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 Kevin Dixon, GNSS product manager, NavCom Technology Inc, USA

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 Kevin Dixon, GNSS Product Manager, NavCom Technology Inc., USA

New GPS Satellite Operational

The fourth in a series of eight modernized Global Positioning System (GPS) satellites that will deliver new capabilities to military and civilian users has been declared fully operational.   Launched from Cape Canaveral October 17, the satellite was given the all clear after an on-orbit checkout by a combined U.S. Air Force/Lockheed Martin team. Read more   The satellite joins three IIR-M satellites and 12 other operational Block IIR satellites within the current 28-spacecraft constellation. The fifth GPS IIR-M satellite is scheduled for launch on 20th December 20, 2007 from Cape Canaveral.     (read more)
2007-11-08 10:32:43

Copernicus Satellite Now Operational

With the commissioning of Sentinel-1A completed and the satellite’s transfer for exploitation, its data is now available to all users. This marks the beginning of the satellite’s operational life, delivering radar coverage for an array of applications in the areas of oceans, ice, changing land and emergency response. Launched on 3 April, Sentinel-1A completed commissioning on 23 September – an important process that ensures the satellite, instruments, data acquisition and data processing procedures are working well. Sentinel-1A passed these tests and reached its target orbit on 7 August and eight anticollision manoeuvres to avoid space debris were performed during this... (read more)
2014-10-07 08:30:00

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

China’s Satellite Success

HY-1A, China's first marine satellite, has sent back data on ocean colour, water temperatures and coastal zones since it was launched in May last year. Since September last year, the satellite has monitored large sea areas of China, the Pacific, Indian, Atlantic and Arctic oceans, as well as the North and South poles. In addition, a large number of remote sensing images on water colour have been obtained. Meanwhile, the satellite has monitored many marine disasters, including red tides along China's coast. As part of the marine environment monitoring system, the satellite has also played an important role in curbing... (read more)
2003-11-11 12:00:00

Global Navigation Satellite Systems

Infrastructure Status and Developments
The concept of GNSS was first introduced by the European Space Agency (ESA), the European Commission (EC) and Eurocontrol in the early nineties. They defined requirements for a European GPS augmentation system, GNSS-1, and a full European satellite navigation system, GNSS-2, later together renamed EGNOS (European Geostationary Navigation Overlay System) and Galileo. Satellite navigation infrastructure status and developments are described here. Nowadays the term GNSS is used for the system of systems comprising GPS and GLONASS, with the later addition of Galileo. Satellite-based and ground-based augmentation systems (SBAS and GBAS) were introduced to augment GPS and GLONASS. Hydrographers were early... (read more)
2008-01-01 01:00:00 Jac Spaans

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. By Conor Cahalane National Centre for Geocomputation;... (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

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
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