The European Geostationary Navigation Overlay Service (EGNOS) provides an augmentation signal to the Global Positioning System (GPS) Standard Positioning Service (SPS). Presently, EGNOS augments GPS using the L1 (1,575.42 MHz) Coarse/Acquisition (C/A) civilian signal function, by providing correction data and integrity information for improving positioning, navigation and timing services over Europe. The "EGNOS Service Definition Document - Open Service" (referred to as EGNOS SDD OS) is intended to give information on the EGNOS Open Service (EGNOS OS), which is one of the three EGNOS services currently available, along with Safety of Life (SoL) and EGNOS Data Access Service (EDAS). The document describes the EGNOS system and Signal-In-Space (SIS), the performance achieved by the Open Service (OS), and provides information on the technical and organisational framework at European level for the provision of the OS. The EGNOS SDD OS provides an insight into the EGNOS service performance which is of use to receiver manufacturers, GNSS application developers and the final users of the EGNOS OS. In this context, the document includes high-level information on GNSS concepts, the GPS Service, EGNOS System/Services, EGNOS Management and EGNOS Interfaces with Users as well as the minimum performance of the EGNOS OS. Some observed performance of EGNOS OS is also presented in a dedicated appendix. This document does not address EDAS or EGNOS SoL service performance. Appropriate information about EDAS and the EGNOS SoL is available in separate documents called the "EGNOS Data Access Service (EDAS) - Service Definition Document" (EDAS SDD - [RD-6]) and the "EGNOS Service Definition Document - Safety of Life Service" (EGNOS SDD SoL - [RD-5]) respectively. This document will be updated in the future as required in order to reflect any changes and improvements to the EGNOS OS Service.
