Signal acquisition and processing for autonomous Space Shuttle Cargo Bay acoustic measurements (NASA G-313)

Abstract

A narrowband trigonal acoustic transducer array and digital signal processing software are described in support of Space Shuttle Vibroacoustic experiment [NASA G-313]. The three co-planar, vibrationally isolated pressure-sensing microphones, the preamplifiers and the filters are designed to meet dynamic range and anti­ aliasing requirements for the digitization and processing of recorded flight data with one Hertz resolution within the 30-780 Hz baseband acoustic spectrum. The experiment is designed to operate in environments up to 160 dB SPL and provides modal recognition and directional information to identify resonances and localize high intensity sound sources within the ambient launch environment of the Space Shuttle Cargo Bay. Also included is a model of the empty Cargo Bay resonances and modal density calculations based on an adiabatic perturbation of a rigid, right circular cylindrical enclosure.