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. WEILAND
Pacific Northwest National Laboratory
Pacific States Marine Fisheries Commission*
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2. Background
Large-Scale Acoustic Telemetry Studies
Survival
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
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3. Introduction
JSATS System Verification
Error 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 hydrophones
Cables are properly connected
Hydrophones are functioning
System performance
Detection range
Detection efficiency of acoustic transmitter relative to background noise levels
(SNR)
December 12, 2013
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4. Processes Involved
Deployment
Survey
Hydrophone
Positions
Remote Test
Boat Operation
Error Analysis

5. Step 1: Survey Hydrophone Positions
Use standard survey equipment and techniques
Use surveyed benchmarks
Develop local controls
Measure horizontal and vertical deployment co-ordinates
Error analyses to verify tracking system performance in 3-dimensional
space
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6. Sensor location Survey
Modified hydrophone trolley
deployed with survey prism or RTKGPS receiver
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7. 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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8. Step 2: Remote Test Boat Operation
Remote controlled test boat
Twin trolling motors
Handheld Trimble GPS receiver with antenna
Deployed from dam and operated throughout detection area of array
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9. 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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10. Signal Detection and Processing
Remote boat operated throughout JSATS detection array
Beacons 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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11. 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-transmitter
Decoded 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 checking
Differences 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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12. Contour Plot of RMS Errors
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13. Computed Source Tag Location in 3D
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14. 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
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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.
December 12, 2013
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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.
December 12, 2013
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17. Acknowledgements
PNNL Staff
•
•
•
•
•
Christa Woodley
Jina Kim
James Hughes
Eric Fischer
Mike Greiner
PSMFC Staff
• Scott Carpenter
• George Batten
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