Maretron DSM570, Руководство пользователя

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Revision 1.8.3 Page 243
Alert Clear Delay
– The distance between the current GPS position and the reference position
must rise above the Inside Radius Alert Clear value for longer than the time in this field in order
for an alert to become inactive.
Latitude
– The latitude of the reference position. This may be typed in as <degrees>:<minutes>
followed by an N or S. If the N or S is missing, North is assumed. Moving the cursor to another
field will reformat the contents of this field.
Longitude
– The longitude of the reference position. This may be typed in as
<degrees>:<minutes> followed by an E or W. If the E or W is missing, East is assumed.
Moving the cursor to another field will reformat the contents of this field.
Get Current Position
– Selecting this line will transfer the current GPS position into the Latitude
and Longitude fields.
8.3.7.9 Trigger Type is Anchor Alert
The Anchor Alert is a special case of the Outside Radius Alert (Section 8.3.7.7). It is used to signal an
alert whenever the vessel moves outside a programmable distance in any direction away from a
reference point (expressed as a longitude and latitude). This alert is useful when the vessel is
anchored or moored and the vessel should not drift outside a perimeter and if it does, an alert is
activated. The point of reference can be selected from the current position or it can be manually
entered.
The Outside Radius Alert and the Anchor Alert are very similar. The Anchor Alert is designed to allow
the input of relatively small radius values and may be displayed graphically through the Anchor Watch
Display (Section 7.1). The radius of the Outside Radius Alert is specified in either Nautical Miles or
Kilometers, while the radius of the Anchor Alert is specified in Feet or Meters.
See Section 8.3.7.7 for details of the configuration of the Anchor Alert.
8.3.7.10 Trigger Type is GPS Quality Alert
The accuracy, or quality, of a position fix provided by a GPS is dependent on the number of satellites
used to compute the position. A position based on less than three satellites is considered a “1D” lock,
three satellites is a “2D” lock, more than three satellites is a “3D” lock, and more than three satellites
with SBAS is a “3D-DGPS” lock. These different locks are indicative of the quality or accuracy of the
given position with 1D having the lowest quality and 3D-DGPS providing the highest quality. The GPS
Quality Alert is used to alert you if the quality of the position falls below a specified quality level.