November 13, 2007

Trimble, the world leader in professional GPS equipment manufacturing and positioning solutions, has donated equipment for five GPS reference stations to Africa through ECA. The donation was first announced during a workshop in Nairobi in August 2007 on the "African Reference Frame" (AFREF) and confirmed during the just-concluded (5 - 7 November 2007) "Trimble Dimensions" user-conference in Las Vegas, USA.

The reference stations will form part of the GPS network that will define a uniform African (Geodetic) Reference Frame (AFREF). So far, each African country has its national geodetic reference system for producing maps and other geoinformation products - some countries even have more than one. The result is that representation of cross-border features on maps cannot be done accurately. For example, roads, watershed and ecosystem boundaries and wildlife reserves may appear disconnected when national maps are joined together for regional planning and decision analysis. Work on large infrastructure projects is normally undertaken in sections and a uniform mapping surface is required to ensure that the sections join up. To unify the reference systems, parameters of the best fitting surface for map projections need to be determined and used by all countries.

This requires the determination of exact positions of a network of points using global navigation satellite system, of which the GPS is the most known technology. With the parameters determined, a network of points would be established such that positioning professionals (surveyors, engineers, environmentalists, agriculturalists, mineral prospectors, etc) would always have access to parameters of at least one reference point within 500Km from any place in Africa. These reference stations will have special GPS equipment installed to continuously receive signals from satellites, which will be used to calculate the parameters for practitioners to enter in their equipment so that determined positions would be in the same reference system.

Trimble's donation of the GPS equipment will add to the network of stations for the determination of the African reference frame as well as being part of network of continuously observing reference stations (CORS). In installing the stations, consideration will be given to the location of existing stations already installed by countries or other organizations and institutions. For this reason, Niger, Cameroon and northern Botswana have been identified for three of the stations. Other considerations include the availability of constant power and computer storage and data transmission, as well as physical security of the sites. Rooftops of ECA offices therefore rank high as possible locations (Niamey and Yaoundé). The site for the remaining two stations will be determined after consultation with experts and other partners, with Addis Ababa (Ethiopia), Dodoma (Tanzania), Kigali (Rwanda) and Lilongwe (Malawi) being considered.

The AFREF project is being overseen by an international steering committee, which is an expanded version of a working group (on AFREF) of the Geoinformation Subcommittee of ECA's Committee on Development Information, Science and Technology (CODIST).