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Open access

Andrzej Felski and Krzysztof Jaskólski

Abstract

Commonly used AIS devices on the ships covered by SOLAS Convention creates ideas of the use of AIS data in the situation of the risk of collision. AIS position report is a source of supplementary information derived from error leveraged radar measurement. However, many of users has opinions with regard to inconsistent AIS dynamic data in the process of decision-making by the officer of the watch. Taking into consideration the recordings of the studies and technical specification of AIS, the results of inconsistent data has been analysed in the context of collision avoidance

Open access

Andrzej Felski and Aleksander Nowak

Abstract

Any SBAS system, as soon as it is permanently monitored by Earth stations, should deliver to the users correct information about quality of the augmented system. According to many sources of information, among them observations of authors, present accuracy of EGNOS service has accuracy about 1,5m (95%), but availability of the service is still controversial. First of all the quality of the system is guaranteed only inside the border of the system coverage which still do not affect all territory of European Union, however observed accuracy at times is better outside this area than next door to the RIMS station. In addition there are evidences that availability has random character and essential differences as well as lack of correlation of this parameter in the different point of observations has been observed. So in author’s opinion Local Monitoring of EGNOS service can contribute to better confidence of local users, especially in critical operations, like for example berthing of big ships or landing operations with EGNOS procedures. The example of EGNOS monitor which is working in real time and performed by the authors will be presented

Open access

Andrzej Felski

Abstract

In the end of XX century we were witnesses of the revolution in a radio-navigation, which led to the present domination of GPS. Dozens of radio-navigation systems disappeared. However now in many papers more and more often we can read an opinion, that GNSS monopoly becomes dangerous. This results from the similar sensibility of all GNSS systems on the same disturbances consequential from the similar radiofrequency band and similarly low powers of the signal. There is a growing approval in the maritime world that GNSS will not provide a required resilience because of common vulnerabilities. An anticipated radio navigation system should be a combination of systems, providing redundancy and effective work when GNSS does not work properly. Lately a lot of authors commonly pointed-out a potential advantages of modified Loran (e-Loran), however surely still it will be only a potential option, particularly for the southern hemisphere, where this system has never existed. An issue of alternative systems becomes urgent, because of the growing concern about GNSS system operation. The solution should not demand high financial effort, well fit to the existing law and utilize a present technology. The paper presents a general outlook of potential development in a present radar devices considering their use as an element of a positioning system. In this context radar seems to be an attractive option, however its utilization as an alternative for GNSS should reach considerably higher technical performances. The accessible information prove that it is possible to reach a higher accuracy of the position obtained from the modified radar in the future, especially with the suitable navigational infrastructure on shore.

Open access

Andrzej Felski

Abstract

Jamming of GNSS signals can be both a consequence of accidental activities and an intentional act. This issue is lately discussed as an essential threat for the use of satellite navigation systems. This is especially dangerous in the face of common usage of GPS - like systems in everyday life and the great belief of everyday users in the truth of devices indications. In spite of the legal prohibition of using them, jammers are commonly accessible, especially in the Internet. Until recently even specialists have shared the conviction that the broadband GPS signal is not a subject of disturbances in contrast to older wireless communication techniques because its power level is below natural level of noises and in addition it is randomly coded. But nowadays jammers are very often successfully applied, which is confirmed in many reports. The average user has not the suitable knowledge about the specificity of the jamming and has no technical possibilities of the detection of jammer signals. Receivers, which can indicate the presence of perturbative signals, became accessible a few months ago only. Presently accessible jamming monitors can also determine the direction of interferer signal transmission. There are also specially designed receivers with anti-jamming mechanism, which are, however, not commonly accessible. The possible way of countermeasure the jamming in the GNSS receiver are discussed in this paper.

Open access

Andrzej Felski and Krzysztof Jaskólski

ABSTRACT

Common use of shipboard AIS creates conditions for the use of a new kind of dynamic data in the situation of the risk of collision. AIS position report is a source of supplementary information derived from error leveraged radar measurement. However, in view of the results of the studies there are opinions with regard to inconsistent AIS dynamic data in the process of decision-making by the officer of the watch. By taking into consideration the recordings of the studies and technical specification of AIS it can be concluded that the results of inconsistent data have significant role in collision avoidance manoeuvring.

Open access

Andrzej Felski, Aleksander Nowak and Tomasz Woźniak

Accuracy and Availability of Egnos - Results of Observations

According to SBAS concept the user should receive timely the correct information about the system integrity and corrections to the pseudoranges measurements, which leads to better accuracy of coordinates. In theory the whole system is permanently monitored by RIMS stations, so it is impossible to deliver the faulty information to the user. The quality of the system is guaranteed inside the border of the system coverage however in the east part of Poland lower accuracy and availability of the system is still observed. This was the impulse to start an observation and analysis of real accuracy and availability of EGNOS service in the context of support air-operations in local airports and as the supplementation in hydrographic operations on the Polish Exclusive Zone.

A registration has been conducted on three PANSA stations situated on airports in Warsaw, Krakow and Rzeszow and on PNA station in Gdynia. Measurements on PANSA stations have been completed permanently during each whole month up to end of September 2011. These stations are established on Septentrio PolaRx2e receivers and have been engaged into EGNOS Data Collection Network performed by EUROCONTROL. The advantage of these registrations is the uniformity of receivers. Apart from these registrations additional measurements in Gdynia have been provided with different receivers, mainly dedicated sea-navigation: CSI Wireless 1, NOVATEL OEMV, Sperry Navistar, Crescent V-100 and R110 as well as Magellan FX420.

The main object of analyses was the accuracy and availability of EGNOS service in each point and for different receivers. Accuracy has been analyzed separately for each coordinate. Finally the temporarily and spatial correlations of coordinates, its availability and accuracy has been investigated.

The findings prove that present accuracy of EGNOS service is about 1,5m (95%), but availability of the service is controversial. The accuracy of present EGNOS service meets the parameters of APV I and even APV II requirements, as well as any maritime and hydrography needs. However introducing this service into the practice demands better availability, because the gaps in receiving the proper information from the system appear too often and are too long at the moment. Additionally it was noticed very random character of availability and no correlation of this parameter in the different point of observations. In spite the correct EGNOS work the accuracy of the coordinates is not predictable in the local conditions. So in authors' opinion Local Airport Monitoring should be deployed if EGNOS would have to serve to the local airport service.

Open access

Andrzej Felski, Krzysztof Naus and Mariusz Wąż

Abstract

Performing any measurement on watercraft is connected with many additional difficulties caused by the sea-environment. The most important is the problem of spatial stabilization of measurement systems, which are usually fastened to craft body. As soon as usually these measurement are executed during the move of the craft additional question is the accuracy of execution the planed trajectory.

This is a problem for all investigators, especially when system use spatially configured beams of any antennas or other sensors, regardless is it receiving or transmitting one.

Different aspects of these question are the subject of research activity of Institute of Navigation and Maritime Hydrography of Polish Naval Academy. In this paper the review of works executed in last years are presented.

Open access

Andrzej Felski and Marta Gortad

Abstract

At present jamming is considered one of the main threats to a GPS receiver’s user, both in dynamic and stationary conditions, and especially regarding telecommunication synchronization. Threats stemming from the use of cheap jammers, more and more commonly referred to as Personal Protecting Devices, available on the Internet, are especially dangerous. Despite the formal ban on using them, there is evidence that they are in common use. Therefore the problem which has hitherto been considered marginal needs to be urgently investigated. Reports dealing with investigations on jamming focus mostly on analyses of effects of various jammers on receivers. This article presents part of the results of experiments focused on the effects and it shows that the effects of jamming when the same device is used depend on both the receiver and the antenna it employs.

Open access

Andrzej Felski and Aleksander Nowak

ABSTRACT

Any SBAS system should deliver to the user corrections to pseudoranges as well as information about the system integrity. In theory, as soon as the system is permanently monitored by RIMS stations, it is impossible to deliver the fault information to the user. However many observations shows that accuracy of EGNOS service in the same time are different in different places, which shows the influence of local conditions on them. In addition evidences on possibilities in jamming or spoofing of GPS signals should be seriously taken into account. According to many sources of information, among them observations of authors, present accuracy of EGNOS service has better than declared. In fact EGNOS accuracy is about 1,5m (95%), but availability of the service happens still controversial and it has random character. According to reports essential differences as well as lack of correlation of this parameter in the different point of observations has been observed. So in author’s opinion Local Monitoring of EGNOS service can contribute to better confidence of local users, especially in critical operations, like for example berthing of big ships or in landing operations with EGNOS procedures. An example of such system which works in real time has been elaborated in Polish Naval Academy and will be presented.

Open access

Karolina Zwolak and Andrzej Felski

Abstract

The paper presents current state of bathymetric survey concerning deep ocean rather than shallow areas, which are better surveyed due to safety of navigation concerns. Rules and requirements of the new challenge, called the Shell Ocean Discovery XPRIZE, became a starting point for a discussion about the possibilities of mapping large areas of the ocean using up-to-date and new technology. The amount of bathymetric data available nowadays and the current state of ocean map compilations are also discussed in the paper as a motivation to inspire the new initiatives in the deep ocean.