Error in GNSS Augmented Heading Systems: Influence of Attitude

The Effect of Antenna Height Difference on Heading Quality
My earlier articles on the alignment of motion reference units (MRU) with the ships reference frame (SRF) did not cover the calibration of GNSS augmented heading systems. Although the alignment can be done in the same way as mentioned in the previous articles, GNSS augmented heading systems need special attention regarding their installation. This article will show that the accuracy of these systems may be seriously affected by the vessel’s attitude if the antennas are not installed at the same mutual height above the X/Y plane of the SRF. The more accurate ROVINS (0.05° x SEC(LAT), which is the accuracy... (read more)
2014-10-15 02:18:48

Shallow Inland Water Bathymetry Meets IHO S-44 Special Order

Application of the Kongsberg GeoSwath System
For many years, the GeoSwath system from Kongsberg GeoAcoustics has been providing an efficient simultaneous swath bathymetry and sidescan seabed mapping solution with accuracies that meet the IHO S-44 Special Order standard for hydrographic surveys. GeoSwath systems have been fitted to a number of small crafts and have been utilised to conduct bathymetric surveys of lakes, ponds, dams and rivers. This article describes two of the vessels that have been employed to undertake this area of work. The use of Unmanned Surface Vessel (USVs) allows surveying in locations and situations in which deployment of conventional platforms is not practical or... (read more)
2018-02-27 01:01:18

Pipeline Survey with Acoustics

Directional Sub-bottom Profiler and Hydrophone Array
A method is presented which greatly increases the efficiency of pipeline survey using sediment echo sounder. These surveys are mostly done sailing cross courses; adding receiving directionality, a course can be sailed along the pipeline. This means 100% inspection of pipe coverage can be obtained in far less time than that required for cross-sailing survey. The receiving element is an array of sixteen hydrophones with optimal signal processing (Kalman filtering). The position and orientation of the transmitting transducer and receiving hydrophone array are also estimated, optimally using a Global Position System and a Motion Reference Unit. A sediment echo-sounder transducer... (read more)
2007-05-09 12:00:00

Extreme Swath Survey: The Dead Sea

A future article in Hydro international will describe our recent multi-beam survey of the Dead Sea. This brief overview extols the virtues of renting a complete multi-beam system as opposed to owning one. The survey presented extreme challenges, overcome by the readiness of manufacturers to venture into unknown waters. Since 2001 we have been mapping Israel’s Mediterranean offshore using my 96-kHz EM1002 multi-beam. The Dead Sea had always been a desired target, but there were excessive problems in transferring the ship, and the system’s high-frequency attenuation. After reading about ELAC’s Seabeam 1050 used in our area by the Turkish Navy,... (read more)
2007-04-04 12:00:00

Kongsberg K-MATE Autonomy Controller for New USV-AUV Platform

K-MATE, an autonomous surface vehicle control system which is the latest marine robotics innovation from KONGSBERG, is to be integrated with SEA-KIT, a new class of maritime autonomous surface vessel being built by UK manufacturer, Hushcraft, and operated by SEA-KIT International. SEA-KIT can carry a deployable and retrievable payload of up to 2.5 tons. It is based on the AUV-USV concept, which could lead to more efficient, safer and cost-effective seafloor mapping operations, as well as providing a platform for numerous applications in a wide range of maritime sectors. The SEA-KIT vessel provides a next generation, long-range, long-endurance ocean capability.... (read more)
2017-08-10 11:15:43

Quality Control of Survey Data

A Continuous Process?
Quality control of survey data is an integral part of any hydrographic survey or inspection operation, but the focus is too often concentrated on the wrong sensors, the carrying out of unnecessary comparisons and ultimately burying real issues in a flood of confusing and contradictory error messages, print-outs and alarms. So what is meant by quality control of survey data, why do we need it, how should we measure it and when is the best time to carry it out? ‘Quality’ is a phrase often used and is expected to be highly visible in the literature and mission statements of... (read more)
2013-09-06 04:37:34

Underwater Detection of Crashed Airplane

Hydrography for SAR Mission of Air Asia QZ8501 in Indonesia
The Indonesian Association of Marine Survey Contractors launched a survey operation in early January 2015 to support the Indonesian National Agency for Search and Rescue. The operation was aimed at searching for a commercial plane, Air Asia QZ8501, reported missing on 28 December 2014 over the NW of the Java Sea, Indonesia. Using MBES, SSS and ROV, major parts of the crashed airplane comprising of the tail, seats, body and wings were discovered and located for recovery. On 28 December 2014, a commercial airplane, Air Asia QZ8501, flying from Surabaya (Indonesia) to Singapore, was reported missing and believed to have... (read more)
2015-07-28 01:41:13

An Adaptable Survey ­Platform for Shallow Water

Bathymetric Charting of Nearshore, Harbour, Estuary and River Settings
High-resolution bathymetry and water quality surveys of shallow shelf and inland water bodies are an increasingly necessary part of environmental management with climate change pressures. This paper describes a new method for data acquisition using a small, stable, adaptable, single-operator survey platform. Development and natural (climate related) changes are placing an ever increasing pressure on our coasts, shallow marine shelves, estuaries, rivers, harbours and inland water bodies. In Europe these pressures have been recognised and attempts made to address the impacts under legislation such as the Water Framework Directive, which seeks to classify all water bodies by their health and... (read more)
2013-01-18 01:45:32

Measuring the Uncertainty of a Swath Bathymetric Sonar

A Statistical Analysis for System Performance and IHO Compliance
In the last few decades, substantial efforts have been made to improve and facilitate the way hydrographic data is obtained. One technology is the EdgeTech 4600, an interferometric phase difference sonar. Unlike traditional interferometers, the EdgeTech 4600 is the first of its kind to offer complete swath coverage of the seafloor, even at nadir. Combining this kind of coverage with a vertical accuracy that exceeds IHO Special Order requirements in depths less than 30 metres, results in a sonar with superior area coverage rates, especially in shallow water. In the summer of 2012, bathymetric survey data was collected using an... (read more)
2013-05-23 02:50:53

Oceanology International 2010 Preview (2)

This is the continuation of the Oceanology International Preview. For companies A - L, see part 1  MacArtney Underwater Technology Group MacArtney will be introducing their newest innovation in multiplexers - the NEXUS MK E electrical multiplexer, which is designed to the same high standards as the fibre optic multiplexer range with the telemetry part of the multiplexer adapted to non-fibre optic cables. Another highlight will be the demonstration of a working active heave compensation winch, the Cormac 3 Stainless Steel winch. It will demonstrate load stability during vessel movement on the sea. MacArtney will show their Focus ROTV, camera... (read more)
2010-03-01 05:03:47
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