A General Guide for Deriving Abundance Estimates from Hydroacoustic Data




















Near-field Distance Calculation

Near-field Distance

If using a transducer with frequency f=120 kHz, with half power beam angle of θ3dB = 7o and speed of sound c=1450 m•s-1, then we may compute first the wavelength λ:


second the wave number k:

wave number

third the active radius a (here given in cm):

active radius

and finally, near-field distance:

near-field distance


Data from within 1.7 m (2•Rnf) of the transducer face should not be included in the analysis.