Raymarine GPS navigation Operation Manual page 68

Manual Lat/Lon Corrections
Although its not very likely that you will choose to correct your GPS L/L
position with any type of manual corrections, the means to do so is included
in the NAV 398 menus. Manual corrections would not be efficient because
the variable errors introduced by the "selective availability" mode to the GPS
satellites negates such fine calibration attempts. GPS fix improvements are
much more likely to occur when the differential Beacon receiver is providing
dynamic corrections to the GPS sensor.
However, to "calibrate" your GPS to the NAVigation charts by using fixed.
correction factors added or subtracted to Lat/Lon readouts use theU/L
correction procedure for loran operation described in paragraph 3.13.2.4. to
determine the needed correction values. Please refer to the description in that
section for further details.
Press thdrd
by a reverse block.
Type the numbers of the Lat correction value
and press -1 . The N/S prompt appears.
Use the softkey, if necessary, to set the desired
direction. Then press//l.
Now type the digits for the Longitude correc-
tion and press -1. The E/W prompt now
appears. Use the softkey again to set the correct
direction, if necessary. Then press the[ENTER
key to finish inputing the correction.
The L/L position correction that is entered for
GPS is only used for GPS mode. If a L/L cor-
rection is made for the loran sensor, that correc-
tion value is only used for the loran.
Correction for GPS TDs
When thepq key is pressed on the
menu appears. The first softkey/rTiD)can
the TD readouts that are converted from the GPS L/L coordinates. Essentially
this menu entry functions in the same manner as the TD corrections for Loran
already discussed in section 3.13.2.3. Please refer again to the instructions
provided in that section.
GEODETIC SYSTEM I)
. GPS menu the GPS2
1
POSITION CORR
be used to input some offsets to
OPERATION 3-55
N 00. 00'
I )