This article presents a simulated and experimental analysis of the effects of the evaporation duct on microwave propagation in the Irish Sea. The evaporation duct is a phenomenon that occurs almost permanently over all the world’s oceans and allows electromagnetic waves to travel beyond the horizon. Weather data logged over several years from four buoys off the east coast of Ireland has been analyzed to find the probability and strength of the evaporation duct. Signal propagation in the evaporation duct has been simulated using the parabolic equation model and compared to results obtained from an experimental setup in the Irish Sea. The best antenna heights and frequencies to maximize signal propagation at this location are also found. Results show that the evaporation duct can be used to provide high bandwidth communications beyond the horizon with an uptime of approximately 40%, and that weather data from buoys can be used to predict the performance of the communications link. While this method of communication is not one that can be relied on all the time, it could be useful to reduce dependency on expensive satellite links or provide nontime critical communications.

This paper presents research and development for achieving advanced ROV manipulation systems with vision based servo control capable of being operated by pilots with auto assist in the dynamic subsea conditions. Underwater inspection and intervention operations are performed by work-class ROVs equipped with robotic manipulators. A standard offshore oil and gas setup includes a human pilot utilising telemanipulation technology to operate both vehicle and manipulators based on the work-site visual feedback provided by camera and sonar systems. For challenging applications in waves or currents where target devices are in motion a new approach is required. A position based visual servoing (PBVS) algorithm designed to follow a moving target with an underwater manipulator is proposed. The developed algorithm integrates Adaptive Neuro-Fuzzy Inference System (ANFIS) network framework for target motion prediction. The effectiveness of the developed software is verified through a series of experiments carried out with an off-the-shelf industrial hydraulic subsea manipulator in the laboratory conditions.

This paper presents the results of a study on the effects of the evaporation duct on microwave propagation in the Irish Sea. The evaporation duct is a phenomenon that occurs almost permanently over the earth's oceans and can be exploited to enable over the horizon communications in the marine environment. The study consisted of an experimental test, where signal strength from a shore-based transmitter was recorded at a number of distances. The results of this experiment were compared to simulated values. Atmospheric data used to simulate the signal propagation was taken from weather buoys in the Irish Sea. It was found that the evaporation duct does have an effect on microwave signals and can be used to extend microwave communications beyond the horizon. This could be useful in enabling high bandwidth communications links to or between offshore assets and equipment including navigation buoys, ships, renewable energy infrastructure and lighthouses which are often situated beyond line of sight of land.

This paper presents autonomous docking of an industry standard work-class ROV to both static and dynamic docking station (Tether Management System - TMS) using visual based pose estimation techniques. This is the first time autonomous docking to a dynamic docking station has been presented. Furthermore, the presented system does not require a specially designed docking station but uses a conventional cage type TMS. The paper presents and discusses real-world environmental tests successfully completed during January 2019 in the North Atlantic Ocean. To validate the performance of the system, a commercial state of the art underwater navigation system has been used. The results demonstrate a significant advancement in resident ROV automation and capabilities, and represents a system which can be retrofitted to the current ROV fleet.

This work presents a detailed study, characterization, and measurement of video latency in a real-time video streaming application. The target application consists of an automatic control system in the form of a control station and the mini Remotely Operated Vehicle (ROV) equipped with a camera, which is controllable over local area network (LAN) and the Internet. Control signal transmission and feedback measurements to the operator usually impose real-time constraints on the network channel. Similarly, the video stream, which is required for the normal system control and maneuvering, imposes further strict requirements on the network in terms of bandwidth and latency. Based on these requirements, controlling the system in real time through a standard Internet connection is a challenging task. The measurement of important network parameters like availability, bandwidth, and latency has become mandatory for remotely controlling the system in real time. It is necessary to establish a methodology for the measurement of video and network latency to improve the real-time controllability and safety of the system as such measurement is not possible using existing solutions due to the following reasons: insufficient accuracy, relying on the Internet resources such as generic Network Time Protocol (NTP) servers, inability to obtain one-way delay measurement, and many solutions only having support for web cameras. Here, an efficient, reliable, and cost-effective methodology for the measurement of latency of a video stream over a LAN and the Internet is proposed. A dedicated stratum-1 NTP server is used and the necessary software needed for acquiring and measuring the latency of a video stream from a generic IP camera as well as integration into the existing ROV control software was developed. Here, by using the software and dedicated clock synchronization equipment (NTP server), it was found that normal video latencies in a LAN were in the range of 488ms – 850ms, while latencies over the Internet were measured to be in the range of 558ms – 1211ms. It is important to note that the values were obtained by using a generic (off-the-shelf) IP camera and they represent the actual latencies which might be experienced during control over long range and across international territory borders.

This paper presents a review of high bandwidth maritime communication technologies. High bandwidth maritime communication technologies can broadly be divided into two main areas - commercially available systems and research based systems. A detailed review of the current technology in each area is undertaken. Several commercially available systems use satellite communications technologies. A number of these systems are reviewed and bandwidth, latency and cost comparisons are made. Point to point links, another commercially available technology, is also discussed and similar criteria are used for their comparison, including range and bandwidth. As well as commercially available technologies, several novel methods of maritime communications are reviewed that are current research topics in the marine communications field. Many of these show interesting possibilities, such as evaporation ducting and tropospheric scatter. The main mode of operation of each technology is discussed, and the possible performance for each in terms of range and bandwidth is compared. Issues and challenges that need to be overcome for the technologies to be viable in the marine environment are also discussed. The aim of this paper is to provide the reader with a deeper knowledge of what technologies are currently available to facilitate high bandwidth maritime communications, and how they compare under a number of key performance metrics. In addition, an overview of new technologies that are currently under research is provided, and the potential benefits these technologies could bring to maritime communications and the technological issues in doing this is discussed.