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ESTABLISHMENT AND EVALUATION ASPECTS OF CYPRUS GPS
PERMANENT NETWORK FOR MAPPING APPLICATIONS
S.Spatalas b , E.Stylianidis 3 , C. Pikridas b , P. Patias b
a Geoimaging Ltd, 6 Georgios Seferis Str., 1075 Nicosia, Cyprus - stratos@geoimaging.com.cy
b Faculty of Rural & Surveying Engineering, Aristotle University of Thessaloniki, Univ.Box. 434, 54124,
Greece-(sspatala, cpik, patias)@topo.auth.gr
Commission VI, WG VI/4
KEY WORDS: Navigation, GPS/INS, Spatial Infrastructures, Urban, Value-added, System, Mobile Mapping
ABSTRACT:
The study describes the design, installation, testing and use of a pilot permanent GPS stations network in Cyprus, for mapping
purposes. In addition, it evaluates its operation in order to produce the infrastructure mainly for mobile mapping applications but
also any other type of relevant applications. The Continuously Reference Station Network is designed and established according to
various quality criteria, which are discussed. Several applications using all the available information in static, kinematic in post
process and RTK using virtual reference station technique and autonomous navigation mode are carried out. Three main groups of
applications for mobile mapping are identified and investigated: the first group concerns applications requiring low accuracies (up to
10m), the second group concerns applications requiring medium accuracies (up to lm), and the final group concerns applications
requiring high accuracies (up to few cm). A detail report about the experimental results, aspects and conclusions is presented.
Emphasis is also put on a digital aerial acquisition project, using GPS/INS measurements. Furthermore, in order to test the
effectiveness of using C/A code-data for low cost DGPS applications in real time, appropriate software using the VRS technique is
developed. For that reason measurements of three permanent GPS stations are analyzed for a determination of a kinematic chain
which took place in the broader area of Pafos, Cyprus. The positional accuracy of the path is finally assessed by comparing the
results with post processed trajectory. The results showed that using the VRS station concept with our developed software named
“3VRS”, similar accuracies can be achieved in distances of up to 20km from the nearest reference station as for short baselines in the
single station concept.
1. INTRODUCTION
The paper presents the results of a research project which
targets on the design, establishment and evaluation of the
operation of a GPS permanent network in Cyprus which was
named Positioning System Improvement (PSI).
According to the design specifications, the PSI network consists
of nine dual frequency GPS receivers which are established at
the territory of the island which is under the control of the
Republic of Cyprus and illustrated in Figure 1. The purpose of
the establishment of each station is to provide single and dual
frequency data for relative positioning and also to transmit
DGPS and RTK data for real time users (Weber G., 2001).
The PSI network may have a wide regional coverage where
ever cellular phone service is available. As a result the GPS
measurements could be used in airborne mapping operations
such as aerial photography, LIDAR, remote sensing,
bathymetric, boundary and cadastre surveys, topographic
surveys, emergency and accident response systems,
construction surveys, tracking asset inventory, utility location
and recovery, mobile mapping-imaging, pavement inventory,
precise timing, as well as, deformation studies, atmospheric
modelling and seismic monitoring. Several case studies using
phase and code GPS data, especially on kinematic mode, are
carried out and the evaluation of the results is discussed.
Figure 1. The designed Cyprus permanent GPS network
2. NETWORK DESIGN AND INSTALLATION
Firstly, the optimum operation of the GPS reference station
network has to be ensured. For this reason, the key factors
which are taken into account in selecting a site for our
permanent stations are introduced below (Leica, 2001).
GPS Sky Visibility
Electromagnetic interferences