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EN
The article presents an analysis of the features of selected correlators impacting the accuracy of determining the receiver’s range and position in VHF marine environment. The paper introduces the concept of various correlators – including the double delta correlator – and describes the proposed measurement scenarios that have been designed to demonstrate the effectiveness of those components. The entire work was performed as part of the R-Mode Baltic and R-Mode Baltic 2 projects, with our goals including analyzing the impact of multipath phenomena, changes in the sampling frequency or Signac type on the determination of the received signal delay at the receiver. The measured data were processed in a signal correlation application and in a TOA-based tool in order to determine the receiver’s position. This process made it possible to compare the selected correlating devices. The results presented in this article are to be used by IALA in developing a current version of the VHF data exchange system’s (VDES) specification.
EN
In the paper, the measurement and simulation results of the VDES (VHF Data Exchange System) terrestrial component are discussed. It is anticipated that VDES will be one of the major solutions for maritime communications in the VHF band and its performance will be sufficient to fulfill the requirements of the e-navigation applications. The process of the VDES standardization (ITU R, IALA) has not been officially completed yet, but substantial amount of technical information about the future system’s terrestrial component (VDE-TER) is already available. The paper is divided into three general parts: (a) theoretical presentation of the system’s physical layer and the radio channels applicable to VDES, (b) simulation results (BER, BLER, channel delay between two propagation paths and its influence on bit rates) and (c) measurement results (useful ranges, BER). It turned out that in real maritime conditions, the VDES system can offer ranges between 25 and 38 km for the configurations assumed during the measurement campaign. Those results are generally compliant with the theoretical data in the line-of-sight conditions. In the NLOS scenarios, where fading becomes the dominant phenomenon, the discrepancies between the measurements and the theoretical results were more significant. The obtained results confirmed that VDES provides a large coding gain, which significantly improves the performance of data transmission and increases the bit rate compared to the existing maritime radiocommunication solutions. It should be noted that the results presented in the article were used by the IALA while developing the current version of the VDES specification.
PL
W artykule zaprezentowano wyniki pomiarów warstwy fizycznej naziemnego segmentu systemu VDES. Wykorzystując krzywe bitowej stopy błędu, dokonano analizy jakości transmisji danych oraz zasięgów uzyskiwanych w tym systemie.
EN
The paper discusses the measurement results of the VDES ground segment physical layer. Using the bit error rate curves, the analysis of data transmission quality and ranges achieved in the VDES system has been performed.
EN
The article introduces a method of performing a radio link quality assessment based on the Link Quality Indicator (LQI) which will be calculated for every system that is available. The method presented has been developed during the netBaltic project completed in Poland and generally applies to the so-called maritime zone A, i.e. the sea area where ships are still within the range of shore-based radio communication systems, particularly 3G/LTE cellular networks. The algorithm was developed based on the results of measurements obtained during two separate campaigns. That measurement data served as a basis for the method’s initial assumptions and was utilized during the method’s verification.
PL
W artykule przedstawiono podstawy funkcjonowania systemu COSPAS-SARSAT LEOSAR. Opisano drogę sygnału po aktywacji radiopławy awaryjnej EPIRB. Zdefiniowano i podano wartości parametrów operacyjnych systemu LEOSAR. Opisano także wymagania eksploatacyjne niezbędne dla zapewnienia skutecznego alarmowania morkich radioplaw awaryjnych systemu LEOSAR.
EN
The article presents the basics of the COSPAS SARSAT LEOSAR system. The signal path when activated EPIRB Radio Beacon has been described. Definitions and the operating parameters of the LEOSAR system has been given. The performance requirements necessary to ensure effectiveness of the alarms of the LEOSAR emergency position-indicating radio beacons has been described as well.
PL
W artykule przedstawiono wyniki pomiarów zasięgów i przepływności sieci WiFi 2,45 i 5 GHz w warunkach morskich. W drugiej części referatu omówiono potencjalne metody oceny jakości łącza bezprzewodowego WiFi.
EN
The measurement results of the ranges and data rates achievable in maritime condition in the 2,45 and 5 GHz WiFi networks have been presented. In the second part of the paper, the methods for the WiFi link quality evaluation have been discussed.
PL
W pierwszej czesci referatu dokonano teoretycznej analizy zasiegów uzyskiwanych przez systemy UMTS i LTE w warunkach morskich. W tym celu wyznaczono odpowiednie bilanse łacza, a nastepnie wykonano obliczenia z użyciem modeli propagacyjnych. W drugiej czesci referatu podsumowano kampanie pomiarowa zrealizowana na Bałtyku, której celem była weryfikacja zasiegów teoretycznych.
EN
In the first section of the paper, the theoretical analysis of the LTE and UMTS ranges in maritime condition has been carried out. To do so, the link budgets have been calculated and the ranges have been estimated using the relevant propagation models. In the second part of the article, the authors described a measurement campaign which was organized to verify those theoretical ranges in maritime conditions.
PL
Omówiono metodologię i przedstawiono wybrane wyniki pomiarów zasięgów i parametrów jakościowych systemów komórkowych (UMTS. LTE) sieci WiFi oraz systemu WiMAX uzyskiwanych w warunkach morskich. Pomiary te wykonano na Bałtyku w ramach Zadania 1 projektu NetBaltic. Słuzyły one ocenie przydatności wybranych technologii bezprzewodowych w kontekście transmisji danych na morzu.
EN
The following paper discusses the methodology and selected results of the measurement campaign in which the ranges and quality parameters of cellular (UMTS, LTE), WiFi and WiMAX networks were evaluated in maritime conditions. These measurements were conducted in the Baltic Sea as a part of the netBaltic project and their main purpose was to verify whether the discussed wireless technologies are suitable for data transmission at sea.
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