Calibration of the matched filter beam output from the triplet portion of the Five Octave Research Array

Abstract

The Five Octave Research Array (FORA) [K.M. Becker and J. R. Preston, Proceedings Oceans 2003, 2607-2610] includes a triplet section in which the elements are three omnidirectional sensors. The elements can be combined as a standard linear array to produce conical beam patterns, or the triplets can be used to form directional beams that allow for “left-right” discrimination. The beam output can then be matched filtered to produce high-temporal-resolution beams over the full 360° azimuth, and identify scattering features in reverberation data. To extract scattering strengths, the calibration of the beams and the matched filter output must be known accurately. Here we look at results from the 2013 Target and Reverberation Experiment (TREX13), where data were received on the FORA array, then beamformed and matched filtered by various procedures that had different normalizations. The broadside beam and several natural beams of the linear array can readily be calibrated against a simple “exact” procedure. No s...