Open Journal Systems

Analysis of the feasible GPS L1/CA receiver precision under the challenger of muiltipath

Julio Cesar Farret, Marcelo Carvalho dos Santos, Eno Darci Saatkamp, Evandro Palma


Since the creation of the NAVSTAR/GPS several sources of observational errors
have been identified and studied. They include, among others, ionospheric delay
and clock offsets. The error caused by multipath, however, persists as a challenge,
especially for applications that demand high accuracy. In Brazil, with the
promulgation of Law 10267/2001 creating the National Cadastre of Rural
Properties (CNIR), this challenge assumes a specific feature since it influences the
applicability of the new cadastral system. The GPS receiver manufacturing
companies have been making large investments in research to deal with multipath,
especially at receiver design level. This work performs an analysis of the applied
technologies involved in the Ashtech Promark 2 GPS receiver in field conditions as
realistic as possible similar to the ones encountered in geodetic surveys satisfying
CNIR’s specifications. The results show the potential of using such receivers to
certification works by the Instituto Nacional de Colonização e Reforma Agrária
(INCRA). It also makes evident their limitations.


GPS; multicaminho; DLL; PLL; multipath; Delay Lock Loop; Phase Lock Loop