Comparing two 38-kHz scientific echosounders
Comparing two 38-kHz scientific echosounders
复制标题
比较两个 38-kHz 科学回声测深仪
DOI：
10.1016/j.icesjms.2005.02.014
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发表时间：
2005
影响因子：
3.3
通讯作者：
L. Hufnagle
中科院分区：
文献类型：
--
作者：
J. Jech;K. Foote;D. Chu;L. Hufnagle
十多年来，EK 500一直是测量海洋鱼类种群的最先进的科学回声测深仪; EK 60是其继任者。在从EK 500到EK 60的过渡过程中，确保性能的可比性至关重要。为了量化各自的性能，使用相同的38 kHz、12°波束宽度、分裂波束换能器，通过外部校准和切换系统交替ping，通过标准目标方法串联校准每个回声测深仪。主要的测量包括分裂光束确定的角度和目标强度，轴上的灵敏度，以及在垂直于声轴的平面中的方向性，如用60 mm直径的铜球测量的。环境噪声，包括体积混响，也进行了测量。主要的比较包括时间序列和直方图的分裂光束确定的目标强度;各自的alongship和athwartship角确定的分裂光束系统;和预期的，在分裂光束确定和实验的目标强度值在垂直于声轴的平面的差异。还比较了离轴角值的平均绝对差。虽然这两种回声测深仪的性能大体相似，但存在系统差异。对于特定的校准测量，轴上目标强度的测量的时间变化对于EK 500是1dB的量级，对于EK 60是2dB的量级。使用EK 500进行测量的目标强度分布为正态分布，标准差为0.2-0.3 dB，而对于EK 60，目标强度分布明显偏斜，标准差变化超过0.3-0.5 dB。差异之间的分裂光束和物理角度的测量。EK 60的尺寸明显更大。两个回声测深仪之间的性能差异表明，新系统需要改进，这将有助于充分发挥其在科学工作中的潜力。
The EK500 has been the state-of-the-art scientific echosounder for surveying marine fish stocks for over a decade; the EK60 is its successor. Ensuring comparability in performance is vital during the transition from the EK500 to the EK60. To quantify the respective performances, each echosounder was calibrated in tandem by the standard-target method using the same 38-kHz, 12° beam width, split-beam transducer, with alternating pinging by means of an external triggering-and-switching system. The principal measurements comprised split-beam-determined angle and target strength, on-axis sensitivity, and directionality in the plane normal to the acoustic axis, as measured with a 60-mm-diameter copper sphere. Ambient noise, including volumetric reverberation, was also measured. Principal comparisons included those of the time-series and histograms of split-beam-determined target strength; respective alongship and athwartship angles as determined by the split-beam system; and as expected, difference in the split-beam-determined and experimental target-strength values in the plane normal to the acoustic axis. The mean absolute difference in off-axis angle values was also compared. While the performance of the two echosounders is generally similar, systematic differences exist. For the particular calibration measurements, the time variability in measurements of on-axis target strength was of the order of 1 dB for the EK500 and 2 dB for the EK60. The target-strength distribution for measurements made with the EK500 was normal, with standard deviation 0.2–0.3 dB, whereas for the EK60, the target-strength distribution was distinctly skewed and the standard deviation varied over 0.3–0.5 dB. Differences were found between the split-beam and physical-angle measurements. They were noticeably larger in the case of the EK60. Differences in performance between the two echosounders suggest refinements to the new system that will help realize its full potential in scientific work.