Performance Analysis of a L1-C/A Code Smoothing Receiver Under Field Conditions of Land Reform in Brazil

Julio C. Farret and Marcelo C. Santos

Abstract:	The recent law 10267/2001 [17] introduced the Brazilian National Cadastre of Rural Lands in Brazil (CNIR). It determines that legal surveys should be attached to the Brazilian Geodetic System with accuracy of 50 cm 1 sigma. It also determines that the professionals who carryout those surveys to be under legal professional responsibility and passive of punishment in case of proved technical errors. This is an aspect which concerns professionals who make intensive use of satellite positioning. The capability of a GNSS receiver to keep in the field conditions same accuracy as its design is not always seen with care and attention needed. It is common professionals not being able to realize in the field the nominal performance of the system, especially in situations which represent a challenge in terms of signal obstruction and, mainly, the multipath. This may bring serious consequences if the professional is penalized for technical errors. Said that it is important to know the quality indicators given by the manufacturers, the adequate use conditions of the receiver and, mainly, analyze correctly the real capability of the internal characteristics of the receiver for realizing the measurements according to its design. The receiver internal characteristics include several ways to treat the interferences, noise, and multipath. This work analyzes the characteristics of a specific receiver, the Leica GS20, due to its use in surveys aiming at attending the CNIR, where it has been an option for problematic sites in terms of coverage, since it gets to maintain tracking in order to estimate the desired coordinates with relatively short occupation time. However, there are still some uncertainties with respect to the real capability of it, especially when using smoothed pseudoranges as basic observable. In this work, we tried to reproduce the common conditions of surveying for georreferencing as given by CNIR. The main technologic characteristics of the analyzed system are the use of special antennas, code smoothing pseudorange by carrier-phase measurements, and the use of correlators with spacing specially reduced in the tracking loops. The analysis of the results was done based on noise, measurement precision and, mainly, in the external analysis of the coordinates accuracy.
Published in:	Proceedings of the 63rd Annual Meeting of The Institute of Navigation (2007) April 23 - 25, 2007 Royal Sonesta Hotel Cambridge, MA
Pages:	327 - 339
Cite this article:	Farret, Julio C., Santos, Marcelo C., "Performance Analysis of a L1-C/A Code Smoothing Receiver Under Field Conditions of Land Reform in Brazil," Proceedings of the 63rd Annual Meeting of The Institute of Navigation (2007), Cambridge, MA, April 2007, pp. 327-339.
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