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MAINTENANCE
No Differential corrections
The possible reason for a white box for differential correction indication (DIF) could be one of the following:
•No differential corrections are input through terminal port P205 or P206 on the Processing unit. If differential corrections are input through one of these terminal ports, check that the parameters are properly set up in the Display unit setup menu Diff. input, see Differential corrections, page 26.
•You can be out of range to a radio reference station and the differential corrections are therefore missing. If the reference station is too far away or it is in the shadow of geographical obstructions or other equipment on board, reception may be unreliable or missing. Pressing the INFO button and the display GPS Information shows the identification number of the reference stations connected to the HS50.
•The reference station can be out of function. Check the status of the reference station with the authorities responsible for it, or consult your nearest Simrad dealer for assistance.
Invalid Heading
The possible problem can be one of the following:
•The number of GPS satellites the Sensor unit is able to see is too few. Press the NAV2/POS button until the Skyplot view appears. Check that at least four satellites are available and that the PDOP value is less than 6. Refer Satellite Skyplot display, page 37. Check also the number of common satellites seen by the two GPS antennas by pressing the INFO button and looking at the value for Common sat. in the advanced heading information display as shown in page 38. The number of common satellites have to be two or higher to determine a heading.
If one of the criteria's above is not fulfilled, the mounting location of the Sensor unit may not be suitable or there may be an obstruction between the Sensor unit and the GPS satellites. Check the mounting location and consider relocation according to Location of the unit, page 10.
If it is still not working after checking the above items, consult your nearest Simrad dealer for assistance.
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