226
Figure7.TheresultsofmeasurementsatCetniewopointin
theGUGiKʹ92ʹcoordinatesystem(coordinatesinmeters)
Gdynia point is located inside the triangleof the
ASG EUPOS reference stations: WLAD (Władysła‐
wowo),Gdańsk(GDA1)andElbląg(ELB).Helpoint
lies outside the aforementioned triangle net‐work of
reference points and therefore uses extrapo‐lated
differential correction. Cetniewo point lies near
WLADreferencepoint.
Intheaforementionedpoints
triplicate measurement results after 10 ses‐sions are
showninfigures5,6and7.
TheanalysisoftheresultspresentedinFigures5,6
and7indicatesthattheresultsobtainedatCetniewo
pointaremuchbetterthanthosefromGdyniapoint,
because Cetniewo point
is located very close to
WLAD reference station. At Hel station , there is
much greater divergence inthe northern component
(up to 4 centimetre) because the corrections of the
RTK/VRSareextrapolated.
An important problem to occur as measured by
RTKwithASGEUPOS network isinternetcoverage
providedby
mobiletelephony.TheORANGEmobile
phonecoveragemapisshowninFigure8.
Figure8.CoverageMapOrangemobileinPoland[22].
Theanalysisofthemapbringstheconclusionthat
mobilephone rangecoversalmosttheentire Gulf of
Gdansk and in the coastal zone of less than 10
nauticalmiles(Nm).Theseinformationareestimates,
because network administrators, unfortunately, do
notprovideaccuratedata.
7 SUMMARYANDCONCLUSIONS
The ASG‐EUPOS
system is a convenient tool to
preciselyspecifythelocationofstationaryormoving
object.TheNAVGEOserviceswillenableto identify
theobjectpositionatsea.Dependingontheexpected
accuracy,itwillbepossibletotakeadvantageofthe
NAWGEO, KODGIS and NAWGIS services. The
applications of all
these services require Internet
connectionto work withthe ASG‐EUPOS network.
Inpractice,thecoverageoftheInternetrangeoutside
themainlandlimitstoadistanceofabout10nautical
miles from shore. Another limitation is the distance
fromthereferencestationatwhichitispossibletouse
the
methodofRTK.Inpractice,thisdistanceisabout
20 kilometres, which is about 10 nautical miles. In
conclusion, the distance of 10 nautical miles from
shorelimitstheapplicationoftheRTKmethodusing
data via the Internet.This disadvantageis mitigated
by the use of the VRS method.
It should be noted,
however,thattheVRSdataatseawillbeextrapolated
which will reflect on the measurement results. The
results of our measurements can be seen at HEL
station, which lies outside the reference station
network. However, even for this station, they were
wellwithinthelimitsprovided
bytheASGnetwork
administrators.ThatmeansfortheNAWGEOservice
– 3 centimetres in horizontal position and 5
centimetresinaverticalone.
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