||Ground-Based Doppler Orbitography by Radiopositioning Integrated on Satellite (DORIS) Cumulative Station Position Product from NASA CDDIS
||Doppler Orbitography by Radiopositioning Integrated on Satellite (DORIS) Cumulative Station Position Product from the NASA Crustal Dynamics Data Information System (CDDIS). DORIS is a dual-frequency Doppler system consisting of a receiver flying aboard a satellite and a globally distributed network of ground beacons. The DORIS receiver on-board the orbiting satellite tracks the dual-frequency radio signals transmitted by the network of ground beacons and generates the DORIS data. A measurement is made of either the Doppler shift or absolute phase as the satellite’s orbit moves over the ground-based beacon. DORIS data records contain a time-tagged range-rate measurement with associated ancillary information. DORIS observations from a global network can be utilized for a variety of products. Analysis Centers (ACs) of the International DORIS Service (IDS) retrieve DORIS data on a regular basis to compute station position solutions for the DORIS beacons supporting the IDS network. The IDS Analysis Center Coordinator combines these individual AC solutions to generate a long-term DORIS position and velocity cumulative solution through a piecewise linear (position+velocity) model to describe the station motions. The cumulative position and velocity solution is obtained from the stacking of the weekly solution files and is then aligned to the current ITRF. The residuals of this stacking are of particular interest since they depict non-linear station motions.