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1

Teaching Celestial Navigation in the Age of GNSS

Ibáñez I.

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

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2018

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Vol. 12, no. 3

573--584

EN

Over the past two decades, we have witnessed the astounding development of Global Navigation Satellite Systems (GNSS). Celestial navigation has gradually been declining, displaced by the availability of these new, accurate, and easy-to-use electronic systems. Nonetheless, according to the International Convention on Standards of Training, Certification and Watchkeeping (STCW), deck officers onboard merchant ships must have been trained in the observance of celestial bodies to plot the ship’s position and to calibrate compass error. It is a real challenge in the current context to which lecturers in nautical astronomy can respond through innovation in their teaching methods. A new approach to training students in celestial navigation at the Nautical College of the University of the Basque Country is discussed in this paper. It has already achieved promising results in comparison with the traditional teaching methodology, and is both efficient and effective. The adoption of institutional measures is also proposed to ensure that the competence acquired in the training phase is at all times present throughout professional practice.

2

Estimation of Slant Tropospheric Delays from GNSS Observations with Using Precise Point Positioning Method

Savchuk S., Khoptar A.

Annual of Navigation

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2018

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No. 25

253--266

EN

Global Navigation Satellite Systems give opportunities for atmospheric parameters analysis in behalf of solving many atmosphere monitoring tasks. The authors of this article demonstrated possibility of slant tropospheric delays determination with using precise point positioning method – PPP. The atmospheric parameters, retrieved from GNSS observations, including zenith tropospheric delays, horizontal gradients, and slant tropospheric delays, are analyzed and evaluated. It was obtained slant tropospheric delays, along the satellite path, for each satellite, at a certain elevation angle and azimuth, at each time, instead of obtaining a single zenith tropospheric delay composed of all visible satellites at one time. The results obtained proved that suggested method was correct.

PL

Globalne systemy nawigacji satelitarnej ‒ GNSS ‒ dają możliwości analizy parametrów atmosferycznych do rozwiązywania wielu zadań związanych z monitorowaniem atmosfery. Autorzy tego artykułu zademonstrowali możliwość estymacji opóźnienia troposferycznego w kierunku do satelity za pomocą metody absolutnego precyzyjnego pozycjonowania ‒ PPP. Parametry atmosferyczne, uzyskane z obserwacji GNSS, w tym opóźnienie troposferyczne w kierunku zenitu, gradienty poziomy i opóźnienie troposferyczne w kierunku do satelity są analizowane i oceniane. Otrzymaliśmy opóźnienia troposferyczne w kierunku do satelity dla każdego satelity pod pewnymi kątami wzniesienia i azymutu w każdej chwili, zamiast uzyskać pojedyncze opóźnienie troposferyczne w kierunku zenitu złożone z wszystkich widzialnych satelitów naraz. Uzyskane wyniki wykazały, że sugerowana metoda była prawidłowa.

3

Sources of error in satellite navigation positioning

Januszewski J.

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

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2017

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Vol. 11, no. 3

419--423

EN

An uninterrupted information about the user’s position can be obtained generally from satellite navigation system (SNS). At the time of this writing (January 2017) currently two global SNSs, GPS and GLONASS, are fully operational, two next, also global, Galileo and BeiDou are under construction. In each SNS the accuracy of the user’s position is affected by the three main factors: accuracy of each satellite position, accuracy of pseudorange measurement and satellite geometry. The user’s position error is a function of both the pseudorange error called UERE (User Equivalent Range Error) and user/satellite geometry expressed by right Dilution Of Precision (DOP) coefficient. This error is decomposed into two types of errors: the signal in space ranging error called URE (User Range Error) and the user equipment error UEE. The detailed analyses of URE, UEE, UERE and DOP coefficients, and the changes of DOP coefficients in different days are presented in this paper.

4

G4 Multi-constellation Precise Point Positioning service for high accuracy offshore navigation

Tegedor J., Ørpen O., Melgård T., Łapucha D., Visser H.

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

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2017

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Vol. 11, no. 3

425--429

EN

Fugro is operating a global GNSS infrastructure for the delivery of high-accuracy multi-constellation Precise Point Positioning (PPP) service, named G4. Precise orbit and clock for all global satellite navigation systems are estimated in real-time and broadcast to the users using geostationary satellites. End-users with a G4-enabled receiver are able to obtain sub-decimeter positioning accuracy in real-time. The system has been tailored for offshore applications where a nearby GNSS station is not always readily available. G4 offers seamless integration of GPS, GLONASS, Galileo and BeiDou in the navigation solution, therefore allowing the user to obtain a reliable and accurate position even in challenging environments, especially in presence of interference, scintillation or partial sky visibility. In addition, carrier-phase integer-ambiguity resolution (IAR) is supported, for those users requiring the highest possible navigation accuracy. This paper presents the G4 system architecture and current performance. The benefits of multi-constellation Precise Point Positioning (PPP) are shown in terms of increased availability, robustness and accuracy.

5

Global Positioning System: Political Support, Directions of Development, and Expectations

Czaplewski K.

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

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2015

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Vol. 9, no. 2

229--232

EN

Over the last decade the Global Positioning System has become a global, multifunctional tool which provides services that are an integral part of U.S. national security as well as the security of other highly developed countries. Economic development, transport security as well as homeland security are important elements of the global economic infrastructure. In 2000 the United States acknowledged the growing significance of GPS for civilian users and stopped intentionally degrading accuracy for non-military signals that are known as “Selective Availability”. Since then, commercial applications of satellite systems have been proliferating even more rapidly, and therefore, their importance in everyday life has greatly increased. Currently, services that depend on information obtained from the Global Positioning System are the driving force behind economic growth, economic development and the improvement in life safety. This economic development would not be possible without the financial and political support of the US government to maintain the operation of the GPS system. Therefore it is important to have knowledge about the intentions of the US government how system GPS will be developed in the future. Decisions taken in the last 3 months are the subject of this article.

6

Evaluation of Positioning Functionality in ASG EUPOS for Hydrography and Off-Shore Navigation

Rogowski J., Specht C., Weintrit A., Leszczyński W.

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

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2015

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Vol. 9, no. 2

221--227

EN

The paper discusses the ASG EUPOS services. There is presented an assessment of the possibility of using this system selected sites in hydrography and off-shore navigation tasks. Presented and analyzed the experiments were carried out in the port of Gdynia and on the Gulf of Gda?sk. The results obtaining in the work confirm the possibility of the position accuracy guaranteed by ASG EUPOS services. The obtained accuracy greatly exceeds the needs and requirements of coastal navigation and underwater mining and exploration of sea bottom.