Bernese GPS Software Version 5.0 - Bernese GNSS Software

5. Preparation of Earth Orientation, GNSS Orbit, and Satellite Clock Information
EPHEMERIS PARAMETERS FOR SATELLITE 3
-------------------------------------
NUM STATUS WEEK T0E A E ... PER
1 1244 169200. 26560287.9 0.01169876 ... 149.332
2 BAD A 1244 172800. 296.1 0.01169863 ... 149.330
3 1244 176400. 26560295.5 0.01169862 ... 149.330
4 1244 255600. 26560328.6 0.01170016 ... 149.328
5 BAD DE 1244 259200. 26560341.2 0.01969999 ... 149.324
6 1244 262800. 26560336.0 0.01169990 ... 149.326
. ... ...... .......... .......... ... .......
CLOCK PARAMETERS FOR SATELLITE 3
---------------------------------
NUM STATUS WEEK TOE TOC A0 A1 A 2
1 1244 169200. 169200. -0.721770D-07 0.100000D-11 0.000000D+00
2 1244 172800. 172800. -0.703150D-07 0.100000D-11 0.000000D+00
3 1244 176400. 176400. -0.684520D-07 0.100000D-11 0.000000D+00
. ... ....... ....... ............ ............ ............
SUMMARY:
-------
SAT. #MSG #OK #BAD #JUMPS
3 9 7 2 0
6 6 6 0 0
9 12 12 0 0
11 13 13 0 0
12 15 15 0 0
13 11 11 0 0
NO JUMPS DETECTED
Figure 5.3: Sample output produced by programs BRDTST or RXNPRE.
different products we refer to Table 2.8 in Section 2.2. This section describes the steps
needed to make precise orbit information available for GPS data processing within the
Bernese GPS Software.
The satellite orbits are distributed by the IGS in the SP3c format [Remondi, 1989] as
Earth-fixed, geocentric positions tabulated every 15 minutes. In order to have access to the
satellite positions at any epoch, the tabular positions have to be interpolated. This may be
achieved by adjusting a polynomial of sufficiently high degree to a subinterval of the table.
The drawback of this approach is a decreasing accuracy of the orbit representation at the
borders of the time interval covered by the table.
The optimum way of interpolation is the adjustment of the tabulated positions by an orbit
fulfilling the equations of motion based on a physical model of the forces acting on the
satellites as described in Section 2.2. This approach is used in the Bernese GPS Software
to generate the so-called standard orbits, an orbit representation in binary format being
used by all programs which require satellite positions. It is important to note that Earth
orientation information is necessary in this context because precise orbit positions are given
in the Earth-fixed system while the equations of motion are formulated in the inertial
system. The same Earth orientation information must be used in all programs that access
GNSS orbits. How to prepare the Earth orientation information is described in Section 5.2.
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