Rover receiver setup guidelines – Trimble Outdoors SPSX51 User Manual
Page 39
SPSx51 Modular GPS Receivers 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. The
system needs five common satellites to provide RTK positioning.
•
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 at the 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
Trimble Planning software is on the Trimble SPS GPS Receiver CD included with
the receiver. You can also download the Trimble Planning software from the
Trimble website
•
The SPS851/SPS751 can track the GPS L2C modernization signal. Additionally,
the SPS851 can optionally track the GPS L5 modernization signal and some
receivers can also track the GLONASS satellite constellation ( for more
information, see
GPS satellite signal tracking, page 114
). 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. In a dual-satellite constellation
operation, for example, GPS and GLONASS, the receiver must track at least six
satellites.
•
To maintain a fixed position solution, the rover must continuously track at least
four satellites that the base station is also tracking. In a dual-satellite
constellation operation, for example, GPS and GLONASS, the receiver must
track at least five satellites.The radio link between the 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.