Tíhové pole Země je složeno z gravitačního pole zemského tělesa a pole odstředivé síly zemské rotace [1]. Předmětem gravimetrických měření jsou tíhové zrychlení a gradienty tíhového zrychlení. Tíhové zrychlení je měřeno relativními a absolutními gravimetry, Relativními gravimetry se měří rozdíly tíhového zrychlení v prostoru a v čase, zatímco pomocí absolutních gravimetrů se měří plná hodnota tíhového zrychlení s přesností až 10-9 g. První přesná absolutní tíhová měření lze datovat od první poloviny 19. století, kdy bylo tíhové zrychlení určováno pomocí kyvadlových přístrojů s přesností okolo 100 μm s-2. Tyto metody, využívající vztahu mezi dobou kyvu kyvadla o známé délce a tíhového zrychlení, byly používány až do 60tých let 20. století s maximální dosaženou přesností 3 μm s-2. Nástup přesného určování tíhového zrychlení z měření délky a času při pohybu tělesa ve vakuu (tzv. balistické metody) lze datovat od 50tých let 20. století. Již pomocí prvních přístrojů tohoto typu bylo dosahováno přesnosti 10 μm s-2. Vývoj přesných absolutních balistických gravimetrů (nejdříve pouze laboratorních a pak i přenosných) probíhal zejména ve Francii, USA, SSSR, Japonsku a Itálii. Nejpřesnějšími absolutními balistickými gravimetry jsou v současnosti gravimetry FG5, které jsou výsledkem téměř 40 let výzkumu započatého prof. Fallerem z University of Colorado [2] a které jsou vyráběny firmou Micro-g Solutions. Přesnost gravimetrů FG5 je 10-20 nm s-2 [3], což znamená, že během padesátiletého vývoje absolutních balistických gravimetrů došlo ke zvýšení přesnosti v určení tíhového zrychlení o tři řády., Jakub Kostelecký, Vojtěch Pálinkáš., and Obsahuje seznam literatury
This research evaluates the potential benefits of the tightly combined processing of a global navigation satellite system together with the additional ranging observations from a satellite based augmentation system. In specific, the experiment presents performance of precise instantaneous single-frequency positioning based on European Galileo and EGNOS navigation systems. Due to currently low number of Galileo satellites, the test observational data were obtained with hardware GNSS signal simulator. All calculations were performed with in-house developed software - GINPOS. The results show that it is possible to obtain improvement in the accuracy and reliability of single-frequency precise positioning when including observations from SBAS systems. However, one must take in to account that at middle latitudes EGNOS satellites are observed at low elevations what results in higher atmospheric errors affecting its signals., Jacek Paziewski, Paweł Wielgosz and Marta Krukowksa., and Obsahuje bibliografické odkazy
The combination method of results of different space geodetic techniques gives two kinds of products. On the one hand, the Earth orientation parameters (EOP) that define the orientation of the Earth in space and, on the other, the coordinates of collocation stations by them the ITRF is realized. Obtained results are based on the method developed by authors, so called “non-rigorous” combination of the data. Approximately eight-year data was successively processed in order to obtain solutions of both products, which were then compared with the results given in ITRF 2005 solution., Vojtěch Štefka, Jan Kostelecký, and Ivan Pešek., and Obsahuje bibliografii
This study shows the test usage of Mobile Automated Astronomical System No. 1 (M AAS-1) in a local network with an are a of approximately 50 km sq. The network has been built-up especially for experimental purposes to compare the local quasigeoid model determined by three different methods, namely GNSS-levelling, astronomical levelling and gravimetry. The network consists of 34 core points where the astronomic and geodetic coordinates have been measured. Subsequently, the measured data have been processed to obtain vertical deflections and to determine the quasigeoid heights by astronomical levelling. Afterwards, the quasigeoid model has been independently determined also using gravimetric measurements and by the method of GNSS-levelling. In this paper the results of th e comparison of quasigeoid models are being presented. The overall agreement of independently determin ed quasigeoids is on the level of 3 mm. After an overall accuracy evaluation of resulting quasigeoid model authors discuss the benef its of astronomical measur ements using MAAS-1., Tomáš Volařík, Radovan Machotka, Michal Kuruc, Lukáš Puchrik and Josef Jurčík., and Obsahuje bibliografické odkazy
Přesné měření je nezbytné pro úspěšné stavební práce i kontrolu stability objektů, to věděli i naši předkové. Dnes existují velmi citlivé přístroje, které odhalí sebemenší pohyby svahů, mostů, hrází či vysilačů a pomohou tak předejít katastrofě. S detailními postupy, jak moderní měřici technologii využít a analyzovat data, přišel tým výzkumníků z Ústavu teorie informace a automatizace AV ČR ve spolupráci s firmou Geodézie Ledeč nad Sázavou. and Leona Matušková, Stanislava Kyselová.
The development of an elevation frame requires a movement model of the Earth's crust. Currently, regardless of the existence of ASG-EUPOS, it seems that the most reasonable approach is to use the model developed from the levelling data. In Poland three maps of vertical crustal movements were developed on the basis of levelling data. The most recent version was published in 2006. In the above mentioned elaborations, the vertical crustal movements were calculated from two subsequent first order levelling campaigns. The results of all four levelling campaigns in Poland were accumulated and digitalized to include more data. The colocation method was used to develop the model. The graphical representation was made with triangulation and linear interpolation. One unified database was developed on the basis of collected and unified data set of unadjusted observations. The first trials of common use of the three first order levelling campaigns were performed in 2008. However the available levelling data was not complete. The goal of this paper is to evaluate the usefulness of the data from the last three campaigns of precise levelling for the development of vertical movement model in Poland., Kamil Kowalczyk and Jacek Rapinski., and Obsahuje bibliografické odkazy
The paper presents the foundations of MAFA method, as well as its application to the pro cessing of new GPS and Galileo signals. The presented numerical tests have been carried out on the basis of data obtained from a hardware GNSS signal simulator as there are currently too few Galileo satellites on orbit. In the proposed methodology, first linear combinations have been formed using new GNSS signals. These linear combinations constitute a data set for a cascade adjustmen talgorithm employing extended MAFA method. Feasibility of a single-epoch precise positioning has been tested. The single-epoch positioning is particularly important for reliable real-time landslide and deformation monitoring. The obtained test results show a high success rate of the extended MAFA method. The number of the correct single-epoch solutions varied from 85 % to over 99 % depending on the baseline length and accuracy of an a priori position. Thus, the MAFA method may be successfully used with new GPS and Galileo signals, even for the processing of single-epoch data., Sławomir Cellmer, Jacek Paziewski and Paweł Wielgosz., and Obsahuje bibliografické odkazy
Four space geodesy techniques, namely VLBI, GPS, SLR and Doris, produce Earth orientation parameters (EOP) and station coordinates independently of each other. A method to combine them in a non-rigorous way (as described elsewhere) was modified by implementing Vondrak’s smoothing. It replaces a simple constraint to tie EOP at adjacent epochs by a more general expression defining smoothness of the resulting curves. This gives the method better stability of derived EOP. The new method was tested on GPS, VLBI and SLR data covering a one-year interval. The results were compared with the results of the original method and with the IERS c04 solution. The former indicates the effect of modification while the latter shows differences of this particular solution from the official IERS series, Vojtěch Štefka and Ivan Pešek., and Obsahuje bibliografické odkazy
Mezinárodní unie pro geodézii a geofyziku (The International Union of Geodesy and Geophysics, IUGG) byla založena 28. července 1919 v Bruselu. Jejím primárním cílem bylo a je podporovat aktivity mezinárodních vědeckých organizací zabývajících se geodézií, geomagnetismem, geoelektřinou, meteorologií, fyzikální oceánografií, seismologií a vulkanismem. and Jana Žďárská.
According to the theory of plate tectonics, the Earth crust is composed of 14 to 16 major independent segments - tectonic plates. These plates are in motion relative to one another. Not all the plate boundaries are exactly defined. The paper focuses on the behaviour of tectonic plates in the collision zones. Space geodesy techniques allow us to determine precise positions and velocities of the sites on the Earth surface. The global horizontal motions of the tectonic plates were derived from the coordinates and velocities of the stations defining the International Terrestrial Reference Frame - ITRF 2005 which is based on these techniques. The method described in (Kostelecký and Zeman, 2000) was employed. In the Mediterranean area, which is a contact area between the Eurasian, the Arabian and the African plate, also relative movements of the points located along the plate boundaries were computed. Further, a continuum mechanics approach was applied to detect surface deformations on the European continent and around collision zones between the tectonic plates all over the globe., Miluše Šnajdrová and Jan Kostelecký., and Obsahuje bibliografii