Altitude and Dynamic Error in TPE and CUBE

Total Propagated Error (TPE) and Combined Uncertainty Bathymetric Estimator (CUBE) help automate data cleaning and filtering. This paper discusses the effect of using altitude in place of heave for survey data processing and that of using error estimates in TPE and CUBE for both variables. Final hydrographic data quality is examined. Total Propagated Error (TPE) and Combined Uncertainty Bathymetric Estimator (CUBE) are designed for use with hydrographic survey data to minimise subjective user intervention and help automate data cleaning and filtering. With the trend in hydrographic surveying towards objective estimation of data quality, these methods rely heavily on error estimates... (read more)
2007-09-04 12:00:00

Hydro Dam Inspection by ROVs

The inspection and maintenance of vital resource facilities is an integral part of any regional health and stability management programme. Providing consistent quality output whilst reducing inspection and maintenance costs is key for those involved in the provision of such services, and requires the monitoring and assessment of relevant new technologies and techniques. By Rob Berlijn, HydroConsult, The Netherlands Over the past forty years Remote Operated Vehicles have become a well-proven component of basic toolkits for getting work done under-water in a wide variety of industrial, scientific, military and law-enforcement activities. In many cases the impetus behind adopting and evolving... (read more)
2008-01-01 01:00:00

PPVRS Rushes in a New Era for Hydrographic Surveying

This paper describes a technique for centimetric positioning in hydrographic surveying using a network of GPS base stations to determine ephemeris, clock and atmospheric errors at the rover location. This technique uses the GPS observations from a Virtual Reference Station to compute a tightly integrated GPS/Inertial solution, with minimum baselines of over 100km.<P> Today’s primary positioningtechnique for near-shore (within 100km) marine hydrography is based on the integration of GPS and inertial navigation systems (INS). The inertial measurement unit (IMU) aids in reducing GPS noise as well as providing high-bandwidth uninterrupted solutions during GPS outages. For high-precision surveys (5cm or better... (read more)
2008-10-15 12:00:00

‘Killer’ AUV Sonar System

In January 2001, C&C Technologies (C&C), a company based in Lafayette (Louisiana, USA), introduced the first commercially successful autonomous underwater vehicle (AUV) to the offshore industry. The AUV’s survey sensor suite, which included an EdgeTech side-scan sonar and sub-bottom profiler, performed well in the Gulf of Mexico and Brazilian offshore environments. However, West Africa proved more challenging – particularly for the sub-bottom profiler. C&C soon began searching for alternative technologies to provide better sub-bottom profiler penetration and higher resolution side-scan sonar imaging.Jim Chance, C&C Technologies (USA) Art Kleiner, EdgeTech (USA)<P> Narrator: Fast forward to the early autumn of 2004… C&C... (read more)
2008-04-02 12:00:00

Hydrographic Surveying: Where Do We Stand?

The Ever-increasing Accuracy of Mapping the Surface Waters
Hydrographic surveying is highly specific and requires a suite of advanced acquisition and positioning sensors attached to a mobile survey platform as well as sophisticated software to allow the correct combination of all the data. For those in the industry, the advances over the last decade may feel more like an evolution rather than a revolution. If we look back one, two or even three decades, we can see the enormous leap that hydrographic surveying has taken. Where do we stand, and what can we expect for the near future? In this article, we will look at the present compared... (read more)
2018-12-11 02:51:31

The Arctic Field Party

It seems ironic that in the early stages of the Cold War, the United States Government sent surveyors and hydrographic engineers to the coldest reaches of the North American continent. For these men, it was truly a Cold War. From 1945 through 1953, field parties of the United States Coast and Geodetic Survey were sent to survey sea routes through the Bering, Chukchi and Beaufort Seas as well as to conduct geodetic surveys to help position Distant Early Warning system radars and help delineate the vast resources of the Alaskan Arctic. These men toiled in obscurity beneath the midnight sun... (read more)
2017-07-04 11:00:42

Wave Radars

A comparison of concepts and techniques
Radar Remote Sensing of ocean surface waves may in general be defined as measuring characteristics of the sea surface by means of electromagnetic waves so that the sea surface is itself not disturbed. The electro-magnetic waves transmitted by the radar antenna are scattered back from the sea surface, modulated in amplitude and phase or frequency by the interaction with the sea surface in motion. This modulation carries information about sea-surface characteristics, surface waves and currents. Oceanographic data is extracted from the backscatter signal by sophisticated signal processing and data analysis. Why remote sensing? Surface ocean waves may be measured by... (read more)
2008-01-01 01:00:00

Valeport Sensors Selected for New Micro AUV

Valeport has recently collaborated with ecoSUB who produce a micro AUV that is both advanced and cost-effective. The small and robust sensors are assisting Autonomous Underwater Vehicle (AUV) manufacturers and users to not only get the data they require, but to make AUVs more accessible in the marine environment. ecoSUB is a micro AUV (0.5 metres long) that uses Valeport’s sensors to autonomously acquire sound velocity profiles and has been jointly developed by Planet Ocean and Marine Autonomous Robotics Systems (MARS) group at the National Oceanography Centre (NOC) in Southampton. Part funded by Innovate UK and the UK Defence Science... (read more)
2018-12-17 09:16:40

Qualifying Heave Performance at Sea

Comparison of ORE MEMS-based MRU Heave Measurement with RTK-GPS
When accelerometer-based heave units were developed, there were limited options for verifying their performance at sea with a recognised standard. With real-time kinematic (RTK) global positioning system (GPS) devices, surveyors today can achieve accuracies of 2cm in altitude measurement. With the advent of small, low-cost, low-power, micro-electrical mechanical systems being employed for motion-sensing, a compact and cheaper alternative is available to measure heave. We have verified the heave of our motion reference units at sea with RTK-GPS. View Larger Map ORE Offshoreadded heavemeasurement to their pitch-and-roll motion reference units (MRU) in April 2009, which use micro-electrical mechanical system (MEMS) sensors.... (read more)
2009-06-26 12:00:00

Technology in Focus: Multi-beam Echosounders

New Technology, New Capabilities and New Markets
The evolution of multi-beam echo sounders (MBES) is leading to systems with enhanced capabilities in their traditional markets, but also provides features to allow the expansion of their use into new areas and applications. This short review highlights some of the features of the latest generation of systems. The attributes of an MBES system are traditionally described by technical specifications, such as operating frequency, pulse length, beamwidth, number of beams and coverage. These technical parameters define the nature of the system, but the fundamental characteristics of greatest interest. By Dave Mann, Gardline Geosurvey, UK. Just as technological advances mean there... (read more)
2013-03-26 02:25:34
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