A QUANTITATIVE EVALUATION OF DGPS PERFORMANCE IN THE POSITION AND PSEUDORANGE DOMAINS

Resumo

This study compares in quantitative terms two methods of differential corrections to GPS positioning from the codebased pseudoranges. The differential method calculated from the coordinates (Latitude, Longitude and Altitude), called Position-Domain DGPS, has simple implementation and easy transmission by the correction vector. The second method, called Pseudorange-Domain DGPS has a more elaborate algorithm, focused on the pseudorange correction for each visible satellite, which consumes more processing time and increases the complexity in the transmission of the corrections. Notwithstanding a few variations from this DGPS techniques proposed, this work intends to verify in a numeric way the bias and precision offered by these two well-known methods in different devices and situations, to assess in which context each method would be more advantageous when one what to apply a simple DGPS correction; showing how much is the gain by way of bias the more elaborated method is. The results demonstrate that in favorable conditions, the Position-Domain offered an improvement of approximately 50% in positioning, 35% in dispersion, but without any significant bettering in altimetry or in the maximum values; wile the Pseudorange-Domain method showed 70% in positioning, 75% in precision, 60% for maximum values and numbers close to zero on average altimetry.