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Low bandwidth network-RTK correction diissemination for high accuracy maritime navigation

Alissa S., Håkansson M., Henkel P., Mittmann U., Hüffmeier J., Rylander R.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

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2021

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Vol. 15 No. 1

171--179

EN

More than half of the incidents reported to EMSA relate to nautical events such as collision, groundings and contacts. Knowledge of accurate and high-integrity positioning is therefore not only a need for future automated shipping but a base for today’s safe navigation. Examples on accidents include Ever Given in the Suez Canal and HNoMS Helge Ingstad in Norway. A Network-RTK (NRTK) service can be used as an augmentation technique to improve performance of shipborne GNSS receivers for future positioning of manned and unmanned vessels in restricted areas, such as port areas, fairways, and inland water ways. NRTK service providers generate RTK corrections based on the observations of networks of GNSS reference stations which enables the users to determine their position with centimeter accuracy in real-time using a shipborne GNSS receiver. Selection of appropriate communication channels for dissemination of NRTK corrections data is the key to a secure positioning (localization) service. In PrePare-Ships project, the modern maritime communication system VDES (VHF Data Exchange System) is proposed to distribute SWEPOS (NRTK in Sweden) correction data to shipborne positioning modules. VDES is a very reliable technique and it is compatible with most onboard functionalities. In order to minimize the impact on the overall VDES data capacity in a local area, NRTK correction data shall only occupy a single VDES slot with a net capacity of 650 bytes. Update rates may vary but are preferably at 1Hz. However, NRTK correction data size changes instantly, depending on the number of visible GNSS satellites, and the data rate can therefore sometimes reach in excess of 1000 byte/s. In this study, a smart technique is proposed to reduce size of NRTK correction data to instantly adapt with the VDES requirements by choosing a combination of specific signals, satellites or even constellations such that the data rate is not more than 650 byte/s, and at the same time it achieves optimal positioning performance with the accuracy required by the PrePare-Ships project application.

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Evaluation of RTKLIB's Positioning Accuracy Usingn low-cost GNSS Receiver and ASG-EUPOS

Wiśniewski B., Bruniecki K., Moszyński M.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

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2013

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Vol. 7, no. 1

79--85

EN

The paper focuses on a comparison of different positioning methods provided by free and open source software (FOSS) package called RTKLIB. The RTKLIB supports real‐time and post‐processed positioning. The most important modes of operation tested by the authors are Kinematic, Static, Fixed and Precise Point Positioning (PPP). The data for evaluation were obtained from low‐cost Global Navigation Satellite System (GNSS) receiver. The tested receiver was based on the u‐bloxʹs LEA‐6T GNSS module. This receiver provides different types of information including raw carrier phase measurements. It gives the possibility for centimeter‐level precision of positioning. As the supporting source of data ASG‐EUPOS system was used. ASG‐EUPOS is a Polish network of GNSS reference stations providing the real‐time corrections and post processing services for the entire territory of Poland.

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Initial evaluation of usefulness of geodetic coordinates obtained with the use of RTK-GPS corrections generated by Malopolski Satellite Positioning System

Siejka Z.

Reports on Geodesy

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2007

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z. 1/82

309-315

EN

The paper presents attempt to find the answer to the question, if the experimentally functioning in Matopolska and Silesia system of reference stations is useful to determine geodetic coordinates, using real time technology when the final result of the measurement is known immediately. To obtain the aim multiple measurements were performed using the RTK-GPS technology on selected points of the POLFER network using corrections generated by the System. On a basis of empirical results of measurements, the evaluation of the usefulness of the system for geodetic applications was performed. Reference stations network of the system ASG-PL which was tested, is one of the so called terrestrial differential systems aiding measurements GPS-RTK (real time kinematic). Networks of the type are very often build in different countries and have national or even continental character.

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Ocena dokładności metod RS i RTK w aspekcie ich przydatności w pomiarach realizacyjnych

Gocał J., Uznański A.

Geodezja / Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie

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1998

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T. 4, z. 1

61-70

PL

Na specjalnie przygotowanej sieci testowej wykonano pomiary doświadczalne pozwalające na dokonanie funkcjonalnej i dokładnościowej oceny dwóch metod GPS: Rapid Static (RS) i Real Time Kinematic (RTK) w aspekcie ich przydatności w pomiarach tyczeniowych. Stwierdzono, iż w rejonach występowania przeszkód terenowych (budynki, drzewa, linie elektryczne) obydwie metody umożliwiają wyznaczenie położenia punktu z dokładnością +/-7 mm. Wskazano też na występowanie dużego rozproszenia wyników pozycjonowania punktów znajdujących się w trudnych warunkach obserwacyjnych

EN

Functionality and accuracy of two methods of GPS surveys: Rapid Static (RS) and Real Time Kinematic (RTK), as applied to setting-out and other project surveys, were examined on an especially designed test network. It was found, that even at places where horizon is partially obstructed by buildings, trees or power lines, both methods allow determination of point position with accuracy of +/-7 mm, though attention is drawn to the substantial spread of these results