Wyniki wyszukiwania - BazTech

1

Subsidence determination in the Central Valley, California

Romero M., Berber M. M.

Reports on Geodesy and Geoinformatics

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2018

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Vol. 106

35--42

EN

Twenty four hour GNSS (Global Navigation Satellite System) data acquired monthly for 5 years from 8 CORS (Continuously Operating Reference Station) stations in Central Valley, California are processed and vertical velocities of the points are determined. To process GNSS data, online GNSS data processing service APPS (Automatic Precise Positioning Service) is used. GNSS data downloaded from NGS (National Geodetic Survey) CORS are analyzed and subsidence at these points is portrayed with graphics. It is revealed that elevation changes range from 5 mm uplift in the north to 163 mm subsidence in the southern part of the valley.

2

Future of National Reference Frames – from static to kinematic?

Poutanen M., Häkli P.

Geodesy and Cartography

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2018

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Vol. 67, no. 1

117--129

EN

Technical development, new applications and requests for increased accuracy in georeferencing are setting new demands for accuracy and reliability of reference frames. Due to crustal deformations and local movements of benchmarks, a static reference network deteriorates with time, thus eventually requiring update of the whole system. Technically, renewal of a reference frame is straightforward and should be done whenever enough new data or updated information exist to get an improvement in accuracy. An example is the International Terrestrial Reference Frame, ITRF, which is renewed regularly. The situation is more complicated with national reference frames which may have been given a legal status, and parameters defined by the national legislation. Even without that, renewal and implementation of such a frame is a multi-million euro project taking years to complete. Crustal deformations and movements deteriorate static reference frames (defined by fixed/static coordinates of benchmarks) with time. Eventually, distortions in a static reference frame will become bigger than the uncertainties of GNSS measurements, thus deteriorating the obtainable accuracy of the measurement technique. Instead of a static reference frame, one can use semi-kinematic or kinematic approach where either the transformation from global to the national reference frame or the coordinates of reference frame benchmarks are time-dependent. In this paper we give a short overview of the topic, and discuss on technical issues and future aspects of the reference frames in the viewpoint of National Mapping and Cadastre Authorities (NMA) with an example on the national strategy in Finland.

3

Reliable Technique of GNSS/RTK Positioning under severe observational conditions

Bakuła M., Pelc-Mieczkowska R.

Reports on Geodesy

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2011

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z. 2/91

67-73

EN

Nowadays GNSS/RTK positioning is a very efficient technique for determination of coordinates especially when it is based on permanent reference stations. It allows every land surveyor to do his work easily and efficiently. However there are some situations when the use of RTK technique makes some difficulties, especially if the GNSS receiver has no full availability for satellites. It is well know that obstructions caused by tress, buildings, power lines etc., limit satellites availability. In those situations gross errors can appear. In order to avoid misleading coordinates occurring we can use more than one receiver has no full availability for satellites. It is well known that obstructions caused by tress, buildings, power lines etc. limit satellite availability. In Those situations gross errors can appear. In Order to avoid misleading coordinates occurring we can use more than one receiver. The paper presents practical tests and description of the GNSS/RTK technology based on the simultaneous use of three different GNSS receivers for the specific control points. Three different GNSS/RTK receivers can be placed on a special mounting beam and additionally RTK positions are send in real-time to a computer. The software on the computer analyses not only the precision but also the accuracy of determined RTK positions. In effects that solution can allow obtaining reliable coordinates even if observational GNSS conditions are very severe.

4

"ASG+": Project for improving Polish Multifunctional Precise Satellite Positioning System

Figurski M., Bogusz J., Bosy J., Kontny B., Krankowski A., Wielgosz P.

Reports on Geodesy

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2011

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z. 2/91

51-57

5

Proposal for new strategy in precise positioning

Cellmer S.

Reports on Geodesy

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2009

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z. 2/87

77-84

EN

In this paper a new approach for GNSS carrier-phase data processing is presented. This approach is based on some properties of Amtoiguity Function Method. New algorithm ensures the condition of integer ambiguities without necessity of cornputing it explicitly. The condition of "integerity" of the ambiguities is ensured through inserting condition eouations in the functional model of adjustment problem. An appropriate, differentiable function for the condition equations is proposed. Some numerical problems connected with new approach were resolved using variable linear combinations of GNSS signals in cascade adjustment algorithm.

6

Mechatroniczny układ pozycjonowania precyzyjnego

Giesko T.

Problemy Eksploatacji

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2000

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nr 1

7-15

PL

W artykule przedstawiono mechatroniczny układ pozycjonowania zwierciadła w układzie regulacji wiązki laserowej z dokładnością do 0,0004 radiana. Omówiono konstrukcje układów, w których wykorzystano walcową przekładnię mimośrodkową oraz walcową przekładnię czołową napędzane przez sterowanie elektronicznie mikrosilniki krokowe. Przedstawiono wyniki analizy parametrów układów regulacji dla obu rozwiązań.

EN

The mechatronic system of the mirror precision positioning in laser beam adjusting system with 0,0004 rad resolution is presented in the article. The structures where are used eccentric gear and cylindrical frontal gear driven by electrionically controlled stepping motors are described. The analisys results of parameters of both positioning systems is presented.