# The EGNOS Augmentation in Maritime Navigation +
## 3 Experimental Setup  
The objective of this work is verifying the performance of EGNOS augmentation using FTP service provided by EDAS to apply EGNOS messages (in EMS format) to GPS measurements collected in static and kinematic mode as explained in the 3.1 and 3.2 subparagraphs.  
The data have been processed using the demo5 version of the RTKLIB that is an open-source version of RTKLIB optimized for low-cost receivers and for practical use. It is based on RTKLIB 2.4.3 version including additional solution features to deal with the sometimes very challenging measurements from lower cost receivers and is also optimized to work with multi-constellation solutions. RTKLIB supports standard and precise positioning algorithms with GPS, Glonass, Galileo, QZSS, BeiDou and SBAS. Different positioning modes are allowed using GNSS data for both real-time and post-processing such as single point positioning (SPP), DGPS (differential code approach), Kinematic, Static, Moving-Baseline, Fixed (carrier-phases- based relative approach), Precise Point Positioning (with different approaches).  
In the current work, a solution, applying EGNOS corrections provided in the EMS file by the EDAS server, is obtained. EGNOS positioning solution has been compared to GPS-only SPP (without any EGNOS correction), DGPS, and PP-Kinematic solutions. In detail, the analyzed configurations are indicated as:  
* \"GPS SPP\" referring to the positioning solutions obtained using only GPS observations in SPP mode, that uses only L1 frequencies; information broadcasted in the GPS navigation message have been used to compute satellite orbit and clock corrections and to reduce ionospheric delay while Saastamoinen model has been used for tropospheric correction;
* \"GPS+SBAS SPP\" indicates the positioning estimates obtained applying EGNOS corrections in SPP mode for satellite orbit and clock, ionospheric and tropospheric delays; also in this case, only L1 frequencies have been used;
* \"DGPS\" representing the position solutions computed applying dual-frequency code-based (L1 and L2 frequencies) differential positioning mode using GPS-only measurements; broadcast ionospheric information and Saastamoinen models have been used for, respectively, ionospheric and tropospheric corrections. In addition, for DGPS setup, observational corrections from the permanent stations located nearby the data collections' places have been also applied. In detail, data from a permanent station located in Naples (NAPO) and belonging to Regione Campania network have been used for the static test, while Rome University (ROUN, Rome) station belonging to Lazio Network has been considered as base station for the kinematic one.
* \"PP-Kinematic\" solution is based on the carrier-phase measurements, and it provides the absolute position by solving the relative distance between the rover and a base station epoch by epoch. The relative distance is solved using the double difference (DD) measurement model, that involves both L1 and L2 frequencies and allows for eliminating the ionospheric effect and reducing the tropospheric one. As in the DGPS approach, the permanent station located in Naples (NAPO) was chosen as base station and measurements from GPS and Glonass systems were processed.  
Finally, as it will be deeply described in Section 4, the performance of the considered configurations has been evaluated in terms of continuity, availability and accuracy in position domain. For the latter one, a positioning error analysis has been carried out considering the well-known coordinates of the selected reference station for the static test as described in subparagraph 3.1, while a reference solution has been computed for the kinematic data collection as detailed in Section 3.2.