5.5.2 Modern GPS Surveying: Field Procedures

RAPID STATIC GPS SURVEYING

 

 

Static positioning with short observation times of 5-20 minutes (vs 1-2 hours) ... giving centimetre accuracies!


Also referred to as fast-static or quick-static. The following characteristics distinguish rapid static techniques from other methods of GPS surveying:


The field procedures are much like those for conventional static GPS surveying except that the occupation times are shorter, the baselines should be comparatively short, the satellite geometry favourable and signal disturbances such as multipath should be a minimum. Since rapid static surveying is a relatively new technique it is not possible to define exactly how much data needs to be collected in order to produce quality baselines every time, and with high reliability. Instrument manuals typically give guidelines. Some receivers give an audio and/or visual indication when enough data has been collected in the field (but this cannot be confirmed until the data is downloaded and processing is completed). If the real-time mode is employed (the base station transmits tracking data to the mobile unit where it is processed immediately) then the "data quantity gamble" for rapid static GPS surveying can be overcome.

Such a technique is well suited for short range applications such as control densification and engineering surveys, or any job where many points need to be surveyed (see Figure below). Unlike the "kinematic" and "stop & go" techniques there is no need to maintain lock on the satellites when moving from one station setup to another.




Field procedure for the "rapid static" surveying technique.

 

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© Chris Rizos, SNAP-UNSW, 1999