Data available from EDAS
The EGNOS Data Access Service (EDAS) is a terrestrial commercial service offering ground-based access to EGNOS data on a controlled access basis (i.e. via the internet and mobile phones). Geared to users requiring enhanced performance for professional use, EDAS provides users with the same data broadcast by the EGNOS satellites (EGNOS Message) in near real-time.
EDAS primarily provides the following data types:
- Raw GPS, GLONASS and EGNOS geostationary satellites observations and navigation data collected by the entire network of Ranging and Integrity Monitoring Stations (RIMS) and Navigation Land Earth Stations (NLES);
- EGNOS augmentation messages, as normally received by users via the EGNOS Geostationary satellites.
In addition to the EGNOS Message, the service also provides GPS and GLONASS measurements at all stations in the EGNOS monitoring network.
For more information, please see the EDAS Service Definition Document.
Raw observations from RIMS network
The data collected by the RIMS network includes dual-frequency GPS data, GLONASS L1, and EGNOS Geostationary Signal in Space (SIS). A set of observables is provided for each RIMS and each satellite tracked. As a result, at any given time, information from each RIMS can be provided with a set of observables from visible satellites. The raw data can be provided in both ASN.1 and RTCM format.
This data is provided by EDAS in real-time with an update rate of 1 second. Each message contains a variable number of sections (depending on the number of tracked satellites). The summary table below lists all the raw observables provided from the RIMS network, which are described in the map:
This data type is the EGNOS augmentation message as uplinked and broadcast from the EGNOS geostationary satellites. The EGNOS augmentation message has been internationally standardised with all other space-based augmentation systems (SBAS). This means its content and format is precisely defined in the following public document: Minimum Operational Performance Standards for Global Positioning System/Wide Area Augmentation System Airborne Equipment, Ref. RTCA DO-229, Revision D, Issued 13 December 2006.
The EGNOS augmentation message is comprised of a number of distinct message types containing various aspects of the overall augmentation message. The message types provided are summarised in the table below. The EGNOS augmentation message is transmitted per second, with each message being 250 bits long. The previous four transmitted augmentation messages are also provided in an EDAS message.
|0||Do not use for safety applications (for SBAS testing)|
|1||PRN Mask assignments, set up to 51 of 210 bits|
|2 - 5||Fast corrections|
|7||Fast correction degradation factor|
|9||GEO navigation message (X, Y, Z, time, etc.)|
|12||SBAS Network Time/UTC offset parameters|
|17||GEO satellite almanacs|
|18||Ionospheric grid point masks|
|24||Mixed fast corrections/long term satellite error corrections|
|25||Long-term satellite error corrections|
|26||Ionospheric delay corrections|
|27||SBAS Service Message|
|28||Clock-Ephemeris Covariance Matrix Message|
The Antenna Phase Centre Coordinates of all RIMS stations are provided in a dedicated message. The coordinates are expressed as Earth-Centred, Earth-Fixed (ECEF) Cartesian coordinates in the World Geodetic System 1984 (WGS84) reference system. Thus this data consists of a set of WGS84 coordinates for 34 RIMS stations.