Post-Processing Gps Data - Thales Z-Max Operation And Application Manual

data is downloaded to a computer for post-processing. Post-processing the data
will compute vectors to determine the position of all points observed.
Static data collection produces the most accurate and reliable results due to the
amount of data collected during each observation. The disadvantage is in
productivity. Long observations at each point reduce the number of points that
can be collected in a day.
Kinematic Data Collection
With kinematic data collection, one of the GPS receivers in the system is
designated as the base and remains stationary throughout the survey. All
surveyed points are determined relative to the base. Once operational, the base
system simply collects and stores raw data from all the available satellites.
The other GPS receiver(s) is designated as the rover. The operator of the rover
system moves around the project site collecting data on points or items of
interest. While moving around the project site, the operator will stop for a short
period of time to position a specific item, such as a manhole. Occupation time of
the point can range from 6 seconds to 60 seconds. Once finished, the operator
moves on the next point. Also, the operator can position linear features, such as
the centerline of a road, by simply walking along the centerline and instructing the
rover system to store a position every five seconds, for example. The result is a
trail of points defining the centerline.
To facilitate the mobility required to utilize the kinematic method of data collection,
the rover system is designed to be man-portable, usually carried either in a
backpack or on a survey pole. The user interfaces with the rover system through
a handheld computer/data collector, and the antenna is mounted on a portable
survey pole.
While it is obvious that kinematic data collection has the advantage of high
productivity, there are disadvantages. Accuracies are not as good as with static
data collection. In addition, the rover system must maintain lock on GPS satellites
as it moves around the project area. Loss of lock requires the user to re-initialize
the receiver.

Post-processing GPS Data

Post-process GPS surveying requires that the collected GPS data be processed after
the data is collected to obtain results. Processing is accomplished by the GNSS
Studio software included with the system. Processing normally occurs on a PC back
at the office, but can also be performed on a laptop in the field.
98 Z-Max Surveying System Operation and Applications Manual