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This research represents the preliminary phase of the investigation of positioning error prediction possibilities based on ground truth data from GNSS reference stations. The preliminary results confirmed known facts, namely the similarities in positioning deviations, i.e. that satellite positioning performing equally or similarly in the relatively small area. The motivation for this research is to build a comprehensive satellite positioning environment with known influencing factors and satellite positioning performance. The aim is to develop a methodology for definition of distance limits within which positioning deviations can be applied to surrounding areas. To this end, several machine learning algorithms have been introduced. The contributions of this work relate to further efforts and research towards boundarization of valid corrections in terms of distance.

Determining the user’s position using Global Navigation Satellite System (GNSS) data depends on the presence of errors in the satellite part of the system, random errors, errors in the system environment, and user errors. If we systematically neglect and do not apply the error reduction algorithms and process the available input position records of the observed GNSS satellites identically, the differences in position accuracy can be attributed to the effect of the geometric position of the satellite expressed by the GDOP (Geometric Dilution Of Precision) coefficient. At the same time, the number of visible satellites is observed considering the applied elevation mask. The results indicate that the differences in the geometric positioning of the satellites and the orbits lead to a non-uniform accuracy of the user’s position, which depends on the latitude of the user’s position. The key parameter is the elevation mask, whereby increasing the number of visible satellites does not contribute to increased accuracy

Global Positioning System (GPS) still represents one of the most widely used satellite navigation systems. However, there are certain shortcomings of the system that could affect the accuracy of the obtained position. One of such shortcomings is the impact of the troposphere on the propagation of the satellite signal, or to be more precise, calculating the tropospheric delay that occurs when the GPS signal passes through the troposphere. This paper analyses how tropospheric delay caused by a tropical cyclone affects the GPS positioning performance

The study discusses the information- and task- centred concepts and possibilities of Electronic Chart Display and Information System (ECDIS), which may facilitate the navigation venture and ease the workload of the Officer of the Watch (OOW). The concepts refer to the development of Global Navigation Satellite System (GNSS) Positioning, Navigation and Timing (PNT) (basic) services relating to main navigational tasks the system is used for or relies on. The proposals represent potential design and foundations for future outlooks of the system, in line with emerging maritime concepts such as digital vessels, cloud-based technologies and e-Navigation, always in the function of safety of navigation improvement.

The paper presents the results of research on the success of the application of the Saastamoinen model of tropospheric correction in the Galileo radionavigation system. The atmospheric layer of the troposphere affects the propagation of the radionavigation signal causing a decrease in velocity and a deviation from the ideal geometric trajectory. These phenomena are commonly described by the term tropospheric delay. The atmospheric causes of tropospheric delay are hydrostatic and non-hydrostatic elements of the atmosphere, including atmospheric dry gases and water vapour in all its forms. A number of tropospheric models have been developed that determine the value of tropospheric error and correct tropospheric delay. The results presented in this paper are based on the study of the absolute deviation of the accuracy of the user position with respect to the value of tropospheric correction generated by the Saastamoinen model and its impact on the positioning accuracy.

This is a keynote lecture presented at the 14th Baška GNSS Conference: Technologies, Techniques and Applications Across PNT and The 1st Workshop on Smart Blue and Green Maritime Technologies, held in Baška, Island of Krk, Croatia, 10 - 12 May 2021. The presentation refers to the summary of the Scientific project uniri-tehnic 18 – 66: Research of environmental impact on the operation of satellite navigation systems in maritime navigation.

The paper presents the application of the pseudo- spatial model of the GLONASS system in determining the navigation parameters of the vessel’s movement together with the applied ionospheric model accuracy. The atmosphere affects the signal reception causing signal delay, which leads to the error of determining the navigation parameters of the ship, with ionosphere causing the greatest impact on error values. By forming and solving the system in which the number of equations corresponds to the number of visible satellites, with the input data of pseudo-range, the constant error of distance measurement and the known satellite coordinates, the current position of the vessel is obtained. Differentiating this system of equations results in a system that gives the velocity of the vessel concerning the three spatial coordinates. By reducing velocity change with respect to the two spatial coordinates, the final speed of the vessel is obtained. Utilizing a known velocity of the vessel with respect to the x and y coordinates, the direction of navigation is also possible to be determined. Various satellite systems with different mathematical algorithms predict the state of the ionosphere and the value of the incurred error. Dual-band receivers of the GLONASS system perform simultaneously receiving, processing and comparison of signals at two frequencies to which the ionosphere has a different level of interaction.

The Sun acts as the main driver of processes affecting the Earth’s ionosphere, directly and indirectly influencing the Global Navigation Satellite System (GNSS) signals’ timing measurements. Solar impacts can be categorized according to different timescales that are short- lasting (regarding minutes during solar events), diurnal, seasonal (yearly) and perennial, covering the duration of the solar cycle. The proposed paper deals with seasonal and solar cycle and its impact on Global Positioning System (GPS) single frequency (L1) positioning accuracy. Solar activity was analyzed during 17 years of available observation data. For this purpose, Sunspot Number (SSN) and Daily Solar Flux 10.7 cm (SFD) were analyzed. Indices were compared with GPS three- dimensional positioning deviations calculated on three locations in the broader region of the Adriatic Sea. Positioning data were calculated as single frequency solutions, obtained from the International GNSS Service (IGS) Receiver INdependent EXchange (RINEX) data. A significant correlation has been found between positioning accuracy and elaborated indices, both with and without the employment of standard ionospheric correction model, as presented. The emphasis was given on unmodelled positioning solution or errors, respectively, to employ a GPS receiver as a partial solar activity indicator. Besides solar cycle related period, seasonal positioning deviations were analyzed in the frame of the Local Equatorial Coordinate System (LECS) with declination and hour angle as main coordinates. Detectable positioning error increase has been observed during periods of positive Sun declination (in Northern hemisphere), based on the scenario of 4 consecutive years within the elaborated period. Obtained results rendered the possibility of predictive modelling of the GPS L1 positioning error. For this purpose, the elastic net regression method was used, employing SSN and SFD indices as predictors. Results are presented and discussed, with observations and findings summarized in the concluding chapter, together with the desirable continuation of the research.

Satellite navigation represents official positioning mean in maritime navigation. Importance of Global Navigation Satellite System (GNSS) increases with the emerging number of the world fleet, standard and critical services as well as the development of autonomous vessels. Quality of the GNSS positioning performance can be assessed by positioning accuracy, availability and Dilution of Precision (DOP), latter representing the influence of satellite geometry. DOP values depend on the relative position of the receiver and visible satellites. The GNSS positioning error is approximately equal to the product of the respective DOP value and the ranging accuracy. In maritime navigation where vertical positioning component can be omitted, DOP is reduced to the horizontal determination (HDOP). Limit values are defined in respective Performance Standards provided by the International Maritime Organization (IMO). The aim is to state the improvement of GNSS performance regarding employment and combination of different GNSSs as related to GPS, being the most commonly used system in maritime navigation. GPS, GLONASS, Galileo and BeiDou observations from four stations located in Italy, Peru, China and the United States were used. These stations were chosen due to their locations and the availability of positioning from all operational GNSSs. For each location, all possible combinations between satellite constellations were made. The HDOP values, single frequency positioning solutions in a horizontal plane and positioning availability were analysed for December 2017. Analyses of HDOP values confirm improvements in satellite positioning compared to GPS. An insufficient number of BeiDou satellites over the United States resulted in large HDOP values at the MDO1 IGS station (Fort Davis, USA). For the same reason, the best average HDOP values were observed at the JFNG station (Jiufeng, China). Although not fully operational the BeiDou system improved positioning performance when it was combined with a GPS system, as proved at the AREG IGS station, located in Arequipa, Peru. Moreover, the GPS/ BeiDou combination had better performance at JFNG and PADO (Padua, Italy) stations when compared with GPS/GLONASS combination.

Navigacija je vještina u kojoj se spajaju znanost i umjetnost. Ona može biti kopnena, zračna, svemirska, osobna... Može biti elektronička, astronomska, satelitska, inercijalna... Navigacija je više od čina vođenja osobe ili objekta s jednog mjesta na drugo, ili od procesa točnog utvrđivanja položaja i praćenja kretanja. Danas je navigacija postala neizostavan dio svih nas i s njom se susrećemo i koristimo ju cijelo vrijeme. Članovi tima 'Navigation and beyond' s Pomorskog fakulteta u Rijeci – David Brčić, Mirano Hess i Serđo Kos pripremili su za Noć istraživača teorijski i praktični pregled navigacijskih znanosti i vođenja pomorske površinske navigacije tradicionalnim načinima, onim modernima, kao i onima koji tek dolaze. Za cilj smo si zadali da svim uzrastima, na slikovite načine prikažemo kako možemo voditi navigaciju: kako se možemo orijentirati u prostoru, pomoću kojih uređaja znamo gdje smo, kojim metodama možemo to isto saznati, i kako znamo kuda moramo poći. I kako možemo biti sigurni da smo baš gdje jesmo. I što je najvažnije, da smo svi navigatori.

The proposed study represents a continuation of the research regarding standard GPS ionospheric delay mitigation. Globally distributed locations were elaborated in terms of positioning solutions, with analyses of the horizontal component of positioning error. The ionospheric delay was calculated on the basis of raw pseudoranges and compared with modelled values. The horizontal GPS positioning error was observed in three main ionospheric regions during the geomagnetic storm which took place in March 2015. Residuals between real and modelled values suggest different behaviour of positioning patterns depending on location. Increase in residual values appears notably after the commencement of the disturbance. The conducted study and noted observations open further possibilities for research in this domain of satellite positioning error mitigation.

Satellite navigation positioning performance should not be considered in absolute terms, but rather matched with the requirements for GNSS- based applications. Here, we present a study of the positioning performance of a commercial- grade single-frequency un-aided GPS receiver for maritime navigation applications in the period of moderate space weather disturbances. Matching the GPS positioning performance results with the maritime navigation applications requirements, we found that the category of GNSS receivers concerned does not meet the requirements of the high-quality maritime navigation applications. We presented and discussed the potential shortcomings caused by such situations and proposed the recommendations that will allow for utilisation of GNSS receivers in high-quality and critical marine navigation applications.

In the proposed paper, structural analysis of relevant parameters of the maritime coastal line ZadarPreko (Croatia) was conducted. Passenger and vehicle traffic are observed during a three-year period. Based on the official data processing, parameters of the existing line capacity utilization are determined on a monthly basis. The passenger and vehicle turnover is presented as well as the utilized and nonutilized carrying capacities of the line. The highly seasonal nature of the turnover is emphasized as a result of tourist season, including the discussion on the line unprofitability for the shipping company which is directly due to the seasonality. In this connection, the need for a Government grant is further discussed with a view to maintaining sufficient carrying capacities and line frequency. For further research, a conceptual system is suggested to be based on computer simulations aimed at optimizing the operation of the terminal.

The main purpose of the Vessel Traffic Service (VTS) is ship traffic monitoring and traffic data gathering. VTS service contributes to life-saving operations at sea, general safety of marine traffic improvement and environment protection as required by the Safety of Life At Sea (SOLAS) Convention. The traffic is monitored by coastal Radars and AIS. These devices provide only ship traffic movement and AIS data. In order to gather more information VTS operators have to establish communication with vessels. Most of the communication at sea, either between two vessels in sight or between vessel and VTS operator, is done by VHF radio communication. The common practice between navigators at sea is watching VHF channel 16. However, some vessels do not maintain radio watch so it becomes impossible for other vessels and VTS operators to establish contact. All SOLAS ships have AIS and the number of non- SOLAS vessels that have AIS is on the increase. To prevent VHF communication issues, AIS should transmit on which VHF channel the watch is maintained. The main purpose of this paper is to investigate if that information should be transmitted by AIS in order to help other vessels and VTS operators to establish contact with the vessels which do not maintain proper watch.

The rise and development of multi- frequency/multi-modal satellite navigation receivers provides improvements in satellite positioning accuracy and increasing positioning, navigation and timing (PNT) services integrity. The proposed research deals with positioning performance of augmented GNSS devices. Three handheld satellite navigation receivers were used in the study: GPS, GPS/EGNOS and GPS/GLONASS/EGNOS receiver, respectively. The research took place in the Middle Adriatic area, comprising static and dynamic segment. The static segment was carried out at single point location during several continuous hours, tracking obtained positions. The dynamic segment was conducted during sea navigation in confined navigation channel, where the same GNSS receivers were used for the positioning solutions obtaining. The satellite positioning environment analysis confirmed favourable positioning signals’ propagation conditions and satellite availability during research periods. Obtained positioning patterns were analysed elaborating positioning errors and deviations, given the time resolution of the data obtained. The analyses were made with reference to precise-positioning service provided by dual-frequency GPS receiver which was used during the research. The reference positioning was augmented by CROPOS networked reference stations system, providing static accuracy of 3-6 mm, and dynamic accuracy of 1 – 3 cm, respectively. The results confirmed positional improvement of augmented devices, showing reduced positioning error and lesser variation scattering in multimodal GNSS receivers, when compared to sole system only. Further research activities were pointed out, originating from the conducted research and conclusions. Various environmental, operational and critical satellite positioning scenarios have to be tested, aiming at new generation satellite navigational receivers’ performance studying in sea navigation.

The IGS VTEC maps represent a reliable source of ionospheric information in areas where TEC dynamics cannot be measured directly. Among various IGS products, predicted and measured VTEC are given on daily basis in corresponding standardised data formats. The aim of this research was the study of ionospheric dynamics in the Northern Adriatic region based on provided VTEC maps. VTEC dynamics, both predicted and measured, were gathered during year 2012. Daily VTEC dynamics were analysed, introducing existence of three types of prevalent daily VTEC patterns. The local daily patterns were detected both with predicted and measured VTEC maps, although particular pattern and value differences were observed. Differences (residuals) between predicted and measured VTEC values in 2012 for all 366 days were calculated. Residual values were analysed and compared with solar and geomagnetic activity, aiming at possible relation between space weather events and residual values’ patterns. Depending on season and daily patterns, residuals can be obtained and predicted VTEC behaviour can be corrected. In relation to daily VTEC fluctuations with space weather activity, season and daytime, predicted VTEC values could be improved for predicting GPS position errors within considered area.

Satellite navigation has become a public good, with the growing number of navigation and non- navigation applications being established on the technology. Potential threats on GNSS performance and operation have become the increasing concern of developers, operators and users of GNSS-founded systems and services, with the especial emphasis given to malicious artificial attacks, such as jamming, spoofing and meaconing (JSM). A targeted artificial attack on GNSS performance and operation can cause a considerable material damage and affects lifes. Here the potential consequences of the artificial attack on GNSS performance on the vessel navigation at the open sea are addressed, and a combined technological- procedural mitigation scheme for JMS- resilient GNSS Position, Navigation and Timing (PNT) performance at the open sea is proposed. Through the technology-supported modifications of navigation procedures a reasonable GNSS Quality of Positioning at the open sea can be achieved, overcoming the potential malicious attack on the vessel in the area with the reduced supporting Information and Communication Technology (ICT) infrastructure.

Automatic Identification System (AIS) has proven to be a quality source for non-SOLAS vessel traffic information. This paper presents possibilities of AIS technology development, and its influence on safety of navigation. The paper investigates development of AIS Class B and its influence on marine traffic supervising and control. It considers if and how is possible to manage marine traffic control with AIS for non-SOLAS vessels. The negative potential of AIS is analyzed by mass usage of AIS Class B. The paper concludes with recommendations, improvement suggestions and future work regarding marine traffic control development in the Adriatic Sea.

Satellite positioning signals’ ionospheric delay presents major single cause of GPS L1 performance degradation, caused by Total Electron Content (TEC) dynamics. Depending on nature of the particular event, TEC processes differ in several timescales, ranging from sudden solar events, solar cycle timescale and storm time periods. In long term, it is assumed that TEC behaviour is governed by Solar Ultra-Violet (UV) flux. TEC regularities have already been modelled, GPS ionospheric model being one of them. Characteristic TEC patterns have been observed in the area of Northern Adriatic (middle latitude region), being the motivation for the conducted research. Three vernal periods were analysed. Computed ionospheric delay was compared with the Klobuchar model. Although TEC showed gradual decrease following the solar cycle decline, several events caused its redistribution and peaking. Simultaneously, latitude and longitude coordinates’ deviations were calculated both with and without ionospheric model correction. Preliminary results showed measurable correlation between ionospheric delay and coordinate deviations’ residuals. Performance of the ionospheric model was discussed in terms of ionospheric delay description, pseudorange corrections and coordinate error mitigation. Modelled and unmodelled coordinate deviation patterns showed measurable correlation in quiet and unsettled periods. During the storm period, trends of patterns showed significant difference in observed values, as discussed. Results are outlined in the final chapter, together with planned continuation of the research.

Natural geographic directions – cargo flows represent the shortest natural traffic route connecting origins and destinations. When redirecting the world's traffic flow, these directions become the most important advantage only when preconditions of provision of competitive technical, technological, organizational and economical services on the specific traffic route are satisfied. The basic aim of the paper is the analytical elaboration and scientifically founded necessity for the redirection of the geotraffic flow from the Far East to Europe. Instead of destination in northern European ports (such as Antwerp, Rotterdam, Amsterdam and Hamburg) – the northern traffic flow, the flow should have to be redirected through the Adriatic sea to the ports of NAPA (North Adriatic Ports Association), that are Ravenna, Venice, Trieste, Koper and Rijeka. This route represents the southern traffic flow. During the research, reference destination in the center of Europe was chosen (Munich, Germany). Conducted analyses and calculation results showed that by the proposed redirection, significant shortening both in sea and land transportation can be achieved. Apart from distance and time thus fuel consumption savings, emissions can be significantly reduced in all related transport branches, especially in maritime transportation. The proposed redirection of elaborated route represents reasonable contribution to sustainable transportation improvements.

S meteorološkog aspekta, svemirsko vrijeme može se promatrati kao klasično vrijeme i odnosne vremenske prilike/neprilike. Moguće je pratiti pojave, razvoj i prijenos poremećaja svemirskog vremena, uz mogućnost prognoze i predviđanja. S kronološkog aspekta, razmatra se učinak utjecaja svemirskog vremena na razne zemaljske, satelitske, biološke i društveno ekonomske sustave. Naglasak je na utjecaj svemirskog vremena na mjerenje kronološkog vremena, što nastupa kao važna značajka principa rada niza tehnoloških sustava. Osim toga, veličina prostora na koji se odnosi pojam svemirskog vremena (Sunčev sustav) otvara pitanja problematike relativističkih učinaka, što se izravno ili neizravno može povezati s pojmom kronološkog vremena i njegovoj ovisnosti o događajima unutar prostorvremena.

The Croatian coast with 1244 islands is very atractive for navigators. Of these 1 244 islands 78 are large islands, 524 are islets, 642 of them are rocks. In Croatia there are over 100, 000 registered boats , the number of this boats in summer time increases by 50% . Most of them are for sport, recreation and leisure, such as yachts, sailboats and powerboats. A very large number of vessels during the summer results in a very intensive traffic, resulting with many maritime accidents. One such maritime accident resulting in death occurred in 2011. From the district court it was requested the expert simulation analysis of this case with a detailed display simulations of boats moving trajectories according to VTS records and weather conditions on that day in that area. The application for that simulation was sent to the Faculty of Maritime Studies Rijeka, which has adequate equipment to perform the demanding simulation. Using the model wizard for boats and marine areas , there are designed : type of boats , sea area where the maritime accident occurred and meteorological conditions. Using official records of VTS , boats moving positions are drawn on a electronic chart. The first position of the boats are drawn six minutes before the collision occured. From VTS are received actual speeds of the boats. Setting the boat to the starting position of movement with a defined speed and meteorological conditions for that day , it was realised expert simulation of boats movements. The final result of expert simulation analysis, contributes to better understanding of maritime accidents , pointed to the possibility of mutual passing boats at a short distance without collision danger.

Electronic Chart Display and Information System (ECDIS) is an intelligent system that should enable the Officers of the Navigational Watch (OOW) safe, easy and effective execution of the navigational transportation venture. As a primary navigation mean, it became an inevitable tool in navigation conducting and decision making assistance. However, implementation of this relatively new technology requires certain levels of adaptation, familiarization and knowledge to be reached. Safety Of Life At Sea (SOLAS) Convention regulations dictates implementation of the system onboard SOLAS vessels no later than 1st of July 2018. This regulation entails several issues, ranging from proper education, training and handling, understanding, familiarization, and acceptance of the new technology which (in a way) replaces and displaces existing, traditional navigational means. With the overall benefits which the system provides, it is necessary to reflect on drawbacks present in the system, recently recognised by International Hydrographic Organisation (IHO), International Maritime Organization (IMO) and International Electrotechnical Commission (IEC). Drawbacks are varying from technical deficiencies, through system errors and finally, to the end- users familiarity and knowledge. The ECDIS EHO research deals with comprehensive and multidisciplinary ECDIS analyses. The research emerged from the noticed/observed need for proper education and training, placing humans in system environment, reducing human factor (aspects) of erroneous actions, all with the aim of incident detection and prevention. One of the research activities is the questionnaire placed among seafarers who operate the ECDIS system. The paper discusses questions and answers regarding interaction of electronics and OOWs and their adaptation to the system. Issues while operating the system were elaborated, ranging from operational problems to menus’ and functions’ inconsistencies. Answers are supported with interviews with OOWs. Along with presented results, survey of maritime accidents was carried out, focusing at and elaborating accidents where the ECDIS system was the main or circumstantial accident cause. The findings and derived inferences are pointed out in the concluding chapter, together with further actions and planned activities in all segments of the research.

As primary navigational mean, Electronic Chart Display and Information System became an inevitable tool and decision-making assistance. ECDIS implementation entails several issues, ranging from proper understanding, education, training, handling and acceptance of this, still relatively new, technology. The navigational tool has changed, however traditional navigational skills remain, or at least, they should sustain. ECDIS EHO is an education-based research project with comprehensive and multidisciplinary ECDIS analyses at different levels, focusing on proper education and training, knowledge required for safe navigation conducting, and all other maritime segments which have found their place in the ECDIS system. Among other objectives, the tendency is to create solid interaction with ECDIS end-users, i.e. officers of the navigational watch. One of the research activities is an international survey questionnaire placed among seafarers forming the part of the navigational watch, ranging from deck cadets to pilots. The survey is focused on OOWs on ECDIS and paperless vessels, containing questions regarding experience, system handling and operation, knowledge, as well as mariners’ opinion. It refers specially to mandatory carriage requirements and possible decommissioning of traditional paper charts which, in fact, represent traditional navigation as such. The proposed paper elaborates question concerning one of the main safety parameters in the ECDIS system: the safety contour. Ways of settings the parameter are discussed, given that no clear regulations exist. The importance of this interactive parameter is underlined, because it represents safety of navigation in whole when sailing onboard paperless vessels in depth- restricted water areas. Answers were analysed and discussed, together with interviews with navigational officers, providing direct end- user feedback on the elaborated. Despite dedicating maritime education and training ashore, inadequate use of ECDIS contour had caused few significant accidents which are described and elaborated in this paper by using several marine accident investigation data bases. The summary of findings is pointed out in the concluding chapter, together with planned activities for the further research.

Space weather effects, and the ionospheric disturbances in particular, have been identfied as the major single component of the GNSS error budget. For that reason, the research into the space weather ionospheric coupling has become the major cornerstone in the development of mitigation techniques for the space weather-induced GNSS vulnerabilities and risks. Here we present a theoretical framework, based on Appleton-Hartree formula and experimental models, that relates the space weather (solar and geomagnetic) indices to the GNSS ionospheric delay, thus establishing a theoretical framework for establishing relationship between the space weather observables and the major source of GNSS positioning error.

Understanding the ionospheric disturbances is the key factor in mitigation of the space weather- induced effects on GNSS (Global Navigation Satellite System) positioning performance. This can be reversed in favour of the GPS (Global Positioning System) receiver to become an ionospheric condition sensor. In addition, the Sudden Ionospheric Disturbances (SID) monitor, a low-cost sensor of lower ionosphere activity recently introduced to scientific community by Stanford University group, offers a good perspective for continuous monitoring of the ionospheric activity, especially in its lower layers. Here we present a concept of the local ionospheric monitoring through correlation between the time series of SID monitor observables and the GPS positioning errors. Assuming the ionospheric disturbances have the key impact on GPS positioning performance, and with reducing the impact of the other sources of GPS positioning errors, the concept offers a prospect for fast identification of the approaching, sudden ionospheric disturbances. Timely identification of these disturbances allows for forecasting of possible disruptions and degradations of GPS positioning service in local area, as well as potential effects on the other technological, social and economic systems. Proposed concept is to be validated through the analysis of continuously collected observables at GNSS laboratory, Faculty of Maritime Studies, University of Rijeka, Croatia.

The proper scheme of legal liability for the management of legal consequences of a GNSS failure has become an important GNSS utilisation issue for some time. As the GNSS has become both the enabling and the underlying foundation to a growing number of systems and services, the quest of legal liability emerges as an important component of the establishment of the GNSS business environment. Considering the current state of the art, the GNSS should be considered a component of the national infrastructure, along with the systems such as those for power distribution or the national airspace. Here we present a proposal for a legal liability scheme in the case of the GNSS failure, which is based on the spatial, technology and business environment shared liability. Reflecting the GNSS utilisation from the service provision perspective, this proposal requests the GNSS risks assessment, and mitigation plan to be prepared by the GNSS business environment stakeholders. Under the proposed scheme, the national regulatory agency and the service providers should take a portion of legal responsibility for provision of the guaranteed level of the GNSS positioning and timing service, thus allowing for sustained provision of the GNSS performance and the quality of GNSS-based services.

Ionospheric disturbances are the proven cause of degradation of the GNSS performance. Resulting from the space weather processes, ionospheric disturbances modify the vertical ionospheric profile, thus changing the Total Electron Content (TEC) encountered by satellites' rays on their way towards the GNSS receiver. Here we report a case of the short-lived ionospheric disturbance, detected by SID monitor located at the GNSS laboratory, Faculty of Maritime Studies in Rijeka, Croatia, and the effects it causes to the GPS positioning performance, as observed by the single-frequency maritime GPS receiver situated at the same venue. Observed correlation between GPS and SID monitor observables points to perspective of establishing a model for the ionospheric disturbances identification, which is to be examined further in the mid-term research.

U e-biblioteci Terminološki rječnici Strune objavljuju se terminološke zbirke koje su nastale kao rezultat pojedinih projekata u okviru programa Izgradnja hrvatskoga strukovnog nazivlja – Struna. Struna je terminološka baza Instituta za hrvatski jezik i jezikoslovlje u kojoj se terminografski i jezično obrađuje nazivlje raznih struka radi stvaranja, usklađivanja i sustavljivanja nazivlja na hrvatskom jeziku. Od 2012. godine baza se može pretraživati na internetskoj adresi http://struna.ihjj.hr/. Cilj je ove biblioteke učiniti pojedinačne terminološke zbirke Strune dostupnima i u cjelovitu tekstualnom obliku koji je moguće pretraživati po raznim kriterijima i po potrebi otisnuti. U ovom se svesku donosi nazivlje obrađeno u okviru projekta Hrvatske zaklade za znanost Hrvatsko pomorsko nazivlje – tradicija i suvremena kretanja koji je vodio prof. dr. sc. Boris Pritchard.

Iz izvornika: ''Što je svemirsko vrijeme i zašto dolazi do poremećaja svemirskoga vremena? Što su i kako nastaju geomagnetske oluje i ionosferski poremećaji? Koji su osnovni elementi satelitske navigacije te kakav je utjecaj svemirskoga vremena na pozicioniranje pomoću GNSS sustava? Pridružite nam se i saznat ćete odgovore na ova i brojna druga pitanja iz svemirskoga vremena i satelitske navigacije.'' U izlaganju je definiran pojam svemirskog vremena, poremećaji svemirskog vremena i njihovo širenje od nastanka do interakcije s geoprostorom. Prikazani su osnovni elementi satelitske navigacije, te utjecaj pojava svemirskog vremena na određivanje položaja satelitskim navigacijskim sustavima kao i na ostale usluge satelitske navigacije.

As we are witnesses of considerable and ongoing changes in university education in recent years, mainly influenced by the advent of electronic technology, it is imperative that IAMU (International Association of Maritime Universities) community considers how technology-enabled education opportunities can be brought more fully into the university education system and lifelong education. Challenges for the maritime universities and roles of the IAMU have been identified and discussed.

The space weather effects are directly affecting the satellite signal propagation, degrading the time measurement accuracy and pseudorange determination, respectively. The factor which governs the features of signal propagation is the total electron content (TEC) the satellite signal encounters while propagating through ionized layers of the Earth's atmosphere. The TEC behavior can be observed in relation to apparently distant events originating in the Sun-Earth environment. By monitoring the space weather phenomena and occurences from the very beginning of their appearance, it is possible to detect and predict the TEC behavior and its impact on satellite signal propagation. In the proposed research, TEC behavior prediction is given regarding relevant space weather parameters which are describing solar, geomagnetic and ionospheric activity. Consequently, space weather parameters are defining satellite signal positioning environment conditions. In this way, risks and possible impact identification of space weather effects on Global Navigation Satellite System (GNSS) Position, Navigation and Timing (PNT) services performance can be identified and mitigated.

Intelligent Transport Systems (ITS) generally rely upon the accurate position determination of mobile objects. A wide-spread utilisation of satellite navigation systems and techniques allows for convenient, accurate and continuous position estimation for ITS. Still, the inherent drawbacks and vulnerabilities of GNSS- based position determination should be taken into account in order to provide trusted ITS Quality of Service. As the result of continuously changing environment for GNSS positioning for a vehicle on the move, an ITS QoS modeller encounters a significant variability of GNSS positioning errors, which is usually left unaccounted for. Here we propose a novel approach in interpretation of GNSS positioning error estimates, taken during the GNSS position estimation process, with the aim to assist the foundation of the ITS QoS. The focus on analysis and treatment of GNSS positioning error series does not only provide an invaluable insight into GNSS positioning conditions, but also opens the room for GNSS positioning process improvement, and an assessment of the impact of the GNSS positioning performance deterioration on the ITS Quality of Service.

The ionospheric delay has been identified as the single major contributor to total position estimation error for satellite navigation systems. Traditionally identified with its common daily dynamics cosine pattern, the GPS ionospheric delay has been modelled accordingly in order to provide the appropriate corrections for commercial single-frequency GPS receivers. Here we report the identification of the different pattern of the GPS ionospheric delay daily dynamics, observed in Summer intervals of quiet space weather. The identified anomaly has a potentially significant impact on the GPS position estimation quality for air and maritime navigation, and, to a lesser extent, for personal and road navigation. The statistical description of the newly observed GPS ionospheric delay daily dynamics is presented, and the prospects for its utilisation in development of the local GPS ionospheric delay model discussed.

Priručnik je namijenjen pomorcima.

In the proposed paper, the research study of smartphones' satellite positioning performance has been described. The research consisted of static (at fixed position) and dynamic (during sea navigation) segment. It was conducted in confined coastal area of middle Dalmatia (bay of Zaton). Using several mobile devices as handheld GNSS receivers (smartphones with GPS and both GPS & GLONASS satellite navigation systems' applications), positioning patterns were measured and recorded. In subsequent statistical analysis, positions derived from DGPS device were used as references. The results of data analysis confirmed improvements in satellite positioning by means of multi-constellation usage. Employing and integrating various GNSS systems, positioning error can be measurably reduced, together with increased integrity of the positioning service.

Handheld GPS devices are nowadays increasingly replaced by smartphones with Android-based GPS applications. Moreover, it becomes a matter of concern, given that the position derived with this application is taken for granted, with over- reliance from users not aware of potential misleadings and errors the position can befall. For this purpose, two mobile devices were fitted at fixed point in south Croatia, previously determinated by differential means. At this obstruction-free location, positioning applications are launched and received positions have been recorded during hours. After several recordings and data post-processing, analysis have been carried out in order to determine position deviations in all directions. Here, the results obtained are presented, giving an insight in GPS positioning accuracy at the time of observation. The paper represents the basis for further work, where the same cell phone application will be elaborated in various, more critical situations.

At present the majority of marine data collected by institutions are largely collected with specific purpose in mind – for instance to exploit marine resources, to ensure safe navigation, to monitor compliance with regulations or to test scientific theories. However, those processing or applying these data face a number of obstacles such as restriction to access, use and re-use of fragmented standards, formats and nomenclature. The paper is focused on the analysis of the European legal sources to establish and implement coordinated monitoring programmes for on-going assessments of the environmental status of marine waters. The authors are urging for sharing of marine data uniformly, efficiently and rapidly in a regulated procedure with the aim of reducing operational costs for marine data users.

Usluge koje pružaju satelitski navigacijski sustavi danas su postale sastavni dio svakodnevnog života. Određivanje položaja i brzine korisnika, te pružanje usluge točnog koriste se na individualnoj, regionalnoj i globalnoj razini. Primjena se kreće u rasponu od standardnih, privatnih aplikacija, do kritičnih usluga od nacionalne sigurnosti. Najpoznatiji satelitski navigacijski sustav je američki GPS, međutim u Zemljinim orbitama danas kruže sateliti ruskog GLONASS sustava, kineskog BeiDou (Compass) satelitskog navigacijskog sustava, uz Europski Galileo satelitski navigacijski sustav koji je u fazi razvoja, i predviđa se da bi kroz koju godinu bio potpuno operativan. Uz niz dodatnih regionalnih satelitskih navigacijskih sustava, ovi sustavi čine jedinstveni Globalni Satelitski Navigacijski Sustav – GNSS. Pomoću višestrukih satelitskih konstelacija, te uz ostala poboljšanja korištenjem satelitskih pomoćnih sustava, postiže se sve veća točnost, pouzdanost i integritet. Unatoč poboljšanjima, položaj određen GNSS sustavima podložan je pogreškama, s obzirom na složen princip određivanja navigacijskih parametara i održivost sustava. Proračunati položaj nikad ne daje istinsku/stvarnu poziciju - točku, već uvijek postoji više ili manje izraženo odstupanje. Ovo odstupanje nastupa kao posljedica niza prirodnih i tehničkih pojedinačnih uzrokam ali i namjernog utjecaja koji rezultiraju konačnom pogreškom u točnosti pružanih usluga, ali i na rad GNSS sustava.

The increase of maritime transport with accomplished 34 billion tons of cargo in the year of 2010. affected the increase of travellers up to 18 billion on cruises. About 50 years ago cruises were taking place on sailing areas mostly around North America and Mediterranean in which most of them still do up to this day, but other sailing areas over the world became of interest for many cruises. The increase and higher number of capacity of cruisers are a result of fast growing and spreading of cruising trend from year to year. The soul purpose and goal of this article is to analyse and show the dispersion of cruises by individual sailing areas over the world. The study offers a number of cruising areas over the world and prescentage of cruises on each ocean. Analysing the offers of cruises and with the systematic showing of monthly or annual number of travels as well as capacity of ships and predominant lenght of cruises by each area of the world.

Short introduction User equivalent ranging error (UERE) GPS ionospheric delay Multipath effects GPS/GNSS error budget Geometric dilution of precision Algorithm for positioning point determination Total GPS positioning determination error Corrections regarding multipath, ionospheric delay... Advanced systems (augmentation and assistance) Differential GPS Satellite based augmentation systems EGNOS Satellite signal multi-frequency processing GNSS

The Automatic Identification System (AIS) is an automatic tracking system used on ships and by vessel traffic services (VTS) for identifying and locating vessels by electronically exchanging data with other nearby ships and AIS Base stations. It is capable of sending and receiving ship information such as identity, position, course, speed, ship particulars and cargo information to and from other ships and shore. One such message includes a text field designated for destination. The mariner is able to enter the ship's destination into the AIS at the start of each voyage, and to keep this information updated. Evidence shows that mariners are using different names for the same location when entering destination data in their AIS units making it difficult for other ships and for VTS to identify the port uniquely. This situation leads to confusion and inefficiency in data interchange. Information about the destination allows to predict each other's courses, which will reduce the risk of collision and thus enhance the safety. Knowledge of the data on the port of destination contributes to the efficiency of VTS. Currently, this information is not provided for the exchange of AIS system. This can be achieved by using the existing destination field for entering both the port of departure and the next port of call. Therefore, there is a need to harmonize data input when entering port information, by adopting an available universal protocol. The International Maritime Organization (IMO) recommends the use of the United Nations code for ports and other locations (UN / LOCODE).

Improving ship safety through accident investigation is important for preventing similar casualties and incidents in the future. The analysis is made of an institutional framework at international level and of the activities of the International Maritime Organization and European Maritime Safety Agency in developing a common methodology for investigating maritime accidents. In author’s opinion current significant differences between marine incident investigation activities and databases resulting from various legal systems support the need for establishing a comprehensive legal framework as a response mechanism. Proposals are made to facilitate to all the states involved to conduct the marine casualty investigation, analysis and reporting in accordance with recognized best practice and to facilitate the implementation of improved environmental standards based on standardized casualty-related data.

Navigation satellite outage has a profound effect on the satellite navigation systems performance. A programmed temporal outage of the PRN24 satellite scheduled for 12thSeptember 2009 motivated a simulation-based study of the satellite outage effects on the overall GPS positioning performance and signal availability. The study was focused on the identification of the GPS performance degradation due to satellite outages in Croatia due to the growing utilization ofthe satellite navigation systems as a component of the national infrastructure. Two GPS reference sites in rural areas were simulated for the determination of open sky view obstructions. The satellite visibility and the corresponding positioning dilution of precision (PDOP) for both sites prior and after the planned temporal outage of GPS PRN24 satellite were determined. The results obtained from simulation using broadcast GPS almanac were compared with those related to the un-obstructed view of the sky. The analysis revealed no significant disruption for the un-obustructed sky view, but a significant impact was identified particularly to sites with natural southward sky-view obstruction.

The majority of maritime accidents occur most often because of increasing traffic density, especially in the channels and approaches to major ports, extreme meteorological and oceanographic conditions in correlation with heavy sea state. The consequence of such accidents could be ship’s damage and accidents that result in the loss of human life and serious pollution of the marine environment. Modern technologies and new methods of ships construction, better legislation at all levels, and better education and training of crew and passengers were significantly reduced damage and loss of human life at sea in recent years. This paper will analyze the maritime accidents that are primarily caused by dangerous weather occurrences and severe sailing conditions i.e. with those involving the weather and oceanographic conditions witch subsequently increased ships damages and human losses. Some proposal for the implementation of appropriate measures to enhance ship's safety and reduce pollution of marine environment in heavy weather conditions at sea will be given in this paper .