsitesinhydrographyandoff‐shorenavigationtasks.Theexperimentspresentedandanalyzedinthe
paperwerecarriedoutin the port of Gdynia and on the Gul
fofGdańsk. The results confirm thattheASG
EUPOS services guarantee positioning accuracy. The obtained accuracy greatly exceeds the needs and
requirementsofcoastalnavigationandunderwaterminingandseabottomexploration.
http://www.transnav.eu
the International Journal
on Marine Navigation
and Safety of Sea Transportation
Volume 9
Number 2
June 2015
DOI:10.12716/1001.09.02.09
222
Due to insufficient accuracy in determining the
position of the aforementioned, marine applications
must apply geodetic measurement methods used in
surveying.
Thedominantworldtrendatthebeginningofthe
21st century in geodesy was starting active national
network activity, such as CORS, SAPOS, SWEPOS,
OS‐AGN. The networks offered
users paid or free
post‐processingservicesaswellasrealtimesignals.
In 2007, the Head Office of Geodesy and
Cartography launched the ASG‐EUPOS Active
Geodetic Network, which is the national permanent
GNSSstations networkofferingservicesforgeodesy
and navigation. That investment ended in July 2008
with
serviceanddatacommunicationstests.
The ASG‐EUPOS Polish national GNSS network
uses mobile communication modems for the
transmission of RTCM messages – i.a. pseudorange
corrections. For this reason, the operating zone is
limited by coverage of cellular mobile networks.
Thus,itseemsreasonabletoundertakearesearchon
the potential
use of the ASG‐EUPOS for precision
navigation, marine construction, hydrography and
otherapplicationsrequiringhighlocationaccuracy.
2 POSITIONINGREQUIREMENTSFOR
HYDROGRPHYANDOFF‐SHORE
NAVIGATION
The International Hydrographic Organization (IHO)
hasbeenissuingStandardsforhydrographicsurveys
(S‐44)since1957.
The 1st Edition of IHO S‐44
entitled “Accuracy
StandardsRecommendedforHydrographicSurveys”
was published in January 1968 with the foreword
which stated that “(…) hydrographic surveys were
classed as those conducted for the purpose of
compiling nautical charts generally used by ships”
and “The study confined itself to determining the
density and precision of measurements necessary
to
portraytheseabottomandotherfeaturessufficiently
accuratelyfornavigationalpurposes.”
Over the years, technologies and procedures
changed, and the IHO established further WGS to
updateS‐44withthe2ndEditionpublishedin 1982,
the3rdin1987,andthe4thin1998.Throughoutthese
revisions, primary
objectives of thepublication have
remained substantially unchanged,the 5th Edition
included.
Beloware the standardsused by most producers
ofhydrographicdata.IHOS‐445thEditionclassifies
surveysintofourdifferenttypes(fourʹintendedusesʹ)
[10]:
Special Order – for specific critical areas with
minimum under‐keel clearance
and where bottom
characteristics are potentially hazardous to vessels
(generally less than 40 metres), such as harbours,
berthing areas, and associated critical channels with
minimumunder‐keelclearances.
Order 1a – for those areas where the sea is
sufficiently shallow to allow natural or man‐made
featuresontheseabed
tobeaconcerntothetypeof
surface shipping expected to transit the area but
wheretheunder‐keelclearanceislesscriticalthanfor
Special Order above. Because man‐made or natural
features may exist that are of concern to surface
shipping,afullseafloorsearchisrequired,
however
thesizeofthefeaturetobedetectedislargerthanfor
Special Order. Under‐keel clearance becomes less
criticalasdepthincreasessothesizeofthefeatureto
bedetectedbythefullseafloorsearchisincreasedin
areaswherethewaterdepthisgreaterthan
40metres.
Order1asurveysmaybelimitedtowatershallower
than100metres.
Order 1b‐for areas shallower than 100 metres
whereageneraldepictionoftheseabedisconsidered
adequateforthetypeofsurfaceshippingexpectedto
transitthearea.Afullseafloorsearchisnotrequired
whichmeanssomefeaturesmaybemissedalthough
themaximumpermissible line spacing will limit the
size of the features that are likely to remain
undetected. This order of survey is only
recommended where under‐keel clearance is not
considered to be anissue. An examplewould be an
area
wheretheseabedcharacteristicsaresuchthatthe
likelihood of there being a man‐made or natural
featureontheseafloorthatwillendangerthetypeof
surfacevesselexpectedtonavigatetheareaislow.
Order 2 – the least stringent order and its is
intendedforthoseareas
wherethedepthofwateris
such that a general depiction of the seabed is
considered adequate. A full sea floor search is not
required.ItisrecommendedthatOrder2surveysare
limited to areas deeper than 100 metres as once the
waterdepthexceeds100metrestheexistence
ofman‐
made or natural features that are large enough to
impact on surface navigation and yet still remain
undetectedbyanOrder2surveyisconsideredtobe
unlikely.
The summary of minimum standards for
positioning in hydrographic surveys, according to
[10],ispresentedinTab.1.
Table1.Standardsforpositioninginhydrographicsurveys
[10]
_______________________________________________
ParameterSpecial 1a1b2
_______________________________________________
Maximumallowable2m 5m 5m 20m
THU(95%)+5%of +5%of+10%of
depthdepthdepth
Maximum a=0.25m a=0.5m a=0.5m a=1.0m
allowable
THU(95%) b=0.0075 b=0.0075 b=0.013 b=0.023
Positioningoffixed 2m2m 2m 5m
aidstonavigation
andtopography
significantto
navigation
Positioningofthe 10m 20m 20m 20m
coastlineand
topographyless
significantto
navigation
Meanpositionof 10m 10m 10m 20m
floatingaidsto
navigation
_______________________________________________
223
Total Horizontal Uncertainty (THU) – represents
horizontal accuracy, with 95% confidence level and
Total Vertical Uncertainty (TVU) is depth accuracy
measurementcalculatedintheverticaldimension.
The GNSS permanent observations implemented
bylarge‐areasatellitenetworkhavebeentransformed
intocomplexdatacommunicationsystem.Theyhave
offerednotonlypost
processing ofGPSservicesbut
alsothecorrectionofreal‐timedata.Thefirststagesof
their development were national passive systems
createdatthebeginningofthe1990s,alsoinPoland
[1].Theyhaveevolvedfromsinglereferencestations
located at technical universities to national systems.
They were characteristic
of autonomous station, and
lacked standardization within the range of unified
report data replacement exploitation and local
character of use [8]. As time passed by, passive
systems gained differential function (GPS) in real
time, becoming active structures – making DGNSS
services possible. A significant broadening of action
zone,similartonautical
DGPSsystem,wasconnected
with new RTCM‐type telegram (updated from
version 2.0 to 3.0) and mathematical simulation of
GPSsurfacecorrection[14].
3 DEVELOPMENTOFPOLISHGNSSSATELLITE
NETWORKS
The idea to create the GNSS permanent station
networkwasinitiatedin1995bytheCommissionon
SatelliteGeodesy of
theSpace andSatelliteResearch
CommitteeofthePolishAcademyofSciences[2].The
networkwasassumedtobemultifunctionalandused
not only for geodesy purposes. As a result of
different centres’ activity, the local stations were
created in Warszawa,Łódź, Gdańsk andthe
intensiveminingindustryareas:
UpperSilesia(Górny
Śląsk)andLubin‐GłogówCopperDistrict(Lubińsko‐
Głogowski Okręg Miedziowy) [3]. Then a six‐point
networkinŚląskandathree‐pointnetworkintheTri‐
Cityareawerecreated[6].
Thedominantworldtrendatthebeginningofthe
21
century was starting active national network
activity, for example CORS, SAPOS, SWEPOS, OS‐
AGN(Fig.2).Thenetworksoffereduserspayableor
unpaidservicesaswellaspayablerealtimeservices
[13]. Modernity of network techniques, compared to
classical coordinates determination with exploitation
singlereferencestationandmovablereceiverin
RTK
method,liesamongotherthingsinimplementationof
correction using virtual reference station VRS [9]. It
enables working out of pseudo‐distance correction
dedicatedtoreceivercoordinates[12].
In 2007 the Head Office of Geodesy and
CartographyrealisedActiveGeodeticNetworkASG‐
EUPOS which is the national permanent GNSS
stations
network offering services for geodesy and
navigation[4].That investmentended inApril,2008
withserviceanddatacommunicationstests[5].
Accessible to researchers at the beginning of the
21st century measurement techniques and
development of the RTK (Real Time Kinematics)
methods have allowed researchers to obtain
measuring accuracy of
one centimetre at 15 Hz
frequencies with necessity of additional altitude
measurement reduction [9]. Meaningful change of
quality has appeared with emission GPS/GPRS
(GeneralPacketRadioService)attransmissionactive
geodeticnetworkservice.In2004yearRTCM(Radio
Technical Commission for Maritime Services)
introduced NTRIP (Networked Transport of RTCM
via Internet
Protocol) which determined usage of
VHFradiocommonlyimplementedin RTK systems.
NTRIP also determined usage of the other
applicationsusingwirelessradiolinksinrelationbase
receiver – rover receiver; their a few metres range
madeGNSSrealisationandsurfacecorrectiontransfer
(VRS,Max,FKPmethods)impossible[15].
a)
b)
c)
Figure2.Architectureofselectedactivegeodeticnetworks:
a)SWEPOS–Sweden,
b)OS‐AGN–GreatBritain,and
c)CORS–USA
The standard RTCM 3.0 version has been
recommended since 2004 [14]. Setting up in 2008 of
theactivegeodeticnetwork service and a significant
qualitychangewithintherangeofpreciseGPS(multi
system receivers, frequency increasing up to 20 Hz,
leveling geodetic model implementation) have
induced interdisciplinary team of researchers
to
undertake a study on GPS usability for geodetic
railwayservices[11].Satellitesurveyingwillenablein
the future to perform the actual state inventory as
well as a regularly updated rough route marking.
Action towards the implementation base of a new
measurement technique for railway should be
undertaken.
224
In 2007 the Head Office of Geodesy and
CartographyrealisedActiveGeodeticNetworkASG‐
EUPOS which is the national permanent GNSS
stations network offering services for geodesy and
navigation [4]. That investment was ended in April,
2008withserviceanddatacommunicationstests.
4 ASG‐EUPOSNETWORK
In the 1990s,
Central and East European countries
started setting up DGNSS stations. They were not
compatiblewiththeWestEuropeanstations.InBerlin
in2002,adecisionwastakenaboutEuropeanPosition
Determination System development in the direction
oftheEast.PolishpartoftheASG‐EUPOSsystemhas
consistedof98
referencestationsevenlycoveringthe
countryarea (Fig. 3). Except forthe newstarting‐up
stations, the system also adapted existing stations
managed by universities, research and development
centres, state administration and private companies.
Atpresent,ASG‐EUPOSiscomposedofthefollowing
referencestationgroups:
84stationswithGPSmodule;
14stationswithGPS/GLONASSmodule.
Additionally, the system has cooperated with
nearly30foreignstations.
Figure3.LocationofASG‐EUPOSreferencestationsystem
National Management Centres, called also
Counting Centres, are the second segment of ASG‐
EUPOSsystem.TheCentralOfficeisinWarsawand
itsbranchesareinKatowice.Theyareresponsiblefor:
controlling and managing the network of stations,
correctionsgeneratingofconductedobservations,and
makingsatellitesurveyingavailabletotherecipients.
All interferences are signalled and analysed; if
necessary, countermeasures are undertaken. Both
CountingCentresareredundantintherangeofdone
services.Besidepositionsurveyingservices,Counting
Centrehasmaintainedareferencesystem.Aweekly
controlmakesitpossibletosupervisetheinvariability
ofpointsdefinedbythesystem.The
highestnumber
of users served by Counting Centre is 1,200. Users,
who use the centre services of real‐time data
provisionandcorrection,exploitmainlyInternetand
GSM. Corrective information is sent to users via
Internet using specially elaborated NTRIP protocol.
GSMhasusedGPRSpackagedatatransfer.Working
farfrom
thecitiescanposeaproblemofbeingoutof
range of one or even all mobile communication
operators.Forthatreason,userswhowanttotakethe
advantage of being delivered the correction data
shouldhaveSIMcardsofafewmobileoperators.
5 EVALUATIONOFTHEUSEOF
SELECTED
SERVICESINCOASTALANDINLAND
NAVIGATION
The main products (services) of ASG‐EUPOS are
presentedinTable2.
Real‐time services are based on the principle of
differential observations using DGNSS (Differential
GNSS) or RTK (Real‐Time Kinematics) utilizing a
referencestationsnetwork[20].Thewholeprocessof
data exchange
is in real time with the use of GPRS
transmission via Internet,therefore the usersreceive
their precise position in the field, in real time.
Depending on the surveying method and hardware
capabilitiestheprecisionofreal‐timeservicesinASG‐
EUPOS vary between 3 metres and 3 centimeters.
KODGIS
and NAWGIS DGPS services are generally
used in GIS applications. The NAWGEO service is
most commonly used in geodetic applications of all
kinds. In NAWGEO service the user has the
possibilitytochoosefromvarioustypesofRTK/RTN
corrections, such as traditional corrections from a
single base station (RTK), although mainly
network
corrections (RTN) like MAC (Master and Auxiliary
Concept),VRS(VirtualReferenceStation),FKP (Ger.
Flächenkorrektur‐parameter)areused.
Table2.ASG‐EUPOSProducts(Services)
__________________________________________________________________________________________________
TypeName Surveymethod Datatransmission Estimatedprecision Minimalhardware
requirements
__________________________________________________________________________________________________
Real‐timeservices NAWGEO kinematicInternet,upto0,03m(hor.) L1/L2RTKreceiver,
(RTK/RTN)GSM(GPRS)do0,05m(vert.) communicationmodule
KODGISkinematicupto0,25mL1DGPSreceiver,
(DGPS)communicationmodule
NAWGISupto3m
Post‐processing POZGEO static,InternetDependsonsurvey L1GPSreceiver
servicesrapidstaticconditions
(0,01‐0,10m)
POZGEOD static,kinematic
__________________________________________________________________________________________________