User's Manual Part 2

Operator Manual
2−98
3748DOC020102 Edition: 14.JAN.2005
2.4.12 Reference target ON/OFF
The reference target feature tracks a fixed target (zero speed) to correct your
own ship’s course and speed errors caused by set, drift, speed log, gyro errors,
or other factors.
The NSC Radar can support this by accepting one echo that the user knows is
geostationary. Radar, after 2 minutes, accurately calculates own ship ground
velocity until the track is lost or a new echo chosen. ARPA is best with water
velocity, so this feature was mostly used to stabilize maps and work up the best
Dead Reckoning (DR) position possible.
Use of Reference Target is not necessary when GPS is available.
If Reference Target work is preferred, GPS must be deselected.
The sequence:
The desired target must be acquired at first.
step 1 opens the ARPA INFO
step 2 selects the desired target (must be a fixed target),
the SHOW symbol indicates the target
step 3 opens the ARPA MENU
step 4 select REF TGT OFF/ON
the SHOW symbol changes to the REFERENCE TARGET
symbol.