Static positioning

 This method is used to give high precision over long baselines such as are used in geodetic control surveys at its simplest one receiver is set up over a station of known X,Y,Z coordinates preferably in the WGS84 reference system whilst a second receiver occupies the station whose coordinates are required Observation times may very from 45 min to several hours this long observational time is necessary to allow a change in the relative receiver/satellite geometry in order to calculate the initial integer ambiguity terms 

More usually baselines are observed when the precise coordinates of nether station are known the approximate coordinates of one station can be found by averaging the pseudo range solution at that station provided that those station coordinates are known to within 10 m it will not significantly affect the computed difference in coordinates between the two stations the coordinates of a collection of baselines provided they are interconnected can then be estimated by a least squares free network adjustment provided that at least one and preferably more stations are known in WGS84 or the local datum then the coordinates of all the stations can be found in WGS84 or the local datum 

Accuracies in the order of 5 mm +_ 1 ppm of the baseline are achievable as the majority of errors in GPS such as clock orbital and atmospheric errors are eliminated or substantially reduced by the differential process the use of permanent active GPS networks established by a government agency or private company results in a further increase in accuracy for static positioning 

Apart from establishing high precision control networks it is used in control densification measuring plate movement in crustal dynamics and oil rig monitoring 

Rapid static 

Rapid static surveying is ideal for many engineering surveys and is halfway between static and kinematic procedures 

The master receiver is set up on reference point and continuously tracks all visible satellites throughout the duration of the survey 

The roving receiver visits each of the remaining points to be surveyed but stays for just a few minutes typically 2-10 min 

Using difference algorithms the integer ambiguity terms are quickly resolved and position relative to the reference point obtained to sub centimetre accuracy 

Each point is treated independently and as it is not necessary to maintain lock on the satellites the roving receiver may be switched off whilst traveling between stations 

Apart from a saving in power the necessity to maintain lock which is very onerous in urban surveys is removed 

This method is accurate and economic where there are many points to be surveyed 

It is ideally suited for short baselines where systematic errors such as atmospheric orbital etc may be regarded as equal at all points and so differenced out 

It can be used on large lines ( >10 km ) but may require longer observing periods due to the erratic behaviour of the ionosphere 

If the observations are carried out at night when the ionosphere is more stable observing times may be reduced