Thales Z-Max, Руководство по эксплуатации и применению

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140 Z-Max Surveying System Operation and Applications Manual
1. Initialize on-the-fly
When using a dual-frequency GPS system such as the Z-Max, there is no
requirement that initializations be performed while standing still at one location. It
is possible to initialize your kinematic survey while moving about the project site
(thus the term on-the-fly). Initialization times are about the same as with the static
survey method. The advantage of the on-the-fly method over the static method is
that during the required to initialize, you can be moving about the project site
productively locating points of interest. The post-processing software will use this
data to initialize and, once initialized, will establish precise positions on the points
observed during the initialization time period.
The trick to this method is that you must collect clean data (no loss-of-lock) during
the initialization period, i.e. the first 5-10 minutes of the observation. If loss-of-lock
occurs during the initialization period, you run the risk of not being able to initialize
the segment of data between the start and the loss-of-lock. Any points observed
during this time period will have poor precision. For this reason, this method of
initialization is best left for project sites where obstructions are a minimum.
Consider a scenario where this method of initialization would be useful:
You have a landfill that you need to topographically survey. Since the project
site is a landfill, most of the area has no obstructions with the possible
exception of trees along the perimeter. You set up your base station in an
open area. You then set up your rover system. You turn on the rover system
immediately. As you finish your preparation, the rover system is collecting
data for initialization on some arbitrary location. After two minutes, you are
ready to begin locating topo points. You decide to start at the northeast corner
of the landfill because it is wide open with no obstructions. It takes you
approximately 1 minute to walk to the location of the first topo shot. By this
time, you have already collected 3 minutes of data that will be used towards
your initialization. You begin collecting topo points. In the next 2 minutes, you
have collected 4 topo points without lose-of-lock. By this time, the system has
collected 5 minutes of data, enough to initialize. Without hesitation, you
continue with your survey.
When this data is processed, the kinematic survey will initialize using the data
collected during the start of the survey. Even points collected prior to
initialization will result in precise positions, as long as no loss-of-lock
occurred.
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