Bernese GPS Software Version 5.0 - Bernese GNSS Software

7. Parameter Estimation
where Q 11 refers to the inverted normal equation matrix block referring to the non-epoch
parameters. Multiplication with the variance factor gives the variance-covariance information
for the epoch parameter i.
With option SIMPLIFIED only the variance information of the epoch parameters are considered,
i.e., based on the equation
Q ii ≃ N −1
ii . (7.38)
This means that the statistical errors of the non-epoch parameters are ignored for the
computation of the variance-covariance information of the epoch-parameters. Their error
information will, therefore, be too optimistic. When selecting the option it has to be considered,
however, that the computation of the errors according to Eqn. (7.37) may be very
CPU time- and memory-intensive. It has to be stated clearly that the option for computing
the variance-covariance information has no impact on the estimated values of the epoch
parameters. Only the reported formal errors are affected.
In case that epoch parameters are pre-eliminated epoch-wise it makes sense to use a priori
scaling of normalized residuals (option NORM APRIORI in “Type of computed residuals” in panel
“GPSEST 3.1: General Options 1”, see Section 7.4.4).
7.6 Flow Diagram of Program GPSEST
Figure 7.3 shows the flow diagram of the actions performed by program GPSEST. The
core of the program is (1) the loop over all epochs in which the observations are read, the
partials are computed and the normal equation is accumulated and (2) the inversion of the
normal equation and computation of the solution. The diagram indicates at which points
the parameter pre-elimination of different types take place.
7.7 Special Applications
7.7.1 Orbit Determination for Low Earth Orbiters
7.7.1.1 Preparation for Processing
The Bernese GPS Software Version 5.0 allows to compute precise orbits for Low Earth Orbiters
(LEOs) equipped with GPS receivers. In order to ensure that the software recognizes
a receiver as spaceborne and gets the necessary additional information, the satellite has to
appear with a well-defined name in several files:
• The satellite may appear in section TYPE 001: RENAMING OF STATIONS in the station
information file (description in Section 22.8.3) in order to rename the satellite/receiver
name from the RINEX file to a well-defined satellite name which is used in all other
files (see Section 4.2.3).
• The satellite (with the translated name) has to be listed with the marker type SPACE-
BORNE in section TYPE 005: HANDLING STATION TYPES in the station information
file. Throughout the software, this entry defines a spacecraft mounted receiver. As a
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