DVL
18
© 2017 Nortek AS
6
Practical Elements of Operation
6.1
Start and Stop
The DVL retains both its configuration and mode of operation when power is removed. This means
that if the DVL was actively measuring when power was removed it will recommence measurement
using the exact same configuration when powered up again. If the DVL was in command mode when
power was removed it will enter command mode again when powered up. The various modes of
operation are described in the DVL Integrator's Guide.
When the DVL is configured from the instrument web page it will generally be measuring and
outputting data all the time, except for the short time when a new configuration is applied. When
configured manually or through the serial interface, the measurement must be started manually after
the reconfiguration. Once started, the DVL will stay in measurement mode until it is explicitly
stopped. This is also true through power cycles as explained above.
one may note that when the DVL starts in measurement mode During a power up sequence, there is
a short (1-2 second) period when the DVL stops pinging to evaluate its network state.
6.2
Coordinate System
BEAM
: Bottom track: The reported velocities are positive when the motion is towards the transducer
.
Current profile: The reported velocities are positive when the motion is away from the transducer.
XYZ
: Cartesian coordinate system. A positive velocity in the X-direction goes in the direction of the X-
axis arrow. Use the right-hand-rule to remember the notation conventions for vectors. Use the first
(index) finger to point in the direction of positive X-axis and the second (middle) finger to point in the
direction of positive Y. The positive Z-axis will then be in the direction that the thumb points.
DVL beam num bering and axes convention. Note that positive Z is pointing
out of the page.
The coordinate system definitions differ between DVL manufacturers. The end user does not need to
take any special consideration of the coordinate system. The correct coordinate system is dictated
by the selection of which data format is used. This means the selection of the correct coordinate
system and all necessary conversions are handled by the Nortek DVL.
The only matter which requires attention is that the X direction is oriented in the vehicles forward
axis. Rotational offsets may be applied to the DVL within the Mounting Angle parameter. The angle
