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By Marc Antoine Leveille, engineer and urban planner.

Shortly after the launch of the Sputnik by the Soviets (in 1957), the USA conceptualized the global positioning system. Riding the technological waves, the U.S. military forces upgraded from the U.S. Transit in 1964 (using 6 satellites) to NAVSTAR GPS (navigation satellite timing and ranging global positioning system) in 1973, which projected the utilization of 24 satellites. Since 1994 the US DOD (U.S. department of defense) declared the system to be fully operational. Under the influence of the U.S. congress, the DOD facilitated the use of GPS for specific civilian applications, markedly geodesy. More precisely, the use of GPS enables with high accuracy, to know the speed and position of an object in real time, anywhere and any time on earth or within its spatial vicinity.

How does GPS works?
Someone who is equipped with a GPS receiver (a device that tracks signals from orbiting satellites) is able to determine with accuracy his or her current and exact geographic position, or even his or her orientation with regards to a given destination. For this type of operation, one has to be sure that the receiver has good sky exposure for visibility, where the antenna can capture unobstructed satellite signals (the surrounding areas of tall trees, the inside of buildings, caves, submarine depths etc…constitute restrictive environments). The positioning is determined based on the computed time it takes signals to travel from a satellite to the receiver. Using the formula for speed (distance/time) with a constant speed (which is none other than that of light 300,000 kms/sec), the required four satellites allow this computation from a terrestrial reference at the time the observation is being made. The process is very complex, but for the sake of simplicity one can grasp the above-mentioned explanation.

Taken in an international context, the American GPS holds an irrefutable   reliability. Just for your information, it is worth mentioning that the Russians put together   GLONASS (global orbitography navigation satellite system), which uses 21 satellites; this positioning system has some operational limitations linked to budgetary lacks. Moreover, GPS requires one or more reference system at the national level for precisions necessary for geodesy, seismology and topography, just to name a few. Hence, in France there exists NTF (nouvelle triangulation française), in the USA there is NAD 27 (North American Datum of 1927), in Europe there exists the ED 50 (European Datum of 1950), at the global level for example, there exists the WGS 84 (World Geodetic System of 1984) and others tailored to geographic and physical peculiarities of their respective countries and areas.

In the scope of international references with continuous observations, the IGS (International GPS Service for Geodynamics) provides high accuracy products to scientific users of GPS, such as accurate ephemeredes (a set of parameters describing the orbit of a satellite) and the parameters of the terrestrial rotation. Paralleling such, the ITRS (IERS Terrestrial Reference System avec IERS pour International Earth Rotation Service) comprises a global network of about 200 points, this global system is the most precise (with an accuracy within centimeters) and provides coordinates from observation campaigns by accurate spatial techniques. There is as well a global IGS network using CORS (continuously operating reference stations). Actually, in the Caribbean region there are 5 CORS noticeably in Cuba, Jamaica, Porto Rico, the Virgin Islands and recently in Haiti, this is based on the U.S. National Geodetic Survey and the IGS. However, the existence of many CORS in the Dominican Republic has yet to be confirmed.    

These activities involving spatial reference and global positioning are very highly contributive to the international scientific community. Through the concerted action of l’UNEPH (l’université épiscopale d’Haïti), of HAES (Haitian American Association of Engineers and Scientists), of HESS (Haitian Earth Science System), of NGS (National Geodetic Survey) and of many conscientious individuals a CORS was installed in Port-au-Prince at the beginning of August 2002. Such scientific infrastructure was supplemented with a meteorological package (Metpack) that will enable it to collect hourly data related to barometric pressure, humidity and ambient temperature. The first will allow Haiti to potentially integrate the IGS, a worthy wish, two additional CORS units would allow receivers to achieve accuracies of 2 centimeters in the horizontal and of 4 centimeters in the vertical(with regards to the ellipsoid of the IGS’ global network). The second(Metpack) will largely contribute in the surveillance and  mitigation of hurricanes in the Caribbean basin. This first CORS, alongside others, will give far-reaching advantages to scientific and professional users of GPS in Haiti. Geodesy, seismology, surveying, topography, telemetry, mapping, geo-technics, civil engineering, precision agriculture without further thoroughness, will be practiced with more ease leading to efficient and economical yields.

Such eventualities must climb the ladder of necessary steps, like:  

--the installation of two other CORS (hence three would be ideal/optimal for Haiti), the definition of a national reference system for Haiti, for instance Republic of Haiti Datum 2005, abbreviated as RHD05.

--establishing a high accuracy reference network with three-dimensional geodetic control points using GPS, the technical training of technical and scientific users of GPS receivers for various purposes, likewise in many academic and professional areas



The technical training phase has already been initiated at UNEPH, from July 31 to August 7, 2002; 22 certified technicians were recognized for completing a seminar in “GPS and its practical applications” sponsored entirely by HESS. In comparison, for an identical seminar, Navtech in the USA charges individually $1.500(US). HESS understood the need and responded to the urgency, it offered scholarships to all the attendees with lunch and books included. HESS’ vision aims at orienting Haitian scientists and professionals towards the frequent use of information networks capable of yielding considerable betterment in their respective application. It planned to spread said vision by broadening internet access, an indispensable asset to the WORLDCLASS citizen. Haitians are not to be excluded.

An emerging reality is the fact that GPS technology, geospatial sciences and the internet are experiencing nowadays a growing interdependence. Aware of such obviousness, gentlemen Peter Kammeyer, Patrice Lerebours, Maxo Erick Val and Marc Antoine Léveillé designed the GPS technical seminar sessions to account for said interdependence. Possibilities for periodic training is being considered by interested institutions such as the Bureau des Mines et de l’Énergie(BME) and HAES. Such feasibility wishes to enable training for staff called upon to ensure the integration of Haiti in a global and multiple applications of GPS as well as its derived services.

With encouraging success and under the auspices of HESS, the U.S.NGS trained three young students to manage and maintain the CORS, as well as for the meteorological package installed at UNEPH. The tireless assistance of HAES must be praised, with   technical backing from its engineers Max Everett Massac and Marc Antoine Léveillé, collaborating with the NGS staff delegated on site. To ensure an efficacious service, an equitable access and the perennial use of the CORS infrastructure, a protocol will dictate the interaction of UNEPH and HAES, as well as that of institutions desirous of   collaboration. That protocol will aim at facilitating access to a host of information available through CORS, like its use as a reliable reference point for many potential sectors countrywide. All suggestions based on experience with the system will be welcomed and are expected. It goes without saying that, such initiative deserves assistance from national and international sectors alike.

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