USER ALERT: CDDIS will be migrating our website from cddis.nasa.gov to earthdata.nasa.gov starting in February 2025 and ending in June 2025. For more information, please see the following web page (https://cddis.nasa.gov/Web_Unification.html)

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Attention GNSS Data Users: Please review the IGSMail messages related to the "Transition to ISO-3166 Alpha-3 codes in the IGS metadata." The changes go into effect on December 4, 2024. See https://lists.igs.org/pipermail/igsmail/2024/008454.html and https://lists.igs.org/pipermail/igsmail/2024/008518.html.

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CDDIS: NASA's Archive of Space Geodesy Data
About the CDDIS GNSS data and products archive

Global Navigation Satellite Systems (GNSSs), such as the U.S. GPS, the Russian GLONASS, and the European Galileo system, provide autonomous geo-spatial positioning with global coverage. Ground (or space-based) receivers collect the signals from orbiting satellites to determine their location in three dimensions and calculate precise time. These receivers detect, decode, and process both pseudorange (code) and phase transmitted by the GNSS satellites.

Since 1992, the CDDIS has supported GNSS data and product archiving for the International GNSS Service (IGS) as one of six global data centers. In this capacity, the CDDIS provides online access to the GNSS data generated by the IGS network as well as the IGS standard, working group, and pilot project products derived from these data.

GNSS receiver
GNSS receivers detect, decode, and process signals from the GNSS satellites (e.g., GPS, GLONASS, Galileo, BeiDou, and others). The satellites transmit the ranging codes on two radio-frequency carriers, allowing the locations of GNSS receivers to be determined with varying degrees of accuracy, depending on the receiver and post-processing of the data.