This paper describes the researches upon the precise short-time GPS solutions made in the Centre of Applied Geomatics, Military University of Technology. The data from ASG-EUPOS (Polish Active Geodetic Network) was processed using Bernese 5.0 software and EPN (EUREF Permanent Network) standards and models. In this study, the adopted 3-hour observation window is shifted every hour obtaining geocentric coordinates in ITRF2005 reference frame. The adjusted network consisted of over 130 stations from Poland and the neighbouring countries, the period covered observations collected from 8.06.2008 to 18.06.2010. These two years of observations allowed to examine short-period oscillations which we found as closely related to the tidal (dynamic) frequencies. The analysis of the residua from IERS2003 tidal model was performed using least squares method with the Eterna software upon the idea of Chojnicki. It confirmed existence of the significant energy in the frequencies corresponding to S1, K1 and K2. The effects in S1 frequency reflect thermal influences, but the reasons of K1 and K2 existence could be both: dynamic (liquid core resonance and non-linearity of K1 are very difficult for modelling as well as the annual modulation of S1) or artificial (GPS satellites’ orbiting period, dynamic changes of satellites’ constellation and network geometry, multipath, residual tropospheric and ionospheric errors etc.). Since the phase of K1 for all 130 sites is very inconsistent the local effects could be also taken into account as one of the possible reasons. The paper describes the idea of the data processing and analysis, presents the results of vertical (Up component) oscillations in main tidal frequency bands, but also includes the discussion on the possible explanation of existence of short period oscillations in GPS precise solutions., Janusz Bogusz and Jan Hefty., and Obsahuje bibliografii
The region of Central Europe, Adriatic region and Balkan Peninsula were subjects of geo-kine matical monitoring in several projects performed since 1992. Independent GPS epoch-wise observing campaigns took place in several regions and the whole territory is now covered by tens of permanent stations. The long-term observational series from permanent stations generally yield reliable site velocities, however distribution of such stations is not dense enough to provide velocity field with sufficient resolution all over the monitored region. On the other si de the epoch-wise campaigns sites are much denser than the permanent ones, however the repeated epoch observations are not very frequent and their referencing is not unique. In the paper we shortly describe velo city fields available from various national and regional GPS geo-kinematics projects and an attempt to homogenize the heterogeneous velocity fields is presented. The intraplate GPS velocities in Central and South-East Europe and their reliability are discussed, mainly focusing on Adria and East Balkan region where the geo-kinematics is mostly variable and complicated., Ján Hefty., and Obsahuje bibliografické odkazy
The Precise Point Positioning (PPP) analysis technique adapted for monitoring of moderate high-rate coordinate variations from GPS observations is applied for measuring actual displacements related to earthquakes. Two approaches are examined: kinematic PPP which is suitable for larger displacements and analysis of residuals from quasi-static PPP which is suitable for detection of minor displacements. Results from simulated horizontal movements of GPS antenna as well as analyses of 1 Hz GPS data from M 9.0 Sendai earthquake, M 6.3 L’Aquila earthquake and M 4.3 Tatabanya earthquake are shown. Our experiments proved the ability to measure dynamic seismic-related short-term coordinate variations at sub-centimetre level with PPP and to detect both strong and weak seismic signals using GPS satellites observations., Ján Hefty and Ľubomíra Gerhátová., and Obsahuje bibliografické odkazy
The paper is focused to the analysis of permanent and epoch-wise GPS networks extending over the region of Slovakia. We considered almost all available GPS data measured in Slovakia and its close surroundings over the period of last 17 years. Our analysis is based on combination of homogenized permanent and epoch-wise network solutions leading to the ITRF2005 related coordinates, velocities and their global covariance matrix. Estimated velocities were further reduced for APKIM2005d plate motion model and submitted to the velocity filtering and smoothing using the least square collocation approach. The obtained homogenized intra-plate velocity field is then used for the surface deformation analysis. The final and partial results of this procedure are discussed in order to extend information about recent regional geo-kinematics of Slovakia., Ján Hefty, Linda Hipmanová, Ľubomíra Gerhátová, Miroslava Igondová and Branislav Droščák., and Obsahuje bibliografii
Series of repeated epoch-wise GPS campaigns performed in Central European region are used for estimation of site velocities. The main features of campaign processing and combination of network solutions are outlined. The velocities obtained from epoch observations within the Central Europe Regional Geodynamic Project covering the 11-year time span are compared at some sites with velocities derived from permenent GPS observations., Ján Hefty and Ľubomíra Gerhátová., and Obsahuje bibliografii