Technical Papers
FSI Riser Monitor and Data Logging Solution
Falmouth Scientific, Inc. has developed a compact Accelerometer Data Logger (ADL-536) which is a lightweight unit designed for long-term deployment studies. Deploying an array of these units, each equipped with its own high-accuracy clock, enables engineers to perform post processing analysis of VIV data and compare it to other data retrieved simultaneously through alternate means.
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FSI Acoustic Current Meter Provides Basis for Complete Hydrographic Monitoring Station
Falmouth Scientific, Inc. 2 Dimensional Acoustic Current Meter (2D-ACM) with optional CTD module offers an integrated platform in which to measure current, temperature, depth (tide), sound-velocity and salinity data. Using the phase-shift acoustic transit-time measurement technique, the 2D-ACM is an easy-to-use, high accuracy current meter, with no moving parts and a finite measurement volume. The phase-shift measurement principle allows the 2D-ACM to measure accurately, even in slow moving water and in water with no reflectors present (e.g. deep water). Internal compass and tilt sensors provide magnetic horizontal current vector direction, without the need for specific orientation of the current meter during deployment.
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A THREE DIMENSIONAL ACOUSTIC CURRENT METER (3D-ACM) update 1998
Brown, Fougere, and Kun.
Much has been learned about ocean dynamics by making measurements of ocean currents with traditional electromechanical type current meters. Flow distortion, large sample volumes, and impeller stalling, however; has limited the ability to use these instruments to make surface and wave deep ocean current measurements. New acoustic measurement techniques offer the potential to overcome these limitations. We present results of laboratory and field tests of a new, low power, acoustic phase shift current meter that transmits a 1 MHz acoustic signal along four paths and uses the along-the-path phase-shift measurement to resolve the three components of velocity.
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APPLICATIONS OF AN ACOUSTIC CURRENT MEASUREMENT TECHNIQUE
Fougere and Kun.
Falmouth Scientific Inc. has a full range of instruments for measuring direction, velocity and, in the case of waves, directional and point spectra. These are the 3D-ACM, the 3D-ACM Wave, and the 2D-ACM. All three instruments use Falmouth Scientific’s acoustic current measurement technique, which is based on measuring and comparing direct path acoustic phase shifts along multiple paths. The technique has proven to provide high accuracy current measurements and its hardware implementation requires very low power.
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A SIMPLE LOW-COST ACOUSTIC CURRENT METER (1992)
Brown
This paper, written and presented by Neil L. Brown at Oceanology in 1992, is the premise of all FSI acoustic current meter technology. Brown introduced an "experimental" acoustic current meter that would provide an alternative method to obtaining water current data.
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A NEW WAVE DIRECTION AND SPECTRUM MEASUREMENT TECHNIQUE
Kun, Fougere, and McComb
This paper describes a new measurement technique for wave spectrum and direction determination. The proposed technique combines acoustic current meter measurements with measurements from high precision pressure sensors. This technique allows the user to measure surface wave amplitude and direction, along with tide and tidal flow, from a single subsurface instrument. If the single instrument is combined with three additional "synchronized" pressure sensors, a complete six-wire-equivalent wave measurement can be attained.
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NEAR-REAL-TIME WAVE/CURRENT SYSTEM
Duchesney, Lassiter, and Phillips.
Falmouth Scientific, Inc. (FSI), Cataumet, Massachusetts, USA, and Geofix, Florida, USA have developed and installed a system to monitor ocean waves and other data from a remote location, using off-the-shelf components. The system monitors ocean currents, temperature, tides and waves. Monitored variables are measured in near-real-time with data sent via a hybrid radio telemetry link to shore. This data provides the local port authority with information to pass to ships navigating entrance to the port and to determine when it is safe for ships to enter or leave the port.
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