Météomodem is a Research and Development (R&D) company created in 1992 bytwo engineers, Georges Ricaud and Patrick Charpentier. Météomodem began to design and manufacture equipements for maritime radio communications. Then, in connection with the main activities of its mother company Géolink, they specialized in designing, GPS positioning and Immarsat satellite communication. Marketing and distribution of these product were in charge of Géolink. Futher an enquiry of ESA (European Spacial Agency) in 1994, Météomodem has been involved into radiosounding. At this time, the question was find a high performance system to mesure accurately wind parametters in order to calculate and define wind gust dimension on Kourou launch site. To that effect, we used a new specific balloon named ''Méduse'' (jellyfish) associated to a new Météomodem sonde GPS400PSK. The distinctive feature of the sonde consisted in using GPS positioning technology whereas only Loran C, Omega or radar tracking were available to measure wind parameters. This association Meduse-Modem sonde has been used successfully during VERHT1 and VERHT2 campaigns in 1996 and 1998. Following these encouraging result with the GPS400PSK, Météomodem engneers were motivate to develop a complete GPS radiosounding system with wind and PTU for meteorological needs.