5.5.5 Modern GPS Surveying: Field Procedures


Centimetre positioning accuracy of moving antenna ...

This is a generalisation of the "stop & go" technique. Instead of coordinating stationary points and disregarding the trajectory of the roving antenna as it moves from site to site, the intention of "kinematic" surveying is to determine the position of the antenna only while it is in motion (see Figure below). In many other respects the technique is similar to "stop & go". That is, the ambiguities must be resolved before starting the survey, and the ambiguities must be reinitialised during the survey when a cycle slip occurs. However, for many applications, such as the positioning of an aircraft (for example, for photogrammetric applications) or a ship (for example, a dredging operation), it is impractical to reinitialise the ambiguities if the "roving" antenna has to return to a stationary control point. Hence much R&D effort has been invested in initially determining (and redetermining after a cycle slip) the ambiguities "on-the-fly". Today the "kinematic" GPS surveying technique is undergoing tremendous improvement and "on-the-fly" ambiguity resolution is a routine procedure (though not yet by any means an entirely foolproof one!), making kinematic surveying techniques ideal for road centreline surveys, hydrographic surveys, airborne applications, etc.


The "kinematic" GPS surveying technique.



There are a number of trends in "kinematic" surveying that are worth noting:


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© Chris Rizos, SNAP-UNSW, 1999