Research on Maritime Radio Wave Multipath Propagation Based on Stochastic Ray Method

Multipath effect in vessel communication is caused by a combination of reflections from the sea surface and vessels. This paper proposes employing stochastic ray method to analyze maritime multipath propagation properties. The paper begins by modeling maritime propagation environment of radio waves as random lattice grid, by utilizing maximum entropy principle to calculate the probability of stochastic ray undergoing k time(s) reflection(s), and by using stochastic process to produce the basic random variables. Then, the paper constructs the multipath channel characteristic parameters, including amplitude gain, time delay, and impulse response, based on the basic random variables. Finally, the paper carries out a digital simulation in two-dimensional specific fishery fleet model environment. The statistical properties of parameters, including amplitude response, probability delay distribution, and power delay profiles, are obtained. Using these parameters, the paper calculates the root-mean-squared (rms) delay spread value with the amount of 9.64 μs. It is a good reference for the research of maritime wireless transmission rate of the vessels. It contributes to a better understanding of the causes and effects of multipath effect in vessel communication

Dynamic Model for Calculating the VHF Radio Horizon at Sea

Very High Frequency (VHF) range covers the range of radio frequency electromagnetic waves from 156 MHz to 162.025 MHz. Marine VHF communication devices have a wide application in navigation onboard convention and non-convention vessels. VHF communication is also partly used in inland waterways, rivers, and lakes. The varied application of the VHF technology implies performing regular and emergency communication during the operation of various services that ensure the safe flow of navigation process by exchanging Maritime Safety Information (MSI). As for their construction and design, marine VHF equipment may be classified as portable and stationary. Regulations provided by local registers of shipping apply to their technical features and design requirements in case of new-built vessels or subsequent fitting of the vessels with such equipment. Although these regulations go into details as they refer to the design and the exploitation of vessels, it can be noticed that they are not sufficiently elaborated in the area of using VHF marine communication devices in dynamic conditions. This paper discusses the impact of dynamic conditions on the range of marine VHF equipment and the development of feasible improvements onboard various types of vessels

Compendium of Applications Technology Satellite user experiments

The achievements of the user experiments performed with ATS satellites from 1967 to 1973 are summarized. Included are fixed and mobile point to point communications experiments involving voice, teletype and facsimile transmissions. Particular emphasis is given to the Alaska and Hawaii satellite communications experiments. The use of the ATS satellites for ranging and position fixing of ships and aircraft is also covered. The structure and operating characteristics of the various ATS satellite are briefly described

NASA Thesaurus Supplement: A three part cumulative supplement to the 1982 edition of the NASA Thesaurus (supplement 2)

The three part cumulative NASA Thesaurus Supplement to the 1982 edition of the NASA Thesaurus includes: part 1, hierarchical listing; part 2, access vocabulary, and part 3, deletions. The semiannual supplement gives complete hierarchies for new terms and includes new term indications for terms new to this supplement

Integrated satellite-terrestrial connectivity for autonomous ships:Survey and future research directions

An autonomous vessel uses multiple different radio technologies such as satellites, mobile networks and dedicated narrowband systems, to connect to other ships, services, and the remote operations center (ROC). In-ship communication is mainly implemented with wired technologies but also wireless links can be used. In this survey paper, we provide a short overview of autonomous and remote-controlled systems. This paper reviews 5G-related standardization in the maritime domain, covering main use cases and both the role of autonomous ships and that of people onboard. We discuss the concept of a connectivity manager, an intelligent entity that manages complex set of technologies, integrating satellite and terrestrial technologies together, ensuring robust in-ship connections and ship-to-outside connections in any environment. This survey paper describes the architecture and functionalities of connectivity management required for an autonomous ship to be able to operate globally. As a specific case example, we have implemented a research environment consisting of ship simulators with connectivity components. Our simulation results on the effects of delays to collision avoidance confirm the role of reliable connectivity for safety. Finally, we outline future research directions for autonomous ship connectivity research, providing ideas for further work

NASA Thesaurus Supplement: A three part cumulative supplement to the 1982 edition of the NASA Thesaurus (supplement 3)

The three part cumulative NASA Thesaurus Supplement to the 1982 edition of the NASA Thesaurus includes Part 1, Hierarchical Listing, Part 2, Access Vocabulary, and Part 3, Deletions. The semiannual supplement gives complete hierarchies for new terms and includes new term indications for entries new to this supplement

Propagation research in Japan

L-band propagation measurements for land-mobile, maritime, and aeronautical satellite communications have been carried out by using the Japanese Engineering Test Satellite-Five (ETS-5) which was launched in Aug. 1987. This paper presents propagation characteristics for each of the mobile satellite communication channels

Dynamic Model for Calculating the VHF Radio Horizon at Sea

Very High Frequency (VHF) range covers the range of radio frequency electromagnetic waves from 156 MHz to 162.025 MHz. Marine VHF communication devices have a wide application in navigation onboard convention and non-convention vessels. VHF communication is also partly used in inland waterways, rivers, and lakes. The varied application of the VHF technology implies performing regular and emergency communication during the operation of various services that ensure the safe flow of navigation process by exchanging Maritime Safety Information (MSI). As for their construction and design, marine VHF equipment may be classified as portable and stationary. Regulations provided by local registers of shipping apply to their technical features and design requirements in case of new-built vessels or subsequent fitting of the vessels with such equipment. Although these regulations go into details as they refer to the design and the exploitation of vessels, it can be noticed that they are not sufficiently elaborated in the area of using VHF marine communication devices in dynamic conditions. This paper discusses the impact of dynamic conditions on the range of marine VHF equipment and the development of feasible improvements onboard various types of vessels