Bernese GPS Software Version 5.0 - Bernese GNSS Software

12. Ionosphere Modeling and Estimation
DOUBLE). In the zero-difference case, the specification of a “Differential code biases” input
file containing DCB values for all satellites of the constellation is highly recommended.
Corresponding files, likehttp://www.aiub.unibe.ch/download/BSWUSER50/ORB/
P1P2.DCB (moving 30-day average), may be downloaded (see Section 4.12.1). A detailed description
on the differential code biases is given in Chapter 13.
To save the estimated ionosphere models for further processing steps, you have to specify a
filename for the ionosphere models at option “Ionosphere models” (panel “GPSEST 2.1: Output
Files 1”, Figure 12.10). If you specify a filename for “IONEX”, you get a file that contains
a set of ionosphere maps in the so-called IONosphere map EXchange (IONEX) format,
a format internationally adopted. The interested user is advised to have a closer look at
Section 22.4.15, where the “IONEX control file” to be specified in panel “GPSEST 1.3: General
Files” is introduced and explained in detail. This file must be adjusted and completed in
advance. Both ionosphere-related files (default extensions are ION and INX) are stored in the
campaign-specific ATM directory. In the double-difference case, do refrain from specifying a
DCB output filename.
In panel “GPSEST 3.1: General Options 1” (see Figure 12.11), the option “Frequency” is essential,
L4 is recommended there; Furthermore, it is recommended to select BASELINE as “Correlation
strategy” in the zero-difference case and CORRECT in the double-difference case.
In the double-difference case it is a good idea to set the ambiguity “Resolution strategy”
to NONE. In an ambiguity-fixed scenario the option Introduce L1 and L2 should be chosen
(see Figure 12.12). In both cases it makes sense to pre-eliminate the “Ambiguities”
AS SOON AS POSSIBLE in panel “GPSEST 5.1: Setup of Parameters and Pre-Elimination 1”.
Figure 12.11: General options for GPSEST (1).
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