Sesame I: Assessment of enhancement in the minimum detectable level using fluctuation‐sensitive processors

Minimum detectable level (MDL) measurements were made using a vertical array in a shallow‐water environment during the Sesame‐I experiment held in Aug.–Sept. 1995. A tapered source comb of four frequencies, 150, 154, 158, and 162 Hz, were broadcast at different levels and two depths at a range of 22 nmi. The MDL data were evaluated in terms of signal excess and standard deviation using the average‐power processor and fluctuation‐sensitive processors. It was found that the fluctuation‐sensitive processors provided a signal enhancement of up to 7 dB in cases when the average‐power processor’s signal excess was zero. In terms of standard deviation, the fluctuation sensitive processors could discern a signal buried deeper in the background noise (where the standard deviation of the noise levels were typically 5 to 6 dB) than could the average power processor. It was determined that fluctuation‐sensitive processors could provide an enhancement of the MDL over the average‐power processor. The methods of analysis will be discussed and the comparative performance of the algorithms will be presented. [Work supported by ONR and NRL].