Processing Direction

Both

When processing Both directions, independent forward and reverse solutions are processed and automatically combined. This method of processing is the default for differential processing.

Combining forward and reverse solutions maximizes solution accuracy and assists in quality control. Depending in part on baseline length, satellite geometry and number of satellites available, forward and reverse solutions may achieve different solution types (fixed/float) for different parts of the survey.

When both directions are combined automatically after processing, inverse variance weighting is applied to ensure the direction with the lower estimated errors receives the most weight in the combined trajectory.

Position differences between forward and reverse directions can be accessed from the Combined Separation and Combined Separation (fixed) plots after processing. The latter plot shows the differences in positions only where both have fixed integer solutions. This plot will help detect incorrectly fixed ambiguities.

Forward and Reverse

Changing the processing direction to Forward or Reverse is normally done only if a problem is detected after processing Both directions. The Advanced dialog can be accessed to customize processing options prior to reprocessing.

Multi-Pass

This method of processing is available when processing GNSS-only PPP or TC (PPP or differential). Multi-pass processing maximizes convergence by passing converging Kalman filter states sequentially between processing directions. This benefits PPP processing, as float carrier phase ambiguities are estimated, and heading convergence for low cost IMUs and low dynamic applications (e.g. pedestrian, marine). Differential GNSS-only processing does not benefit from multi-pass processing, and is thus not an available selection in the processing mode, due to ARTK (fixing carrier phase ambiguities).