# XML Schemas for Assisted GNSS-SDR

GNSS-SDR can read assistance data from [Extensible Markup Language (XML)](https://www.w3.org/XML/) files for faster [Time-To-First-Fix](https://gnss-sdr.org/design-forces/availability/#time-to-first-fix-ttff), and can store navigation data decoded from GNSS signals in the same format. This folder provides XML Schemas which describe those XML files structure.

[XSD (XML Schema Definition)](https://www.w3.org/XML/Schema) is a World Wide Web Consortium (W3C) recommendation that specifies how to formally describe the elements in an XML document.


GPS L1 C/A
----------

 - [ephemeris_map.xsd](./ephemeris_map.xsd) - GPS NAV message ephemeris parameters.
 - [iono_model.xsd](./iono_model.xsd) - GPS NAV message ionospheric model parameters.
 - [utc_model.xsd](./utc_model.xsd) - GPS NAV message UTC model parameters.
 - [gps_almanac_map.xsd](./gps_almanac_map.xsd) - GPS NAV message almanac.


GPS L2C and L5
--------------

 - [cnav_ephemeris_map.xsd](./cnav_ephemeris_map.xsd) - GPS CNAV message ephemeris parameters.


Galileo
-------

 - [gal_ephemeris_map.xsd](./gal_ephemeris_map.xsd) - Galileo ephemeris parameters.
 - [gal_iono_model.xsd](./gal_iono_model.xsd) - Galileo ionospheric model parameters.
 - [gal_utc_model.xsd](./gal_utc_model.xsd) - Galileo UTC model parameters.
 - [gal_almanac_map.xsd](./gal_almanac_map.xsd) - Galileo almanac.

-------

Please check https://gnss-sdr.org/docs/sp-blocks/global-parameters/ for more information about the usage of XML files in GNSS-SDR.

You could find useful the utility program [rinex2assist](https://github.com/gnss-sdr/gnss-sdr/tree/next/src/utils/rinex2assist) for the generation of compatible XML files from recent, publicly available RINEX navigation data files.
