User's Manual

SPSx50 Modular GPS Receiver User Guide 37
Setup Guidelines 4
Rover receiver setup guidelines
For good rover operation, observe the following setup guidelines:
• Place the GPS antenna in a location that has a clear line of sight to the sky in all
directions. Do not place the antenna near vertical obstructions such as
buildings, deep cuttings, site vehicles, towers, or tree canopy. GPS rovers and the
base station receive the same satellite signals from the same satellites: if you
obscure the signals at times, the system will be unable to provide RTK Fixed
positions.
• Place the GPS and radio antennas as high as possible to minimize multipath
from the surrounding area. The receiver must have a clear line of sight to the sky
at all times during operation.
• GPS satellites are constantly moving. Because you cannot measure at a specific
location now does not mean that you will not be able to measure there later,
when satellite coverage or location improves. Use GPS planning software to
identify the daily best and worst satellite coverage times for your location, and
then choose measurement times that coincide with optimal GPS performance.
This is especially important when operating in the worst GPS locations.
• The SPS850 Extreme and SPS880 Extreme GPS receivers have the ability to track
the GPS modernization signals L2C and L5, and the GLONASS satellite
constellation. These signals help you to get positions at the worst times of the
day and in the worst GPS locations, but do not guarantee that you will.
• To get a fixed position solution with centimeter accuracy, initialize the rover
receiver. For initialization to take place, the receiver must track at least five
satellites that the base station is also tracking.
• To maintain a fixed position solution, the rover must continuously track at least
four satellites that the base station is also tracking. The radio link between base
and rover receivers must also be maintained.
• Loss of the satellite signals or loss of the radio link results in a loss of centimeter
position accuracy. From Fixed, the receiver changes to Float or Autonomous
mode:
– In Float mode, the rover has connection to the base station through a radio,
but has not yet initialized.
– In Autonomous mode, the rover has lost radio contact with the base
station receiver, and is working by itself with the available GPS signals.
• On a vehicle or marine vessel, place the GPS antenna in a location as free from
shock and vibration as possible. For the modular receivers, a single magnetic
mount is normally sufficient to hold the antenna in a suitable location, whereas
for the larger smart antenna, a triple magnetic mount is normally
recommended. Alternatively, a 5/8 thread bolt in a suitable location on the roof
bars, or a door mounted pole bracket is a good option.