Raymarine GPS navigation GPS Receiver User Manual


 
3.10.4.3 Averaging for Loran
Gn the
LORAN AVERAGING
menu we can select
1
AVERAGING
LORAN
1
averaging periods for the Loran L/L readouts and
Ln
POSITION.
*
one for the Speed readouts. Averaging periods of
=lyBllm
SHORT, MEDIUM, LONG, canbeselected.
SPEED
)
imlaLQ6
*
Press the
[
wL
POSITION
[
softkey
repeatedly to
mssaEulmm
scroll the selections for the position readout. Press
thdWisoi?key
repeatedly to scroll the selections for the Speed readout.
“SHORT”-
Shortest averaging, quickest response, slightly erratic readings.
“MEDIUM”-Gives smooth readings with more response.
“LONG’‘-Longest averaging period. Gives smoothest readings.
Generally for Loran , For L/L Short or Medium averaging is recommended.
For Speed, Medium or Long is recommended.
When correct, presslCLEARpo return to the Main Menu Directory.
3.10.5 NAV Setups
-
GPS
This section covers the NAV SETUP menus that are particular to GPS
operation. The
COURSE/BEARINGS
menu of the
NAV SETUPS
menu happens
to have the same operations for both Loran and GPS. The operations for
selecting magnetic bearings were covered in section 3.10.4.1. However, for
GPS operations, the
POSITION CORR
.
and
AVER
A
GI
N
G
menus are unique to
GPS and are discussed in the following paragraphs.
3.10.5.1 Position Corrections
-
GPS
In the NAV 398 there are actually three forms of correction available in the
GPS mode. They are:
l Geodetic datum
l Manual L/L correction
l Manual TD correction
When the GPS sensor converts the ranging measurements from the satellites
into Lat/Lon coordinates it uses a mathematical formula (or datum) to arrive
at the L/L solution. In preparing charts or maps, cartographers also rely on a
particular mathematical formula or geodetic datum (scaling system)on which
to calibrate the Latitude/Longitude coordinate structure of the charts. The
type of datumused to make the chart is normally listed on the chart in the
table area.
OPERATION 3-52