The gravitational geopotential produces the principal
acceleration on Earth. Therefore a precise orbit
restitution applying dynamic methods requires a precise
model of the geopotential with resolution ...
The precise orbit results from a data reduction
process in which all available tracking data (SLR, radar
altimeter crossovers, PRARE range and doppler data) and
most accurate correction, transformation ...
Preliminary orbit products (PRL) are based on fast
delivery tracking data: SLR, radar altimeter height, ERS-2
PRARE range and doppler data. These products are an
improvement of the initial knowledge ...