NorthStar 961 Reference Manual page 35

Differential GPS (DGPS) is a
technique for correcting basic
GPS position data by
receiving additional radio
signals to increase its
accuracy.
Introducing the
chart screen's menu
961/962 Operations and Reference Manual, Rev. A
The zoom number in the chart-scale box changes with each
press of the IN or OUT key.
Distance scale bar
On the left-hand side of the CHART screen is a vertical ruler
with alternating red and blue sections. The primary purpose of
the ruler is to provide an approximate scale of distances on the
CHART screen. On the DISPLAY SETUP screen, you can set
the distance units to statute miles (mi), nautical miles (nm), or
kilometers (km).
DGPS indicator
In the upper left-hand corner of the CHART screen is the word
DGPS, which indicates whether the system is receiving DGPS
corrections to its GPS signals. If corrections aren't being
received, the DGPS indicator won't appear on the screen.
The CHART screen is controlled by six menu keys that are
located in a vertical row to the right of the display screen. Each
of these keys controls a function to its left:
keys
GO TO provides several options to select and navigate to
•
new position coordinates. For details, see "Navigating to a
point" starting on page 1-24.
NEW CHART lets you select a different chart for your
•
vessel's location from the chart database, or display a
basic plotter grid. For details, see "Selecting new charts"
starting on page 4-8. Each time you briefly press NEW
CHART, the 961/962 cycles automatically through all
appropriate charts. When you press and hold the key,
more chart-selection options are displayed.
OVERLAY provides the option to superimpose graphic
•
displays of tide data, currents, and a small echo sounder
picture (if the 490 is installed) onto the CHART screen. For
more information about overlaying graphic displays, see
"Alarms, TideTrack, Currents, and Echo Sounding" starting
on page 12-1.
Chapter 1 - Quick Start
Page 1-21