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In those years Codevintec Italiana (Milan), WILD
Heerbrugg, now Leica, Geotop (Ancona) and may be others
lent some GPS receivers to the Universities: therefore these
companies gave a very important contribution to the
progress of GPS researches in Italy.
Some Italian Universities, under the leadership of
Politecnic of Milan, performed very important theoretical
researches in particular on the processing methods and in
geoidal models.
In 1990 IGM began the measurements for the GPS first
order network, IGM95, which is now tha backbone of
italian geodesy and cartography.
In the hardware domain, Elettronica SpA, Rome designed
and constructed a small number of GPS geodetic receivers
for the Italian Space Agency.
2. ACTUAL SATELLITE POSITIONING
Fast Static, OTF (On The Fly) are well known methods
which has been commercially delivered since 1995. No
other so much important techniques have been introduced
in the last years, even if several electronic innovations have
reduced the weight and speeded up the GPS receivers.
GPS is now at consumer level; a TV geographic play uses
GPS. Nevertheless the diffusion of GPS is less fast than
expected. The main limitation to the diffusion of GPS is the
lack of a national RTCM radiodiffusion service. Hence our
present main effort is to push the production of this service,
after having experimented and choosen the best system,
among the available, which are
Terrestrial diffusion
-LOW FREQUENCY:
ALF, Accurate Positioning by Low
Frequency, operated by Bundesamt fuer Cartographie
und Geodesie (BKG) in Frankfurt am Main
Marine Radiobeacon as operated in
the past from Venice and now from Vieste (Foggia)
-HIGH FREQUENCY (VHF,UHF):
RDS (Radio Data System)
DARC(Data Radio Channel)/Swift
(System for Wireless Infotainment Forwarding and
Télédistribution): it is used by ORF, the Austrian Radio
Television Company, on the FM band, to diffuse RTCM
and RTK in whole Austria
DAB (Digital Audio Broadcasting): it is
under test in Germany and in Italy, province of Bozen
(RAI and RAS)
Mobile telephones
The University of Trieste has been carried out some
kinematic experiments, also in cooperation with RAS,
Bozen, on DAB as well as on ALF and on Marine
Radiobeacon and with mobile telephones. The results have
shown a general feasibility of the methods in terms of
accuracy, while the mobile telephone link suffered frequent
interruptions
Satellite telecomunication diffusion
RACAL , OMNISTAR are world wide commercial services;
EGNOS , European Geostationary Overlay Service , is a
European Community project bom for air traffc control.
All of them diffuse the RTCM corrections on a carrier in the
same band of the GPS signals.
The service is at least continental so that Wide Area
refractivity models have to be used in order to reduce the
errors due to the long distances from the Master station.
Being based on geostationary satellites, their signals can be
eclipsed by buildings and other obstacles so that they are not
feasible in a limited sky environment like urban areas.
3. RECENT GPS APPLICATIONS IN ITALY
In the last years, the Italian Universities have participated to
the repetition of several very important Mediterranean and
Europen geodinamical GPS campaigns. Also many geodetic
GPS campaigns have been performed for cartography, soil
movement monitoring, costruction of transport infrastructures
and survey of glaciers. Experiments have been carried out on
road survey by means of intergrated GPS/INS and Laser
scanning, GPS+GLONASS terrestrial vehicle trajectories ,
oscillation measurements of a chimney by means of high
sampling rate GPS , Airborne Laser Scanning , atmospheric
pollution monitoring by GPS positioned vehicles equipped
with gas sensors .
Several GPS reference stations are in operation, the first one
has been installed in Matera by the Italian Space Agency.
Nuova Telespazio SpA operates some reference stations too
and participates together ENAV, the Air Traffic Control
Authority, to EGNOS: flight experiments have been already
done in Ciampino (Rome) airport.
