Frank M. Caimi

Smart structures and fiber optic sensor research at Florida Institute of Technology: 1990

This paper discusses several novel concepts being investigated in the Center for Fiberoptic Sensor Systems and Smart Structures at Florida Institute of Technology associated with fiberoptic sensors, actuators and processor technology, and efforts to integrate these components into distributed smart systems. Projects include: a polarimetric sensor with active phase tracking test set, a combination polarimetric/two mode sensor, an N-mode sensor with neural processor, damage assessment using embedded fiber-optic arrays and a neural processor, a pulsed interferometric sensor, neural network-processed polarimetric sensor signals, and optically-energized shape-memory alloy actuators.

Pattern classification approach to underwater acoustic communications based on the Wigner-Ville distribution

This paper describes an approach and preliminary results associated with the use of pattern recognition techniques to identify transmitted information (symbols) in a temporally variant acoustic channel. The method allows the observation of the transmitted signal simultaneously in both time and frequency space and does not necessary rely on the application of adaptive algorithms for reception. The observation of the symbol energy from the Wigner-Ville Distribution as 2D pattern can allow the determination of channel characteristics over short symbol sequences and can provide a means for symbol detection. For the QPSK modulation used, wavelet filtering provides a basis for noise reduction and WVD cross tem separation. The process used for development of the pattern classifier is described and results are presented for shallow water acoustic data on a limited data set.

Ocean acoustic impulse response measurement and characterization for ACOMMS performance prediction

Characterizing shallow water impulse response (SWIRM) is desirable when developing acoustic communications systems for the extremely reverberant ocean acoustic environment. The impulse response (IR) quantifies the sum of acoustic energy at a receiver for energy radiated from a source through diverse paths including direct paths, surface reflections, bottom reflections, and refractive paths between the source and receiver. The relatively shallow depths (less than 100 meters) and relatively long range (greater than 10 times the depth) of shallow water environment ensures that a significant portion of the acoustic energy has travelled through multiple paths off the ocean surface and bottom before reaching the receiver. Our research methodology characterized shallow water IRs using ocean experiments and computer simulations. We utilized acoustic hardware, data acquisition, analysis of ocean acoustic experimental data, adaptation of systems identification (SID) techniques for shallow water acoustic communications, development of an equalizer using SID (EQSID) as a digital communications model, and the testing of the EQSID model using noise and a Markov process for generating IRs. The analysis also utilized the systems integration of the EQSID communications model with the MMPE acoustic propagation model, into software tools collectively called Harbor Branch Oceanographic Acoustic Toolbox (HBOAT). HBOAT is continually evolving but includes the programs used in our SWIRM research for characterizing simulated shallow water IRs and using the IR characterization to predict the performance of the EQSID digital communications model.

Design and performance characterization of simultaneous reflectance and surface-mapping laser scanner for application in underwater inspection

In this paper we describe an approach and present results from a recently developed system that produces video-rate, 3D maps of the image space using a scanning laser configuration and a patented micro-channel plate intensified detector. The scene is viewed from a separate location to provide depth information via triangulation. The detector provides an estimate of position of the apparent landing spot of the laser beam for each scan angle from which a depth estimate is calculated. The system is designed to scan an approximate 15 X 15 degree field-of-view at distances from 1.5 to 2.5 meters with a resolution of 1.5 cm at rates of 10 - 30 full images per second, and can accommodate range gating to reduce scattered light interference.