Statistical analysis of different low cost GPS receivers for indoor and outdoor positioning

The greater part of modern low-cost GNSS receivers are able to guarantee a fair positioning performance almost everywhere: difficult environments as indoor and urban canyons are also considered. The aim of this work is to investigate the effective potentialities of this kind of receivers, in particular in static and kinematic positioning using post-processing techniques. The high number of GPS permanent stations and the continuous increase of the number of GNSS multi-constellation permanent stations, will give a good opportunity to improve accuracy and precision levels. Several GPS mass-market chipsets have been used considering different scenarios. The benefits of the DGPS service made available by the test GPS network of the Politecnico di Torino have been taken into account. This research permits to measure the advantages provided by the use of low cost receivers with post-processing techniques and DGPS corrections. This was done comparing the results with the solutions obtained with a geodetic dual frequency receiver. The raw data collection has been performed thanks to the SAT-SURF & SAT-SURFER suite. SAT-SURFER is a software (developed by the NAVSAS group) allowing data collection (including differential ones from Virtual Reference Stations) in different formats. SAT-SURF is the hardware part of the suite: a flexible platform able to host different kinds of GPS chipsets. During the test the receivers were used in a unconventional way, not only because they were used with a GNSS Network, but also because of the realization of an ad hoc logging architecture. The tests bring to have interesting results, in particular about the level of accuracy in post-processing and in real time, where the contribution of the GNSS network is less appreciable. The level of accuracy is sufficient for some applications such as the thickening of the cartographic and cadastral network. The analysis of the results obtained from the real tests shows that it is possible to state that low cost receivers are suitable for applications requiring a good quasi real time positioning such as navigation and topographic applications.