Development GNSS L1 receiver of high accuracy and low cost for geodetic positioning

Abstract

The positioning needs and knowledge of the Earth's surface are mandatory part of modern mapping activities, geodetic survey for urban planning and infrastructure projects in the areas of Civil Engineering and Transportation. All urban planning and infrastructure or any other deployment, service or maintenance to be performed in a given location must have a previous survey of such information for decision making. One of the technologies that has been very currently used in various applications of human knowledge to obtain surface points of coordinates is the GPS (Global Positioning System), most recently with the emergence of similar systems has to be called GNSS (Global Navigation Satellite system). The considerable increase in the use of this technology is due to several factors, the most relevant being: convenience, ease and speed. The placement through GNSS can be performed from different techniques and observable, which provide accuracy levels ranging from tens of meters to a few millimeters. In mapping the GNSS technology is used in determining the geographic position and, together with a software that controls the data collected can feed a pre-existing database or create a new database, this is called System (GIS Geographic information). Through GNSS maps are made directly in the field for any level of detail that is desired (Segantine, 2001). Mapping / GIS is fundamental to decision making in providing essential services companies such as electricity, sanitation, gas and others. The accuracy required in this type of work should be better than 50 cm. In Brazil, unlike the United States and European countries has no free system of differential correction via geostationary satellites such as WAAS in the USA and EGNOS in Europe, depending on the equipment used can enable such details directly in the field. Therefore, the problem facing the Brazilian mapping is that most existing products currently only has the possibility of postprocessed use, ie, it is first necessary to collect field data and then performing the processing of the office with specific software, that hinders the development of the work will be as only possible to know the quality of positioning after processing. To be able to view information about the field in precision high investment is needed in GNSS receivers that have the authorization to work in real time, the so-called RTK, and are equipped with internal GSM / GPRS modem to receive RTK corrections via NTRIP derived from free IBGE service called RBMC-IP. In both cases, such equipment is imported, and has proprietary software platform for the control of receivers and for handling and data entry and pre-established database which greatly hinders businesses mapping sector to put your information or bank data specific to their work methodology. Sometimes some manufacturers provide the software development kit to enable companies to aggregate the information required to collect the data within the application of the equipment, but it has a high cost. This project proposes to develop a GNSS L1 RTK receiver high accuracy with open software platform for further development, this will be developed in Android environment, low cost and meeting all the current needs mapping and geodetic survey of the Brazilian market. The project is a partnership between the company GeoSurv Engineering and Geomatics and Surveying and Geodesy Laboratory of the Polytechnic School of the University of São Paulo. (AU)