Resolvable Target Distance 1.0

Organisms must be sufficiently separated to be resolved as individual targets for valid TS measurements to be obtained. Pulse duration (?Ya*z, s) and sound speed (c, m*s-1) affect the separation of echoes through the relationship:<br />Equation 18 [18]<br /><br />where ???a* R is the range between two resolvable targets (R1 and R2, m). Targets that are closer together cannot be separated (Simmonds and MacLennan 2005). Although frequency is not a factor in the calculation of acoustic resolution, higher frequencies can generally operate at shorter pulse durations (e.g., 0.2-0.3 ms), thus allowing the resolution of targets closer together.<br /><br />If data are collected at c = 1450 m*s-1,with ?Ya*z = 0.0003 s (??a*?Z0.3 ms), then<br /><br />eqn.18.1<br /><br />Targets must be separated by at least 21.8 cm to be individually resolvable.

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Keyword:	Acoustic,  Calculation,  Factor,  Frequencies,  Frequency,  Higher,  Maclennan,  Resolution,  Simmonds
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