Comparison of measured and modelled transmission loss in emerald basin

Brian H. Maranda, Nicole E. Collison

Abstract


The measured and modeled transmission loss (TL) in the Emerald Basin was investigated. An acoustic projector was towed at 50-m depth by the research ship CFAV Quest. The transmitted signal consisted of 11 continuous-wave (CW) tones spaced 100 Hz apart from 1010 to 2010 Hz. The sonobuoy receivers were set for a depth of either 60 m or 120 m, and the received acoustic signals were relayed to the ship over a radio-frequency (RF) telemetry link. A sound-speed profile from the day of the experiment shows a pronounced duct with an axis close to the source depth. The data collected during the sea trial were later processed to yield estimates of the transmission loss through the equation TL = SL-SPL, where SL is the projector source level and SPL was the sound pressure level at the receiver. The curves at the different frequencies cluster quite closely together, but the TL was markedly less for the 60-m receiver than for the 120-m receiver. It was observed that the TL curves for the 60-m receiver display the low loss.

Keywords


Acoustic receivers; Acoustics; Radio receivers; Ships; Sonoluminescence; Thermoluminescence; Acoustic; Acoustic signals; Continuous; Different frequencies; Low losses; Sea trials; Sound pressure levels; Source levels; Speed profiles; Transmission losses; Transmitted signals

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