Coordinate System : Selections are
TD | : Loran TD |
UTM | : Universal Transverse Mercator Grid |
dddmmm.mm : Degrees minutes and hundredths of minutes ddd mm.mmm : Degrees minutes and thousands of minutes
ddd mm.sss : Degrees Minutes and Seconds (default)
The Loran TD selection allows the chartplotter to be set up so the user can enter in LORAN TD’s directly into the GPS chartplotter. After the TD’s have been entered, and the user changes to ddd mm.sss (Degrees Minutes and seconds) the TD’s will be converted to Lat / Lon coordinates.
To use the TD coordinate system the user must setup the Chain and Pair information of the TD’s. If you do not know this information, refer to paper charts that show the chain and pair information.
ASF1/2 | : Additional Secondary phase Factor (TD Coordinates System) |
| Correction to TD1/2 values which can be inserted by the user. |
Alter | : Alternate Solution (TD Coordinates System) |
| Parameter selected by the user that is applyed in the conversion of TD values to |
| geographical coordinates Lat/Lon. It defines which of the two possible solutions can be |
| used. |
Map Orientation Resolution: Sets the angle the vessel has to change before the chart is redrawn. The default setting is 30 degrees. Example: if the vessel is heading 000T at a speed of 25 Knots, the display will redraw:
| a. In home mode the chartplotter centers the location of the vessel in the center of |
| the display. To keep the vessel in the center of the display the chartplotter will |
| occasionally redraw. |
| b. If the vessel changes course greater than 330T or more than 30T the chart will be |
| redrawn. |
Map Datum | : Allows selection of Map Datums. The default Datum is WGS84 as |
| has been compiled using the WGS84 Datum. |
Static Navigation | : Sets up a threshold for the speed. When the speed received from the positioning device |
| is under that threshold, the chartplotter displays zero. The default setting is 0.9 Kts. |
11.2COMPASS
The Plotter computes compass direction from the constellation of GPS Satellites. For the chartplotter to compute direction the vessel must be moving through the water. This menu allows the chartplotter to customize the following selections:
Bearings : Selects between True and Magnetic. When Magnetic bearings is enabled, the chartplotter applies the selected Magnetic Variation (Auto or Manual, see next paragraph) to compute True bearing.
Variation : Allows the user to select Auto or Manual. When Auto mode is selected the chartplotter computes the offset by the current GPS fixed location. Manual mode allows the user to enter in a magnetic variation that is applied in the True conversion.
Calibration : This function allows a user to enter in the offset for areas that the vessel may cruise instead of entering in a manual offset for one location. This offset is useful for cruising vessels or vessels that travel internationally often.
Figure 11.2 - Compass Table
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| GPS chartplotters |
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