The petroleum and gas industry’s move from traditional shallow-water activity into deeper waters demands greater efficiencies in exploration, installation and maintenance. Video is now used in almost every offshore scenario, from survey, installation, maintenance and inspection to structural repair, and has become one of the underwater tools of critical importance to the industry, where real-time high-quality video monitoring and transmission can improve underwater safety protocols in the field and affect bottom line financial decisions.
The video is fed by umbilical from diver or ROV (remote operated vehicle) to surface vessel, and from there transmitted to larger surface vessels or to land over wireless. Standard video transmission protocols depend on an analogue link from the survey vessel; however this technology has a number of inherent drawbacks including limited range, poor quality and high susceptibility to interference and breaks in transmission.
In 2008, Aberdeen-based Seatronics Group, which specialises in electronic subsea equipment, approached Wood & Douglas to help develop a ground-breaking new digital video solution for subsea exploration.
By adopting high-quality digital transmission with COFDM modulation, the SeaVision system is able to avoid virtually all of the interference issues which plagued previous analogue systems, including issues of multipath, fading and re-propagation from large structures, which causes ghosting and interference within the image. SeaVision actually uses reflection and re-propagation to add to the signal strength, improving, as opposed to decreasing, quality of transmission.
With digital transmission it becomes easy to extend the range of operation to as much as 20 kilometres at sea. Antenna placement remains a major issue, with survey vessels commonly encountering breaks in transmission as a result of using a single antenna. Wood & Douglas has solved this issue with a unique approach that uses a process known as dual diversity, placing two small, separate antennas either side of the wheel house, to deliver a full 360-degree clear path for transmission.
“With high-quality digital transmission of video now a reality, irrespective of location, weather or depth, these live, real-time feeds are a prime example of a technology that will help to improve the efficiency and reduce the long-term costs of safe exploration, installation and maintenance.”
David Currie, Managing Director, Seatronics Group
- Reliable, secure one-way ship-to-ship-to-shore radio link for video, audio and data
- Reduces interference from reflection and re-propagation
- Unique dual-diversity transmission solution
- Helps secure the safety of divers operating in shallow water or to extremes at the 300m/1000ft limit.