User Guide

9
As soon as GPS signal is acquired and tracked,
the HI-204 III -USB will transmit valid navigation information
through its serial interface. The navigation data contains
following information:
• Receiver position in latitude, longitude, and altitude
• Receiver velocity
• Time
• DOP error-magnification factor
• GPS signal tracking status
The HI-204 III -USB will perform 3D navigation when four or
more satellites are tracked. When three or fewer satellites
are tracked, altitude-hold is enabled using the last
computed altitude and 2D navigation mode is entered.
With signal blockage or rising and setting of the satellites,
where a change in satellite constellation used for position fix
occurred, large position error may result. The HI-204
III -USB
incorporates a proprietary algorithm to compensate the
effect of satellite constellation change, and maintains an
accurate smooth estimate of the receiver position, velocity,
and heading.