Technical data

30 Post-Process GPS Surveying
Determine if the GPS receiver is observing satellites and storing raw data.
This can be accomplished by either using the field application software
running on the handheld computer or the interface on the receiver.
Your Z-Xtreme receiver is now collecting static data. No further interaction
with the system is required for the duration of data collection at this location.
Continue data collection until it is determined that enough data has been
collected to precisely position this point. The amount of data required is
dependent on a number of factors including the quality of the satellite
geometry (PDOP), existence or lack of obstructions, vector length (distance
between this GPS receiver and others collecting data simultaneously),
whether single or dual-frequency receivers are being used, etc. A
conservative occupation time for the Z-Xtreme receiver is 10 minutes plus 1
minute for very kilometer of vector length. For example, if three receivers are
collecting data simultaneously and the longest vector being observed is
approximately five kilometers, observation time would be 15 minutes for each
receiver. This is a conservative observation time. An optimistic observation
time would be 5 minutes plus 1 minute for very kilometer of vector length.
This would result in a 10-minute observation for a five-kilometer vector. If
obstructions exist at the location of any point being surveyed at any given
time, observation times should be increased. Experience will give you the
ability to take in all the factors and determine an appropriate observation time
for any given situation.
Once data collection is completed at this location, the Z-Xtreme receiver
system can be moved to the next location for another data collection session.
Figure 4.5 shows what the Z-Xtreme system should look like when configured
for static GPS surveying.
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