The GNSS RTK-Networks have been aroused a great interest for the advantages in the surveying of the territory in comparison to the traditional RTK methodology. The DISTART in the last year has improved a Network for RTK positioning. At present the net is composed by 8 permanent stations. The control centre is nearby the Department of DISTART of Bologna University. This network is fundamental to investigate all aspects concerning the networks for real time applications. Particularly, not only the topographic feature is investigated, but a very important aspect concerning the data transmission infrastructure is analyzed. In fact the first experimentations demonstrated that the performance of the topographic network depends on the guarantee of a correct data transmission from the GNSS permanent stations to the Control Centre. To investigate on this field we built a network composed by mixed physical data transmission infrastructure between control centre and the permanent stations on the territory (topographic baselines about 70-80 Km) using university Italian network (GARR) and commercial networks. We studied the time of latency of data transmitted, that is an important aspect of the network, because to solve ambiguities every software for real time network solution needs that the GNSS permanent station observations arrives with a latency not too much greater than a second. Parallely we studied other important aspects of the data transmission in the network like the NAPs (Network Access Protocols), the velocities, the data formats (RTCM 2.X, RTCM 3.0). In this work we want to give the direction to characterize a procedure step by step of a network installation, wit h the purpose to define a standard, possibly certified, about procedures, materials, softwares to use to install a network of GNSS permanent stations for RTK positioning.
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... THE TREATMENT OF TIME SERIE S DATA OF GPS PERMANENT STATIONS FOR EXTRACTING GEODETIC SIGNALS F.Vespe(l), P. Rutigliano(2) , R. Pacione(2) (I) Agenzia Spaziale !taliana , Centro di Geodesia Spaziale "G. Colombo". 75100 - Matera, Italy (2'relespazio S.pA Centro di Geodesia Spaziale "G. Colombo" - 75100 Matera, Italy Abstract It is wen known that the coordinates and the zenith total delays, estimated by the GPS, provide a big amount of information. Currentły a lot of stations with a very long data time series are present all over the world which malee now feasible to perform a critical analysis of the coordinates helpful for the detection of signals, such as: height displacements, velocities and strain rate suitable for geophysical interpretations. In the present work a method to assess the reliability of the time series is described and applied to some stations with a period of observations long 5 years at least. The method essentially build a "fingerprint" which give information how long time a signal can emerge ITom the time series. Furthermore with the method, harmonic signatures and jumps on the time series are detected and analysed. The method does not only detects the value of the jumps but also where they are placed along the time series. The good efficiency in the detection and evaluation of jumps is of utmost importance because they introduce spurious signatures which could dramatically delay the enhancement of the signals. So our method allows to detect jumps that could be neglected or not assessed or be themselves a signal to detect.
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