Research Concepts RC4000 - Manual (Page 143)

RC4000 Antenna Controller Chapter 4 Support
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distance from the last position that it generated a navigation solution, the time it takes to generate a
solution may go beyond 4 minutes. When the GPS is powered up, it assumes it is at the same lat/lon as
when it was powered down. It also has stored the ephemeris data it had at that time. While powered
down the GPS’ real time clock will continue to timekeep.
The GPS will not generate a navigation solution if it cannot “see” 4 satellites. Check that the GPS unit has
a clear view of the sky. If parked next to a tall building, even if the GPS has a seemingly clear view of the
sky, the current GPS satellite constellation may be such that too many satellites are masked.
RF Interference. Strong interference from transmitting antennas close to the GPS receiver may also
disrupt the receiver’s ability to “see” satellites. Attempt to turn off transmitting sources (satellite phones,
etc.) close to the GPS antenna to see if that affects the GPS’ performance.
4.4.5 Fluxgate Compass
The interface between the RC4000 and the optional fluxgate compass is via a RS-232 serial port.
NO COMPASS. This message indicates that the compass_present item in the System Components
(3.3.1.2.1) configuration item has been set to 0 indicating that no compass is attached to the RC4000.
No attempt will be made to parse compass data in this state. If a compass is truly attached, set the
compass_present item to 1 or 2. Note that if the compass option was not purchased with the controller,
the compass_present item will not be allowed to be set to a value other than 0.
“*****” in compass data field. The “*****” string in a position where compass data should normally
appear indicates that the RC4000 cannot parse a valid heading string from the compass. Use the
Fluxgate Serial Port Maintenance screen (3.3.2.7) to see if data from the compass is arriving at the
RC4000.
If the heading string within the compass data shows “800.0” instead of a valid heading value (0.0 to
359.9), the compass is reporting that the magnetic field it is sensing is either too high or too low. Usually
this means that another strong magnetic field is close to the compass. Try to relocate the compass away
from any sources of magnetic fields (generators, air conditioners, etc.) Sometimes equipment that
normally doesn’t generate a magnetic field may become magnetized by some event such as a nearby
lighting strike.
COMM ERROR during compass calibration. During a compass calibration procedure, the RC4000
sends commands to the compass and checks for correct replies. The COMM ERROR message
indicates that a) a response from the compass was not received correctly or b) the calibration command
from the RC4000 was not received by the compass. First check communication from the compass as
above. If correct data is coming from the compass, then inspect the wiring to determine if the transmit
(from RC4000 to compass) line is correct.