Potential Use of Broadband Acoustic Methods for Micronekton Classification

The Tropical Atlantic Observing System

“…Parameters of each model component (zooplankton, micronekton, exploited species and fisheries) are estimated using observations and data assimilation methods. A recent major development is the use of acoustic observations at multiple frequencies rather than a single one (usually 38 kHz) to reconstruct a proxy of micronekton biomass, since various species or groups of species can be distinguished by their specific responses in frequency space (Verma et al, 2017;Proud et al, 2018).…”

Estimating target strength and physical characteristics of gas-bearing mesopelagic fish from wideband in situ echoes using a viscous-elastic scattering model

“…The discrete narrowband frequency response information is usually not sufficiently detailed to separate acoustically similar species or different size groups of a single species (De Robertis et al, 2010). In comparison, broadband acoustic backscatter can provide frequency response over broad frequency intervals (Horne, 2000) that can potentially enhance acoustic identification and provide information on target properties such as morphology or size (Reeder et al, 2004;Kubilius et al, 2020), and has led to improved species discrimination (Stanton et al, 2010;Verma et al, 2017;Bassett et al, 2018). In addition, broadband acoustic backscatter signals can provide significantly increased range resolution compared to narrowband systems through matched filtering (Lavery et al, 2010;Stanton et al, 2010), thereby enabling TS measurements of single organisms in denser aggregations.…”

Performance of the matched filter in sonar systems having time variable gain

“…The noise includes the ambient noise of the underwater acoustic (UWA) channel as well as the receiver noise and is often modelled as being white and stationary [4, 5]. In sensing applications that use a known transmitted signal such as active sonars [6], a matched filter [2, 7, 8] maximises the SNR of the received signal in the presence of white, stationary noise. The impulse response of the matched filter for white stationary noise is simply the time‐reversed complex conjugate of the transmitted signal.…”