Thales Z-Max Operation And Application Manual page 149

1. Determine if point location is suitable for GPS observations
As discussed earlier, obstructions between the GPS antenna and the GPS
satellites interfere with data collection. The best results are obtained while
observing points that have a clear view to the sky. When obstructions are
present, observation times need to increase to obtain the same level of
accuracy. With enough obstructions, it becomes impossible to obtain enough
quality data to determine an accurate position for the point. If the exact
location of the point to be surveyed is flexible, select a location that contains
the least amount of obstructions. If the location is not flexible and is
obstructed, extend the observation time for the point. With a severely
obstructed point, it may be necessary to observe a pair of points offset from
the point of interest. The position of the point of interest can later be
established through conventional means using the offset points. Determining
if a location is suitable for GPS observations is not an exact science but it
benefits from care and common sense. Successes and failures will eventually
give you a feel for the suitability of a location.
2. Connect system components
Connect the system modules together as listed below. Check these
connections to ensure the connectors are seated properly. Refer to the
previous chapter on how to establish these connections.
• GPS Antenna Module
• Power Module
• V-Module
• External power source
Using the handheld computer to configure the receiver for a static survey is
optional, as the receiver can easily be configured and monitored using the
front panel user interface interface of the GPS Receiver Module. If the
handheld device supports Bluetooth it can be used to communicate with the
GPS Receiver Module wirelessly. If the handheld computer does not support
Bluetooth, then a direct cable connection can be used.
3. Position tripod over point to be surveyed
Accurate positioning and leveling of the tripod are critical to an accurate static
survey. The GPS Antenna Module is the data collection point for GPS
observations, i.e. the computed position for the point will be the location of the
GPS antenna. Therefore, it must be precisely positioned over the point to be
surveyed. The two most common mounts for the receiver antenna are a
conventional tripod and a fixed-height GPS tripod (Figure 4.3). Either is sufficient
for the task but the fixed height tripod is recommended since it eliminates the
possibility of incorrectly determining the instrument height of the antenna.
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GPS Receiver Module
GPS Receiver Module
GPS Receiver Module
GPS Receiver Module (if applicable)
Z-Max Surveying System Operation and Applications Manual