Bernese GPS Software Version 5.0 - Bernese GNSS Software

14.4 Satellite Clock Validation
(4) In the last step the size of the clock jump is estimated using a polynomial. The
assumption is that the clock can be modeled as a polynomial with the degree specified
in the option “Polynomial degree for jump size estimation” over the entire time interval.
This is only a verification of the detected clock jump. The results are printed on
request into the program output.
Those four steps are executed for each clock in the combined output array. The assumption
is that the alignment to a reasonable reference clock has been done before. Therefore, the
clock jump detection is performed after the reference clock selection.
14.3.6 Clock Extrapolation
If the time window specified in panel “CCRNXC 2.1: Time Window” is not completely covered
by clock values from the input clock RINEX files the program CCRNXC may extrapolate
the clock values. The combined clocks are aligned to a reference clock and clock jumps are
identified. The clock values are then modeled in the following way:
δ(t) =
m
ai(t − t0)
i=0
i +
polynomial part
n
(bsj sin(ωjt) + bcj cos(ωjt)) periodic part
j=1
+ ck clock jump .
The parameters of this function (ai, bsj, bcj, and ck) are computed for each clock using
a least-squares adjustment. The polynomial degree m and the frequencies for the periodic
functions ωj are specified by the user in panel “CCRNXC 7: Options for Clock Extrapolation”.
The clock jump term is setup for each epoch for which a clock jump was detected.
Two parameters trigger the extrapolation of a particular clock: The RMS of the least-squares
adjustment for the parameters must be lower than a specified threshold (option “Maximum
allowed RMS for fit” in panel “CCRNXC 7: Options for Clock Extrapolation”) and a minimum
number of clock values used to determine the model parameters may be requested (option
“Minimum number of clock values for fit” in the same panel).
14.4 Satellite Clock Validation
If satellite clocks are estimated together with receiver clocks in program GPSEST (see Section
14.2) the resulting satellite clock corrections are expected to be consistent with the used
satellite orbits and the Earth orientation parameters. If the clock corrections are aligned to
a linearly behaving reference clock in program CCRNXC (see Section 14.3.4) it is expected
that all linearly behaving receiver clocks can be represented by a linear clock model.
A linear model for receiver clocks introducing satellite clock corrections can be estimated
with the program CODSPP (”Menu>Processing>Code-based clock synchronization”, description in Section
6.3). The linear clock model for the receiver clocks is activated if the option “Clock
polynomial degree” in panel “CODSPP 2: Input Options” is set to 1. Figure 14.8 shows the
CODSPP summary file from session 1390 of year 2003 from the clock determination example
described in Section 20.4.4 (file ${P}/EXAMPLE/OUT/TT 03139.SMC). You can see that
Bernese GPS Software Version 5.0 Page 305