Step 6. Your Rover Receiver May Be Malfunctioning; Rover Computing Position With High Uncertainties; Step 1. Is The Gps Receiver Set To Function As An Rtk Rover; Step 2. Are Base And Rover Tracking At Least 5 Common Satellites - ashtech Z-Xtreme System Manual

d. If not, you will need to perform your survey at another time.
e. Go to step 6) below if the problem is not yet resolved.
2. Move base or rover if sites have satellite obstructions.
a. If your base or rover site have any obstructions above 15° to the horizon,
the obstructions may be blocking essential satellites. If obstructions exist
at the base or rover, more the system to an open area.
Tracking 4 satellites
Go to step 6 below.

Step 6. Your rover receiver may be malfunctioning

Contact your local dealer or Ashtech customer support for assistance.

Rover Computing Position With High Uncertainties

Using the field application software you find that the rover is computing a position but
the uncertainties (HRMS, VRMS) assigned to the position are unacceptably high.
Follow the steps outlined below to troubleshoot this problem.

Step 1. Is the GPS receiver set to function as an RTK rover?

The rover GPS receiver must be set to function in RTK rover mode in order for it com-
pute accurate RTK positions. If not set in RTK rover mode, the receiver will compute
autonomous positions which could contain about 10 meters or more of error. This is
probably the problem if HRMS and VRMS values are in the 10s of meters. Use the
field application software to determine if the rover GPS receiver is set to RTK rover
mode.
Not set to function as RTK rover
Set the rover receiver to RTK rover mode. Use the field application software
to set the receiver to RTK rover mode.
Set to function as RTK rover
Go to step 2 below.

Step 2. Are base and rover tracking at least 5 common satellites?

Although the rover receiver is capable of computing a position with only 4 common
healthy satellites with the base, the rover will not attempt to fix ambiguities unless 5
common healthy satellites are observed. Fixing ambiguities is a required process for
the rover system to compute highly precise RTK positions. Your field application soft-
ware will inform you if you currently have a fixed ambiguity solution or a float ambigu-
86 Real-Time Kinematic Surveying