Bernese GPS Software Version 5.0 - Bernese GNSS Software

14. Clock Estimation
#OBS : Number of observations contributing to the epoch parameter (code and
phase observations are counted separately).
STATION : Name of the station following a #–character.
The second part lists the epoch-wise estimated satellite clock corrections. The program
output is similar to the output for the station clocks (see Figure 14.3). Instead of the
station name at the end of the line the satellite number is reported in the second column
labeled by SAT. The a priori information for the satellite clock corrections are directly taken
from the “GNSS clock corrections” file specified in panel “GPSEST 1.1: Input Files 1”.
If the clock parameter is estimated in the main normal equation the formal error (reported
in column RMS(NSEC) of the program output) is computed, as usual, from the a posteriori
covariance matrix. If the epoch-wise pre-elimination/backsubstitution algorithm is activated
and the option “Var-covar wrt epoch parameters” in panel “GPSEST 3.2: General Options 2” is set
to SIMPLIFIED, the non-epoch parameters are assumed to be free of errors when introduced
from the solution of the main normal equation into the epoch solution. The RMS reported
here is computed from the a posteriori covariance matrix of the epoch solution only. When
the option “Var-covar wrt epoch parameters” is set to CORRECT the error propagation for the
parameters introduced from the main normal equation into the epoch solution is included.
The formal errors for the epoch parameters are then correct but the procedure is very time
and memory consuming.
In the part EPOCH WISE STATION CLOCKS of the program output listed in Figure 14.3
the character R just after the number of observations indicates that the clocks are used as
reference clocks. In this case the reference clock was realized by a zero-mean condition for
all station clocks. If either all station clocks or all satellite clocks are fixed (e.g., for a PPP)
the corresponding part is not printed to the program output.
In the case of a local network (e.g., like in the processing example) not all satellites can
be observed for each epoch. The three observations reported in the program output for
satellites 18 indicate that this value is not well determined and should not be included
into an external result file (“GNSS clock corrections” file or “Clock RINEX” file specified in
panel “GPSEST 2.1: Output Files 1”). A minimum number of observations contributing to a
clock parameter can be defined in the input panel separately for station and satellite clock
parameters (see Figure 14.2). If less observations contribute to the clock parameter the
corresponding value is not written to the external clock file and is marked by an asterisk in
the column containing the number of observations in the program output.
The program GPSEST is able to write the results of the clock parameter estimation to
a clock RINEX formatted output file. The header information is taken from the input
panel “GPSEST 6.6.2: Clock Estimation 2”. Enter the correct name and identification of your
institution here. Although the clock RINEX format is an international format for exchanging
precise clock values, it is also used as an internal file format in the Bernese GPS Software,
Version 5.0 . It is, e.g., officially not allowed to store clock values in the clock RINEX file
when a zero-mean condition is used to realize the reference clock. Such files should, therefore,
only be used within the Bernese GPS Software and should not be distributed.
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