Satellite Positioning

Within the last twenty years Global Positioning System (GPS) receivers have revolutionised navigation. Integrated devices are capable of providing time, position, height, direction, heave and attitude to accuracies of a few nanoseconds time, 1cm position or 0.01 degree heading. All potentially displayed on a digital chart background with radar and auto-identification system overlays. In this first of two articles we look at current Satellite Positioning systems, how they work and how we can make them better. In a second article, to appear next month, we explore the future development of Satellite Positioning and the implications for navigation. How does Satellite... (read more)
2008-01-01 01:00:00

Satellite Navigation

Over the last twenty years Global Positioning System (GPS) receivers have revolutionised navigation. Integrated devices are capable of providing time, position, height, direction, heave and attitude, to accuracy of a few nanoseconds time, 1cm position or 0.01-degree heading. This article explores the future development and implications of Satellite Positioning. Satellite Positioning dominates navigation at sea, in the air and on land and is now available in our cell phones and wristwatches. How it currently works was explored in the October 2006 issue of Hydro international in an article titled ‘Satellite Positioning’ (pp 35-39). But how will it work in the... (read more)
2007-01-12 12:00:00

Satellite Derived Bathymetry Migration

From Laboratories to Chart Production Routine
Much has been said about Satellite Derived Bathymetry (SDB), but with the exception of SHOM, which led to the introduction of a number of SDB charts into the French chart series, next to nothing has been implemented within the international hydrographic community. This article aims to update readers as SDB, thanks to new generation satellites and modelling, seeing the light after going through a thirty years’ tunnel. In 2014, detailed tests and analysis conducted by government hydrographers, cartographers and recognised satellite scientists operating for a number of projects initiated by the European Space Agency, the WWF and other stakeholders, were completed,... (read more)
2015-10-12 04:09:41

Precision Satellite Navigation System

Fugro Seastar AS has announced the introduction of the MarineSTAR Manoeuvring System. The system provides a highly accurate, stable position reference for ship's bridge systems such as ECDIS. Fugro Seastar claims the data to be of the highest integrity and reliability available in this industry.   In addition to position data, MarineSTAR can provide an alternative to conventional navigation aids such as gyro compass and rate of turn indicator. As well as heading, the system displays and outputs speed over the ground in both the fore and aft and athwartships directions.   The system utilises differential navigation sensors located in... (read more)
2009-06-09 12:00:00

Landsat Satellite Spots Shipwrecks

An estimated three million shipwrecks are scattered across the planet’s oceans. Most maritime mishaps occur close to shore where hazards to navigation — such as rocks, reefs, other submerged objects and vessel congestion — are abundant. It is desirable to know where they are located for many practical reasons. Streams around the wrecks create plumes that can be seen on satellite imagery in depths up to 15m, making wrecks easier to find as a recent test in Belgium showed. Belgian scientists tested this using four wrecks near Zeebrugge. Their plumes were seen by Landsat-8; the trace was followed, leading to the wrecks. The... (read more)
2016-03-15 02:53:30

Glonass-K Satellite Launched

The Russian Space Forces have successfully launched a new Glonass-K navigation satellite from the Plesetsk space center, a Defense Ministry spokesman said Saturday. The previous launch under the Glonass project in December 2010, supposed to conclude the forming of the satellite grouping, was unsuccessful as the rocket veered off course and sunk in the Pacific Ocean. The loss cost Russia 2.5 billion rubles (USD86 million) in direct damages. The Glonass-K, which has a service life of ten years, will beam five navigation signals - four in the special L1 and L2 bands and one for civilian applications in the L3... (read more)
2011-02-28 11:42:39

Galileo Satellite Transmitted Signal

Europe’s fifth Galileo satellite, one of two delivered into an incorrect orbit by the VS09 Soyuz-Fregat launcher in August, transmitted its first navigation signal in space on Saturday, 29 November 2014. It has reached its new target orbit and its navigation payload has been successfully switched on. A detailed test campaign is underway now that the satellite is in a more suitable orbit for navigation purposes. The fifth and sixth Galileo satellites, launched together on 22 August, ended up in an elongated orbit travelling up to 25,900km above Earth and back down to 13,713km. A total of 11 manoeuvres were... (read more)
2014-12-04 08:30:00

Improving Satellite-derived Bathymetry

Using Spatial Regression Algorithms
Bathymetry is traditionally acquired using singlebeam or multibeam echosounders. This method produces accurate depth measurements along transects but is constrained by operating cost and an inability to survey in very shallow waters. Airborne Lidar is able to produce accurate bathymetric information over clear waters at depths up to 70m, but can be costly and is limited by a relatively coarse bathymetric sampling interval. Experience in Irish waters has resulted in very poor seabed detection along the east coast and limited penetration on the west coast. An efficient and cost-effective alternative is satellite-derived bathymetry. Calculating Depths by Satellite Satellite Derived Bathymetry... (read more)
2016-12-20 01:33:10

Satellite-derived Bathymetry

A Reconaissance Tool for Hydrography
A study was conducted to evaluate the use of a satellite-derived bathymetry (SDB) procedure to map shallow-water bathymetry in a GIS environment, and to identify areas that require a new hydrographic survey. Publically available, multispectral satellite imagery and published algorithms are used to derive estimates of the bathymetry. The study results indicate a potential use of the procedure by national hydrographic offices as a reconnaissance tool. In some developing countries, the information available to plan and prioritise hydrographic surveys is typically based on visual inspection of existing nautical charts. However, due to the age of many existing charts and lack... (read more)
2013-12-04 11:21:17

Global Navigation Satellite Systems

A Status Update
In this feature the current status and future development of four Global Navigation Satellite Systems (GNSS) are briefly presented. These four systems are the American Global Positioning System (GPS), the Russian Glonass, the European Galileo and the Chinese BeiDou Compass. All four systems offer, or will offer, civil navigation services (publicly open), as well as restricted access navigation services, which means for GPS, Glonass and most likely for Compass as well, military services. The European Galileo system will offer so-called Publicly Regulated Services (PRS) for use by the government. The basic principle of satellite navigation – referred to as standalone... (read more)
2011-03-16 12:04:30
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