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Revista Brasileira de Geof´ısica (2006) 24(1): 63-80
© 2006 Sociedade Brasileira de Geof´ısica
ISSN 0102-261X www.scielo.br/rbg O USO DO GPS EM LEVANTAMENTOS GEOF´ISICOS TERRESTRES
Marcelo Soares Teles Santos1 e Nelsi Cˆogo de S´a1,2
Recebido em 9 setembro, 2005 / Aceito em 8 fevereiro, 2006
Received on September 9, 2005 / Accepted on February 8, 2006

ABSTRACT. From analysis of the GPS positioning of 38 bench marks, in a profile located at S˜ao Paulo State, some procedures for GPS use in terrestrial geophysical surveys are suggested. The static relative positioning by dual frequencies receivers, from sessions of 60 minutes, was used as reference. The geodetic coordinates were obtained by using several processing strategies, varying the receiver type (single and dual frequencies), the number of baselines (1 and 3), the length of baseline (2 to
250 km) and the session time (10 to 60 minutes). The orthometric heights were obtained in a relative way, using the 5 nearest stations of RGSP. The statistical analysis of residuals of the obtained coordinates and heights with respect to the reference values, generated information about the accuracy of the geodetic positioning by GPS, as a function of analyzed parameters. From the obtained results, the GPS positioning methods were specified to local and regional geophysical surveys, according to its characteristics. Therefore, to obtain an accuracy of 10 cm from baselines greater than 30 km, dual frequency receivers and sessions greater than 30 minutes must be used. For baselines lower than 30 km, may be used dual or single frequency receivers with 30 minutes sessions.
Keywords: GPS positioning, levelling by GPS, geophysical surveys.

RESUMO. A partir da an´alise do posicionamento por GPS de 38 Referˆencias de N´ıvel, num perfil localizado no Estado de S˜ao Paulo, s˜ao sugeridos procedimentos de uso do GPS em levantamentos geof´ısicos terrestres. Como referˆencia, foi realizado o posicionamento relativo