SAT-SURF and SAT-SURFER: a flexible platform for both R&D and training on GNSS

This paper describes a set of hardware and software tools currently being ready-to-use for R&D and training purposes on GNSS called SAT-SURF & SAT-SURFER. The whole idea behind the creation of SAT-SURF and SAT-SURFER is to allow users “to put hands on and touch” GNSS receivers and theirs outputs. In fact it allows powerful multi-format data log (e.g: Rinex, Excel® and Matlab®). Every measurement (including raw data) made by the GPS receiver and the GSM module on board can be stored and made available. SAT-SURF is the hardware box: it comes with a Quad Band GSM/GPRS modem and a socket able to host a number of GPS chipsets from different manufacturers. SAT-SURFER is the Software suite that, running on a standard PC, enables the control of the hardware box and provides a complete and user-friendly Graphical User Interface. The couple can be considered a sort of super-evaluation kit for studying, developing and testing hybrid NAV/COM strategies as well as new Location Based Services. SAT-SURF can be equipped with different GPS modules by uBlox® and SiRF®. Others will be available in the future: the hardware has been studied to guarantee the maximum flexibility. The GSM modem, enabling communication with Local Elements, provides the access to Assisted-GPS (OMA-SULP compliant) and Differential GPS (through NTRIP protocol). Furthermore SAT-SURF is able to exploit EGNOS differential corrections both via satellite and via internet with SISNeT service and EDAS in the future. SAT-SURFER can also control other stand alone receivers as Septentrio® and Magellan®, via TCP/IP or COM port, permitting low level configuration of the GPS chipsets and receivers in order to fit every user need. The goal of this paper is to demonstrate how SAT-SURF and SAT-SURFER can be used in R&D activities. By means of raw measurements collections, the evaluation of the positioning accuracy of different receivers has been performed. Furthermore different DGPS techniques and PVT strategies have been applied and tested using SAT-SURF and SAT-SURFER. In adjacent, several kinematic tests were conducted in various environments wherein differential data were provided via GPRS connection. Another major test with SAT-SURF and SAT-SURFER is monitoring integrity in road transport. Like in many other GNSS applications, also in road transport the Required Navigation Performance (RNP) has to be satisfied. The usage of GPS device in the urban environment indicates clearly limitations and vulnerabilities of GPS signal reception. The limitations are in the areas of accuracy, reliability, integrity, and availability. However, several GPS augmentation systems (i.e. WAAS, EGNOS, …) now operational were conceived to minimize these limitations. The aim of these tests is to examine the performance of mass market GPS receivers with respect to RNP in some different situations typical of urban transportations (e.g.: urban canyons, tree canopy, bridges overhead). With raw data and navigation parameters acquired by SAT-SURF, augmentation data received from EGNOS and correction data coming from internet (via GPRS connection), a RAIM algorithm has been developed and tested. Finally, selected results from these tests will be plotted and commented.