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Bernese GPS Software Version 5.0 - Bernese GNSS Software

Bernese GPS Software Version 5.0 - Bernese GNSS Software

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8.3 Ambiguity Resolution Algorithms<br />

If you have activated the option “Save resolved ambiguities” the resolved ambiguities are stored<br />

in the header of the observation files (as demonstrated in Figure 8.4). If you mark option<br />

“Introduce widelane integers” or “Introduce L1 and L2 integers” in panel “<strong>GPS</strong>EST 3.2: General<br />

Options 2”, the ambiguities resolved in previous runs will be introduced as known values.<br />

All other ambiguities will be introduced as unknown parameters and estimated – as all<br />

ambiguities, if you do not mark the “Introduce” options. These ambiguities may or may<br />

not be pre-eliminated according to options in panel “<strong>GPS</strong>EST 5.1: Setup of Parameters and<br />

Pre-Elimination 1”.<br />

8.3.1 ROUND Algorithm<br />

This is the simplest ambiguity resolution strategy which only rounds the real-valued estimates<br />

to the nearest integers without using any variance-covariance information. Actually<br />

there is usually no need to use this strategy. The SIGMA strategy can do exactly the same<br />

work, if necessary. We do not recommend to use the strategy ROUND on baselines longer<br />

than a few kilometers. It is not a safe strategy.<br />

8.3.2 SEARCH Algorithm<br />

The SEARCH strategy is related to the so-called FARA (Fast Ambiguity Resolution Approach)<br />

algorithm (see [Frei and Beutler, 1990], [Frei, 1991]). The following information<br />

from the initial least-squares adjustment is used:<br />

Figure 8.6: Options for ambiguity resolution strategy SEARCH.<br />

<strong>Bernese</strong> <strong>GPS</strong> <strong>Software</strong> <strong>Version</strong> <strong>5.0</strong> Page 173

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