Abstract:

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].