
Introduction
15
Intr
od
ucti
on
In the kinematic data collection mode, the GPS receiver systems simultaneously collect raw
data from all available satellites while a receiver is moving. In most cases, one GPS receiver
system is located on a known point serving as a base station collecting data at that location for
the duration of the survey. Additional GPS receiver systems are used to locate linear objects
such as roads or collect data in a linear fashion for developing topographic elevation data. The
recording interval should be set to collect the amount of data needed relative to the speed of
travel. A recording interval too long will result in insufficient data. A recording interval too
short will result in too much data. After data collection is complete, data is downloaded form
the GPS receivers to an office computer for post-processing using the Ashtech Solutions
software. The post-processing activity computes positions of all observed points relative to
one or more fixed point positions. The kinematic data collection method is best used for
delineating linear type features such as roads, fences, lakes, etc.
Navigating with ProMark2
The ProMark2 includes a wide range of navigational capabilities that you will find useful in
your day-to-day surveying operations. Two useful navigation features are:
•
The street database and map screen can be utilized to help you find a project site.
•
The ProMark2 serves as an excellent reconnaissance tool. You can enter the known
coordinates of the feature you wish to recon as a waypoint, and use ProMark2 to
navigate to within 3 meters (10 feet) of the feature in the field. Be sure to select the
correct map datum and coordinate system (use the user-defined feature to define State
Plane grid zones).
ProMark2 includes the capability to utilize the Wide Area Augmentation System (WAAS) and
the European Geostationary Navigation Overlay System (EGNOS) to provide improved
positioning accuracy. These systems calculate errors in the GPS signal, then transmit
correction messages to capable GPS receivers. Typical accuracy with WAAS augmentation is
three meters, although this accuracy can be degraded by multipath reflections and poor satellite
geometry. More information on WAAS is available at the FAA web site http://gps.faa.gov/
Programs/WAAS/waas.htm. More information on EGNOS is available at http://www.esa.int/
EGNOS/.
For details on how to utilize your ProMark2 receiver for navigation, refer to the
MAP330 User
Manual
.
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