Fix Bad Baselines

The following sections contain ideas to try when attempting to fix bad (red) baselines in GrafNet.

Fixed Static Solutions

If a fixed integer solution is not achieved, consider lowering the ARTK quality acceptance criteria to its lowest setting (Q0) and reprocessing. When doing so, it is important to check any loop, check and duplicate tie points in the traverse report to ensure the quality of the solution.

If a fixed integer solution is still not achieved, check the baseline distance and plot the number of satellites, DOP and estimated carrier RMS in order to check if conditions are not favorable to integer ambiguity determination.

Change the Processing Direction

Switch from Forward to Reverse processing. The reverse solution might pick a different base satellite and have a different solution that passes.

Change the Elevation Mask

GrafNet by default uses a 15° elevation mask. This is because tropospheric, ionospheric and multipath errors increase significantly on low elevation satellites. Lowering the mask to 10° allows more satellites into the solution, strengthening the geometry. The improved geometry may more than compensate for increased measurement errors.

Change the Processing Time Range

The start / end times can be modified from within the General tab. Sometimes a data set will benefit if a problematic section is removed, such as an extended period where very few satellites are available (plot the Number of Satellites to check this).

Satellite Omission

A bad satellite has many bad data warnings in the message log file (FML/RML). Omit this satellite with the Advanced tab options.