B2. Istanbul 2004
ata is possible with
le of application and
in the Geomatic
'e n?4).
luetooth connection
SIM card for data
m has requested the
s S55) and above all
The procedure has
the applications and
e upgrade with the
om the compact flash
quired more than two
nations of its initial
start the initialization
onfiguration.
graphical coordinates
-oordinates has been
M connection through
TIM permanent GPS-
4 System
are directed from the
y the GPS Leica GS20
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B2. Istanbul 2004
The resolution of the ambiguity effected by the permanent
station is very fast.
The following transmissions of the corrections to the rover are
not influenced in strong way by the growth of the distance
between master and rover.
All the ambiguities have been resolved in very small times with
the attainment of the default accuracy of the tool (50 cm or less)
after few minutes.
Purpose of the present job it will be to verify the accuracy of
use of GSM telephone system in the transmission of
corrections from a master to a GPS "low-cost" rover.
The experimental tests will consist in the survey of some
“known” points and some Italian GPS Reference Network (IGM
95) vertexes taken with RTK configuration set.
The vertexes IGM95 chosen for the experimental tests, has
been: Bari S. Spirito, Palombaio, Palo del Colle, Altamura,
Locorotondo: the “known” point is the Polytechnic of Bari
permanent GPS-station.
The choice is due to the growth of the vertex distances from
permanent GeoTIM GPS-station of Bari (from 7.5 km to 6
km): the purpose it's to verify the possible diluition of precision
with the increasing of distance among the receiver and the fixed
station.
The tool adopted to transfer GPS raw data has been Leica GIS
Data Pro Version 2.1(figure n°6).
This software rapresent a link beetween GPS collected data and
Geographic Information System (GIS).
pe a
pe TYE Tal
Sd pT
Fig 6. GIS-Data Pro 2.1.
The tool Leica GIS Data Pro software has been used in the
phase of data transfer from the GPS receiver (this operation 1s
allowed with a serial cable RS-232 and also in wireless
modality).
The software allows the transformation d the coordinates
WGSS4A into into local coordinate system, opportunely defined
or imported.
It's possible to display background files underneath collected
GPS data: the imported CAD or ESRI shapefiles can be edited
with GIS Data Pro: aside from shapefiles, it can accept data
imported from a GIS in different formats.
In the figure n? 6 are displayed the feature browser, the map-
view and the GPS summary view: this important characteristics
show the attitude of this software to link GPS survey data and
GIS informations.
3. CONCLUSIONS
Some results gotten in the surveys are brought in following
table n. 1. It is showed the comparison between GS20 PDM
data, in DGPS-RTK configuration set, and the known
coordinates.
vorticelcMes [distance] DN | DK
[km] | [+m] | [+ m]
PALO DEL COLLE 73 025 | 0,04
BARI S. SPIRITO F5 0.32 | 0,05
POLYTECHNIC 9,5 0,40 | 0.06
PALOMBAIO 14 Gis | 635
ALTAMURA 36 01 10,28
LOCOROTONDO 60 053 | 0.30
Table n.1: Comparison beetween RTK “GS20 PDM” data and
known coordinates
The results show the increasing of the differences with the
growth of the distance from the permanent GeoTIM GPS-
station of Bari Modugno.
The accuracy is sub-metric, coherently with how anticipated in
the planning session.
It is possible to hypothesize that the values gotten in this first
phase are confirmed by the following survey measurements, for
the other different vertexes of the IGM95 Network.
In the following phases of the research, still in course of
execution at the Polytechnic of Bari, we propose ourselves to
complete the planimetric surveys and also to investigate the
orthometric height in all the points.
The wireless Bluetooth system, after the firmware upgrading
and the initial configuration, effected in the laboratory, is very
simple to use: it is an easy solution for the collection of
submeter GPS/GIS data, while during the survey some
correlated problem to the use of the batteries is manifested.
The GSM connection to the reference station is fast and it has
been maintained during the survey without problems.
The data in the table n°1 have been gotten using the internal
GS20 antenna: it has expected that the accuracy of the measures
can increase using the external antenna (AT501 — tracks LI
only).
The survey has also been conducted using different kinds of
devices [Caprioli et alii,2003].
In the prevoius tests, the same survey has been conducted with
LEICA system 500- SR530" (tracks the L1 C/A code and L2 P-
code, Wavecom GSM module with business SIM card for data
transmission) in order to realize many kinds of data comparison.
The DGPS RTK results brought in table 2 have been gotten
with higher accuracy obtained, obviously, with an *high cost"
receiver.
VerticoIGMoS oo nee) DN | DF
[km] {+ m] | I+ m]
PALO DEL COLLE 75 | 0.047 | 0,035
BARI S. SPIRITO 73 | 0014 | 0,046
POLYTECHNIC 95 | 0,016 | 0,041
PALOMBAIO 14 | 0.014 | 0.047
ALTAMURA 36 [0,005 [0.029
LOCOROTONDO 60 [0.125 [0.048
Table n.2: Comparison beetween RTK “SR530” data and
known coordinates
