Calibrating Two Scientific Echo Sounders
Abstract
The Simrad EK500 has been the state-of-the-art scientific echo sounder for surveying marine fish stocks; the EK60 is its successor. Both echo sounders have been calibrated with the same 38-kHz, 12-deg-beamwidth, split-beam transducer by the standard-target method at the acoustic calibration facility on Iselin Dock at the Woods Hole Oceanographic Institution. The principal measurements were on-axis target strengths and the two-way directivity patterns of the main lobe, measured with a 60-mm-diameter copper sphere. For each echo sounder, the respective split-beam-determined and directly measured angles of the standard target are compared. The directivity pattern as approximated by Simrad firmware is fit to the experimental data, and both the splitbeam- determined and newly compensated values of target strength are expressed through histograms. Target strength distributions are compared for two spheres: a 60-mm-diameter aluminum and 38.1-mm-diameter tungsten carbide with 6% cobalt binder spheres.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 2003
- Accession Number
- ADA497845
Entities
People
- Dezhang Chu
- J. Michael Jech
- Kenneth G. Foote
- Lawrence C. Hufnagle Jr.
- Terence R. Hammar
Organizations
- Woods Hole Oceanographic Institution