GPS Receiver User Guide

Surveying with ProMark2 61
Surveying with ProMark2
The rover antenna is transferred to the rover pole after initialization is completed, Figure 3.28.
Kinematic Initialization
Overview
A unique aspect of the kinematic mode of data collection is the requirement to initialize the
survey. The initialization process is required to produce highly precise positions. Prior to
initialization, data collected by the kinematic rover system will produce positions at a degraded
level of accuracy. The accuracy prior to initialization could be anywhere from 0.15 meters (0.5
ft) to a couple meters (several feet). The initialization process is required to fine-tune the rover
system. Once initialized, the rover system will function at it’s specificed level of accuracy until
initialization is lost.
Let’s devote a few sentences here to the technical aspects of the initialization process. In order
to accomplish centimeter-level positioning with GPS, you must collect enough data to
calculate a set of parameters termed Integer Ambiguities. During the initialization process, you
are collecting the data required to calculate the Integer Ambiguities. Once the integer
ambiguities have been calculated, your current location can be determined very precisely.
Solving for the integer ambiguities is the most time consuming part of GPS data collection.
Once solved, the position of your current location is instantly known. In addition, once you
have calculated the integer ambiguities, they stay fixed as long as you maintain locked on at
least 5 satellites. If you happen to loose lock on satellites due to an obstruction, and go below
the 5 satellite threshold, the integer ambiguities will be lost and must be calculated again, i.e.
you must initialize your kinematic survey again. If you do not, all data collected after loss of
initialization will produce positions at the degraded level of accuracy discussed above. All data
collected prior to loosing the initialization is not affected by your lost of initialization.
ProMark2 supports several methods to initialize your kinematic survey. Each method is
Figure 3.28 Rover Antenna from Initializer Bar to Range Pole