Effects of fast Fourier transform window size on the target strength spectra measurements of Japanese anchovy (Engraulis japonicus) using linear frequency modulated signals

IF 2.2 2区农林科学 Q2 FISHERIES

Fisheries Research Pub Date : 2025-01-01 DOI:10.1016/j.fishres.2025.107267

Jing Liu , Tomohito Imaizumi , Kazuo Amakasu

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引用次数: 0

Abstract

The signal processing in broadband echosounders differs from that in conventional narrowband echosounders, particularly in the requirement of fast Fourier transform (FFT) with a reasonable window size (WS) to calculate accurate TS spectra from pulse-compressed echo waveforms. However, the reasonable FFT WS for the pulse-compressed echo waveforms has not been sufficiently and quantitatively investigated. This study aimed to investigate the effects of FFT WS on the TS spectra measurement of Japanese anchovy (Engraulis japonicus) through simulation and in situ experiments. First, the pulse-compressed echo waveforms of calibration spheres were simulated, then the effects of FFT WS on TS spectra measurement were investigated and compared with the results in the tank experiment. Then, the pulse-compressed echo waveforms of Japanese anchovy were simulated, the effects of FFT WS on TS spectra measurement were investigated based on the simulated echo waveforms, and finally the reasonable FFT WS of anchovy was verified with in situ data. The results demonstrated that the measured TS spectra with a narrow FFT WS of 0.05 m differed significantly from other cases (FFT WSs of 0.2, 0.4, and 0.8 m). As the FFT WS increased, the measured TS spectra became more similar and stable. Considering the exclusion of pulse-compressed echo waveforms from other targets, a 0.2-m FFT WS was deemed to be reasonable for the TS spectra measurement of Japanese anchovy.

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来源期刊

Fisheries Research 农林科学-渔业

CiteScore

4.50

自引率

16.70%

发文量

294

审稿时长

15 weeks

期刊介绍： This journal provides an international forum for the publication of papers in the areas of fisheries science, fishing technology, fisheries management and relevant socio-economics. The scope covers fisheries in salt, brackish and freshwater systems, and all aspects of associated ecology, environmental aspects of fisheries, and economics. Both theoretical and practical papers are acceptable, including laboratory and field experimental studies relevant to fisheries. Papers on the conservation of exploitable living resources are welcome. Review and Viewpoint articles are also published. As the specified areas inevitably impinge on and interrelate with each other, the approach of the journal is multidisciplinary, and authors are encouraged to emphasise the relevance of their own work to that of other disciplines. The journal is intended for fisheries scientists, biological oceanographers, gear technologists, economists, managers, administrators, policy makers and legislators.