Furuno GP-39 - Page 53

7. OTHER FUNCTIONS
7-3
Rhumb line: This method calculates the range and bearing between two points drawn
on a nautical chart. Since the bearing is kept constant it is ideal for short-range navi-
gation.
Great circle: This course line is the shortest course between two points on the surface
of the earth, like stretching a piece of string between two points on earth. Frequent
bearing changes are required to navigate by this method. For long-range navigation,
divide the Great Circle route into several routes, and navigate each route by Rhumb
Line.
Smooth Position
When the receiving condition is unfavorable, the GPS fix may change randomly, even
if the boat is at a stop in water. This change can be reduced by smoothing the raw
GPS fixes. The setting range is from 0 (no smoothing) to 999 seconds. The higher the
setting the more smoothed the raw data, however too high a setting slows response
time. This is especially noticeable at high boat speeds. “0” is the normal setting; in-
crease the setting if the GPS fix changes randomly.
Smooth S/C (speed/course)
During position fixing, your boat’s velocity (and course) is directly measured by receiv-
ing GPS satellite signals. The raw velocity data may change randomly depending on
receiving conditions and other factors. You can reduce this random variation by in-
creasing the smoothing. Similar to 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. The setting range is
from 0 (no smoothing) to 9999 seconds.
Lat Offset, Lon Offset
If there is the error between the positions shown on your equipment and chart when
docking at a pier, you can apply an offset to latitude and longitude position. Mark the
own ship’s position on the chart to calculate the error with latitude and longitude, then
enter the values.
Disable SV (satellite)
Every GPS satellite is broadcasting abnormal satellite number(s) in its Almanac,
which contains general orbital data about all GPS satellites. Using this information, the
GPS receiver automatically eliminates any malfunctioning satellite from the GPS sat-
ellite schedule. However, the Almanac sometimes may not contain all of the available
information. You can disable an inoperative satellite manually. Enter satellite numbers
(max. three satellites) in two digits.
SV ELV (satellite elevation)
Set the minimum elevation of satellites to use to fix position.
Roll Over
Set the year when the roll over occur. The GP-39 will automatically turns off and on to
reset the satellite observation.