Mieczysław Bakuła

Study of Reliable Rapid and Ultrarapid Static GNSS Surveying for Determination of the Coordinates of Control Points in Obstructed Conditions

This paper presents a method for the surveying and reliable processing of Global Navigation Satellite System (GNSS) observations in rapid and ultrarapid static surveying for determination of control-point coordinates. The presented technique allows for reliable determination of coordinates, even in the case of highly difficult observation conditions (e.g., for control points situated along forest edges or entirely in the forest, near buildings, or in the vicinity of power-transmission lines). The paper also analyzes different projects of the global positioning system (GPS/GLONASS) networks from the perspective of their credibility and reliability. The control-point coordinates are determined by three GNSS receivers positioned in line on a special base, providing a credible control of GNSS baselines during rapid and ultrarapid static surveys. The GNSS receivers are separated by the distance of 0.5 m. Given the gross errors in baseline coordinates determined that happen in practice, simultaneous use of three receivers for position determination of a control point allows reliable determination of the coordinates even under significantly obstructed access to satellites. The practical surveys were conducted using Topcon and Trimble receivers using real and virtual reference stations. The presented survey and GNSS data-processing methodology allow obtaining centimeter-level accuracy in a few minutes of GPS/GLONASS observations for control points located in obstructed conditions.

Reliable and Redundant RTK Positioning for Applications in Hard Observational Conditions

Reliable and Redundant RTK Positioning for Applications in Hard Observational Conditions It is well known that RTK (Real Time Kinematic) positioning is a very efficient technique for determination of coordinates in real time, directly on location. Although this technique has been well known since the mid-nineties of the last century, the common use of this technique developed since permanent reference GNSS (Global Navigation Satellite Systems) stations started operating as the national reference systems. Positioning in real time is very convenient for users who do not need to know any advanced technique of post-processing, especially in cases when no obstructions exist around the measured point exist. However, in practice, there are some situations when the use of RTK technique makes some difficulties, especially if the GNSS receiver has no full availability of satellites. Obstructions caused by trees, buildings, power lines etc. limit satellite availability and in consequence decrease the reliability of determined coordinates significantly. In those situations gross errors of even meters can appear in RTK positioning. In order to avoid misleading coordinates occurring we can use more than one RTK receiver simultaneously. The paper presents an approach to the RTK technology based on the simultaneous use of three different RTK receivers. Three different GNSS/RTK receivers can be set on a special mounting beam and additionally RTK positions are sent in real time to a computer. The computer software analyses not only the precision but also checks the accuracy and reliability of the RTK positions determined. Consequently, the new approach to RTK survey presented can allow obtaining reliable coordinates of centimeter accuracy even under very severe forest conditions.

Study Of Differential Code GPS/GLONASS Positioning

Abstract This paper presents the essential issues and problems associated with GNSS (Global Navigation Satellite System) code differential positioning simultaneously using observations from at least two independent satellite navigation systems. To this end, two satellite navigation systems were selected: GPS (Global Positioning System, USA) and GLONASS (GLObalnaya NAvigatsionnaya Sputnikovaya Sistema, Russia). The major limitations and methods of their elimination are described, as well as the basic advantages and benefits resulting from the application of the DGNSS (Differential GNSS) positioning method. Theoretical considerations were verified with the post-processed observations gathered during a six-hour measurement. The data from selected reference stations of the ASG-EUPOS (Active Geodetic Network — EUPOS) system located at different distances from the rover site was used. The study showed that the DGNSS positioning method achieves higher accuracy and precision, and improves the stability of coordinate determination in the time domain, compared to positioning which uses only one satellite navigation system. However, it was shown that its navigational application requires further studies, especially for long distances from the reference station.

Application of Ground Penetrating Radar Surveys and GPS Surveys for Monitoring the Condition of Levees and Dykes

This paper analyses the possibility of using integrated GPS (Global Positioning System) surveys and ground penetrating radar surveys to precisely locate damages to levees, particularly due to the activity of small fossorial mammals. The technology of intercommunication between ground penetrating radar (GPR) and an RTK (Real-Time Kinematic) survey unit, and the method of data combination, are presented. The errors which may appear during the survey work are also characterized. The procedure for processing the data so that the final results have a spatial character and are ready to be implemented in digital maps and geographic information systems (GIS) is also described.

Initial Results of RTK/OTF Positioning Using the Ntrip Data Teletransmission Technology@@@Wstępne Wyniki Pozycjonowania RTK/OTF z Wykorzystaniem Technologii Teletransmisji Danych Ntrip

The paper presents the initial results of RTK/OTF satellite measurements made using NTRIP Internet data transmission. Two permanent reference stations belonging to the University of Warmia and Mazury in Olsztyn were used for test measurements. As a result of measurements taken at three measurement points situated 1,5 to 20 kilometers from the reference stations the accuracies of up to a few centimeters were obtained for points situated in the open terrain. The accuracies obtained at the point with numerous covers in the form of tree branches ranged from several centimeters to almost 3 meters, which is characteristic for GPS measurements taken under conditions of limited availability of satellites.