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1
Where Are the Fish… Really???
Verifying the Accuracy of Acoustic Estimates of Fish Location
BISHES RAYAMAJHI, SHON A. ZIMMERMAN, DARIN J. ETHERINGTON*, TYLER D. MITCHELL*,ZHIQUN (DANIEL) DENG, TAO FU, GENE R. PLOSKEY, AND MARK A. WEILANDPacific Northwest National LaboratoryPacific States Marine Fisheries Commission*
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Background
Large-Scale Acoustic Telemetry StudiesSurvival
Route of passage
Behavior
Results are used to make structural and hydraulic changes to improve passage and survival of juvenile salmon out-migrating to the ocean
April 11, 2023 3
Introduction
JSATS System VerificationError analyses to verify tracking system performance in 3-dimensional space
Verify accuracy of target position
Calculate error in position through out dam forebay
Verify operation and installation JSATS cabled array hydrophonesCables are properly connected
Hydrophones are functioning
System performanceDetection range
Detection efficiency of acoustic transmitter relative to background noise levels (SNR)
Processes Involved
Survey Hydrophone
Positions
Remote Test Boat Operation
Error Analysis
Deployment
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Step 1: Survey Hydrophone Positions
Use standard survey equipment and techniques
Use surveyed benchmarks
Develop local controlsMeasure horizontal and vertical deployment co-ordinates
Error analyses to verify tracking system performance in 3-dimensional space
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Sensor location Survey
Modified hydrophone trolley deployed with survey prism or RTK-GPS receiver
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Survey Data Processing and Adjustment
Survey data processed in Trimble Business Center
Coordinates based on dam configuration and are adjusted to account for piernose slope, project azimuth, and hydrophone deployment depth
If position doesn’t lineup….resurvey
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Step 2: Remote Test Boat Operation
Remote controlled test boatTwin trolling motors
Handheld Trimble GPS receiver with antenna
Deployed from dam and operated throughout detection area of array
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Beacon and Acoustic Transmitters
Acoustic beacons and JSATS acoustic micro-transmitters are fixed below remote boat at known depths
Programmed to transmit coded signals every second
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Signal Detection and Processing
Remote boat operated throughout JSATS detection arrayBeacons or acoustic micro-transmitters suspended beneath boat
Tracking baseline within about 150 m of dam face
Transmitted signals are received by hydrophone array on dam
Acoustic signals are decoded on network of computers on dam
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Step 3: Error Analysis
• Differences in actual recorded GPS coordinates for each of the tags at known time are compared with the coordinates computed by the tracking algorithm to determine the positional errors.
3-D tracking of acoustic micro-transmitterDecoded signals are validated and filtered in MATLAB
An acoustic signal must be detected on at least four hydrophones with accurate time of arrive (TOA) data to estimate an acoustic transmitters location in 3-D (x, y, z)
Time of arrival differences (TOAD) of the valid signal detected on four hydrophones are used to solve for the 3-D location of the acoustic transmitter
Error checkingDifferences in actual recorded GPS coordinates for each acoustic transmitter at known time (from GPS receiver on mobile boat) are compared with the coordinates computed by the tracking algorithm to determine the positional error
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Contour Plot of RMS Errors
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Computed Source Tag Location in 3D
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Factors Affecting Location Accuracy
Error in hydrophone position accuracy
Surveying error
Cable management issue
Position of the source tag respective to the hydrophone locations
Signal to Noise Ratio (SNR) of the decoded signal
Velocity of sound in water
Error in GPS time synchronization
Multipath
April 11, 2023 15
Conclusion
This process ensures the JSATS cabled array system will provide accurate positional data for tagged fish location, movement, and dam-passage location.
Also, provides a cross check on any probable errors on hydrophone location survey points and cable hook up.
April 11, 2023 16
References
Deng, D.Z., Weiland, M.A., Fu, T.,Seim, T.A., LaMarche, B.L., Choi, E.Y., Carlson, T.J., and Eppard B.M. 2011. A Cabled Acoustic Telemetery System for Detecting and Tracking Juvenile Salmon: Part 2. Three-Dimensional Tracking and Passage Outcomes. Sensors, ISSN 424-8220.
Ehrenberg, J. E., and Steig, T. W. 2002. A method for estimating the ‘‘position accuracy’’ of acoustic fish tags. ICES Journal of Marine Science, 59: 140–149.
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Acknowledgements
PNNL Staff• Christa Woodley• Jina Kim• James Hughes• Eric Fischer• Mike Greiner
PSMFC Staff• Scott Carpenter• George Batten