Research
> CGPS
Precise
Point Positioning Strategy
Precise
Point Positioning (PPP)
is performed using RINEX GNSS Observation Data from a number of
stationary
ground receivers defining the IGS Reference Frame along with the Pole,
Precise
Orbits and Satellite Clock files from the IGS, as well as from the
individual
contributing Analysis Centers, in order to obtain a set of station
coordinates and
velocities.
A
PPP solution is acquired on a daily basis for each station. The
processing procedure consists of three main parts:
1)
Preparation Part Satellite
Positions from the Precise Orbit files are adjusted to the Bernese
extended
orbit model (6 osculating elements and 9 dynamical parameters) using
associated
Pole files. Satellite Clock files are also converted to Bernese format.
2)
Pre-processing Part Pre-processing
of the RINEX Observation Data is accomplished to identify and eliminate
cycle
slips. Smoothed data are converted into the Bernese format
(zero-difference
code and phase observation files) and used (code observations only) for
the
receiver clock synchronization.
3)
Processing Part Station
specific coordinate files are estimated using code and phase
measurements. The
procedure involves a station by station data reduction with iterative
post-fit
cleaning. Modeling of the tropospheric delay is done using the Niell
Mapping
Function (NMF) and meteorological data from a standard sea-level
atmosphere.
A weekly combination
of the daily
generated PPP files is performed in order to compute the final
coordinate and velocity
file. Over time, the PPP processing reveals information about the
stability of
the station coordinate determination and the realization of the
reference
frame.
The time Series in ITRF2005 can be found in:
|