ADP Expanded Description
Contents:1. Introduction
2. ADP System Configurations
3. ADP Standard Features
4. ADP Options
Figure 1. Standard and Mini-ADPs
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Figure 2. ADP Depth Cells
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Figure 3. ViewADP
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The SonTek/YSI ADP (Acoustic Doppler Profiler) is a high-performance current profiler that
is accurate, reliable, and easy to use (Figure 1). The
ADP measures 3D velocity in a user-specified number of depth cells over a range of up to
220 m (Figure 2). The first current profiler designed
specifically for shallow water applications, the ADP has revolutionized the current
profiler market since being introduced in 1994. Our Windows-based ViewADP (Figure 3) post-processing program makes it easy to display and analyze data.
The ADP is available in a wide range of configurations for applications including
real-time current monitoring, detailed current surveys, detailed river surveys (RiverSurveyor System) and long-term autonomous deployments.
The ADP uses our proven Doppler technology to make the most accurate and robust
current measurements possible. With no moving parts, the ADP is highly resistant to
biofouling even in the most challenging environments. The ADP is simple to use,
affordable, and does not require recalibration or factory maintenance.
The ADP uses state-of-the-art transducers and electronics designed to reduce side lobe
interference problems that plague other current profilers. This allows the ADP to make the
near-boundary (surface or bottom) current measurement critical to many shallow water
applications.
The SonTek/YSI ADP is a breakthrough in price and performance for current profilers.
Complete ADP systems are priced competitively with traditional single-point current
meters.
Our ADPs are available in a variety of configurations, and while the SonTek/YSI ADP with
three acoustic transducers is one of our most-recognized products, many ADP users are
unaware that we also offer 2-beam and 4-beam systems for specialized applications (Figure 4).
Figure 4. Typical ADP Beam Configurations
The 2-beam configuration (SL-ADP) is commonly used in a "side-looking"
orientation for horizontal current profiling applications.
Four-beam transducers arranged in a Janus configuration are typically used for
applications where wake contamination of one or more beams is possible, such as lowered
(L-ADP) systems. The fourth beam also gives data-quality information (because of its
redundancy) similar to the standard deviation information we report with our 3-beam
systems.
ADPs can also be configured with the fourth beam in a vertical position for water-level
measurement (for bottom-mounted ADPs) or depth (when used from a moving boat).
Some of the more typical configurations are described here.
2.1. Stand-Alone ADP - Real-Time Current Monitoring
The Stand-Alone ADP is the most popular configuration for real-time current monitoring.
The transducers, receiver, processing electronics, and optional sensors are contained
within a single canister for simple installation and operation (Figure 5). The instrument uses an external power supply and outputs serial data that can be
captured or relayed with a variety of computer, data logger, or telemetry systems.
Figure 5. Stand-Alone ADPs
The Stand-Alone ADP is used extensively for real-time current monitoring in ports,
harbors, rivers, lakes, estuaries, and the near-shore. A single cable (maximum length 1500 m) is used for power and serial communications. An internal recorder is available for
backup data storage. The rugged design provides years of maintenance-free operation in the
most hostile environments.
2.2. Mini-ADP System - Real-Time Current Monitoring
The Mini-ADP is designed for applications where small size is critical. The
sensor contains the acoustic transducers, receiver electronics, and optional sensors,
while the processing electronics are located in a separate housing (Figure 6). The system operates from external power and outputs
serial data for integration with a variety of computer, data logger, or telemetry systems.
Figure 6. Mini-ADP
The Mini-ADP is ideal for bottom-tracking applications (e.g.,
CurrentSurveyor,
RiverSurveyor, RiverCat) as the
transducer head is easily mounted over the side of a boat (1.5 and 3.0 MHz
Systems only).
2.3. 2D ADP - Horizontal Current Profiling
All ADPs are available as 2D systems for horizontal current profiling (Figure 7). These systems are commonly used for current monitoring
from underwater structures such as channel walls and bridge/pier pilings. They can also be
used for 2D vertical profiling in narrow channels to avoid interference with channel
walls. ADP 2D systems are available in the same frequency and system configurations as the
standard 3D profilers.
Figure 7. 2D ADP
2.4. Autonomous ADP - External Battery Housing
Autonomous ADP deployments use battery power and internal recording for self-contained
operation with deployment periods up to one year or more. The most popular configuration
uses an external battery housing (with 3 battery packs) connected to the Stand-Alone ADP
with internal recorder (Figure 8). Common applications include
long-term bottom mounted installations in ports, estuaries, rivers, lakes, and the
near-shore. Trawl resistant bottom frames are available.
Figure 8. Autonomous ADP (standard and mini)
with External Battery Housing
The Autonomous ADP supports highly flexible sampling strategies to meet a variety of
measurement needs and deployment lengths. These include reduced duty cycle operation and
burst sampling to optimize data storage and battery life. Both alkaline and lithium
battery packs are available.
The standard features available with ADPs are described below.
3.1. Acoustic Frequency
The most important choice when selecting an ADP is acoustic frequency. This determines
the range of the ADP and the resolution within the profile. Lower frequencies giver longer
ranges, while higher frequencies give shorter range with higher resolution. The ADP is
available in five standard frequencies -- 0.25, 0.5, 1.0, 1.5, and 3.0 MHz.
3.2. Programmable Sampling Parameters
All parameters relating to ADP operation can be easily selected by the user. These
include depth cell size, number of depth cells, and averaging time for each profile. The
ADP also supports a range of flexible sampling strategies for reduced duty cycle operation
and burst sampling.
3.3. Diagnostic Parameters
All ADPs record extensive diagnostic parameters with each profile. These include signal
strength (to determine the effective profile range and estimate suspended sediment
concentration) and standard deviation of velocity data (a direct measure of the accuracy
of velocity data).
3.4. Temperature Sensor
All ADPs include a temperature sensor to automatically compensate for changes in sound
speed. The ADP uses sound speed to convert the measured Doppler shift to water velocity.
3.5. Input Voltage Measurement
All ADPs measure and record input supply voltage with each profile. This is used to
monitor battery capacity on autonomous deployments.
3.6. Serial Communication Protocol
All ADPs support RS232 and RS422 serial communication. RS232 is used for operation on
cable lengths to 100 m. RS422 is used for cable lengths to 1500 m.
The ADP can include a number of optional sensors to greatly expand its measurement
capabilities. Typical options are describe below.
4.1. Compass and 2-Axis Tilt Sensor
An internal compass and 2-axis tilt sensor allows the ADP to report velocity data in
Earth (East-North-Up) coordinates. The sensor has a built-in calibration feature to
compensate for magnetic distortion. The user can easily modify the compass installation
for up- or down-looking operation.
4.2. Internal Recording
A recorder is available for internal data storage on the Stand-Alone ADP. The recorder
is available in a range of capacities to meet almost any sampling requirement. For use as
a memory backup, an optional buffer mode can be enable that overwrites the oldest data
when the recorder is full.
4.3. Pressure Sensor (Strain Gage)
A strain gage pressure sensor can be installed in the ADP housing to measure deployment
depth and surface elevation (although it is not suitable for high-accuracy tide or stage
monitoring). The pressure sensor is available in a variety of ranges to operate in most
any environment.
4.4. Pressure Sensor (Paroscientific)
An interface to a user-supplied Paroscientific pressure sensor is available for
high-accuracy tide or river stage monitoring. The sensor is externally mounted and
connected with a special interface cable. Data collection is controlled by the ADP.
4.5. CTD (MicroCat)
An interface to the SeaBird MicroCat CTD is available. The sensor is externally mounted
and is connected with a special interface cable. Data collection is controlled by the ADP.
4.6. OBS (D&A)
An interface to the D&A OBS sensor is available. The sensor is externally mounted
and is connected with a special interface cable. Data collection is controlled by the ADP.
4.7. Custom Systems
In addition to the options listed here, we have constructed several custom ADPs
(including systems for full ocean depth deployment). Please
contact SonTek/YSI to find a
solution to your specialized application.
Details about this SonTek/YSI product can be found at:
