ashtech HDS800, Reference Manual

Page: 38 / 678

22
Receiver Description
ensure electrical connection of the battery to the
HDS800.
GNSS Antenna Setup for Heading Measurements
Choosing the
Baseline Length
In theory, the baseline length (i.e. the horizontal distance
between the phase centers of the two GNSS antennas used,
also called antenna separation) can be set between
50 centimeters and 1,000 meters.
In practice, you will choose the baseline length taking into
account the level of expected accuracy as well as the various
installation constraints in the vehicle.
Elevation Offset
Ideally, the two antennas should be installed at the same
elevation. You may however be facing some installation
constraints on your vehicle compelling you to install the
antennas at different elevations. If that is the case, this is
how you should calculate the elevation offset between the two
antennas after measuring the elevation deviation and the
baseline length. The sign of the elevation offset is also
provided on the diagram below (elevation offset positive if
Antenna #1 is higher than Antenna #2, negative if lower).
The elevation offset should not be greater than 45 degrees (or
less than -45 degrees)
, or the receiver will consider the
antenna setup to be invalid and so will not deliver any
heading, roll or pitch measurements.
Baseline length
Baseline Length (m)
Elevation Deviation (m)
Elev
ation
De
v
ia
ti
o
n
Antenna #2
Antenna #1
Elevation Offset (°)
Elevation Offset (°)
=
arcsin
[+]
[-]