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8–1
8. MENU SETTINGS
8.1 GPS Menu
Menu description
Fix mode
Two position fixing modes are available: 2D
and 2/3D. The 2D mode provides two dimen-
sional position fixes (latitude and longitude
only) and is used when three satellites are in
line of sight of the GPS receiver.
The 2/3D mode switches between two and
three dimension position fixing automatically
depending on how many satellites (three or
four) are in light of sight of the GPS receiver.
Disable satellite
Every GPS satellite is broadcasting abnormal
satellite number(s) in the Almanac. Using this
information, the GPS receiver automatically
eliminates any malfunctioning satellite from
the GPS satellite schedule. However, the Al-
manac sometimes may not contain this infor-
mation. You can disable an inoperative
satellite manually on the GPS SETUP menu.
GPS smoothing, position
When the DOP or receiving condition is un-
favorable, 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 0 and 9 is available.
The higher the setting the more smoothed the
raw data, however too high a setting slows
response time to change in latitude and longi-
tude. This is especially noticeable at high
ship’s speeds. "0" is the normal setting; in-
crease the setting if the GPS fix changes
greatly.
GPS smoothing, speed
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 receiv-
ing conditions and other factors. You can re-
duce 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 "0." "5" is suitable for most
conditions.
Speed average
Calculation of ETA and TTG, etc. is based on
average ship’s speed over a given period. The
default setting is one minute.
Geodetic datum
Select the geodetic chart system you are us-
ing. WGS-84 (standard GPS chart system) and
NAD 27 can be directly selected. For other
charts, select "OTHER" and enter chart num-
ber referring to the geodetic chart list in the
Appendix.
Position offset
You may apply an offset to position gener-
ated by the internal GPS receiver, to compen-
sate for difference between GPS position and
chart position.
Time difference
The GPS system uses UTC time. If you would
rather use local time, enter the difference in
hours between local time and UTC. Use the
[+] and [–] keys for times later or earlier than
UTC, respectively.
Position
Enter ship's position when cold starting (no
satellite information in memory) the GPS re-
ceiver, to fix position faster. Accuracy should
be within 10°.