1     Definition

Global Navigation Satellite System (GNSS) Data for a constellation of satellites that transmit positioning and timing data to GNSS receivers to determine their location.

2       Functional Requirements

GNSS Data can come from four GNSSs – GPS (US), GLONASS (RU), Galileo (EU), BeiDou (CN) and two regional systems – QZSS (Japan) and IRNSS or NavIC (India). Position accuracy depends on the GNSS system.

3       Syntax


4       Semantics

Label Size Description
Header N1 Bytes GNSS Data Header
– Standard 9 Bytes The characters “CAV-IGN-V”
– Version N2 Bytes Major version – 1 or 2 Bytes
– Dot-separator 1 Byte The character “.”
– Subversion N3 Bytes Minor version – 1 or 2 Bytes.
InputGNSSID N4 Bytes Identifier of Input GNSS Data.
GNSSSensorID N4 Bytes Identifier of GNSS Sensor.
InputGNSSTimeSpace N5 Bytes Total duration of Input GNSS Data.
– Duration N6 Bytes Duration of GNSS Data Block.
– SpatialAttitude N7 Bytes CAV’s Spatial Attitude when getting Data.
InputGNSSData N8 Bytes Set of Input GNSS Data
– InputGNSSFormatID N9 Bytes Format ID of Input GNSS Data.
– InputGNSSDataLength N10 Bytes Data Length of Input GNSS Data in Bytes.
– InputGNSSDataURI N11 Bytes Location of Input GNSS Data.
InputGNSSAttributes[] N12 Bytes Set of Input GNSS Data Attributes
– InputGNSSAttributeID N13 Bytes ID of Attribute of Input GNSS Data
– GNSSAttributeFormatID N14 Bytes ID of Attribute Format of Input Audio Data
– InputGNSSAttributeLength N15 Bytes Number of Bytes in Input GNSS Data
– InputGNSSAttributeDataURI N16 Bytes URI of Data of Input GNSS Data

5       Data Formats

Some data formats are:

  1. GPS Exchange Format (GPX): an XML schema providing a common GPS data format that can be used to describe waypoints, tracks, and routes.
  2. Environment Geodetic System (WGS): definition of the coordinate system’s fundamental and derived constants, the ellipsoidal (normal) Earth Gravitational Model (EGM), a description of the associated Environment Magnetic Model (WMM), and a current list of local datum transfor­mations.
  3. International GNSS Service (IGS) SSR: format used to disseminate real-time products to support the IGS (igs.org) Real-Time Service. The messages support multi-GNSS and include corrections for orbits, clocks, DCBs, phase-biases and ionospheric delays. Extensions are planned to also cover satellite attitude, phase centre offsets and variations and group delay variations.

6       To Respondents

Respondents are requested to:

  1. Comment on the functional requirements.
  2. Propose Data Formats and Attributes for use in the future Technical Specification: Data Types, Formats, and Attributes (MPAI-TFA).