Analysis Procedure for the Bottom Reflectivity Measurements Program.
NAVY UNDERWATER SOUND LAB NEW LONDON CONN
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A bottom reflectivity measurements program has been undertaken to determine the acoustic reflection coefficient for specific areas of ocean bottom as a function of incident angle and frequency. Pulsed single frequency signals are used for these measurements. Deep submerged source and receivers are oriented so that the direct and first-order bottom reflected pulses are separable in time and are not interfered with by the first-order surface reflected pulses. The travel time for the propagation of both the direct and bottom reflected pulses is accurately determined and recorded along with the desired acoustic signal. Since multiple receiving hydrophones are used, the data is also recorded in a multiplexed form. The requirement for efficient and expedient data analysis along with the complexity of the measurement has necessitated the writing of a digital computer program. This program computes the reflection coefficient and angle of incidence for each reception of data. the program corrects for difference in path length, taking into account the depth of the source, receivers, and water, the bottom slope, the velocity gradient and the recorded travel time for each reception. This memorandum, therefore, discusses 1 the acquisition and processing of the acoustical data 2 the definitions of the reflection coefficients 3 the theoretical relationships that properly determine the angle of reflection and reflection coefficient, which are governed by the geometric configuration of the source and receivers and 4 the computer program along with the input and output requirements.