movement between occupation sites, but this is not recommended). This feature provides the surveyor
with a more favorable positioning technique since obstructions such as a bridge overpasses, tall
buildings, and overhanging vegetation are common. A loss of lock resulting from these obstructions is
more tolerable when pseudokinematic techniques are employed.
(1) Pseudokinematic techniques require that one receiver be placed over a known control station.
A rover receiver occupies each unknown station for 5 minutes. About 1 hour after the initial station
occupation, the same rover receiver must reoccupy each unknown station.
(2) Pseudokinematic techniques require that at least four of the same satellites are observed
between the initial station occupations and the requisite reoccupation. For example, the rover receiver
occupies Station A for the first 5 minutes and tracks satellites 6, 9, 11, 12, and 13; then 1 hour later,
during the second occupation of Station A, the rover receiver tracks satellites 2, 6, 8, 9, and 19. Only
satellites 6 and 9 are common to the two sets, so the data cannot be processed because four common
satellites were not observed between the initial station occupation and the requisite reoccupation.
(3) Mission planning is essential in conducting a successful pseudokinematic survey. Especially
critical is the determination of whether or not common satellite coverage will be present for the desired
period of the survey. During the period of observation, one receiver (the base receiver) must
continuously occupy a known control station.
(4) Pseudokinematic survey satellite data records and resultant baseline-processing methods are
similar to those performed for static GPS-Ss. Since the pseudokinematic technique requires each station
to be occupied for 5 minutes and then reoccupied for 5 minutes about one hour later, this technique is
not suitable when control stations are widely spaced and the transportation between stations within the
allotted time is impractical. Pseudokinematic survey accuracies are similar to kinematic survey
accuracies of a few centimeters.
e. Rapid-Static Surveying. Rapid-static surveying is a combination of stop-and-go kinematic,
pseudokinematic, and static surveying methods. The rover receiver spends only a short time on each
station (loss of lock is allowed between stations) and accuracies are similar to static surveying.
However, rapid-static surveying does not require reobservation of remote stations like pseudokinematic
surveying. The rapid-static technique requires the use of dual-frequency GPS receivers with either cross
correlation, squaring, or any other technique used to compensate for AS.
(1) Rapid-static surveying requires that one receiver be placed over a known control point. A
rover receiver occupies each unknown station for 5 to 20 minutes, depending on the number of satellites
and their geometry. Because most receiver operations are manufacturer specific, following the
manufacturers' guidelines and procedures is important.