Furuno GP-1640, Operator'S Manual

Page: 63 / 96

10-5
POS SMOOTHING
When the DOP or receiving condition is
unfavorable, the GPS fix may change greatly,
even if the vessel is dead in water. This
change can be reduced by smoothing the raw
GPS fixes. A setting between 000 to 999 is
available. The higher setting the more
smoothed the raw data, however too high a
setting shows response time to change in
latitude and longitude. This is especially
noticeable at high ship’s speeds. 000 is the
normal setting; increase the setting if the GPS
fix changes greatly.
SPD/CSE SMOOTHING
During position fixing, ship’s velocity (speed
and course) is directly measured by receiving
GPS satellite signals. The raw velocity data
may change randomly depending on receiving
conditions and other factors. You can reduce
this random variation by increasing the
smoothing. Like with latitude and longitude
smoothing, the higher the speed and course
smoothing the more smoothed the raw data. If
the setting is too high, however, the response
to speed and course change slows. For no
smoothing, enter all zeroes. The default setting
is 5 (sec).
GPS SPEED AVE
Calculation of ETA is based on average ship’s
speed over a given period. If the period is too
long or too short calculation error will result.
Change this setting if calculation error occurs.
The default setting is 60 seconds, which is
suitable for most conditions.
LAT OFFSET, LON OFFSET
GPS generated position may be off by some
seconds due to GPS signal variation. You may
apply an offset to GPS position to refine
position accuracy.
DISABLE SATELLITE
Every GPS satellite is broadcasting abnormal
satellite number(s) in it’s Almanac, which
contains general orbital data about all GPS
satellites, including those which are
malfunctioning. Using this information, the
GPS receiver automatically eliminates any
malfunctioning satellite from the GPS satellite
schedule. However, the Almanac sometimes
may not contain this information. If you hear
about a malfunctioning satellite from another
source, you can disable it manually. Enter
satellite number (max. 3 satellites) in two digits
and press the ENTER soft key or the [ENTER]
key.
LATITUDE, LONGITUDE
The default latitude and longitude position is
San Francisco, USA (38.00.00’N,
123.00.000’W). When the unit is turned on first
the first time it begins searching for its actual
position. To lessen the time required to find
position, you may enter your position manually.
To switch from North to South and vice versa,
use the N<-->S soft key, and to switch from
West to East and vice versa, use the soft key
W<-->E. Finally, press the ENTER soft key or
the [ENTER] key.
ANT. HEIGHT
Enter the height of the antenna unit above sea
surface. For further details refer to the
installation manual. The default setting is 5 m.
FIX MODE
You can choose the position-fixing mode from
2D or 2D/3D. 2D requires three satellites to fix
position; 2D/3D requires three or four satellites,
whichever is available. The default setting is
2D/3D.