Análise da precisão posicional de coordenadas obtidas através de smartphone dotado de receptor de dupla-frequência em diferentes cenários urbanos

Abstract

In May 2016, during the Google I / O conference, the company Google announced the possibility of accessing the raw GNSS data collected by smartphones and tablets through the Android Nougat platform (version 7). With this, several studies and research were carried out to verify the accuracy of the surveys made from receivers embedded in telephone sets. In 2018, the first smartphone with the capacity to receive and record data from two carrier waves was launched, which supposedly would imply sub-positional accuracy in the surveys carried out using these smartphones. In this sense, this work aims to analyze the accuracy of three-dimensional coordinates, in urban areas covered by trees and buildings (Scenario 1) and in open areas (Scenario 2), through data collected by the Xiaomi Mi 8 smartphone using methods of absolute and relative survey. In Scenario 1 there are topographic points with previously known coordinates, which were used to carry out the static-relative and absolute survey. The absolute survey in Scenario 1 was performed with the cell phone parked at a topographic point called C2. The smartphone collected data from the satellites in a period of 5 hours and 02 minutes and then post-processing was performed using the Leica Geo Office software and the online service IBGE-PPP. Still in Scenario 1, the Relative Static survey was carried out, based on the GNSS Topcon GRS-1 receiver positioned in a topographic point called E1 while the smartphone collected data from points A2, B2, C2 and D2, forming a closed polygonal. For each point of the polygonal, data were collected for different periods: 5, 10 and 20 minutes. In Scenario 2, two surveys were carried out: the absolute that took place similarly to that performed in Scenario 1, differentiated only by the absence of topographical points, and the cinematic survey. Eight methods of post-processing of the data were performed comparing the standard deviations of each one. For the absolute survey carried out in Scenario 1, the processing that obtained the smallest standard deviation had a value of 11 centimeters, while the absolute survey in Scenario 2, the lowest standard deviation found was 4.95 centimeters. The values ​​found with the post-processing of the static-relative survey were compared to those of the topographic points with previously known coordinates, in which a high planialtimetric error was obtained due to the value of the heights found being high.