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Progression of clock DBD changes over time

Maciuk Kamil, Varna Inese, Kudrys Jacek

Metrology and Measurement Systems

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2023

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Vol. 30, nr 3

499--505

EN

Day-boundary discontinuity (DBD) is an effect present in precise GNSS satellite orbit and clock products originating from the method used for orbit and clock determination. The non-Gaussian measurement noise and data processing in 24 h batches are responsible for DBDs. In the case of the clock product, DBD is a time jump in the boundary epochs of two adjacent batches of processed data and its magnitude might reach a couple of ns. This article presents the four GNSS (Global Navigation Satellite System) systems DBD analysis in terms of change over an 8 year period. For each of 118 satellites available in this period, the yearly value of DBD was subject to analysis including standard deviation and frequency of outliers. Results show that the smallest DBDs appear in the GPS system, the biggest - for the BeiDou space segment. Moreover, the phenomenon of changes in DBDs over time is clearly seen at the beginning of the analysed period when the magnitude and number of the DBDs were larger than for current, newest clock products.

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Prediction of Earth Rotation Parameters With the Use of Rapid Products From IGS, Code and GFZ Data Centres Using ARIMA and Kriging - A Comparison

Michalczak Maciej, Ligas Marcin, Kudrys Jacek

Artificial Satellites : Journal of Planetary Geodesy

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2022

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Vol. 57, Special Issue 1

275--289

EN

Real-time prediction of Earth Orientation Parameters is necessary for many advanced geodetic and astronomical tasks including positioning and navigation on Earth and in space. Earth Rotation Parameters (ERP) are a subset of EOP, consisting of coordinates of the Earth’s pole (PMx, PMy) and UT1-UTC (or Length of Day - LOD). This paper presents the ultra-short-term (up to 15 days into the future) and short-term (up to 30 days into the future) ERP prediction using geostatistical method of ordinary kriging and autoregressive integrated moving average (ARIMA) model. This contribution uses rapid GNSS products EOP 14 12h from IGS, CODE and GFZ and also IERS final products - IERS EOP 14 C04 12h (IAU2000A). The results indicate that the accuracy of ARIMA prediction for each ERP is better for ultra-short prediction. The maximum differences between methods for first few days of 15-day predictions are around 0.32 mas (PMx), 0.23 mas (PMy) and 0.004 ms (LOD) in favour of ARIMA model. The maximum differences of Mean Absolute Prediction Errors (MAPEs) on the last few days of 30-day predictions are 1.91 mas (PMx), 0.30 mas (PMy) and 0.026 ms (LOD) with advantage to kriging method. For all ERPs the differences of MAPEs for time series from various analysis centres are not significant and vary up to maximum value of around 0.05 mas (PMx), 0.04 mas (PMy) and 0.005 ms (LOD).

3

Development of a precise local quasigeoid model for the city of Krakow - QuasigeoidKR2019

Banasik Piotr, Bujakowski Kazimierz, Kudrys Jacek, Ligas Marcin

Reports on Geodesy and Geoinformatics

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2020

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Vol. 109

25--31

EN

A geoid or quasigeoid model allows the integration of satellite measurements with ground levelling measurements in valid height systems. A precise quasigeoid model has been developed for the city of Krakow. One of the goals of the model construction was to provide a more detailed quasigeoid course than the one offered by the national model PL-geoid2011. Only four measurement points in the area of Kraków were used to build a national quasigeoid model. It can be assumed that due to the small number of points and their uneven distribution over the city area, the quasigeoid can be determined less accurately. It became the reason for developing a local quasigeoid model based on a larger number of evenly distributed points. The quasigeoid model was based on 66 evenly distributed points (from 2.5 km to 5.0 km apart) in the study area. The process of modelling the quasigeoid used height anomalies determined at these points on the basis of normal heights derived through levelling and ellipsoidal heights derived through GNSS surveys. Height anomalies coming from the global geopotential model EGM2008 served as a long-wavelength trend in those derived from surveys. Analyses showed that the developed height anomaly model fits the empirical data at the level of single millimetres – mean absolute difference 0.005 m. The developed local model QuasigeoidKR2019, similar to the national model PL-geoid2011, are models closely related to the reference and height systems in Poland. Such models are used to integrate GNSS and levelling observations. A comparison of the local QuasigeoidKR2019 and national PL-geoid2011 model was made for the reference frame PL-ETRF2000 and height datum PL-KRON86-NH. The comparison of the two models with respect to GNSS/levelling height anomalies shows a triple reduction in the values of individual quartiles and a mean absolute difference for the developed local model. These summary statistics clearly indicate that the accuracy of the local model for the city of Krakow is significantly higher than that of the national one.

4

Wysokości EVRF2007 w Krakowie

Michalik Dorota, Suwaj Mariusz, Banasik Piotr, Bujakowski Kazimierz, Ligas Marcin, Danielski Aleksander, Kudrys Jacek

Przegląd Geodezyjny

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2020

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R. 92, nr 10

19--26

PL

Stosowanie różnych systemów wysokości i różnych poziomów odniesienia w Europie utrudnia wykorzystanie danych wysokościowych do prac wykraczających poza obszar jednego kraju. Z tego powodu wprowadzono jeden europejski układ wysokości – EVRF2007. Wprowadzenie w Polsce nowego wysokościowego układu odniesienia powoduje konieczność transformacji wysokości z układu PL-KRON86-NH na PL-EVRF2007. W artykule szczegółowo przedstawiono algorytmy transformacji i ich zastosowanie w bazach Państwowego Zasobu Geodezyjnego i Kartograficznego dla obszaru Krakowa. Przedstawiono charakterystykę danych wykorzystywanych do opracowania algorytmu transformacji wysokości, metodykę tworzenia algorytmu oraz jego weryfikację. W artykule omówiono również aspekty transformacji pomiędzy różnymi historycznymi układami odniesienia obowiązującymi na terenie Krakowa, w tym Układem Lokalnym Krakowskim i Układem Lokalnym Huty. Opisano również metodykę konwersji danych zgromadzonych w bazie GEO-INFO, a także organizację prac Ośrodka Dokumentacji Geodezyjnej i Kartograficznej podczas aktualizacji bazy danych.

EN

The use of different height systems and different reference levels in Europe makes it difficult to use height data for work that goes beyond a single country. Because of this, a single European height system/frame EVRF2007 was introduced. The introduction of the new height reference system in Poland makes it necessary to convert heights from PL-KRON86-NH to PL-EVRF2007 frames. This paper presents, in detail, transformation algorithms and their use in databases of the National Surveying and Cartographic Resource (Państwowy Zasób Geodezyjny i Kartograficzny) for the area of Cracow. Characteristics of data used to develop an algorithm of height transformation, methodology of algorithm development and its verification are presented. Moreover, the article discusses historical aspects of transformations between various reference systems, which were valid in the area of Cracow, including the Układ Lokalny Krakowski and the Układ Lokalny Huty. Methodology of conversion of data stored in the GEO-INFO database is also described, as well as the organisation of works of the Surveying and Cartographic Documentation Centre (Ośrodek Dokumentacji Geodezyjnej i Kartograficznej) during database updates.

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Lokalna precyzyjna quasi-geoida na obszarze Krakowa

Michalik Dorota, Suwaj Mariusz, Banasik Piotr, Bujakowski Kazimierz, Ligas Marcin, Kudrys Jacek

Przegląd Geodezyjny

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2020

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R. 92, nr 3

13--18

PL

W pracy scharakteryzowano lokalny model quasi-geoidy niwelacyjnej Quasi-geoidaKR2019, opracowany dla obszaru Krakowa. Model powstał we współpracy Wydziału Geodezji Urzędu Miasta Krakowa i Katedry Geodezji Zintegrowanej i Kartografii Akademii Górniczo-Hutniczej w Krakowie. Podstawą modelu quasi-geoidy były anomalie wysokości, obliczone na podstawie wyników obserwacji GNSS i niwelacyjnych, wykonanych na kilkudziesięciu zaprojektowanych punktach. Scharakteryzowano etapy opracowania modelu: projekt sieci punktów, realizację obserwacji, metodykę modelowania powierzchni quasi-geoidy. Model został opracowany w obowiązujących w Polsce układach odniesienia i układach wysokości. Opracowano program komputerowy, za pomocą którego można korzystać z modelu. Przeprowadzono szkolenie dla geodetów, dotyczące możliwości wykorzystania modelu quasi-geoidy w pracach niwelacyjnych, realizowanych techniką RTK/RTN.

EN

The paper discusses a local model of GNSS/levelling quasigeoid named Quasi-geoidaKR2019, developed for the area of Cracow. The model was developed in cooperation with the Department of Geodesy of the City Hall of Cracow and the Department of Integrated Geodesy and Cartography of the AGH University of Science and Technology in Cracow. Height anomalies calculated on the basis of GNSS and levelling observations made on several dozen designed points constituted the base for the quasigeoid model. In the paper the following stages of model development are discussed: design of point network, realization of observations, methodology of quasigeoid surface modelling. The model was developed in reference frames and height datums valid in Poland. The quasigeoid model may be accessed by means of developed software. A training course for surveyors concerning the possibility of using the quasigeoid model in levelling works with the use of RTK/RTN technique was carried out.

6

Szczyty do wykorzystania

Kozioł Krystian, Kudrys Jacek, Maciuk Kamil, Skorupa Bogdan, Szombara Stanisław

Geodeta : magazyn geoinformacyjny

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2020

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nr 6

40--44

7

Spectral analysis of multi-year GNSS code multipath time-series

Kudrys Jacek

Budownictwo i Architektura

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2019

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Vol. 18, nr 4

15--22

EN

In the presented study multi-year time series of changes in the L1 pseudo-range multipath are analysed. Data from 8 stations of the EUREF Permanent Network (EPN) were used in the study. Periodic components present in the signal and their stability over time were analysed. Also, the type of background noise was determined, based on the spectral index. In some cases, the presence of weak components with a 1/2 and 1/3 of the Chandler period has also been found. Time-frequency analysis shows that periodic signals are not stationary in most of the examined cases, and particular signal components occur only temporarily. The analysed signals were char-acterised by pink noise in the lower frequency range and by white noise for higher frequencies, which is also characteristic for time series of coordinates obtained from GNSS measurements.