400m Aquadopp 3D current meter
The most versatile ocean current meter available
The Aquadopp is probably the most versatile single-point current meter
on the market. It is cost-effective, robust and has a wide range of
applications. The system electronics integrates accurate Doppler velocity
measurements with standard sensors such as temperature, pressure, tilt, and
compass. It is low maintenance, has no moving parts, requires no recalibration,
and has no zero-point drift over time. The instrument can be used in real-time
applications but also comes standard with an internal recorder, batteries and a
highly sophisticated power management that makes it the system of choice for
self-contained deployments.
The Aquadopp includes a complete suite of Windows® software for real-time
data collection and for planning and control of a self-contained deployment. It
is also designed to be integrated with third party controllers using the
RS232/RS422 interface (binary or ASCII), analog outputs, or from a Windows®
computer using ActiveX controls.
Applications
The flexible transducer design is the key to the wide range of Aquadopp
applications. Instead of using machined parts, the sensor head is molded to
allow the transducer beams to point in any way imaginable. New configurations
are made continually and some of the more common ones can be downloaded
here (PDF).
- The most common
Aquadopp application is classical
in-line mooring use, where one or more
instruments are mounted on a rope or
cable that stretches from the bottom to
a subsurface float. In some cases, the
instrument is clamped to the rope, in others the
instrument is mounted in the Aquafin, which is bolted
into the mooring line. Typical unique reasons for using the Aquadopp in mooring
lines is the use of the diagnostic mode, the large
number of auxiliary parameters that are collected (acoustic signal strength,
tilt, compass, etc) and the choice of all-plastic and titanium materials in the
design. The variable power output makes it is possible to get longer deployment
times in waters with high scattering levels.
- The Aquadopp can be combined with other sensors, such as Valeport or
MicroCAT CT sensors to include conductivity and with an OBS to measure turbidity
simultaneously. More on this can be found here.
- Many Aquadopps are fixed mounted, either on surface buoys, on pilings, or on
bottom frames. The main challenge is then to ensure that the measurements are
undisturbed by the mounting structure. In these cases, the programmable blanking
and the flexible transducers
configuration (PDF brochure) is a huge advantage since and there is – for
every mounting structure – a corresponding transducer configuration that allows
high quality measurements to be gathered.
- In channels, rivers, and in harbors, the Aquadopp can be side-mounted on the
wall to avoid sedimentation on the sensor head. The acoustic beams are then
projected horizontally into the flow. In this case, the currents can be measured
as far as 5m from the mounting point and the instrument operates as a 2D sensor,
measuring only the two horizontal components.
- Finally, the Aquadopp can measure wave height, period, and direction using
what is commonly is referred to as PUV processing. This means that the 2D
velocity (U and V) is measured at 1 Hz intervals along with the pressure sensor
(P) and later processed with the Nortek
WaveExtract software or Matlab routines
that can be freely downloaded
from the WEB. As a wave sensor, the Aquadopp requires extra memory, but it
is clearly the most cost-effective PUV instrument on market.
Nortek shipped the first Aquadopps in 1998. Today, it is used by scientists
and engineers at well-known oceanographic institutions in most large countries
throughout the world. Please contact NortekUSA for a
detailed customer reference list.
Diagnostic Mode
In addition to the regular data collection, the Aquadopp can be set to
collect data at 1Hz for a specified duration and at user specified intervals.
This diagnostic mode is a unique feature for the Aquadopp. This mode was
originally introduced to learn more about mooring motion, but it quickly proved
popular also for wave data collection.
Key functions
(Detailed specifications are provided in the
PDF brochure)
Recorder Parameters (standard):
- 3D Velocity (East/North Up or X/Y/Z or Beam 1/2/3)
- Acoustic signal strength (Beam 1/2/3)
- Compass
- Tilt
- Temperature
- Pressure
- Battery voltage
- Status code
- Error code
In diagnostic mode, all the above parameters are recorded.
Power:
- Internal battery or external DC source. AC/DC converter comes standard with the Aquadopp
External Interface:
- Two analog input channels (0–5V) can be powered and read by the Aquadopp and
integrated into the standard data structure
Data communication:
- I/O: RS232 or RS422 at baud rates of 300 to 115200. Binary and ASCII
- Analog outputs: (3 velocity components)
- User control: Handled via WIN32 software or ActiveX components
Data Recording:
- Capacity: 9 MB, upgradable with 24 MB, 76 MB or 152 MB extra boards
Mechanical:
- Delrin housing, epoxy molded parts, titanium screws
- Weight in air is about 3.5 kg, in water approximately neutral
Options:
- Non-standard range for pressure range
- Increased recorder size
- External battery housing
- Internal wiring harness for a variety of communication protocols
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