Autoria: SHIRATSUCHI, L. S.; ZIVIANI, A. C.; MARTINS, F. da S.

Resumo: ABSTRACT: After the liberation of Selective Availability (S/A) several GPS receivers started to have enough accuracy or precision for work with grid sampling in Precision Agriculture. There are few articles describing the accuracy and precision of these receivers. The objective of this work was compared and calculated the accuracy of two models very used for grid sampling in Brazil. The study was done in a flat surface, common in the Cerrados region. The geographical reference was determined by DGPS collecting data for 10 hous. The tested models (Garmin GPSIII Plus and Garmin etrex Vista) were evaluated for 5 days in the period of 7 a.m. to 17 p.m. The concept of Circular Error Probability (CEP) was uded for the accuracy and precision calculation. The model Garmin GPSIII Plus presented CEP 50% = 3,6m, CEP 90% = 6,7m, CEP 95% = 7,4 and CEP 98% = 8,2m. The model Garmin etrex Vista presented CEP 50% = 3,3m, CEP 90% = 6,2m, CEP 95% = 6,2 and CEP 98% = 7,6m. Both models presented different error patterns, while the model GPSIII Plus presented aleatory error the etrex Vista presented systematic error (several points overlapped). It was also noticed that the GPS error increased a lot after 15 p.m. for both. In the Cerrados region the grid sampling used by the farmers is much larger than this; therefore the accuracy and precision are enough for grid sampling.

Ano de publicação: 2004

Tipo de publicação: Folhetos

Unidade: Embrapa Cerrados

Palavras-chave: Agricultura de Precisão, Circular error probality, Equipamento Agrícola, GPS, Precision farming, Sensoriamento Remoto