657
1 INTRODUCTION
Document IHO S‐44 [IHO 2008] determines strict
minimum standards for hydrographic surveys for
special order for harbours, berthing areas, and
associatedcriticalchannelswithminimumunder‐keel
clearances. Also Canadian Hydrographic Service
[CHS 2003] determined an additional standard for
hydrographic surveys: exclusive one for shallow
water in
harbours, berthing areas, and associated
critical channels with minimum under‐keel
clearances.Horizontal accuracy (95% confidence
level) is [IHO 2008, CHS 2003, MoD 2018] 1m for
Exclusive Order and2m for Special Order.It
should be emphasized that the reliability of
bathymetric data is an important element of the e‐
Navigationconceptdevelopedtodayinthemaritime
navigation[WeintritA.,2018;UrbańskiJ.etal.2008],
especiallyintheECDIS[Weintrit,A.2009].
Althoughthereareotherlocal[KelnerJ.etal.2016;
Sadowski J., Stefański J., 2017] or long range
[Czaplewski K., 2018] positioning system solutions
available on
the sea other than GNSS, but maritime
DGPSisthemainsystemthatisusedinhydrography
duetoitsrange(100‐200km),accuracy1‐2m(p=0.95)
[DziewickiM.,SpechtC.2009]andintegrity.Itcanbe
used for positioning in Special Order areas. For
Availability of the GNSS Geodetic Networks Position
during the Hydrographic Surveys in the Ports
C.Specht
GdyniaMaritimeUniversity,Gdynia,Poland
A.Makar
PolishNavalAcademy,Gdynia,Poland
M.Specht
GdyniaMaritimeUniversity,Gdynia,Poland
ABSTRACT:GeodeticnetworkGNSSreceiversaremorecommonlyassociatedwithpositioningsystemsused
inmaritimehydrography.Intermsofpositioningaccuracywhennoterrainobstaclesarepresent,theymeet
international hydrographic surveys standards (S‐44) fully. Those standards are defined as 1m (0.95) for
ExclusiveOrder
and2m(0.95)forSpecialOrder.Itisequallyasimportanttoensureaccesstopositionwhich
errorisnothigherthanabovementionedmaximumvalues.Thisismostoftendeterminedbythedensity of
portinfrastructure.
This article presents the results of analysis of availability of hydrographic system that
operates based on
geodetic GNSS networks. Hydrographic surveys in question were undertaken in inner basins with diverse
infrastructure. Three representative types of ports were selected for this reason: fishing type (Hel), medium
sized,moderncommercialtype(Gdynia)andhighlycongested,narrowcanaltype(Gdansk–Motlawa).Anon‐
public,geodeticGNSS
networkwasusedforallsurveys.Itisworthmentioningthattheabovenetworkisatthe
momenttheonlyavailablenetworkthatprovidesbothGPSandGLONASScorrections.
ThesurveysprovidedevidencethatgeodeticGNSSnetworkscanbesuccessfullyutilisedtodetermineposition
ofhydrographicvessel inlowand
moderatelydevelopedportsaswellasinExclusiveandSpecialOrders.In
highly congested ports however, the availability of the above mentioned method of measurement can be
insufficienttorealiseasurvey.
http://www.transnav.eu
the International Journal
on Marine Navigation
and Safety of Sea Transportation
Volume 12
Number 4
December 2018
DOI:10.12716/1001.12.04.02
658
Exclusive one it is insufficient and e.g. real time
geodeticnetworkshouldbeusedinstead[SpechtC.et
al2017].
It should be noted that availability of precise,
actualised seabed data is crucial for maritime safety
[Neumann T. 2018], especially for dangerous cargo
[Guzeet.al.2017].
The main issue
for measurements utilising GNSS
istheavailabilityofsatellitesignalinurbanisedareas.
Bathymetric surveys undertaken in port basins, the
following factors determine the accuracy of
measurement: the type and height of port
infrastructure, its density and number of satellite
systems used by the geodetic GNSS receiver
[CzaplewskiK.,Goward
D.2016].
In order to determine the influence of density of
portinfrastructureonavailabilityofselectedvalueof
positioning error of the geodetic GNSS receiver, a
percentage of time when its measurements meet all
conditionsofExclusiveorder(1m) andSpecialOrder
(2m)wasdefined.
Threerepresentativetypesofbasins
wereusedas
describedinFig.1,2and3.
Figure1. Hydrographic vessel’s trajectory in fishing port
(Hel)
Figure2.Hydrographicvessel’strajectoryinmediumsized,
moderncommercialport(Gdynia)
Figure3. Hydrographic vessel’s trajectory in highly
congested,narrowcanalarea(Gdansk–Motlawa)
2 MODELOFTHEAVAILABILITYOFTHE
CERTAINVALUEOFPOSITIONERROR
Thenewapproachwhichjoinstheaccuracyandone
ofthereliabilitycriterionsistheterm–availabilityof
the certain value of position error. Let’s define the
availability of certain value of position error – as a
probability
that in any moment of time
t the
position error of determining coordinates
n
is
lower or equal then the arbitrary acceptable value
U
, which mean than U
n
,
,...2,1n
(Fig. 4.).
The suggested approach treats the lifetimes and the
times of failure as the random variables being in
relation in the fixed value of the position error and
also it introduces the measures which making the
reliabilityestimationpossible.
t
t
t
''
0
Z
'
1
Z
'
2
Z
1
X
1
Y
2
Y
2
X
3
X
''
1
Z
''
2
Z
0
1
decision limit
for position error
specifid for application
availability of certain value of postion error
Figure4.Ideaofavailabilityofthecertainvalueofposition
error.
Let’s define the reliability process in which the
relation between the single measurement error
n
and the parameter U decide about its state
(work or failure). Let
t
be the binary
interpretationofthereliabilitystateoftheprocessas:
''
1
'
1
'
1
''
,0
,1
nn
nn
ZtZ
ZtZ
t
for
,...1,0n
(1)
The state
1)(
t
means that in the moment t
the error of the single measurement is less or equal
than
U .Intheoppositecasefor U
n
,thesystem
isinthestateoffailure.
Thenwecanrecognizetwostates:theworkingone
– the state where the error
U
n
for ,...2,1
n
659
and the state of failure where
U
n
. Let
,...,
21
XX
be the working times while
,...,
21
YY
are
the times of failures. Hence the moments:
nnn
XYYXYXZ
12211
'
... , ,...,2,1
n
are the moments of failures and
nnn
YZZ
'''
, are
the moments of renewal. Assume also that the
random variables
ii
YX , , ,...2,1i are
independentand the workingfailure times have the
samedistributions.
Let’sdefinetheanalyticalformofthedistributions
ofthevariables
n
X and
n
Y as
yFxXP
i
, (2)
yGyYP
i
for ,...,2,1
i (3)
where:
xF
,
yG
meansthedistributionfunctions
of
n
X and
n
Y .
Thentheavailabilityofacertainvalueofposition
errorwillbedenotedas[SpechtC.,2003]
UtPtD )()(
. (4)
According to [Specht C. 2003] final form for
availability of the certain value of position error as
follows
t
xdHxtFtFtD
0
11
, (5)
where
1n
n
xxH
(6)
isarenewalfunctionofstreammadeoftherenewal
moments.
Typical realizations of the operating time in
navigational systems are characterized by the
exponentialdistributionsofthelifetimeandthetime
of failures due to the property called the
”memoryless” property. Let define the exponential
processwherethe
distributionfunctionsas
0for0
0for1
t
te
tF
t
, (7)
0for0
0for1
t
te
tG
t
, (8)
where
,
arefailureandrenewalrates.
, 11
11
0
0
exp
t
xtt
t
xdHee
xdHxtFtFtD
(9)
where
tD
exp
denotestheavailabilityofthecertain
valueof position error inthe navigationalsystemin
the case of the exponential life and failure times
distributions. After few simple transformations
[SpechtC.,2003]finallyformcouldbefindas
t
etD
exp
(10)
andavailabilityfactor(limitingvalue)ofcertainvalue
ofpositionerror‐
exp
A canbecalculatedas
11
1
exp
A
. (11)
3 EXPERIMENT
Dualfrequencyphasereceiverworkinginrealtimein
GNSS geodetic TPI NETpro network was tested on
board a hydrographic motorboat Homar‐1 during
sonar surveys (Gdynia, President’s Basin) and
bathymetric one (Hel, the harbour). The motorboat
was equipped with an interferometric echosounder
and a towed sonar. For dynamic
tests geodetic
satellite receiver Topcon HyPer II with 10 Hz
positioning frequency has been used. The data,
recorded in Sokkia SHC25 controller, has been
postprocessed in TopconLink application, which
allowstoselectgeometricalratesHDOP,VDOPand
accuracyone:horizontaland verticalprecisions.The
receiver’s antenna has been located on
board the
motorboat, which have not influenced on satellites
visibility or covering upper hemisphere [Makar,
2018a,b].
TheTPINETproGNSSnetworkprovides5types
of fixes (DGNSS, NET RTCM 2.3, NET RTCM 3.0,
RTK RTCM 2.3 and RTK RTCM 3.0) that differ in
generationmodeandobtainedaccuracy.Irrespective
of the
type of fixes, before the measurements are
taken, the network user connects to a control center
calledtheNTRIPserverandsendsoneʹsapproximate
positionusingtheNMEAGGAmessage.FortheNET
RTCM 2.3 or 3.0 correction, the system generates a
virtualreferencestationforit,usuallywithin
5kmof
the receiver, pointing towards the nearest actual
referencestation[SpechtC.SpechtM2018].
660
Figure2.TPINETproGNSSgeodeticnetwork.
4 RESULTS
Surveys recorded the following number of points:
Gdynia–19023points,Hel–30116pointsandGdansk
– 2353 points. The above were analised based on
relationshipspresentedinchapter2.Thecalculations
utilised data registered by GNSS receivers and
Mathcad15.Thebenchmarkofpositioningerrorhas
been assumed
as its horizontal orientation, essential
duringhydrographicsurveys.Collectiveresultsofthe
analyses of position’s availability with defined
positioningerror(1cm,2cm,5cm,10cm,1m,2m)are
presentedinTab1.
Table1. Availability factors for positioning errors: 1cm,
2cm,5cm,10cm,1m,2m–Gdańsk,GdyniaandHelports
_______________________________________________
Port Availabilityfactors[%]
1cm 2cm 5cm 10cm 1m 2m
_______________________________________________
Gdansk8.23 74.41 82.81 82,95 83.12 88.74
Gdynia 47.04 97.10 98.37 98.80 99.34 99.81
Hel 64.69 85.67 100% 100% 100% 100%
_______________________________________________
Figures below present examples of functions and
availability factors for positioning error defined as
10cm, 1m, 2m – determined for measurements in
Gdynia.
Figure3.Examplesofavailabilityfunctionsandavailability
factors for positioning error defined as 10cm, 1m, 2m –
determinedformeasurementsinGdynia
5 CONCLUSIONS
This article presents the mathematical model of
availability of certain values of positioning error
calculations.
Hydroacoustic surveys realised in both Gdynia
and Hel ports indicatedthat Geodetic GNSS
networks can successfully be used in maritime
hydrographicsurveysinportareas.Theyalsoproved
highavailabilityofpositions,exceeding95%,
whichin
turnprovesthatthemethodologyinquestioncanbe
usedforpositioninginmaritimehydrography.Itcan
beobserved,thatterrainobstaclesinPortof Gdynia
did not have meaningful influence on decrease of
accuracyofdeterminingposition.Themainlimitation
ofgeodeticGNSSnetworksisthecoverage
ofmobile
networks.
Gdańsk case is an exception as measurements
were undertaken in close vicinity to high density
infrastructureandvesselsmooredtothebearth. The
research proved, that in order to achieve positions
availability of 1m and 2m error values requires
additional planning of observations campaign that
minimisesthe
valueofDOPcoefficients.
REFERENCES
CHS (2013). Standards for Hydrographic Surveys, June
2013,Edition2.
Czaplewski K., Goward D. (2016). Global Navigation
Satellite Systems – Perspectives on Development and
Threats to System Operation, TransNav, the
International Journal on Marine Navigation and Safety
ofSeaTransportation,Volume10,Number2,June2016:
pp.183‐192.
Czaplewski K.
(2018). Does Poland Need eLoran?, 18th
International Conference on Transport System
Telematics,TST2018,Krakow,Poland,March20‐23:pp.
525‐544.
Dziewicki, M., Specht, C. (2009). Position Accuracy
Evaluation of the Modernized Polish DGPS. Polish
MaritimeResearch,Volume16,Issue4,pp.57‐61.
IHO (2008). Special Publication S‐
44, Standards for
Hydrographic Surveys, International Hydrographic
OfficeMonaco.
KelnerJ.,ZiółkowskiC.,Nowosielski,L.,WnukM.,(2016).
Reserve navigation system for ships based on coastal
radio beacons, IEEE/ION Position Location and
Navigation Symposium, PLANS, Savannah, GA, USA,
DOI:10.1109/PLANS.2016.7479726.
Makar, A. (2018a). Determination of Inland Areas
Coastlines. 18th International
Multidisciplinary
ScientificGeoConferenceSGEM2018, vol. 18 (22), 2018,
pp.701‐708.
MakarA.(2018b).DynamicTestsofASG‐EUPOSReceiver
in Hydrographic Application, 2018, 18th International
Multidisciplinary Scientific GeoConference SGEM2018,
18(22),Albena,743‐750.
Sadowski J., Stefański J. (2017). Asynchronous phase‐
locationsystem,September2017,
DOI:10.1080/20464177.2017.1376372
Specht C. (2003).
Availability, Reliability and Continuity
Model of Differential GPS Transmission, Polish
AcademyofSciences,AnnualofNavigationno5.
Specht M., Specht C. (2018). The Use of GNSS Geodetic
NetworksontheAproachtothePorts=GulfofGdansk
Study, 18th International Multidisciplinary Scientific
GeoConference SGEM 2018, Conference Proceedings,
Vol.18,
Issue23,Albena,Bulgaria,pp1075‐1082.
661
Specht C., Specht M., Dąbrowski P. (2017). Comparative
Analysis of Active Geodetic Networks in Poland, 17th
InternationalMultidisciplinaryScientificGeoConference
SGEM2017,ConferenceProceedings,Vol.17,Issue22,
29June‐5July,Albena,Bulgaria,2017,pp.163‐176.
SpechtC.,SpechtM.,ŚwitalskiE.(2017).Applicationofan
Autonomous, Unmanned
Survey Vessel (ASV/USV) in
Bathymetric Measurements, Polish Maritime Research
Volume 24, Issue 3, pp. 36‐44. doi:10.1515/pomr‐2017‐
0088.
Specht, C., Koc, W., Smolarek, L., Grządziela, A.,
Szmagliński, J., Specht, M. (2014). Diagnostics of the
TramTrackShape withtheuseoftheGlobalPositioning
SatelliteSystems(GPS/Glonass)
Measurementswitha20
Hz Frequency Sampling, Journal of Vibroengineering,
Volume16,Issue6,pp.3076‐3085,ISSN1392‐8716.
Stateczny A., Wlodarczyk‐Sielicka M., Gronska D., Motyl
W. (2018). Multibeam Echosounder and LiDAR in
Process of 360‐Degree Numerical Map Production for
Restricted Waters with HydroDron, Baltic Geodetic
Congress(BGC
Geomatics),288‐292.
Stateczny A., Gronska D., Motyl W. (2018). Hydrodron‐
New Step for Professional Hydrography for Restricted
Waters,BalticGeodeticCongress(BGCGeomatics),226‐
230.
Ministry of Defence of the Republic of Poland (2018).
Minimum requirements for hydrographic surveys. Dz.
U.poz.888
NeumannT.(2018).TelematicSupportin
ImprovingSafety
of Maritime Transport, TransNav, the International
Journal on Marine Navigation and Safety of Sea
Transportation,Volume12,Number2,pp.231‐235.
Guze S., Neumann T., Wilczyński P. (2017). Multi‐Criteria
Optimisation of Liquid Cargo Transport, Polish
MaritimeResearch,SpecialIssue2017S1(93)2017Vol.
24;pp.
89‐9610.1515/pomr‐2017‐0026.
Urbański, J., Morgaś, W., Specht, C. (2008). Perfecting the
Maritime Navigation Information Services of the
European Union, In 1st International Conference on
InformationTechnology,18‐21May2008,pp.1‐4,
DOI:10.1109/INFTECH.2008.4621631.
Weintrit, A. (2018). Reliability of navigational charts and
confidencein
thebathymetricdatapresented.Scientific
JournalsoftheMaritimeUniversityofSzczecin,54(126),
pp.84–92.
Weintrit, A. (2009). The Electronic Chart Display and
Information System (ECDIS). An Operational
Handbook. A Balkema Book. CRC Press, Taylor &
Francis Group, Boca Raton – London – New York –
Leiden.
