2665 Series Operation Manual
EZT-2665-8000/6
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21
of
64
The simplest method is to hang the transducer over the side of the vessel. This
method is suitable for the smaller vessel with minimal movement. However, should
the vessel move too much, the transducer can be buffeted to the extent where the
internal compass and pitch & roll sensors cannot compensate for the movement.
Note:
The Compass must be switched
ON
if the transducer is free hanging over the side of the vessel.
5.6
I
S ABSOLUTE POSITIONING OR A RELATIVE POSITIONING REQUIRED
?
A relative position is a position that is relative to a local reference point, typically a
position on a vessel, but can be a beacon that is on the seabed.
An absolute position is a position that conforms to a national or international
geographical system; Easytrak Alpha uses Universal Transverse Mercator (UTM)
referenced to the WGS84 ellipsoid. To have an absolute position, the compass
must be enabled; also either the internal or external GPS receiver must be used
with Easytrak Alpha. Easytrak Alpha then uses the data from the compass and
GPS receiver to derive the absolute position of the target. To preserve accuracy,
DGPS is strongly recommended over standard GPS. The GPS receiver in Easytrak
Alpha is SBAS
6
enabled and automatically selects the appropriate service for the
location.
5.7
W
HAT RANGE IS REQUIRED
?
Select a beacon suitable for the working range. Consult the beacon manufacturer’s
manual for specified working ranges, or contact Applied Acoustics Engineering Ltd.
for advice.
5.8
W
HAT ACCURACY IS REQUIRED
?
To improve accuracy keep ranges as short as possible, make local measurements
of the velocity of sound in water, use manual depth at low depression angles
(shallow water).
Note:
It is strongly recommended that DGPS is used otherwise overall accuracy could be
compromised.
6
Satellite Based Augmentation System
