Furuno GP-3500F - Manual (Page 132)

9. CUSTOMIZING YOUR UNIT
9-18
SPEED SMOOTHING
During position fixing, ship’s velocity (speed) 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 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.
SPEED AVERAGING (INT)
Calculation of ETA and TTG 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
the setting accordingly if calculation error occurs.
SPEED AVERAGING (EXT)
Speed averaging for the ship’s speed data received from external equipment in
NMEA format.
LATITUDE OFFSET, LONGITUDE OFFSET
GPS-generated position may be off by some seconds because of various factors.
In this case, you can apply an offset to GPS position to refine position accuracy.
Calculate the error on a nautical chart.
1. Rotate the [ENTER] knob to select LATITUDE OFFSET or LONGITUDE
OFFSET.
2. Press the numeric keys to enter the error value.
3. To switch North and South (East and West), press the [CURSOR ON/OFF]
key.
4. Press the [ENTER] knob.
The L/L offset icon ( L
L
) appears at the bottom of the PLOTTER (or PILOT)
display.
DISABLE SATELLITE
Every GPS satellite is broadcasting abnormal satellite number(s) in its 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.