Operation 31
Operation
• Position Mode 2
At least three satellites with elevation equal to or above the position
elevation mask are needed to compute a position. Only the latitude and
the longitude are computed and altitude is always held fixed even if the
receiver is tracking more than three satellites. The receiver stops
computing positions if the number of satellites tracked falls below three.
• Position Mode 3
At least three satellites with elevation equal to or above the position
elevation mask are needed to compute a position. Only the latitude and
longitude are computed, and the altitude is held if only three satellites are
locked. If more than three satellites are used and the HDOP is less than
the specified HDOP mask, all three polar components are computed. If
HDOP is higher than the specified HDOP mask, the G12 automatically
goes into the altitude hold mode. The receiver stops computing positions if
the number of satellites tracked falls below three.
• Point Positioning Mode
The Point Positioning option improves the accuracy of a stand-alone
absolute position of a stationary receiver from about 50 meters to less than
five meters over a period of four hours, and can typically get down to a
couple meters level after ten hours. Point positioning uses an averaging
technique to reduce the effects of Selective Availability (SA) and other
fluctuating errors. Point positioning mode can be set using the
$PASHS,PPO command. Refer to Chapter 3 for details of this command.
The Point Positioning receiver option [T] must be set in the receiver for this
command to work.
Fixed Altitude Modes
Two modes define the altitude setting when the G12 is in altitude hold mode. The
$PASHS,FIX set command (page 67) can be used to select between modes .
• Fixed Altitude Mode 0
The most recent altitude is used. This is either the altitude entered by
using the $PASHS,ALT set command or the one computed when four or
DEFAULT SETTINGS
$PASHS,PMD— Position Mode 1
G12RevD.book Page 31 Tuesday, April 2, 2002 4:33 PM
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