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Argonaut-DVL Expanded Description
 The demand by the underwater vehicle industry for smaller and more power-efficient
platforms led to the development of SonTek's Argonaut Doppler Velocity Log (DVL).
A previous generation of Doppler sonar equipment was bulky, costly, and required power
at upwards of 50 watts. Based on the popular Argonaut product line, SonTek introduced the
next generation of Doppler velocity logs that are compact, affordable, and consume up to 100
times less power (on the order of 0.2 to 0.5 W while
operating). Whereas a previous generation of underwater vehicles could never consider
using a DVL, there is now a practical alternative in the Argonaut-DVL.
The small size and low power draw is as suitable to small AUVs as it is to work-class
ROVs. This versatile instrument can serve as a navigational instrument, current meter, and
altimeter -- all in one package. Options include an internal flux-gate compass and
a full-ocean depth (6000 m) rated housing.
It is worth noting that as a speed sensor, the Argonaut-DVL measures its speed relative
to a user-programmable cell layer that is located remotely from the vehicle (see below).
This feature allows you to measure ocean current or vehicle speed away from the
contamination caused by the vehicle itself. This is a key advantage of using an
Argonaut Doppler instrument instead of electromagnetic or mechanical current meters.
Furthermore, the Argonaut-DVL does not require calibration or other significant
maintenance, which keeps the long-term operational costs to a minimum.
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Water-tracking information is obtained from a programmable
depth cell area that extends outside the wake field caused by the vehicle's motion. |
Offering bottom-tracking, the Argonaut-DVL uses sophisticated
digital signal processing with 8-bit A-to-D conversion. This assures you of
robust operation over the entire velocity range without having to pre-program or
set velocity range scales.
Argonaut-DVL Models
- The "M" models are available in 1.5-MHz or 3.0-MHz
versions and are housed in a 10.2-cm (4 in.) diameter cylinder that can be made of
either Delrin plastic (600-m pressure rating) or solid titanium (6000-m pressure rating).
Compass/tilt sensors are optional.
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- The "X" models are available in 1.5-MHz,
or 3.0-MHz versions and are housed in a 15.2-cm (6 in.) diameter
cylinder made of Delrin plastic (200-m pressure rating). Compass/tilt sensors are optional.
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Argonaut-DVL Features
- Water-Track / Current Measurement - The Argonaut-DVL continuously
outputs 3D water velocity information in either XYZ coordinates (referenced to the DVL
itself) or East-North-Up coordinates (referenced to Magnetic North). The DVL measures
water velocity from within a user-programmable sampling volume that extends away from the instrument. This is a key advantage over electromagnetic or
mechanical velocity sensors in that the measurement volume is not contaminated by the wake
of the vehicle itself.
Therefore, when the DVL/vehicle is still, the DVL will measure the three-axis current
within the specified range cell. When the DVL/vehicle is in motion, the DVL measures its
relative speed with respect to the water, and any effects of turbulent eddies around the
vehicle or cage can be effectively blanked out by selecting a sampling volume far away
from the vehicle.
- Bottom-Track - Bottom-tracking information and a data quality factor
are continuously output from the DVL. When the DVL's range to the bottom exceeds the
maximum, this is indicated by the data quality factor. The maximum bottom-tracking range
is dependent upon system frequency and local environmental conditions. Generally speaking,
a 3.0-MHz system can be expected to reach 5-8 m; for a 1.5-MHz system, 10-25 m.
- Altimetry - As the DVL is bottom-tracking, it also records the distance
to the bottom for each of the three beams. These three values are then cosine-corrected
and are reported independently and as an average in the data output. Maximum range is
dependent on system frequency (up to 8 m for a 3.0-MHz system; up to 25 m for a
1.5-MHz system). This feature helps reduce vehicle
instrumentation costs as the need for a separate altimeter is not necessary.
- Compass Integration - An internal flux-gate compass can be included
within the DVL housing. This provides for instant changes in heading, pitch, and roll,
which can be compensated for within the DVL's vector averaging algorithm.
- Output Data - The DVL continuously outputs a data stream of 25 parameters that include information about water-track, bottom-track, altimetry, heading,
pitch, roll, temperature, data quality factors, and begin/end points of the water-track cell.
- Power Consumption - The DVL accepts an input voltage of 8-16 VDC
and consumes less than 0.5 W while it is operating. This represents
over an order of magnitude improvement over previous Doppler sonars. Whereas a few years
ago some AUV manufacturers would have never considered the use of a Doppler log because of
the excess battery capacity required on their vehicles, the Argonaut-DVL power
requirements are low enough to place it on almost any platform.
- Maintenance and Calibration - Doppler sonars have no moving parts and
are not subject to drift, so no calibration is required. This is a distinct advantage over
mechanical and electromagnetic meters that require periodic calibration. Additionally,
velocities measured by the DVL are not affected by biological growth on the instrument, as
those effects are cancelled by Snell's Law.
Details about this SonTek/YSI product can be found at:
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